ESE's works engine tuner

[husaberg]

Around 50 years ago when EFI wasn't even a dot on the horizon, Irving suggested constant flow injection via the big end. Hilborn injection was pretty much state of the art then with Lucas and Bosch just getting progress on mechanical injecion.
It's still a viable scheme - just vary the pump output to suit.

The 1930's Velocette GTP had a Autolube set up. Not sure exactly how it worked.
Irving referred to the bike as Generally Tight Piston:lol:

Velocette GTP
Villiers had one even earlier.
http://classic-motorbikes.net/images/gallery/10679.jpghttp://www.users.globalnet.co.uk/~pattle/nacc/arc0596k.jpg
OF course DKW had steel reeds years before Yamaha was making bikes as well.



Actually would the GP125 be set up like this as standard?



No ....
PS What set up was the oiling on the GP125 std Rob? just a metered suply into the intake stream?

[Flettner]

Grumph, yes if you want to inject into the intake constant flow injection would be the way to go ( like a carb ). I made a version of this previous ( not electronic ), sort of worked. I ended up realising that an electronic variable pump was the way to go ( constant flow ) but in the mean time thought I would have a go at standard ( ish ) EFI in the interim. As it has turned out this is the way forward ( port injection ) not inlet injection.
I have pointed this out earlier that the pulsing of the injectors at below 1/3 ( approx ) throttle the injectors are on for a very short time. So within the intake phase only a small part of that flow has fuel the rest is just air. The crank case is not a 100% pump so some volume is trapped behind each cycle. The small parcel of fuel MAY NOT be fully transfered to the cylinder each cycle ( mixture strength not constant ) The engine will run and run apparently ( to the ear ) clean but no real power. Transfer injection allows for the full fuel dump each cycle to be transfered to the cylinder nothing left over to affect the next cycle. I worried about the oiling but on inspection it appeared all was oily.
As it happens the F9 is in bits now, a 1973 gearbox bearing let me down. Last trail ride there was some squealing ( from the engine not rider this time ). Sounded like a gearbox bearing, worse on decel and sure enough main input shaft bearing behind the clutch. Engine itself is still in good condition ( and oily ).
I mix at 40 to 1 Micro T with a little castor, injectors and general fuel system seems to be fine with this mixture. Although my fuel burn is approx 1.8 / 1.9 to that of petrol.
DO NOT run dead loss electrical system. Run a suitable aulternator, it doesn't take much voltage loss to affect the injector on time ( it will run lean as voltage drops ). Small high output aulternators are available.
You will spend hours and hours trying to tune something that will never tune. The goal posts are always changing! You NEED constant voltage. I'm sure I've written this before on this forum but I had a regulator that would randomly cut out ( get hot ) and the computer would have to run on battery power for a while until the regulator cooled and decided to work again. The engine was constantly going from lean to rich ( I had it set rich to try and compensate for the lean times ) UN TUNABLE! I ended up running a small digital volt meter for a while after this episode, didn't trust the new regulator!
Just relaying my experiences so others don't fall in the same traps.

[Grumph]

Irving's idea was injection via the big end - ie, fuel under pressure fed into the crank and exiting via the big end slots, cooling the bearing as it passed - and incidentally being well vaporised in the process.
Interesting comments re electrical supply - and all true in my experience too.
Some years back I was asked advice on small alternators by a local engineering firm doing a small 4 stroke aero engine. They had space and weight probs and thought a bike alternator could help. Sadly I couldn't point to one small enough for them. The internet and advances in rare earth magnets have made available just what they needed.
One of the biggest probs Rob Selby had on the Britten motor was packaging the alternator securely. He was never really happy with it.

[speedpro]

I mix at 40 to 1 Micro T with a little castor, injectors and general fuel system seems to be fine with this mixture. Although my fuel burn is approx 1.8 / 1.9 to that of petrol.

So you are running 40:1 but nearly 2X the fuel compared to if you were running normal petrol. Effectively then you are running about 20:1. That much oil per engine revolution anyway.

[husaberg]

Although (i think) 6 volt and i don't think 3 phase the CB100 rotor stator is tiny 75mm ish with a bit of work....Mabye the last ones in the UK in the 80's were 12V cb100n
<img src="http://images.cmsnl.com/img/partslists/honda-cb100-super-sport-k2-usa-l-crankcase-cover-ac-generator_bigma000138e04_73bf.gif" width="240px"/>
The Cb175 i think is 12 volt and 3 phase and also smallish.
<img src="http://i.ebayimg.com/00/s/NDgwWDY0MA==/$T2eC16ZHJHIE9nyseyvCBQ3iMZ3uHw~~60_3.JPG" width="340px"/>
I guess a lot of the Scooters have decent 12v set up these days.
but how much does it need i guess it is at least 3 amps on the pump?

The Aprilia RSA sure looks looks tiny.........

PS thanks to the Dutch Stig i now have a Honda CVT designed for a 2 Stroke and Special Honda Crank and a Very ugly scooter..
2.23-1.22 ratio range.
Built for a 9 hp bike so i hope Honda have over-engineered it a bit:niceone:

[Frits Overmars]

Around 50 years ago when EFI wasn't even a dot on the horizon, Irving suggested constant flow injection via the big end.... just vary the pump output to suit.I had the same plan, though not for the same reason.
I was working on 6.5 cc MB40-engines for F3D model airplanes. The fuel tank position in the fuselage of these little planes is critical as they pull a lot of g's in corners (we don't know how many g's exactly because the g-sensor's maximum is 'only' 36 g). When the fuel level drops, the mixture strength changes; not nice.
My plan was to replace the cruel fuel system (fuel in a bladder with exhaust pipe pressure squeezing the bladder from the outside) with a pump injection. It had to be constant flow because I could not find injectors capable of delivering the required tiny amounts of fuel to a 36,000 rpm engine.
I found suitable pumps here: http://shopping.netsuite.com/app/site/site.nl?alias=flightworks (http://shopping.netsuite.com/app/site/site.nl?alias=flightworks) . These pumps are designed for model jet turbines but the snag is that the DC pump motors cannot run slowly enough for a small piston engine; the pump would drown the engine at the first start attempt.
Stepper motors were considered but the problem with those would be that when rapid pump acceleration is required, the stepper motor may miss steps and the engine will lean out without any feedback other than a complete cut-out because of a molten glow plug.
Pulse width modulation for the original DC pump motor was considered next, but then other things took priority so the idea never got finished.

[speedpro]

Honda CRF(?) on my MB

[diesel pig]

Honda CRF(?) on my MB

That looks sexy, Anybody know whats that off for shore? Would make it alot easier looking on E-bay or trademe;)

[Grumph]

I had the same plan, though not for the same reason.
I was working on 6.5 cc MB40-engines for F3D model airplanes. The fuel tank position in the fuselage of these little planes is critical as they pull a lot of g's in corners (we don't know how many g's exactly because the g-sensor's maximum is 'only' 36 g). When the fuel level drops, the mixture strength changes; not nice.
My plan was to replace the cruel fuel system (fuel in a bladder with exhaust pipe pressure squeezing the bladder from the outside) with a pump injection. It had to be constant flow because I could not find injectors capable of delivering the required tiny amounts of fuel to a 36,000 rpm engine.
I found suitable pumps here: http://shopping.netsuite.com/app/site/site.nl?alias=flightworks (http://shopping.netsuite.com/app/site/site.nl?alias=flightworks) . These pumps are designed for model jet turbines but the snag is that the DC pump motors cannot run slowly enough for a small piston engine; the pump would drown the engine at the first start attempt.
Stepper motors were considered but the problem with those would be that when rapid pump acceleration is required, the stepper motor may miss steps and the engine will lean out without any feedback other than a complete cut-out because of a molten glow plug.
Pulse width modulation for the original DC pump motor was considered next, but then other things took priority so the idea never got finished.

Impressively complicated....beyond me. Hilborn mechanical pumps with what's pretty much a linear delivery with revs work reasonably well. Don't know about very high revs though - probably cavitate. Most of the speedway applications I've been involved with use a reduction drive to get the pump revs and hence delivery into the right range for the motor.

[Ocean1]

Around 50 years ago when EFI wasn't even a dot on the horizon, Irving suggested constant flow injection via the big end. Hilborn injection was pretty much state of the art then with Lucas and Bosch just getting progress on mechanical injecion.
It's still a viable scheme - just vary the pump output to suit.

Most early aviation radials didn't have oil pumps, the engine WAS a centrifigal pump. Fueling via the bigend would have the same effect, in fact you'd have to experiment to find the (minimal?) supply pressure required across the rev range and map accordingly. I can see the required pump pressures being quite low.

[husaberg]

I had the same plan, though not for the same reason.
I was working on 6.5 cc MB40-engines for F3D model airplanes. The fuel tank position in the fuselage of these little planes is critical as they pull a lot of g's in corners (we don't know how many g's exactly because the g-sensor's maximum is 'only' 36 g). When the fuel level drops, the mixture strength changes; not nice.
My plan was to replace the cruel fuel system (fuel in a bladder with exhaust pipe pressure squeezing the bladder from the outside) with a pump injection. It had to be constant flow because I could not find injectors capable of delivering the required tiny amounts of fuel to a 36,000 rpm engine.
I found suitable pumps here: http://shopping.netsuite.com/app/site/site.nl?alias=flightworks (http://shopping.netsuite.com/app/site/site.nl?alias=flightworks) . These pumps are designed for model jet turbines but the snag is that the DC pump motors cannot run slowly enough for a small piston engine; the pump would drown the engine at the first start attempt.
Stepper motors were considered but the problem with those would be that when rapid pump acceleration is required, the stepper motor may miss steps and the engine will lean out without any feedback other than a complete cut-out because of a molten glow plug.
Pulse width modulation for the original DC pump motor was considered next, but then other things took priority so the idea never got finished.

When you Say "exhaust squeezing" does that mean the exhaust pressurises the tank bladder?

Honda CRF(?) on my MB

Wob got me one the same but what is the output?
I had an idea they were from the late Cr125 to power the ignition and the Carb gublins, I think Dave has one too?
I guess the Fuel injected MX bikes have a higher power one for the aditional electrics

[F5 Dave]

That looks sexy, Anybody know whats that off for shore? Would make it alot easier looking on E-bay or trademe;)

Def not CRF, they are poxy 4 strokes & should not be used, besides they are well different.

CR250 or CR125. Think about '07 vintage. there are after market lighting kit high output stators, but I opted for a stator flywheel combo.
[edit[] I bought an 02. Avoid 03/04 125 as only 4 pole

You'll need the regulator too, or just find a small one like RG50 & a hua capacitor tied together.

[teriks]

When you Say "exhaust squeezing" does that mean the exhaust pressurises the tank bladder?
I'm not Frits, but that's how it's done.
The tank have a hard outer shell, and a soft bladder inside.
Fuel goes in the soft bladder, exhaust pressure in the space between the bladder and the outer shell.

[Grumph]

I'm not Frits, but that's how it's done.
The tank have a hard outer shell, and a soft bladder inside.
Fuel goes in the soft bladder, exhaust pressure in the space between the bladder and the outer shell.

I've seen a similar setup on a roadrace chair. Small air reservoir, regulator and the tank is pressurised to feed carbs.
Pump up the reservoir at a service station on the way to the track and it did a days racing comfortably.
If you're keen, you could use frame tubes as the reservoir.

[Flettner]

http://i1056.photobucket.com/albums/t380/uniflow/IMG_0861_zps154814c0.jpg
http://i1056.photobucket.com/albums/t380/uniflow/IMG_0860_zpsd2a7c1e5.jpg

I have four of them, two new, two second hand. These produce enough current to run EFI.
I only need one for the next project and perhaps one spare.

[Flettner]

This was my E90 pump, inside is a Honda 50 ( fourstroke ) oil pump element running in an alloy bronze housing. I ran this off the outside of the flywheel with a small tooth belt. Fuel was regulated by a needle on the throttle slide. More revs, more fuel pressure.

http://i1056.photobucket.com/albums/t380/uniflow/IMG_0859_zpsc19871bc.jpg
http://i1056.photobucket.com/albums/t380/uniflow/IMG_0858_zps67d6c92e.jpg

[husaberg]

The wiring diagram thread
http://www.bikechatforums.com/viewtopic.php?p=2322761#2322761

Many service manuals
http://www.carlsalter.com/motorcycle-manuals.asp

One thing to remember TZ is to start a bike with CVT it will need a crankshaft kick or a electric atarter:niceone:

[Flettner]

husaberg, whats happening? are you sending me some patterns to look at? Send them depot only Hamilton and I'll pick them up. We are rural.

[husaberg]

husaberg, whats happening? are you sending me some patterns to look at? Send them depot only Hamilton and I'll pick them up. We are rural.

I was planning on flying up with them.... so i could see how it all works.
The misses has ok'd it and all.
Just the logistics to sort. When it suits you and the foundowndry.

[Frits Overmars]

Impressively complicated....beyond me. Hilborn mechanical pumps with what's pretty much a linear delivery with revs work reasonably well.Think small, Grumph. That Hilborn pump is probably heavier than the airplane...

[TZ350]

What set up was the oiling on the GP125 std Rob? just a metered supply into the intake stream?

Yes ... But there is no pump drive now so I might make a metered suck supply that drips into the intake for some supplementary oiling.

[Forgi]

Hi everybody !

Wobbly!

I put some nozzle into the exhaust duct to check out where is the best point to narrow it. So far I didn't have the chance to test and measure, but once I get results I'll let you know. By the way didn't you have similar tests? Here you can see three variations.
The first was made the way that the duct narrows as soon as possible and keeps the shape all along, so the area is 75% with 25 mm behind the port and it stays the same through the entire length of the duct which is 65 mm. The second is almost the same as the first, the only difference is that at the end of the duct the area expands to 100%. The third one is tapering all along and at the end of the duct the area will be 75%. You can see some pictures to show how I've resolved the abovementions.

http://kepfeltoltes.hu/130407/DSC01238_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01239_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01240_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01241_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01242_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01243_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01244_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01245_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01246_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01247_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01248_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01249_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01250_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01251_www.kepfeltoltes.hu_.jpg

http://kepfeltoltes.hu/130407/DSC01253_www.kepfeltoltes.hu_.jpg

[wobbly]

I havnt tested variations like yours - only reducing the duct as far back as it is possible to weld, and having the 75% at the manifold face.
Then expansion out to 100%.
A CNC transition from oval to round made more power than the stepped face into a round spigot did.
Only point I would add is that you should also look into grinding the aux ducts all the way along the length to the pipe.
This helps promote the blowdown flow when the piston has only partially opened the top 1/2 of the Exhaust.
Edit - once you have done the nozzle test have a go at modernising the ports as well.

[Flettner]

http://i1056.photobucket.com/albums/t380/uniflow/IMG_0866_zps8964ffd6.jpg
http://i1056.photobucket.com/albums/t380/uniflow/IMG_0865_zps55ddea47.jpg

TZ, is this what you had in mind?

[TZ350]

TZ, is this what you had in mind?

Yes that looks excellent, I will be able to make a top hat cover for the plenum with the control cables running through it for the ball valve.

[Frits Overmars]

You'd better copy Flettners rotary valve cover, TZ. Then you get it all: an extremely short inlet tract, variable valve closure timing and ride by (bowden) wire.281189

[wobbly]

I was thinking about a conversation we had a while ago Neil about using the variable timing rotary valve slider as a throttle,as well as its normal function as a port area control.
This then makes the ball valve redundant, but of course keeps the short bell intake.
Will make Frits happy as well due to making it even simpler.
Seems like a good time to try the idea on the old Kawasaki, but dont work on this till you have finish CNCing my TZ400 tripple clamps.

[Frits Overmars]

I was thinking about a conversation we had a while ago Neil about using the variable timing rotary valve slider as a throttle,as well as its normal function as a port area control. This then makes the ball valve redundant, but of course keeps the short bell intake. Will make Frits happy as well due to making it even simpler.You too, Wob? I had the same conversation with Neil a couple of months ago: http://www.pit-lane.biz/t3173p810-gp125-all-that-you-wanted-to-know-on-aprilia-rsa-125-and-more-by-mr-jan-thiel-and-mr-frits-overmars-part-2#139860
Now he has no option but to build it :msn-wink:.

[F5 Dave]

Well continuing my mantra (when I am smart enough to follow it, or can be bothered) of testing obvious improvements. I'd found this before but decided last time I'd tested it I had a different pipe, porting & slightly different headshape.

So time to test a rinkydinky R7376 plug instead of my old B9EGV.

No diff. Well maybe teeny bit slightly worse, but in the realms of 2 different runs.

I hate the dyno. Can't imagine how powerful I would imagine the bike would be without using it. Maybe the placebo effect would make me faster.:lol:

[Flettner]

Frits, I don't think Rob's computer will " fly by wire " the throttle. The Link will.
Best to just copy the F9 for the minute, it works.
I'm fitting this fly by wire throttle / variable valve cover to my new engine the 360 rotary valve but it might be a while yet, still making patterns for the cases. It will be using the Link Storm computer.

[Frits Overmars]

Frits, I don't think Rob's computer will " fly by wire " the throttle.Agreed; that is why I wrote 'by bowden wire' , controlled by the computer in the saddle. We can't call him dumb, can we?


Best to just copy the F9 for the minute, it works.So do four-strokes, I'm told; not a reason to copy them though, eh? :msn-wink:


I'm fitting this fly by wire throttle / variable valve cover to my new engineI am looking forward to it.
By the way, the 990 cc three-cylinder Aprilia (with a little help and a stiff bill from Cosworth) was the first MotoGP bike with computer-controlled throttle operation which caused the riders 'some problems'. As one of them said fly-by-wire, the technical director corrected him: 'It is not a plane so you should call it ride-by-wire'.
Rider reply: 'you ride it, then you'll see how high you fly!'

[Forgi]

I havnt tested variations like yours - only reducing the duct as far back as it is possible to weld, and having the 75% at the manifold face.
Then expansion out to 100%.
A CNC transition from oval to round made more power than the stepped face into a round spigot did.
Only point I would add is that you should also look into grinding the aux ducts all the way along the length to the pipe.
This helps promote the blowdown flow when the piston has only partially opened the top 1/2 of the Exhaust.
Edit - once you have done the nozzle test have a go at modernising the ports as well.

Yes, I made such a nozzle which is on your drawing. This is the same as the third variation of mine, where the area of the nozzle is 75% only at the end of the duct.

http://kepfeltoltes.hu/130411/w1_www.kepfeltoltes.hu_.jpg


Regretfully I can't do the subsequent modernization of the cylinder.
It's true that the bottom of the main exhaust port became too wide.
Concerning the aux ports' shape I make them rectangular, cos it is easier to calculate with them and it is also easier to prepare them as they are handmade. The latest version is the same as you draw. The ports of the Gp KTM 125 are also rectangular, aren't they?

Concerning the A transfer ports we can't modify them because of the pharameters of the cylinder and the block. The best you can do is this:

http://kepfeltoltes.hu/130411/w2_www.kepfeltoltes.hu_.jpg

This way although the TA of the ports decreases, the scavenging will be better.

[wobbly]

If you can reshape the A transfer as you have drawn, then this will allow you to drop the main port, as well as the Aux, with more timing difference between them.
This will then give more blowdown capability, with less timing, bumping up mid power and overev.
A win, win.
The Aux ports flow the most when just opening, thus need to be the widest at the top. This is due to there being the greatest pressure delta across them as they crack open.
Transfers are the opposite, thus reducing the interaction of the Aux and transfers by reducing the Aux width at the bottom helps power everywhere.

[Flettner]

I am looking forward to it.
By the way, the 990 cc three-cylinder Aprilia (with a little help and a stiff bill from Cosworth) was the first MotoGP bike with computer-controlled throttle operation which caused the riders 'some problems'. As one of them said fly-by-wire, the technical director corrected him: 'It is not a plane so you should call it ride-by-wire'.
Rider reply: 'you ride it, then you'll see how high you fly!'

:lol: Perhaps. Yes the 360 may end up computer "assisted" rather than full fly by wire but I want to have a go at it. Yes the "timing throttle" could be run by cable just another thing to concentrate on when riding, not too much throttle too early. I'm interested in this technology to help control wheel spin / hookup on a dirt bike. Try and get the twostroke a little more like the fourstrokes on corner exit. There is even the possibility if injecting straight into the cylinder to miss an injection every cycle or other cycle ( no wasted fuel ) at low rpm say up to 1/3 throttle to get better bite, fire every second or third shot ( like a fourstroke ).
The issue will be blending this back to full injection with out a lump in the power?
I too am looking forward to it.

[Frits Overmars]

...the "timing throttle" could be run by cable just another thing to concentrate on when ridingI did not intend to say that this should be your approach; only a way for TZ350 to get going. Of course if you have a computer capable of handling ignition, injection, disc timing and throttle opening, you should free the rider from these tasks.


... not too much throttle too early. I'm interested in this technology to help control wheel spin / hookup on a dirt bike. Try and get the twostroke a little more like the fourstrokes on corner exit.Making throttle response linear can be a big improvement. In the Aprilias it was done by linking ignition timing and power valve and power jet settings to rpm, throttle position and gear selector position, striving for a linear relation between throttle opening and rear wheel torque.


There is even the possibility if injecting straight into the cylinder to miss an injection every cycle or other cycle ( no wasted fuel ) at low rpm say up to 1/3 throttle to get better bite, fire every second or third shot ( like a fourstroke ).

That may be an insurmountable enterprise. If you cut one in two combustions in a two-stroke, the gas dynamics in the pipe will collapse and you will lose far more than 50% of engine power.


The issue will be blending this back to full injection with out a lump in the power?That will be issue number two then.

[husaberg]

That may be an insurmountable enterprise. If you cut one in two combustions in a two-stroke, the gas dynamics in the pipe will collapse and you will lose far more than 50% of engine power.
.

When i seen Neil's response, (we had discussed it before) My take is to skip far less ignition cycles and fueling cyles. Say 6000rpm is 100 times per second. I think skipping only just a few would be enough, Maybe even just having a few wrongly timed where they make little contribution to the output.
My diesel (Husaberg) has a simple Duel ignition curve, (Maybe just the base advance and the limiter i don't know what it does actually) the results of changing between the curves are never the less quite dramatic.

But i take you point re the dynamics. But where i guess Neil intends to alter the Gas Dynamics, are well...... Not to.... Dnyamic anyway.

On another subject Frits your 50cc project what layout do you intend to use regarding the primary and the reductions. I are trying to get my head arround one with a CVT but there must be a simpler solution, Than what i have schemed which is basically a scooter setup.
To fit in a disc, i are also either mounting the ignition outboard (which i hate) or driving it off a counterbalancer, neither which i like.
I see advantages in driving the CVT after an initial primary reduction as i think i can get away with less modification to a std CVT setup

Lastly the RSW125 side profile drawing in the Frits files. Is it acculturate enough to scale crankcase dimensions off? or is it a illustration?
I have collected an number of Pictures but intriguingly there no drawings of the Crankcase yet plenty of the Cylinders available.
I recall you saying 1mm (or was it 2mm) was the miniumun to run to counter drag for the Crankwheel-crankcase clearance i assume this is what the Aprilias ran?

[Frits Overmars]

My take is to skip far less ignition cycles and fueling cyles. Say 6000rpm is 100 times per second. I think skipping only just a few would be enough, Maybe even just having a few wrongly timed where they make little contribution to the output.In theory Neils plan to skip injection events instead of sparks is better for fuel consumption and for the environment. But as I said above, it's not gonna be simple.
Your take may be the way to go: skipping for example 1 in 10 cycles, then going to 1 in 12, then to 1 in 14, 1 in 16, etc. That is fairly easy to program.
Honda's quickshifter used to cut engine power not by omitting sparks but by heavily retarding them; by 50° if I remember correctly. But I would not recommend that as a means of reducing normal riding power, as it would heat up the engine real quick.

On another subject Frits your 50cc project what layout do you intend to use regarding the primary and the reductions. I are trying to get my head arround one with a CVT but there must be a simpler solution, Than what i have schemed which is basically a scooter setup.I think you can't get much simpler than a scooter setup. But I would add an outrigger bearing to the CVT side of the crankshaft. Seeing how much that shaft bends when you just push at the V-belt, will make you shiver.


To fit in a disc, i are also either mounting the ignition outboard (which i hate) or driving it off a counterbalancer, neither which i like.You should get the ignition signal directly from the crankshaft; you could use the RSA125-setup with a sensor looking at a notch in the circumference of one of the crank webs. You can then run the generator from any place that is convenient.
281246281247281248

BTW: that crankshaft is not from an RSA125 but from a Rotax Max kart engine; they use the same setup.


I see advantages in driving the CVT after an initial primary reduction as i think i can get away with less modification to a std CVT setup.Maybe, but remember that running the CVT slower will increase the torque upon it, requiring more clamping force on the V-belt.


Lastly the RSW125 side profile drawing in the Frits files. Is it acculturate enough to scale crankcase dimensions off? or is it a illustration?Did I post an RSW side profile drawing showing the crankcase? I can't remember that for the life of me.
EDIT: I think I found what you meant. It is accurate all right, but you can hardly take dimensions from so tiny a picture, can you?
281250

I recall you saying 1mm (or was it 2mm) was the miniumun to run to counter drag for the Crankwheel-crankcase clearance i assume this is what the Aprilias ran?1 mm is correct, irrespective of engine size.

[husaberg]

Thanks Frits
The drawing was this one.(below)

These were other good side profile pics i had found (below)

Re the Primary drive yes you are of course right.
Its just with the scooter set up to stay with a conventional Japanese left side drive set up (for a rs1125 frame)it pushes everythink out the left a lot to line up the sprocket. Maybe i should do a frame with right side drive.(Cross over shaft for the counder shaft)

I think Wob showed a pic of the trigger long long ago or at least maybe the Pulse Swisauto one?

Makes me wonder why was the Works NSR250 Right side drive?

Re the drawing i haven't yet tried but how acturate is this
http://img294.imageshack.us/img294/9268/carter3ud1gq7.jpghttp://img451.imageshack.us/img451/1684/carter4rx0wt8.jpghttp://img129.imageshack.us/img129/1566/senzanome1sm2.jpg
I assume it is a attempt at a RSV250 but i haven't got around to translating it yet.

I know the crank wheels are 49mm wide on the rsw125.

[Frits Overmars]

Re the drawing i haven't yet tried but how acturate is thisI can't say; I am on tour.


... i haven't got around to translating it yet.Don't bother; there's nothing in there that you don't already know. Translating it will only show how good the italians are at using a lot of beautiful long words to say next to nothing.

[Forgi]

If you can reshape the A transfer as you have drawn, then this will allow you to drop the main port, as well as the Aux, with more timing difference between them.
This will then give more blowdown capability, with less timing, bumping up mid power and overev.
A win, win.
The Aux ports flow the most when just opening, thus need to be the widest at the top. This is due to there being the greatest pressure delta across them as they crack open.
Transfers are the opposite, thus reducing the interaction of the Aux and transfers by reducing the Aux width at the bottom helps power everywhere.

@Wobbly: I think I can understand what you are writing, but is it a good idea to decrease the timing of the exhaust port, even if the TA and the blowdown stay the same or because of the modifications it will be bigger? I think that Frits is right when he says that the best exhaust degree is about 190 degrees due to the resonance. If we could rely on engmod, 195 degrees would be even better, cos the peak of the blowdown is at 15 degrees after the opening of the port. What do you think?

http://kepfeltoltes.hu/130412/w3_www.kepfeltoltes.hu_.jpg

Because of the abovementioned reasons I didn't want to decrease the exhaust's timing. This way the TA and the blowdown are convenient meanwhile if I modify them according to your drawing the two values would be too high for certain rmp.
I don't know if I'm right or not, so feel free to correct me!

Dear Frits! By any chance do you have your article titled "De Expansie-uitlaat" in english? I'd read it!

[Frits Overmars]

Dear Frits! By any chance do you have your article titled "De Expansie-uitlaat" in english? I'd read it!Dear Forgi, sorry, no. But remember: that article may be older than you are; it's from 1978.

[wobbly]

It all depends upon the power you are wanting - or the power that the weakest link in the engine is capable of.
Yes, the best power bandwidth is to be had down at 190 Ex duration, but this is rarely used as no matter how you jig the ports, you are always looking for more blowdown when after good peak power.
But if the engine has shortcomings in other areas, and will never generate a bmep over say 150psi, then you dont need high timings with a 3 port, as its easy to
get the required blowdown STA.
Thus my comment about dropping the main port, and dropping the Aux even more.
With a radius on the A port top front corner, its then easy to get plenty of Aux blowdown STA.
But , if cutting the ports this way gives an excess of Blow STA, then simply drop the ports some more and get an even better powerband width.

When you drop the main port you get a wider rpm band of superposition wave reinforcement, and when you have plenty of separation between the main and aux timings,the mid power comes up even more.
Its the old story told 1000 times, low and wide is best, with the one caveat that the best combination with 3 ports is a 68% main, with the biggest Aux you can fit to get the blow STA needed.

Edit - the Pulse/SwissAoto design had two round magnets embedded at 180* in a crank wheel.
Each one had reverse polarity, ie one was S the other N facing out.
The trigger saw this as two distinct signals and the ECU was able to determine LH and RH cylinder pairs for correct ignition sequencing.

[Flettner]

Frits, intake length, how short is too short?

[wobbly]

The very short intake length is needed on a RV to reduce the effects of multiple fuel signals affecting the carburation.
With no such issues affecting injectors then the intake length can be tuned in EngMod to improve cylinder filling at any rpm you want.
But you are still faced with the problem of trying to fit any sort of normal length bellmouthed intake on the side, without compromising either flow, with a tight bend,or overall width
with a straight tube - hello Mr rear RV.

[husaberg]

The very short intake length is needed on a RV to reduce the effects of multiple fuel signals affecting the carburation.
With no such issues affecting injectors then the intake length can be tuned in EngMod to improve cylinder filling at any rpm you want.
But you are still faced with the problem of trying to fit any sort of normal length bellmouthed intake on the side, without compromising either flow, with a tight bend,or overall width
with a straight tube - hello Mr rear RV.


The tuned intake length testing I did with the reed engine was based on Dynamation sim results and as I have shown here before,involves combining the
case pressure ratio dropping below atma,at the same time as the intake length resonates with a + ratio at the reeds.
This opens them real quick,and fast,initiating intake flow early in the cycle.
Having around 135mm from bell to reed tips gives a good result centred around 12,000 rpm so works well on alot of 125s.
This tunes the intake to the 2rd harmonic from memory as it gives the best energy recovery over the widest range.
Using this approach on a 250 power unit gives really good gains ( making the length around 50% longer again ) and proves that the only reason the factories use 125 size carbs and manifolds
on these MX bikes ,is simply that there is no room.
Another pointer is that for example on the old TZ250 piston port.
If you are silly enough to remove the 20mm phenolic spacer fitted by the factory to "get some more top end ", all that happens is the the tuning range moves up past 12,000
and it is impossible to jet the thing at lower rpm.
Same with the tossers selling shortened carbs for the TZ350, simply throwing away a bunch of free mid power with no addition of any top end at all - the factory chose the big/long body Mikuni for a reason..

The RV scenario probably is working on the short 3rd harmonic, with less energy recovery, but also the very short length is mechanically desirable and reduces the deleterious effect
of the standing waves on the fuel delivery from the jets.



Thanks for the flowers, RAW.
You can have an intake length that is too short in combination with intake diameter, intake timing, crankcase volume and desired rpm, in which case the engine will express its displeasure by blowing back some of the inhaled mixture. I prefer to shorten the intake length as much as possible and shorten the intake timing accordingly.
By varying intake length, intake timing or crankcase volume you can adapt the induction system to different rpms. I think the best way to adapt to low revs is to advance the intake closing; it will make for a docile engine with a clean, easy to set carburation.

Varying exhaust pipe length seems to be a far better way of increasing overrev than retarding the ignition or leaning out the mixture; it would be a waste not to utilize all inhaled oxygen. Varying the pipe length can also markedly lower the beginning of the power band.
One Frits and Wob prepared earlier.

I was thinking about the rear disk the other day i seem to remember Wobs and Frits and Jan saying the Conrod was in the way and disrupting the flow a lot i guess a heck of a lot near or near bdc and likely more at TDC. But if the cylinder was on more of a forward angle like say a Rumi or even the classic Aermacchi layout wouldn't that lessen the issue? OK not as good as the rear disk but helpful? ....likely not i guess as the fatter part is still disruption maybe a Alpha or Ariel Arrow like hollow section rod shape
http://southernskies.net/page_pics/miss/two-stroke_c.gif

So, Jan Thiel gave his ok. A few pics I found interesting:

https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash2/58100_163122007033936_100000084143345_499030_56350 58_n.jpg


"Jamathi cilinder 1967"
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc7/s720x720/432142_2705047274658_1511052910_31821015_203156668 1_n.jpg


Derbi ignition trigger
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/s720x720/425265_2704871750270_1511052910_31820964_125386035 9_n.jpg


Cylinder inspecting - with Giovanni Sartorato e Matteo Marini
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc7/s720x720/419655_2700427319162_1511052910_31819524_162373812 1_n.jpg


"Brno 1969, our best win! On the right is my Czech friend Olda Fiser."
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/s720x720/417117_2700019388964_1511052910_31819392_929438763 _n.jpg


"With my friend GJ Rigter at the Aprilia flowbench. The tool in my hand is for flowing the transfers. We flowed them with the piston in 4 different positions."
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/s720x720/429839_2700198193434_1511052910_31819441_137903243 6_n.jpg


"The front half of an Aprilia crankcase. The crankshaft could be fixed in various positions by a springloaded ball. We used this for flowbench testing. We could see that the conrod disturbed the flow very much, so the idea of the rear inlet RSA was born!
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc7/s720x720/429494_2685369942737_1511052910_31813005_192701034 3_n.jpg

I can't see dinamiks pic's here wish i could

[Frits Overmars]

Frits, intake length, how short is too short?Zero would be fine. But like Wobbly says, you need a bellmouth.
I do not bother with getting inlet harmonics in sync with rpm. Any harmonic higher than 2rd will be too weak to do much good and low harmonics require a long inlet tract. Strong harmonics can also severely mess up the carburation when at certain revs a pressure peak position coincides with the carb needle jet position,
pushing the fuel down, back to the float bowl. So halleluja once again for injection.
I prefer to keep the gas column in the inlet tract as short as possible so the crankcase can start inhaling without having to overcome a lot of column inertia, as soon as case pressure drops below atmospheric - that would be around 10° after BDC at max.torque rpm.


I was thinking about the rear disk the other day i seem to remember Wobs and Frits and Jan saying the Conrod was in the way and disrupting the flow a lot i guess a heck of a lot near or near bdc and likely more at TDC. But if the cylinder was on more of a forward angle like say a Rumi or even the classic Aermacchi layout wouldn't that lessen the issue? OK not as good as the rear disk but helpful? ....likely not i guess as the fatter part is still disruption maybe a Alpha or Ariel Arrow like hollow section rod shapeThe conrod being in the way in a side disk engine was the main reason for Jan to design the rear disk Aprilia RSA125. Tilting the cylinder on a side disk engine will not change anything because the inlet opening in the case has to correspond to the transfer passage in the case and the transfer cut-out in the piston skirt.
I don't think I am familiar with the Alpha or Ariel Arrow like hollow section rod shape you mention. Have you got pictures?

[Flettner]

Thank you Frits / Wobbly / Husaberg
The set up on my new engine puts the cylinder as far forward as I can in the frame so there is not a lot of room forward to run a disc or reed for that matter ( frame tubes in the way ). Exhaust is pointing rearward so not a lot of room there either. Side inlet is handy for my application. I can run the bell mouth straight onto the rotary valve housing, straight portion of the inlet at say approx 10mm long. Crank is running reverse.
Yes maybe missing an injection shot or two might not work, I'm keen to try anything to help " hook up" and help old people like me ride better :rolleyes:

[husaberg]

Zero would be fine. But like Wobbly says, you need a bellmouth.
I do not bother with getting inlet harmonics in sync with rpm. Any harmonic higher than 2rd will be too weak to do much good and low harmonics require a long inlet tract. Strong harmonics can also severely mess up the carburation when at certain revs a pressure peak position coincides with the carb needle jet, pushing the fuel down, back to the float bowl. So halleluja once again for injection.
I prefer to keep the gas column in the inlet tract as short as possible so the crankcase can start inhaling without having to overcome a lot of column inertia, as soon as case pressure drops below atmospheric - that would be around 10° after BDC at max.torque rpm.

The conrod being in the way in a side disk engine was the main reason for Jan to design the rear disk Aprilia RSA125. Tilting the cylinder on a side disk engine will not change anything because the inlet opening in the case has to correspond to the transfer passage in the case and the transfer cut-out in the piston skirt.
I don't think I am familiar with the Alpha or Ariel Arrow like hollow section rod shape you mention. Have you got pictures?

Neither can I.

I was just looked at some Van Veen and Kreidler and took another look at the animated GIF and seen the obvious as well:crazy:

What i described as hollow may be a misnomer (they might not be but they feel that light one would think they are) section rods were made By alpha as part of there Villiers replacement bottom ends. Herman Meier used something similar on the Arrow he for for the IOM Ariel kept it on the production arrows as it was cheaper to make and worked better. It is obviously better suited to the rear inlet which is a shame. but i think a streamlined rod wouldn't do much harm.........

I had had a look for pics this is the best of a bad bunch i am afraid.
The rod profiling is also mentioned in either or both tuning for speed and Speed and how to obtain it.
<img src="http://farm6.staticflickr.com/5147/5638754522_bddbb8807c_z.jpg" height="300px"/><img src="http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=281299&d=1307083511" height="300px"/>

Seen this while looking..... well worth a look 3 cylinder water cooled 200cc Yamaha and the rotary sleeve QUB250 (http://yorkshireferret.blogspot.co.nz/2011_05_01_archive.html)
<img src="http://2.bp.blogspot.com/-4LvjntDVhl4/TdEAbVxJA-I/AAAAAAAAAIk/ZdVXxN0uuvk/s640/DRM2.jpg" height="100px"/><img src="http://2.bp.blogspot.com/-FWa1ZK6T22o/TcKEEhB6sqI/AAAAAAAAAHs/5kOIL5W7gMQ/s640/QUB+engine+whole.JPG" height="100px"/><img src="http://1.bp.blogspot.com/-QUjCZaWtEMo/TcKEaiytmaI/AAAAAAAAAH0/vKffgq1DNo0/s640/QUB+complete+bike.JPG" height="100px"/>

EDIT

I went back and looked for a picture and guess what same conversation 18 months ago even the ignition on the Pulse and RSA thats twightzone stuff.

EDIT EDIT just noticed the balancer position missed that previously


Oval and knife-shaped conrods are better streamlined and meet a little less resistance when cutting through the contents of the crankcase. But I doubt whether they have any structural advantages.

The notch in the crankweb triggers the ignition. There's a Hall sensor at the crankcase looking at the crankshaft circumference. That gives a more accurate timing signal than a sensor looking at the end of a swaying shaft.
Below are some pictures of the Aprilia RSA125; the red arrows indicate the ignition sensor.
<img src="http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=250929&d=1321749311" height="300px"/><img src="http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=250939&d=1321753260" height="300px"/><img src="http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=250938&d=1321753282" height="300px"/><img src="http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=249820&d=1320083116" height="300px"/>


That notch for timing reminds me of one of the cleverest triggering setups I have seen.
In the SwissAuto/Pulse flying web engine there were two magnets at 180* in one crank web with only 1 sensor, setup much as the pic of the RSA125.
I spent ages trying to figure out how it worked, untill one day I grabbed another magnet and discovered that each one inside the crank
was orientated N & S pole outward.
The trigger sensed the N pole as cylinders 1,3 and the S pole as 2,4, bloody clever and as simple as it could be made.

[dinamik2t]

Those pics where from Jan's facebook profile, along with his comment.
At the time I used the img link from facebook and as the link changed or the photo was deleted/transfered in a different album, the old link wouldn't work.
Anyway, here are some of them, as I don't remember the Jamathi '67 and the Brno '69 photos in order to locate them in my archives.

---------------------------

Cylinder inspecting - with Giovanni Sartorato e Matteo Marini
281304


"With my friend GJ Rigter at the Aprilia flowbench. The tool in my hand is for flowing the transfers. We flowed them with the piston in 4 different positions."
281307281303


"The front half of an Aprilia crankcase. The crankshaft could be fixed in various positions by a springloaded ball. We used this for flowbench testing. We could see that the conrod disturbed the flow very much, so the idea of the rear inlet RSA was born!
281306

Two extra:

"Giovanni Sartorato who worked with me in the Aprilia racing department"
281302

"Alfredo, who worked with me for quite some time, a very good worker and a nice guy. Unfortunately he got killed in a motorcycle accident when going to work. We were very shocked!"
281300

[dinamik2t]

These are the derbi pics: balancer, pick-up hall (I guess) and left-hand cover view.
281310281311281312

Interesting story: "the photo is from 2000, when I did not work for Derbi, it was a kind of 'spying' by Aprilia! Aprilia payed a photographer for making 'spy' photo's, these were then showed in Witteveen's office. This is just one of the many...."
281313


And two for fun.
Jan at the Garelli Halloween party :p
281308

"With Luc Foekema, he seems to be burning my brain out with his hot coffiecup! (:p) He is a very good tuner and is still active in drag-racing."
281309

[Flettner]

I imagine that's why a twin RV both sides of the crank case might work well ( if they have to be on the side ).
The smaller the engine the worse the problem? Con rods don't shrink much as the capacity drops but room in the crank case does.

[Flettner]

http://i1056.photobucket.com/albums/t380/uniflow/IMG_0868_zps6f424fcc.jpg
http://i1056.photobucket.com/albums/t380/uniflow/IMG_0869_zps21666b82.jpg
http://i1056.photobucket.com/albums/t380/uniflow/IMG_0867_zps8fac704f.jpg

The YZ 250 EFI peoject. Ready to run?

[Grumph]

No - fuel lines at least and a clutch would be nice too. The silver painted plasticine over the transfers gets a B minus.

[Frits Overmars]

I wonder what the big end bearing has to say about the reduced lubrication and cooling.

[teriks]

The YZ 250 EFI peoject. Ready to run?
If you are as fast on the track as in the shop, I think you'll podium more or less every time.

What's up with the ignition cover? -Does look a bit, unsealed, to me. If so, could get interesting in a mud race ;)


I wonder what the big end bearing has to say about the reduced lubrication and cooling.
That too. Reminds me of an interesting FI/DI design from ArcticCat.
281421
http://www.arcticinsider.com/Article/Tech-Insight-Inside-the-new-Arctic-Cat-600-C-TEC2-Engine


Dual-Stage Injection: At lower engine loads, the system injects fuel directly into the combustion chamber, on top of the piston. At higher engine loads fuel is also injected into the crankcase area and into the transfer ports, improving the fuel/air transfer time for added efficiency while also lubricating vital engine components

Slotted Piston: The unique open-window/slotted piston design allows fuel/oil mix to be injected into the crankcase area and then into the transfer ports as part of the Dual-Stage Injection design.

Key to this design is the injection of fuel (with oil) at the piston rod bearing, which a competitive DI system does not achieve (and which is known for problems).

[husaberg]

I imagine that's why a twin RV both sides of the crank case might work well ( if they have to be on the side ).
The smaller the engine the worse the problem? Con rods don't shrink much as the capacity drops but room in the crank case does.
Yeah i am no RV guru for sure the twin disk or rear would be neat but f-ing problematic i did see another design from another later motor that was similar but can't remember where it was Mirhindra or something i think


The YZ 250 EFI peoject. Ready to run?
<img src="http://i1056.photobucket.com/albums/t380/uniflow/IMG_0868_zps6f424fcc.jpg" width="300px"/><img src="http://i1056.photobucket.com/albums/t380/uniflow/IMG_0869_zps21666b82.jpg" width="300px"/><img src="http://i1056.photobucket.com/albums/t380/uniflow/IMG_0867_zps8fac704f.jpg" width="300px"/>


Love milled stuff. Also must show you how to resize pics hit reply with quote :yes:


No - fuel lines at least and a clutch would be nice too. The silver painted plasticine over the transfers gets a B minus.
Hey Greg were the Alpha conrod's hollow and do you have a decent pic of one?

[Flettner]

Yes, that bloody cover! The original plastic cover fits over this, covering everything, 4.5mm wider. This is using a 450F alternator. The customer already had the unit so it had to be fitted. It will work. Not as elegant as using an alternator shown earlier in this thread.

Big end, if you look real hard there is a small port on the drum throttle valve to accept an oiler. We have a small solenoid pump that is computer controlled. There is a capscrew blocking the hole in the picture, behind the throttle cable.

Big end cooling? we will have to see how that goes. My 350 has done 50 hours with no problems.

[Grumph]

[QUOTE=husaberg;


Hey Greg were the Alpha conrod's hollow and do you have a decent pic of one?[/QUOTE]

No and no...but I have seen the inside of an Alpha rod - wrapped around a Dot frame member....what there was of it was solid.

[husaberg]

No and no...but I have seen the inside of an Alpha rod - wrapped around a Dot frame member....what there was of it was solid.

Not so Devoid of Trouble.
The old man still has two, his original 53 8E and a 60's Marcelle headed 34a or 36a

[2T Institute]

For Zeeltronic users here is the Hall Effect Sensor wiring. This method of triggering would be ideal converting reed engines to disc valve.

[TZ350]

281427

http://www.freepatentsonline.com/6691649.html

Free Patents Online is a bit of a gold mine of ideas, its worth a look at the Two Stroke stuff.

[Forgi]

It all depends upon the power you are wanting - or the power that the weakest link in the engine is capable of.
Yes, the best power bandwidth is to be had down at 190 Ex duration, but this is rarely used as no matter how you jig the ports, you are always looking for more blowdown when after good peak power.
But if the engine has shortcomings in other areas, and will never generate a bmep over say 150psi, then you dont need high timings with a 3 port, as its easy to
get the required blowdown STA.
Thus my comment about dropping the main port, and dropping the Aux even more.
With a radius on the A port top front corner, its then easy to get plenty of Aux blowdown STA.
But , if cutting the ports this way gives an excess of Blow STA, then simply drop the ports some more and get an even better powerband width.

When you drop the main port you get a wider rpm band of superposition wave reinforcement, and when you have plenty of separation between the main and aux timings,the mid power comes up even more.
Its the old story told 1000 times, low and wide is best, with the one caveat that the best combination with 3 ports is a 68% main, with the biggest Aux you can fit to get the blow STA needed.

Edit - the Pulse/SwissAoto design had two round magnets embedded at 180* in a crank wheel.
Each one had reverse polarity, ie one was S the other N facing out.
The trigger saw this as two distinct signals and the ECU was able to determine LH and RH cylinder pairs for correct ignition sequencing.

@ Frits: I'm sorry that you don't have the article in english! Pretty sure that the article is older than me! :-)

@ Wobbly: Of course the goal is to get the best power which is determined somehow by the gear ratio.

I suppose you know the original 70cc simson cylinder which isn't a tuning-friendly thing. :-)

http://img.alibaba.com/photo/282549185/Motorcycle_Parts_motorcycle_Cylinder_Simson_38MM_. jpg

12,5K rpm, 0,0175 ex TA (195 ex timing), also convenient (Blair suggests) Blowdown, Tr and Inlet Time Area. If I modernise everything I have to decrease the ex timing with max. 2-3 degrees to keep the suggested ex TA value.
But regretfully it is hard to make such a perfect job by hand, as the bore 45 is too small and every single decimal mm counts!

So according to you if I modernise everything and I resolve somehow that at 185 degrees the TA (and of course ex, blowdown, tr) will be the same as at 190 or at 195, then at 185 the system works better? I'm affraid Frits will not agree! :-)

If we have a small bore at 13K rpm, we can get a convenient TA if our exhaust port timing is low enough.
This way in case of 25 (suzuki rk67) or 50cc 180, max 190 degrees are enough. But of course in case of 125cc if we have 195-200 is still hard to make a big blowdown and STA.

[Muciek]

You should see what guys in Poland make with those cylinders http://bikepics.com/members/hopit/projekt2013/ http://bikepics.com/members/nightfire007/p5/ http://bikepics.com/members/chylo00/p7/ http://bikepics.com/members/chylo00/p13/ http://bikepics.com/members/chylo00/p45/ http://bikepics.com/members/przemas222/87s51/default.asp?i=2348005&s=0 70cc 77cc 83cc and other :) They use exhuast ports that are 23mm from TDC for 10000 to 11000 rpm.

[wobbly]

The real point I was making is that lower and wider is better - assuming you end up with the STAs matched to the required performance.
Case in point is 125cc TM kart race engines, that make 44Hp at the sprocket, on my dyno, with a 30mm carb.
The real factory tuned engines have around 196* Ex duration and as delivered will rev to around 14300.
The engine i built that has just won our National Champs, has 194* but the Aux are hugely deeper and wider, and the transfer stagger is reversed, to get extra room over the A port
This makes 46Hp and easily revs to 15,000, and in the process destroyed a real expensive,super secret, genuine factory World Cup winning engine.

BUT - I dont know that going from 190* down to 185 will be better, as any engine with only 190* in the first place could not make any serious power to begin with.

[RomeuPT]

Finally made it to the end. :sweatdrop

Hi, I am Romeu, I am from Portugal, been reading this topic for the last three weaks, founded here a 2 stroke treasure, probably the most valuable one in the internet.

I have been on pit-lane and the information there is huge too, but this topic talks more about reed induction 125 race engines, many thanks to wobby.

While reading a great amount of questions surged in my mind. The more important is what follows:

Wobby when you talk about oval to round transition at the exhaust flange is using the aprilia exhaust duct exit shape type or it would be done on the oval Honda RS duct exit too?
I am confused, because using the oval duct exit of 41 lenght by 34 height from the honda RS to a 41 round exhaust flange and having to keep a kink on the roof and floor where is the space for the taper?
I hope you could understand my confusion, doesn't the taper exhaust flange from the aprilia goes from an oval 46,5 width duct exit to 41,5 exhaust flange, making it possible to be taper...?

TZ350, you have done a great job. One of the most interesting bucket projects I have seen. :yes:

Thanks everyone for this great great topic.

Regards
Romeu

[TZ350]

Finally made it to the end. :sweatdrop

Hi RomeuPT, congratulations on reading the whole thread, marathon effort. I too have learned a lot from all the people who post on here.

[wobbly]

The most powerfull Honda type exhaust duct, for the T port, that I dyno developed for a customer in Belgium, was a 41 wide by 32 high oval at the flange face.
This went out to a 41mm header diameter via an oval to round transition.
The stepped transition, with simply a round 41mm spigot ID lost around 1.5 to 2 Hp comparred to the CNC lofted shape.
We have a slightly different situation with the 3 port Aprilia.
In this scenario we have the flow from the Aux ports, that we need to promote as much as possible - helping blowdown efficiency, and the Aprilia has the cutouts for these side ducts going all the way down to the header.
The Aprilia flange face still has steps, where the cylinder bolts up to the flange, and it is my gut feeling, that two things are in play here.
Firstly is that Jan Thiels philosophy was to reduce the duct volume as small as possible, consistent with the huge power being produced, and the result of this was high header entry velocity,along
with a higher Helmholtz resonance.
I simply dont know at this point if Aprilia R&D tried a CNC transition, with the flange matching the duct exit shape exactly, ie no steps,then exiting as a round shape into the header, as per the Honda example.
Frits or Jan, could elucidate on this idea, if they choose to, but my feeling is that more power could be had with the transition, BUT, I also believe that just maybe things change when you are up at 55Hp
from a 125.
If you believe the steps reduce reversion flow, more than they reduce exit flow, and thus make more power, maybe you are right - this for sure isnt the optimum case with a T port, but the Aprilia is SOTA and you simply cant argue with the results gained by Jan and the factory - even when a bunch of uninformed idiots changed things after he retired.

[cotswold]

I have been reading through this guys stuff and some of you may find it interesting (or most likely seen it already)

http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop?

[husaberg]

Hi Wax

277120

I purchased some new GY6 125/150 CVT parts, because they are pretty cheap here and there are after market parts available for them. The parts come in plain brown box's without any of the naughty words that would define them as illegal for Moto4 (Bucket) racing.

I need an old crank half and reduction box input shaft for their splines. I plan on extending the shafts so they can be run in carrier brgs mounted in the engine plates.

As best as I can figure out the CVT has a range of 3.25:1 to 0.8:1 which is pretty much the same as the GP gear box. So all I would need is a 3:1 primary or final gear reduction ratio.

So the plan is to have on the right hand side of the engine, a 3:1 straight cut reduction gear set to a cross shaft to the front CVT sheave mounted on the left side (keeps the rotation direction correct that way).

And the front chain sprocket behind the rear CVT sheave. That should put the front chain sprocket in the right place relative to the swing arm. The front reduction gear set could be lubed between races with a squirt of chain grease, life expectance does not have to be great.

If you can find an old crank half and reduction box input shaft for a GY6 125-150 I would be very greatful.


http://www.ncy-motor.com.tw/product3.php?lang=en&car=&car2=&car3=&search=&page=13
I doubt i came apon the right page (in this link)but pretty sure the shaft you want was there...no crankhalf but i guss Newmanz and co if you can't find SH


Thanks Frits does it sound plausible that the RSA could be bigger (I won't hold you too it you are most patient with me already)
I am not sure you have mentioned where you currently are working? if thats not to intrusive


Thanks Husa I remember it now, $8 USD each from memory.


Okay thanks to Yow i found a CVT it is for a 2 stroke 125 and i was thinking cool going from 10 wheels to 17 plus 4000rpm extra would make it still be ok.

Well er not so much....
Ii hadn't factored in my final drive reduction.
Using Berts gear spreadsheet it would only do about 100kph (don't worry about 2nd to 5th i just put some ratios in there to fill the gaps.

The standard scooter drive reduction is huge.(attached)
Like TZ something around 3.5 is what i need.
I are beginning to think maybe it is a bridge too far.
Once i get a look at the Lead engine i guess we will see if there is a simpler solution.
I really like the idea of a CVT with a custom disk crankcase and a Aprilia inspired 100cc.

[RomeuPT]

The most powerfull Honda type exhaust duct, for the T port, that I dyno developed for a customer in Belgium, was a 41 wide by 32 high oval at the flange face.
This went out to a 41mm header diameter via an oval to round transition.
The stepped transition, with simply a round 41mm spigot ID lost around 1.5 to 2 Hp comparred to the CNC lofted shape.
We have a slightly different situation with the 3 port Aprilia.
In this scenario we have the flow from the Aux ports, that we need to promote as much as possible - helping blowdown efficiency, and the Aprilia has the cutouts for these side ducts going all the way down to the header.
The Aprilia flange face still has steps, where the cylinder bolts up to the flange, and it is my gut feeling, that two things are in play here.
Firstly is that Jan Thiels philosophy was to reduce the duct volume as small as possible, consistent with the huge power being produced, and the result of this was high header entry velocity,along
with a higher Helmholtz resonance.
I simply dont know at this point if Aprilia R&D tried a CNC transition, with the flange matching the duct exit shape exactly, ie no steps,then exiting as a round shape into the header, as per the Honda example.
Frits or Jan, could elucidate on this idea, if they choose to, but my feeling is that more power could be had with the transition, BUT, I also believe that just maybe things change when you are up at 55Hp
from a 125.
If you believe the steps reduce reversion flow, more than they reduce exit flow, and thus make more power, maybe you are right - this for sure isnt the optimum case with a T port, but the Aprilia is SOTA and you simply cant argue with the results gained by Jan and the factory - even when a bunch of uninformed idiots changed things after he retired.

Now I understand. My confusion was about keeping the steeps, because aprilia's have them. Thanks.
Some years ago I have buyed one 89' Honda RS 125 cylinder, to fit in one NSR 125 engine. Before that it had one CRM 125 cylinder, actualy tuned it quite whell in area and timing (200º ex/ 133º transfer) and the exhaust duck exit was 37 round, I builded one 804mm lenght exhaust matching exacly the 37 duck exit, 118 belly, strong diffuser angles and 14º reflector cone with 193mm duration using Mota software. (I had the luck to do very good peak power not knowing half of what I know today).
Today with the honda RS cylinder slightly tuned, and having Honda Exhaust layouts from Honda and the one from frits I have now a more drivable bike, but the power after 12k is lower than with the CRM cylinder. Of course there are other variables, but :brick:

I notice certain Honda cylinders have different transfer rear angles, why is that?
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=281514&d=1366200788

Another small question I would really like to know, how much moment of inercia (kg·m²) would be needed for a dyno used to measure power from 80cc/100cc and 125's till 50 hp ?
Has I readed on this forum I think I will try a 40cm tube, filled with concrete.

Thanks

[Frits Overmars]

... how much moment of inercia (kg·m²) would be needed for a dyno used to measure power from 80cc/100cc and 125's till 50 hp ?That is an unanswerable question, Romeu. It completely depends on the gearing.

I think I will try a 40cm tube, filled with concrete.I think you are too young to kill yourself. Don't even think of filling a tube with whatever. You will need either a thick-walled steel tube filled with nothing, or a solid steel flywheel. Not even cast iron will be safe for this purpose.

[RomeuPT]

I think you are too young to kill yourself. Don't even think of filling a tube with whatever. You will need either a thick-walled steel tube filled with nothing, or a solid steel flywheel. Not even cast iron will be safe for this purpose.


I see what could happen.
A full steel rod is really expensive and hard to transport.
So I should use a steel tube, and have a flywhell inside some safe box in case of something went wrong?!

Thanks

[Flettner]

Fuel injection runs again, phone call today and all I could hear on the other end was the sound of a twostroke running. The YZ 250 EFI port injection lives, only took a couple of kicks! It is running on the F9 program so needs a little bit of tuning. Next trick is to hook up the power valve to the computer take control away from revs alone.

[Sketchy_Racer]

Another small question I would really like to know, how much moment of inercia (kg·m²) would be needed for a dyno used to measure power from 80cc/100cc and 125's till 50 hp ?
Has I readed on this forum I think I will try a 40cm tube, filled with concrete.

Thanks

You will need at a minimum 6kg-m^2 to have a reasonable run time with 50hp, but generally the more the better as the longer run lengths help show up weak spots in the motor. I have a small 2.2kg-m^2 dyno that is useful for up to 25hp but the run lengths get short (around 8 seconds)

As mentioned, you need either a solid bar of steel or a pipe with thick walls with end caps welded on. Just remember you are going to have to have the assembly dynamically balanced once finished.

http://wotid.com/dyno/content/view/16/35/

That is a good site for info.

[TZ350]

Fuel injection runs again, The YZ 250 EFI port injection lives.

Congratulations ... that makes it two, home brew, competition 2-Strokes running EFI that you have put together.

[TZ350]

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=281514&d=1366200788

I notice certain Honda cylinders have different transfer rear angles, why is that?


I would be very interested in that too...

[Yow Ling]

I would be very interested in that too...

Is it just a land for the ring gap to run on ?

[Frits Overmars]

Is it just a land for the ring gap to run on ?Yes it is. The asymmetric bridges between B- and C-port appeared in Honda cylinders from the previous millennium. Now that the ring gap is center rear, running over the C-port, the need for the asymmetry no longer exists.

[Frits Overmars]

You will need at a minimum 6kg-m^2 to have a reasonable run time with 50hp, but generally the more the better as the longer run lengths help show up weak spots in the motor. I have a small 2.2kg-m^2 dyno that is useful for up to 25hp but the run lengths get short (around 8 seconds) As I wrote yesterday, you cannot make such a categorical statement. If you gear your small flywheel twice as fast, the acceleration time will quadruple. But you will have to make sure it will be up to the centrifugal forces which will also quadruple.

BTW: 8 seconds is a fine acceleration time, provided you start at the lower rpm of the power band. Starting the measurement much lower won't do any good as the acc. time will then be strongly influenced by erratic engine behaviour.

Attached you will find a little program; play with it; see what happens if you change the gearing or the desired acceleration time.

EDIT: Damn! I cannot even upload a zipfile here.

[dinamik2t]

Frits, you could try changing the extention to .jpg for example. And then we turn it back to .zip or .rar or whatever.

edit: I checked the attachment help and you better use .doc, because .jpg's are limited to 750kB per file. Doc is up to 2MB.

[Sketchy_Racer]

As I wrote yesterday, you cannot make such a categorical statement. If you gear your small flywheel twice as fast, the acceleration time will quadruple. But you will have to make sure it will be up to the centrifugal forces which will also quadruple.

BTW: 8 seconds is a fine acceleration time, provided you start at the lower rpm of the power band. Starting the measurement much lower won't do any good as the acc. time will then be strongly influenced by erratic engine behaviour.

Attached you will find a little program; play with it; see what happens if you change the gearing or the desired acceleration time.

EDIT: Damn! I cannot even upload a zipfile here.

Yes this would be true for an engine dyno where gearing up is simpler. I assumed he was talking of a chassis dyno where generally the "flywheel" is the roller driven by the wheel(s)

[Frits Overmars]

Yes this would be true for an engine dyno where gearing up is simpler. I assumed he was talking of a chassis dyno where generally the "flywheel" is the roller driven by the wheel(s)You may be surprised to learn that people actually manage to alter the gearing of a motorcycle :whistle:.



Frits, you could try changing the extention to .jpg for example. And then we turn it back to .zip or .rar or whatever.
edit: I checked the attachment help and you better use .doc, because .jpg's are limited to 750kB per file. Doc is up to 2MB.If that works, I can send the EXE-file directly, disguised as a DOC-file. So right-click attachment FLYWHEEL.DOC, select 'Save Target As' , rename it to FLYWHEEL.EXE and have fun.

[Forgi]

The real point I was making is that lower and wider is better - assuming you end up with the STAs matched to the required performance.
Case in point is 125cc TM kart race engines, that make 44Hp at the sprocket, on my dyno, with a 30mm carb.
The real factory tuned engines have around 196* Ex duration and as delivered will rev to around 14300.
The engine i built that has just won our National Champs, has 194* but the Aux are hugely deeper and wider, and the transfer stagger is reversed, to get extra room over the A port
This makes 46Hp and easily revs to 15,000, and in the process destroyed a real expensive,super secret, genuine factory World Cup winning engine.

BUT - I dont know that going from 190* down to 185 will be better, as any engine with only 190* in the first place could not make any serious power to begin with.

@Muciek: Thank you for the pics, as I can see in Poland people like simsons as much as here in Hungary.

„Polak, Węgier, dwa bratanki, i do szabli, i do szklanki.” :)

@Woobly: Ok, I can understand what you are saying, and thank you for sharing your experience.

I plan to make a nozzle in which the aux port's duct helps to get better blowdown (just like on your Fig. 3.), but of course at the end the area will be 75%. It is true that this way the volume of the duct will be bigger as the duct will be wider (now I can't modify the height of it), but I hope that the effect of these changes will be positive on the whole.

Once I get results I will share them.

[RomeuPT]

Yes it is. The asymmetric bridges between B- and C-port appeared in Honda cylinders from the previous millennium. Now that the ring gap is center rear, running over the C-port, the need for the asymmetry no longer exists.

I thought it was something else, because some newer cylinder I posted on pit-lane have that too.

[RomeuPT]

You may be surprised to learn that people actually manage to alter the gearing of a motorcycle :whistle:.


If that works, I can send the EXE-file directly, disguised as a DOC-file. So right-click attachment FLYWHEEL.DOC, select 'Save Target As' , rename it to FLYWHEEL.EXE and have fun.

Very nice tools you have Frits. Many Thanks
I will test it later with more time, If all went whell the dyno will be a summer project :Punk:

Another thing that was newer to me was that in a picture Wobby posted showed a T port with the highest part of the exhaust port not at the brigde but at the sides....
Was that just to get BlowDown area and maybe leave the bridge a litle more cool?

Thanks

[wobbly]

Cant hide anything on the internet - that drawing was from many,many years ago.
The idea was that as the outer edges of a T port form the longest part of the duct, they should be opened first, to get a more coherent,bigger amplitude wave
front exiting down the header.
It was used for quite a while in many GP winning engines - but I tested it more rigorously later on, and made more power by simply raising the whole port,back to flat again - bugger.

[TZ350]

Injector Sizing and Locater page


http://www.nitrostreet.com/injectors.htm (http://www.nitrostreet.com/injectors.htm)

A place to go to, to calculate the size of injectors needed.

Because it is a 4-Stroke site and assumes a full 100% duty cycle of 720 degrees as apposed to a 2-Strokes 360 degrees I had to halve my required duty cycle to get a 2-Stroke result.

Ie., my designed maximum duty cycle is 120 degrees or 33% then instead of 0.33 I had to enter 0.16 in the Duty Cycle field.

281621

It was pleasing to see the numbers came out to be the same size as I had previously calculated from the simulated EngMod2T fuel demand curves.

DIY EFI ... might be worth a look. http://www.diy-efi.org/

EFI links list here. http://www.nitrostreet.com/efi.html#EFI%20related%20software%20for%20PC%27s

[TZ350]

Things I am learning about EFI ..... edited scrapes below.

Speed Density

There are several different ways to control the air/fuel ratio. Speed density requires just two main inputs to establish a base fuel map: engine rpm and load. Speed density assumes that a certain amount of air will enter the engine at any particular combination of rpm and load.

This works as long as the engine remains unchanged. Modifications to the engine to increase airflow (and therefore power) at any point would tend to make the engine run lean, since the engine would inhale more air at that rpm and load point than it did when it was stock.

If you take in more air, a proportional amount of additional fuel must also be delivered to maintain the same air/fuel ratio. Speed-density systems cannot perform this function without reprogramming.

Mass Airflow

Systems outfitted with a mass airflow (MAF) sensors. This sensor measures the amount of air entering the engine, giving more precise control over the air/fuel ratio. MAF systems are more accurate.

Alpha-N

There is one other EFI control system that is generally used only in racing called an Alpha-N system.

This control system’s major inputs are throttle position and rpm. This system was developed because race engines often operate at idle and part-throttle with very little manifold vacuum.

This makes using a MAP sensor difficult. This system is less precise than speed density or MAF and is therefore generally only found in racing or on heavily modified street engines with big camshafts. A MAP sensor can still be used with Alpha-N, but it is generally employed as a barometric pressure sensor to detect altitude changes.

[TZ350]

16 x 12 Input Tables or Maps for my EFI unit.

All the variables RPM, MAP, TPS, Load, VE and Lambda values can be adjusted.

281634

Speed Density Map

281633

Alpha-N Map

281635

Desired Lambda Map

I am trying to get my head around these and figure out how much info from the EngMod2T graphs I can use here.

[RomeuPT]

Cant hide anything on the internet - that drawing was from many,many years ago.
The idea was that as the outer edges of a T port form the longest part of the duct, they should be opened first, to get a more coherent,bigger amplitude wave
front exiting down the header.
It was used for quite a while in many GP winning engines - but I tested it more rigorously later on, and made more power by simply raising the whole port,back to flat again - bugger.

Thanks for this info. Really avoid confusions and wasting time for me in the future :)

Recent Honda cylinder's seem to have the outer edges lower than the old 96/95 cylinders.

Honda Nx users go with 108/109 and 110 rods, the pistons have 21,5 height from top of the pin to the top edge. You said that around 1.3 primary Comp. works best for reed induction engines.

So, why not use 115 rods, with a piston pin about 1,5mm near the top and filing the case a bit where it least affects thus keeping primary compression?

Regards

[RomeuPT]

A link about rod lenght

http://www.eatel.net/~stentorian/wristpinplacement.swf

[chrisc]

I was reading Practical Sportsbikes magazine, specifically the AR50 100MPH project and noticed that the ESE thread was mentioned! I hope that they don't mind me posting this, it's advertising on their behalf so I doubt they will, but see the attachments for some sneak peaks.

It's a good build and I hope they achieve their goal, actually, it's a great magazine with lots of stink wheel articles and builds. We've just subscribed to the magazine too.

Anyway, congrats to ESE for attracting world wide attention as well as the welcomed input from Jan and Frits. It's a great thread and I probably spend more time on it than I do watching TV.

281658281659281660

[TZ350]

I was reading Practical Sportsbikes magazine and noticed that the ESE thread was mentioned!

281660





281665
(http://www.kiwibiker.co.nz/forums/showthread.php/153656-Chris-Bucket-photo-thread-Bandwidth-warning/page7?p=1130533059#post1130533059)
This is Thomas a Vietnamese race mechanic, (http://www.kiwibiker.co.nz/forums/showthread.php/153656-Chris-Bucket-photo-thread-Bandwidth-warning/page7?p=1130533059#post1130533059)Team, ESE's Tuner is fettling number 9. and adjusting the port timing for Taupo. (http://www.kiwibiker.co.nz/forums/showthread.php/153656-Chris-Bucket-photo-thread-Bandwidth-warning/page7?p=1130533059#post1130533059)
(http://www.kiwibiker.co.nz/forums/showthread.php/153656-Chris-Bucket-photo-thread-Bandwidth-warning/page7?p=1130533059#post1130533059)This was the very first post on the ESE thread in 08, could Thomas be nearly world famous.

Below, scraped from Chrisc's thread. is some video of F4 racing at Tokoroa last weekend.

<iframe src="http://player.vimeo.com/video/64253234" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen="" frameborder="0" height="281" width="500"></iframe>

F4 Tokoroa GP 2013 - Practice and campground walk (http://vimeo.com/64253234) from Christopher (http://vimeo.com/christophercain) on Vimeo (http://vimeo.com).

http://www.kiwibiker.co.nz/forums/showthread.php/153656-Chris-Bucket-photo-thread-Bandwidth-warning/page7?p=1130533059#post1130533059 (http://www.kiwibiker.co.nz/forums/showthread.php/153656-Chris-Bucket-photo-thread-Bandwidth-warning/page7?p=1130533059#post1130533059)

[husaberg]

I have never noticed before but Thomas is wearing a butchers apron.:nono:

<img src="http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=281665&d=1227163070" height="140px"/>

[TZ350]

I have never noticed before but Thomas is wearing a butchers apron.:nono:



Your the first person in 5 years to notice..... :laugh:

We did manage to get him used to wearing company overalls eventually.

[jasonu]

World famous in NZ

[F5 Dave]

I was reading Practical Sportsbikes magazine, specifically the AR50 100MPH project and noticed that the ESE thread was mentioned! I hope that they don't mind me posting this, it's advertising on their behalf so I doubt they will, but see the attachments for some sneak peaks.

It's a good build and I hope they achieve their goal, actually, it's a great magazine with lots of stink wheel articles and builds. We've just subscribed to the magazine too.

Anyway, congrats to ESE for attracting world wide attention as well as the welcomed input from Jan and Frits. It's a great thread and I probably spend more time on it than I do watching TV.

281658281659281660

yeah I've been following that article on & off. Don't think hes got a chance,.

[rgvbaz]

yeah I've been following that article on & off. Don't think hes got a chance,.

Why do you think it will fail, Dave?


Dave.

[wobbly]

Honda 2T race engines have used 105 ish rods forever, I could never really figure out why.
But using a longer rod and keeping the case vol without using a spacer would be a very good test to try.
Biggest issue from memory was that the Honda pins are much bigger than anyone else uses thus restricting availability of suitable rod kits.
I have made hardened and ground sleeves to use a longer 110 rod in a RS125 kart engine, that won alot of races, but didnt have a dyno facility at the time,so never confirmed the actual performance change.

[RomeuPT]

Honda 2T race engines have used 105 ish rods forever, I could never really figure out why.
But using a longer rod and keeping the case vol without using a spacer would be a very good test to try.
Biggest issue from memory was that the Honda pins are much bigger than anyone else uses thus restricting availability of suitable rod kits.
I have made hardened and ground sleeves to use a longer 110 rod in a RS125 kart engine, that won alot of races, but didnt have a dyno facility at the time,so never confirmed the actual performance change.


Besides Samarin Rods for Honda, there is also 112mm rod from TM 144cc and TZ 250 110mm rod from 2000 onwards that use the same pin diameter (24) and width (16). The wheight? The quality needed, I don't know

[chrisc]

At 50 seconds, a NF4 RS125 frame with a 2 stroke CVT set up. Does a 3.00s 1/32mile pass. I laughed


http://www.youtube.com/watch?v=9fyGGFSdW6E

[TZ350]

A NF4 RS125 frame with a 2 stroke CVT set up.

281697

Its a Honda RS125 chassied drag scooter alright .... but why does the pilot hold in what appears to be the clutch? or could that now be the rear brake?

[husaberg]

1/32 mile equals 50 meters.

[Frits Overmars]

1/32 mile equals 50 meters.Drag racing for me has always been 1/4 mile, or 402 meters in real money. It has been devaulated to 1/8 mile, and then to 150 meters; it's a pity.
But 50 meters? No need for an engine; I could jump that far (well, almost).

Another funny thing in that video: blocking the front wheel position at the start line. What's the use? I would be glad to have my front wheel blocked at a drag race. Then I could creep half a meter backward before launching. Those first 50 cm are decisive because they're the slowest part of the sprint. I could easily gain 0.1 second with such a 'flying start'. Blocking the rear wheel would be the sensible thing to do.
281762

[TZ350]

281787

281790
Auckland Bucket Champs Table curtsy of David D.

281788 281789 281791

Tokoroa sorted on laps.

[F5 Dave]

Why do you think it will fail, Dave?


Dave.

He needs a sustained 25hp from an aircooled bike that will be under load for a serious amount of time & a considerably oversquare linered arcane engine with quite a small carb. + it doesn't sound like he has the experience with small engines.

Yes it can be done. Speedpro's engine downsized to 83cc handily makes 25hp, but that is assuming a shrink ray type shrink, not just destroke it to 50cc bottom end & hope it will be as efficient.

Also there is the revs he is not talking enough to get that power I think.

I just don't see someone knocking it up in the timeframe of a magazine article. I predict a 92mph with a lot of 'gallant effort' & 'if onlys'

prepared to be proven wrong, best wishes & all.

[TZ350]

yeah I've been following that article on & off. Don't think hes got a chance,.Dave.
Why do you think it will fail, Dave?


As well as Dave's comments, did they publish any STA's for the ports, that would give us a few clues about what they might achieve, and if there is a target RPM and HP figure we could use the BMEP concept to judge if their engine performance target is possible.

Maybe it is possible, if anyone has the article, it would be interesting to know the details of their build plan then we could check it out with a bit of analysis to see what their chances are.

STA - specific time area.
RPM revolutions per minute.
HP horse power.
BMEP brake mean effective pressure.

[rgvbaz]

He needs a sustained 25hp from an aircooled bike that will be under load for a serious amount of time & a considerably oversquare linered arcane engine with quite a small carb. + it doesn't sound like he has the experience with small engines.

Yes it can be done. Speedpro's engine downsized to 83cc handily makes 25hp, but that is assuming a shrink ray type shrink, not just destroke it to 50cc bottom end & hope it will be as efficient.

Also there is the revs he is not talking enough to get that power I think.

I just don't see someone knocking it up in the timeframe of a magazine article. I predict a 92mph with a lot of 'gallant effort' & 'if onlys'

prepared to be proven wrong, best wishes & all.

I agree it certainly won't be easy but I found this on BDKs webpage, they recon just under 20hp at 10K, and 98 mph, here: http://www.bdkraceeng.co.uk/Bike5.html

A program I have that predicts top speed 1/4 mile etc also seems to think 21hp may just do it (with no wind on a nice day with no slope :confused:) It also uses a predicted Cd.

Dave

Dave

[rgvbaz]

As well as Dave's comments, did they publish any STA's for the ports, that would give us a few clues about what they might achieve, and if there is a target RPM and HP figure we could use the BMEP concept to judge if their engine performance target is possible.

Maybe it is possible, if anyone has the article, it would be interesting to know the details of their build plan then we could check it out with a bit of analysis to see what their chances are.

STA - specific time area.
RPM revolutions per minute.
HP horse power.
BMEP brake mean effective pressure.

I did a little mock-up in EngMod, STA wise it can do about 27hp at the crank, but not sure about the inlet?

Dave

[TZ350]

STA wise it can do about 27hp at the crank ...

Thanks, being a fellow air cooled traveler and all, in my heart I would like them to succeed.

So it looks like they have half a chance, if the challenges F5Dave mentioned dont catch them out.

If your following their progress please keep us informed as I think its realy interesting.

[chrisc]

Thanks, being a fellow air cooled traveler and all, in my heart I would like them to succeed.

So it looks like they have half a chance, if the challenges F5Dave mentioned dont catch them out.

If your following their progress please keep us informed as I think its realy interesting.

I'm following their progress and will keep informed.
I thought about scanning and putting up the previous editions of the article but I don't want to piss them off. I wonder, because: you can't buy the old editions of the magazine, it may encourage you all to buy the future magazines and it's advertising for them. What you all think?

[RomeuPT]

I would like the opinion of everybody on this.

I will measure my engine primary compression (NSR 125 engine with old RS gp Cylinder), a couple years ago I have seen someone using grease to fill the exhaust and the reed cage, so oil does not exit the crankcase. What is the better way to do this? Thick grease and thick oil, so there are no leaks?

With the numbers Wobby as exposed he calculated primary comp. with the total displacement. In theory should'nt the displacement after transfer close also taken into account?

My idea is to fit a longer Rod, the crankcase is more enclosed a bit than the RS, but, because the cranck halfs have less volume than those of the RS 125 I suspect that primary Comp might be very identical. So if the value is already low I would have little possibility to play with rod lenght.

Regards

[TZ350]

What do you all think?

Ask them, and send a link so they can see were interested.

[Flettner]

http://i854.photobucket.com/albums/ab102/GerbilGronk/Mr%20VMX%2010th%20Anniversary%20Series%202012%20-%202013/Round%205%20Wanganui%2020%20April%202013/IMG_6687_zpsbda45d16.jpg

Fuel injected twostroke second in national MX series. Only failures throughout the whole season were a foot peg braking off and a clutch bearing failure. EFI performed seamlessly through out the whole series. Who says EFI twostrokes can't work?
No it didn't come first but that's not the bikes fault!
It will be interesting to see how TZ's EFI works out.

[F5 Dave]

I agree it certainly won't be easy but I found this on BDKs webpage, they recon just under 20hp at 10K, and 98 mph, here: http://www.bdkraceeng.co.uk/Bike5.html

A program I have that predicts top speed 1/4 mile etc also seems to think 21hp may just do it (with no wind on a nice day with no slope :confused:) It also uses a predicted Cd.

Dave

Dave

I've assumed 25hp as that's what derestricted UK 125s seemed to need to break 100 in old mag tests (going from a foggy & not hugely invested interest). they weren't building a stream liner, just a std bike.

Sorry TZ seem to have misplaced the older mag with BMEP estimates. If BDK were able to get almost 20hp out of a 93cc aircooled at only 10,000rpm then it exceeds anything I've touched so I'll have to shut my mouth, but I'd want to see it on a known dyno & smelt the petrol before I paid out any sort of bet.


oh yeah in mag they are running a 26mm oko.

[husaberg]

He needs a sustained 25hp from an aircooled bike that will be under load for a serious amount of time & a considerably oversquare linered arcane engine with quite a small carb. + it doesn't sound like he has the experience with small engines.

Yes it can be done. Speedpro's engine downsized to 83cc handily makes 25hp, but that is assuming a shrink ray type shrink, not just destroke it to 50cc bottom end & hope it will be as efficient.

Also there is the revs he is not talking enough to get that power I think.

I just don't see someone knocking it up in the timeframe of a magazine article. I predict a 92mph with a lot of 'gallant effort' & 'if onlys'

prepared to be proven wrong, best wishes & all.

Not familiar with the bike or magazine, but if they want 100MPH why do they need 25 HP? NSU achieved 121 mph with only 12.8hp (50cc supercharged with a wankel? i think supercharger) in the 1950's with clever aerodynamics.

Anyway something i didn't know until i glanced at a book today was Wankel also supposedly did design or work on a disk valve engine for a torpedo in WW2 disk valve foul stroke.
http://www.douglas-self.com/MUSEUM/POWER/unusualICeng/RotaryValveIC/KM8%20torpedo%20a.gif

Left: Cross-section of a Junkers Jumo KM8 disc-valve engine, enclosed in its torpedo casing.
The disc valve is visible on the right side of the engine, just above the piston.

The engine had eight liquid-cooled cylinders of 90mm bore by 85mm, stroke arranged as a V-8 with a 90deg angle. The total swept volume was 4.34 litres and the compression ratio was 6.6 to 1. Output was 275 HP at 3650 rpm. It ran on a mixture of petrol, oxygen, and its own exhaust gas- the latter presumably to dilute the oxygen to a manageable content.

A production order for 100 engines was issued towards the end of WW2 but was never completed. A prototype was examined by British and American intelligence engineers, who concluded it was "a progressive trend in automotive development." It would appear they were wrong.


http://www.douglas-self.com/MUSEUM/POWER/unusualICeng/RotaryValveIC/RotaryValveIC.htm#fw
http://www.douglas-self.com/MUSEUM/POWER/unusualICeng/RotaryValveIC/KM8%20torpedo%202a.gif

Above: Longitudinal section through one cylinder bank of a Junkers Jumo KM8 disc-valve engine.
The disc valves are fitted between upper and lower cylinder heads. They had teeth on their periphery, and formed two gear trains without the need for idlers or extra gearwheels. The train of valve discs was driven by bevel gears from the crankshaft, with splined connections to allow valve timing to be altered.


In 1951 NSU became interested in Wankel's rotary engine project, and he joined them. It seems very likely he was involved in the design of the Froede rotary valve shown above.

NSU allegedly hired him for his disk valve sealing expertise for engines, for 2 stroke development which later lead to the Wankel rotary engine.

Walter froede was at the time NSU head of research.

[TZ350]

Fuel injected twostroke second in national MX series.

Only failures throughout the whole season were a foot peg braking off and a clutch bearing failure.

EFI performed seamlessly through out the whole series. Who says EFI twostrokes can't work? No it didn't come first but that's not the bikes fault!

It will be interesting to see how TZ's EFI works out.

Excelent result ... OK, so now we know, home brew 2-stroke fuel injecting at the sharp end of competition is a real possiblity and reliable to boot.

Thank you for helping me out with my own EFI project.

[F5 Dave]

Not familiar with the bike or magazine, but if they want 100MPH why do they need 25 HP? NSU achieved 121 mph with only 12.8hp (50cc supercharged with a wankel? i think supercharger) in the 1950's with clever aerodynamics.
. . ..
If you read my post form 10 min ago you'll see its supposed to be a street sleeper Moped, not a tricky speed tool.

[husaberg]

If you read my post form 10 min ago you'll see its supposed to be a street sleeper Moped, not a tricky speed tool.

No it doesn't and neither does Robs?


okay the other one might (No not really) but i was adding the NSU and junkers stuff...........

I guess the post time and order is decided when you submit a reply rather than when you hit reply to Quote?

[TZ350]

281862

Got me a nice new 10mm ball end milling cutter today.

281863

Its great for digging holes and leaves a nice radius on the back of the newly excavated transfer ducts.

281868

Hopefully I will have better directional control of the flow streams this time.

Following Wobblys mantra of "Low and Wide".

The plan is to make the transfers as wide as possible and open the main port at 116 and the secondary's and boost at 117.5 ATDC.

With 1ex, 73% wide, that opens 80 deg ATDC. STA's and EngMod2T simulation at 83% combustion efficiency. Transfer Port Details.

[TZ350]

if BDK were able to get almost 20hp out of a 93cc aircooled at only 10,000rpm ... and they are running a 26mm oko.

OK lets have a look at something Bucket and Thomas put together.

Data goes into the yellow squares, answers appear in the green ones.

Enter 20hp (this number should be crank hp), 0.093L for 93cc and 10,000 rpm in the 2-Stroke BMEP calculator.

281880

I make it 140 psi BMEP or 9.6 bar, pretty good numbers for an air cooled, but certainly possible.

[RomeuPT]

281862

Got me a nice new 10mm ball end milling cutter today.

281863

Its great for digging holes and leaves a nice radius on the back of the newly excavated transfer ducts.

281868

Hopefully I will have better directional control of the flow streams this time.

Following Wobblys mantra of "Low and Wide".

The plan is to make the transfers as wide as possible and open the main port at 116 and the secondary's and boost at 117.5 ATDC.

With 1ex, 73% wide, that opens 80 deg ATDC. STA's and EngMod2T simulation at 83% combustion efficiency. Transfer Port Details.

Will you point the rear angle of the secondary's transfers really towards the exhaust?

Once I had a little experience, a cylinder I was working had that angle, almost towards the center of the exhaust, then I opened the secondarys to give more area, just a bit, without knowing I changed that angle and now was directed more to the main transfers, as result I felt I had loss a bit of peak power, but the engine was broader and botton end seemed a bit better to. This was way before Frits exposed the pizza tower concept on pit-lane. My thoughts were that short circuiting to the exhaust at some point would compliment the power when the exhaust is working on his ideal resonance rpm.

Filling the transfers with epoxy to make the final internal angles might even help keep the gases a little cooler before entering the cylinder than if they are exposed to the aluminium. Right?

Regards

[FastFred]

Fuel injected two stroke second in national MX series.

There should be a brass band playing and ticker tape parade up main street for Flettner.

A fuel injected racing air cooled 2-Stroke. Proving itself over a whole race series, now that's a very good effort, a world first maybe.

[Flettner]

It's just that there is a lot of negitive press about EFIing Twostrokes. I've been told it can't be done, even by those that have had a go. This result must at least show that those that say "can't" are uniformed or doing it wrong. I'm sure what I've cobbled up could be much better with some serious development.

[F5 Dave]

OK lets have a look at something Bucket and Thomas put together.

Data goes into the yellow squares, answers appear in the green ones.

Enter 20hp (this number should be crank hp), 0.093L for 93cc and 10,000 rpm in the 2-Stroke BMEP calculator.

281880

I make it 140 psi BMEP or 9.6 bar, pretty good numbers for an air cooled, but certainly possible.

Actually I did re-read one of the latest issues & realise its not a 83cc kit the mag is using its a 93cc like the BDK example. 10cc will make quite a difference.

Still think 10,000 & a 26mm carb will be a step too far, but I don't want to sound like a knocker & I'm seemingly unintentionally taking that role.

[F5 Dave]

No it doesn't and neither does Robs?




. . .. they weren't building a stream liner, just a std bike.



how much clearer do you want?

[wax]

It's just that there is a lot of negitive press about EFIing Twostrokes. I've been told it can't be done, even by those that have had a go. This result must at least show that those that say "can't" are uniformed or doing it wrong. I'm sure what I've cobbled up could be much better with some serious development.

I think alot of the negative press is by some clown called hgt causing all that. He was the most arrogant prick out there and so everyone just enjoyed watching him fail. Which he did on numerous occasions quite badly.
With the collective mind of a few smart people I think you could get it to work as to how well Im not sure. The issue I see so far so is no one is measuring airflow.

[FastFred]

With the collective mind of a few smart people I think you could get it to work as to how well Im not sure.

Flettners one already works and has completed the National VMX series finishing second overall, so the setup must be fairly stable.

TeeZee's one is in the early stages so not to sure about that but as you say, a few collective minds and with Flettners experienced input it should be a runner too, then there is Burts 2-Stroke EFI project.

[TZ350]

Posted as someone wanted to see what they looked like.

281891

25 and 45 L/hr Fuel Pumps and 3K Ohm TPS.

281892

128g - 248g - 490cc - 650cc injectors

281890

The smaller injectors have a securing screw hole the bigger ones need to be clamped down by the fuel rail.

These are some of the optional parts that can be purchased with the EFI Kits from Ecotrons.

http://www.ecotrons.com/2_Stroke_Small_Engine_EFI_kit.html

[husaberg]

There should be a brass band playing and ticker tape parade up main street for Flettner.

A fuel injected racing air cooled 2-Stroke. Proving itself over a whole race series, now that's a very good effort, a world first maybe.
http://www.motorcycle.com/manufacturer/honda/quick-take-honda-exp2-15170.html

In fairness to Neil their R&D team and budget was a little larger...........like a million times.

It's just that there is a lot of negitive press about EFIing Twostrokes. I've been told it can't be done, even by those that have had a go. This result must at least show that those that say "can't" are uniformed or doing it wrong. I'm sure what I've cobbled up could be much better with some serious development.
I must admit i was one of the nay thinkers ,so virtual hat has now been virtually eaten.

how much clearer do you want?
err...I wasn't replying to that quote though :bleh::rolleyes: anyway thanks for clearing it up.
I wonder why they went for such a small carb. The local Kawa ar80 "ish" seems to go pretty well.
Judging by Vid. At Ruapuna it seemed able to chew quite a few FXR150's

[F5 Dave]

Ahh that blue RS framed 80, yes it went ok, but my MB could chew it up & spit it out. Also that is a late watercooled model.

[husaberg]

Ahh that blue RS framed 80, yes it went ok, but my MB could chew it up & spit it out. Also that is a late watercooled model.

You might have a point re the motor, to tell you the truth i have never looked at it (Greymouth is a big city don't ya know.)
Not sure exactly what the motor is I think it might be Philippino or something ? His father called in to work one day, but unfortunately it was one of those rare days when i was a bit distracted with work, Rather than visa versa:shifty:


http://www.youtube.com/watch?feature=player_embedded&v=NiDJedW5ts0#t=220s
The Video bike is the Dutch Stig. Ruapuna. Everytime i watch most the North Isand video's i can't help but think how lucky us South islanders are what with all that space for straights and larger tracks.
This is the Kawa Dave and i were talking about.(It appears around 3.40 on the timer) Maybe someone will chip in with some info?

The Rider on 981 hasn't ridden in the last 3 years.He is filling in for Justin ,whilst Justin is out of action with his shoulder injury.All in all Liam rode the ar80 ,like he hasnt been out of racing for 3 years .Well done YOW you showed them their is life in the old dog still.

The other Video of the Dutch stig out by himself is also worth a look (if not a listen.)

http://www.youtube.com/watch?feature=player_embedded&v=5CUU_HBYRNw

I hope Mike doesn't mind me posting them:niceone:

[Yow Ling]

. The issue I see so far so is no one is measuring airflow.

You could make a pretty reasonable approximation from throttle position and rpm. this would be similar to the alpha N stuff tz was describing. one of the problems with measuring airflow is the sensor, it big, has restrictions, even the hot wire and ultrasonic ones with low restriction are usualls sized for car sized engines

[TZ350]

281895

Friday night, a few beers and chewing the fat looking at what can be done with the CVT idea.

281896

Interestingly the straight cut primary/starter gears from a 4-Stroke mini/pit bike have the same primary gear shaft centers as the GP. Expect to see straight cut primary gears from a pit bike in my next GP engine.

281897

The CVT has pretty much the same gear ratio range as the GP gear box.

So one possibility is to run the variator of a modified gear box input shaft and run the rear pulley on a shaft through the engine mounting plates with the front chain sprocket behind it. Effectivly replacing the GP's gearbox with the CVT.

That would have the benefit of reduced rotational speeds on the variator and clutch and friction from pulling the belt out from between the sheaves, which I like, but the disadvantage of increased torque having to be transmitted by the belt and clutch shoes.

281894

Another possibility is to cut the rear reduction box off and weld the whole thing onto the back of a GP engine that has had its own gear box cut away.

[richban]

Everytime i watch most the North Isand video's i can't help but think how lucky us South islanders are what with all that space for straights and larger tracks.


Not going to let you get away with that one. We have plenty of big tracks mate. We are just lucky we have some great short ones as well. For hard, mental, crazy racing you just can't go past a Kart track.

[TZ350]

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=281514&d=1366200788



Will you point the rear angle of the secondary's transfers really towards the exhaust?

281905

I was planning on a rear transfer like the one on the left in your picture. I have heard about having a hook in the transfer and imagined that was what the one in the picture was.


Once I had a little experience, a cylinder I was working had that angle, almost towards the center of the exhaust, then I opened the secondarys to give more area, just a bit, without knowing I changed that angle and now was directed more to the main transfers, as result I felt I had loss a bit of peak power, but the engine was broader and bottom end seemed a bit better to. This was way before Frits exposed the pizza tower concept on pit-lane. My thoughts were that short circuiting to the exhaust at some point would compliment the power when the exhaust is working on his ideal resonance rpm.

Thanks for the tip, I will look at this some more.

281907

Yes your right, it looks like the type 2 boost port will be better.


Filling the transfers with epoxy to make the final internal angles might even help keep the gases a little cooler before entering the cylinder than if they are exposed to the aluminum. Right? Regards

I am going to position the injectors in such away that any excess wet fuel impinges on the transfer walls, the idea being that as it evaporates it also cools the cylinder. 2-Strokes have always been fuel cooled to some extent, I am just going to make a virtue from it.

[TZ350]

Page 760 .....

282885


I have looked and read that info about pipes twice. Very Useful.

Thing is, when I was using the demo Expansion Chamber Design Prog (http://www.bevenyoung.com.au/mota.htm) that is very used here and having all the Honda desing's in the table I notice that Mota makes ultra sharp final diffuser cone, so the previous exhaust's I built all have around 11º degree diffuser angle, the mid section is longer, and the diffuser starts later than the 30/33% rule of thumb.

Other thing is all Honda Exhaust have the last diffuser the steepest one, and Aprilia uses the other concept of biggest and longest middle diffuser, I would like to know if anyone used a pipe in Honda RS with the Aprilia type.

I just want to discuss the angles and length's.


Here is the hell RS125 pipe design that has basically everything I know embedded in its concept, the 800mm length is for a 200* Ex only with a
proper ignition curve and powerjet switching.

The first 25 mm is an oval transition flange ( 41 by 32 ) in the duct, out to a 41 header.
The stinger nozzle is 23.2 with 25 stinger pipe. Dual stage header, and steep mid diffuser create the deepest and widest depression around BDC at 13,000, with tons of overev power.

The 120mm Honda and Mota pipes wont even get close, especially with the final diffuser being the steepest,it creates the Ex port depression way too late in the cycle to help at the natural peak of a 200* Ex around 13,000 and into the all important overev past 14,000.

Several details can be jigged to work better than this design, but thats for you guys with a good code to work with to figure out from looking closely at the pressure ratio traces.


For this top bmep engines we use 14º baffle angles, right, and if we go for slower less reving bikes, should we decrease this angle right? I have seen an amount of longer pipes (both handmade and aftermarket), like 950 and 1000 mm lenght for bikes who get peak power around 9k/10k rpm that have short baffles, like the ones of RS lenght, and the YZ and CR 125 have very long baffles.

So I guess someone is doing a really bad job.

Made an Exhaust for a friend with a DTR 125 (peak at 9500/10000), using one 235mm 12,1º baffle, worked better against a known good aftermarket exhaust, my friend already sold the aftermarket pipe.... :cool:


The position of the start of the mid diffuser is the key to making top end and overev power.
Earlyer Aprilia and Honda designs had the steep diffuser starting right after the header, but this pulls the Ex depression down too early around BDC.

It works alot better for power production to space the main cone further along, and make the angle steeper to promote higher depression values by using a shallow last diffuser angle.
This also increases the main body volume.

I have been making the first and last diffusers around the same angle, just coz it feels right, and the sim says fill your boots.
Steep rear cones will work on any engine needing a high specific output, but you must have a digital ignition and powerjet switching, to stop the fast powerdrop off past peak that the short cone will naturally create.

A longer rear will suppress the peak value and allow more natural overev characteristics without digital trickery.


I also believed what I had been told previously ,that large changes in initial diffuser angle would cause flow separation and massive turbulence due to choking.
I built a heap of pipes to come up with a new design for CR125 Moto in SKUSA racing.
One of the tests was to try a design similar to the older Aprilia, with a very steep diffuser directly after the header.
This pipe made good power, but i was sure that if I added a short 25mm section ( the length of a bend segment in the U bend ) between the header and the main diffuser, with
only 1/2 the angle change - it would make more power.
Sadly no free lunch, it was worse by a small margin - bugger, another wives tale down the dunny.
I went on to discover the relationship of best power production, to the shape of the depression waves amplitude around BDC - was super critical to where the main diffuser started.


You have to be careful when using retard to heat the pipe in the overev.
If you continue the retard slope too far,especially if the motor then continues to make serious power - the egt will continue to rise with rpm, and you then end up running a richer main to suppress the now too high egt.
This means you are using fuel to cool, not burning it to make power.
You must flat line the ignition retard as soon as you can in the overev, to stabilise the egt when running full throttle at those peak revs.

You have got the wrong end of the stick re pipe temp Romeu, the highest temp is seen just into the header, the lowest in the belly, and it increases again at the stinger.
Lower temps are seen right at the flange, due to unburnt air/fuel sitting there waiting to be shoved back in.
Aprilia used probes in the flange due to reliability issues I understand,but they would for sure have found a correlation between the readings there, and the " normal " one along the header.

Three angle rear cones were a legacy design that Jan was forced to use, as Frits explained.
But it is a long time issue for me that so often a sim will be strongly telling me that the system works well ( and it annoys Neels as well I know ) but in reality I have never been able to get more power on the dyno
than a 14* straight tailcone - believe me I have waisted so much time on this, and have given up.

In a KZ2 125 kart engine with the main Ex port opening at 82.5* you would normally have the Aux about 1.5mm lower - lift them up flat and you loose around 3 Hp at 10,000, 1 at peak 13,000, but worst is
up to 6Hp at 14,000 where the curve is dropping rapidly.
I tested a cylinder with the main down at 84* and the ports all opening flat made the most power there, but sadly that power was well down on what is possible with a higher main and staggered Aux.

Re the diffuser position for RS125 - the Aprilia rotary valve engine was , by design, run to 14500 on track, so was able to use the slightly shorter header end position.
The reed valve Honda is virtually impossible to get to run up there with any effective gains, so makes more power in its useable band with the slightly longer header.



If I were to explain pipe design I would need to write a book,but in general things are pretty straight forward in relation to the % values.
End of header is always 31 to 33% and end of diffuser is always 62 to 68%.
To see the effect of a silly long header, you can watch the pressure ratio at the Ex port, and thus the effect this has on the depression in the cylinder.
We are looking for the lowest and widest negative ratio we can get around bdc when the transfers are fully open.
A long header delays the beginning of the depression too late in the cycle, when in the power band.


The % I quoted for header means that portion of the length from piston to rear cone end.
Its from the piston to the beginning of the diffuser, what happens in between isnt relevant.
Unless of course you use a small Ex duct and a bigger header, that makes more power.
And of course same for the diffuser end, that is simply 66% of the length from the piston to the end of the rear cone.

So to start with, I understand some of the key elements are.

(1) The end of header is always 31 to 33%

(2) The end of diffuser is always 62 to 68%.

(2) We are looking for the lowest and widest negative ratio we can get around bdc when the transfers are fully open.

Time to warm up my EngMod2T program and use the Pipe Development part of it to get started.


In a race 2T we are always fighting power range Vs peak power.
Shorter diffusers create steeper angles,thus greater wave amplitude, but this narrows the effective band width.
So - in general the best compromise is around 66%.

The plan is a peaky pipe at 9k rpm and to extend its range using the Trombone effect.


The short answer is yes. But why is it that each time you people sit down for five minutes to write a question, I have to sit down for two hours to write an answer?:msn-wink:

When the exhaust port opens, a pressure pulse starts moving through the exhaust pipe. It is reflected at the end cone and it should be back at the cylinder just before the exhaust port closes.
Next a part of this reflected pulse bounces off the partly-closed exhaust port and a residual pulse starts moving down the exhaust pipe. This residual pulse too is reflected by the end cone and starts moving back to the cylinder. Ideally it will arrive at the exhaust port just when the port opens again. Then the cylinder pressure and the pressure of the residual pulse combine their energy and the resulting pulse will be stronger than the pulse from the previous cycle. And the combined pulse from the next cycle will be stronger still, and so on; we have achieved true resonance.

Some may argue that we want a low pressure in the exhaust pipe when the port opens because then the spent gases will experience less resistance while leaving the cylinder. But that is not true. Gas flow depends on a pressure difference ratio. But once that ratio reaches 2, the flow velocity will reach Mach 1, the speed of sound. Raising the pressure difference any further will not raise the flow velocity any further.
The cylinder pressure at exhaust opening can be as high as 7 bar and the pressure of the reflected pulse will be about 2 bar. Thus the pressure ratio is well above 2, so lowering the pressure in the exhaust duct outside the cylinder will not do any good to the flow.

What has the exhaust timing got to do with the 'true resonance' I mentioned above?
The initial pulse starts moving at Exhaust Opening and it has to be back at Exhaust Closing, or a little earlier. This pulse travels with the speed of sound and its journey up and down the exhaust pipe will take t seconds.
The residual pulse starts moving at Exhaust Closing and it has to be back at the next Exhaust Opening. This pulse also travels with the speed of sound and its journey up and down the exhaust pipe will also take t seconds.
So from EO to EC takes t seconds and from EC to EO also takes t seconds. In English: the exhaust port should be open just as long as it should be closed.
Assuming that the crankshaft rotates with a uniform speed, this means that the crank angle during which the exhaust is open must be equal to the crank angle during which the port is closed. So both angles must be 180°.

I developed this line of thought some 40 years ago, but when I first published it in 1978 (in the motorcycle magazine Moto73 of which I was the technical editor) everybody called me crazy. Some people still do, but I got used to it :p.

Above I made a couple of assumptions. The crankshaft does not rotate with a uniform speed, but at high revs the deviation is negligible. In case you really want to know, I did the math for the Aprilia RSA125. At a nominal rpm of 13,000 the minimum rotation speed is 12970 rpm @ 107° after TDC and the maximum value is 13031 rpm @ 356° aTDC. What's more significant: the deviation in crankshaft position from truly uniform rotation is always less than 1°. So that really is negligible.

Second assumption: both the initial pulse and the residual pulse move with the speed of sound. Not true: the pulse pressures in exhaust waves are so high that acoustics rules do not apply any more. We are dealing with gas dynamics here and the stronger a pulse, the faster it moves. Since the residual pulse is weaker than the initial pulse, they move at different speeds. But we will leave this aside for now.

Third assumption: the initial pulse starts moving as soon as the exhaust port starts opening. More or less true, but we are not interested in the first weak appearance of the pulse; we want to know when the pulse reaches its maximum amplitude. And that requires a certain amount of open exhaust port area. It turns out that for our desired theoretical exhaust timing of 180° we will need a geometrical exhaust timing of about 190°, depending on the shape of the port: does it open gradually or does it open over its full width all at once.

The obvious question will be: why has the Aprilia RSA125 a geometrical exhaust timing of about 200°? True, at 190° the maximum torque value would be higher, but the engine would not want to rev because the blowdown time.area would be too small.
The 200° are a compromise: a bit less torque and a bit more revs; as long as the torque decline is smaller than the rpm rise, we gain horsepower.


Any sim you are using to design any part of a 2T engine, and dont take full account of the ignition timing regime - is a waste of time.
I can design a completely shit pipe, and with ignition tricks, make it work 1/2 way reasonable - in a sim and on the dyno.
But its impossible to design a really good pipe that will work well in reality, if you dont define exactly the ignition curve it will see when running.
You can change the temp in the header as seen by the egt probe, from 450 to 650C by simply taking away 4 degrees of timing when in the overev,so the pipe that before had a vertical power drop off
at 13500, now holds 50 + Hp out to 14500.
Same with having the solenoid powerjet scenario,you can easily make a pipe that will spin to 14,000 in the sim, but sadly it has no mid power to speak of at all.
Change the A/F ratio from 12:1 to 14:1 past torque peak, and a MUCH longer pipe, now has a ton of mid, then holds its torque up long enough for that " too long " TL to work at least another 1000 rpm than before,due to
the burning mixture now dumping a huge heat load out the port.


Cheers, I'd thought that would be the case based on what you have posted before.

It seems a little backwards designing the pipe to suit an ignition with a fixed curve shape but I'm going to have to go that way until I can afford to upgrade to an Ignitech or similar. That's going to have to wait for a long time though.
It would be great to able to change it but I have to make some compromises due to available resources.

Do you find the A/F ratio change in engmod close to reality? or do you just apply experience in that area?

Also I WILL be designing a completely shit pipe, relatively speaking, I just hope to get it less shit with the sim.

Using the Sim I've been able to compare different designs and I'm confident I can make more 'Simpower' than other pipes that I could be putting on the bike.
I would have thought the RG400 (I think it is anyway...) pipe I have on it now would be reasonably close but it appears miles off in practice and in the sim.

That is one thing about the 100 vs an Air Cooled 125; a random pipe of any old 125 seems to work OK compared to putting the same pipe on a 100.


You will spend more time and money friggin round with the old unknown ignition just over a longer period than biting the bullet for a programmable.
I went through this with suspension, spent countless hours rebuilding shocks, buying shims and seal heads. Finaly bought a set, bolted them on set the rebound and have not touched them since. They work 100 times better than my best efforts.

MOTA is a massive compromise especialy on the ignition side. However it will provide some useful info on the return wave timing which is what you should concentrate on. As Wob has said probably 100 times and it's worth repeating "big depression/lowest pressure at BDC" and return wave arriving before the exhaust port closes. Get that right then look to get the rpm peak where you want it, finaly jiggle the TL length %'s to what Wob has already posted. Viola no more shit pipe.

[wobbly]

I experimented with the B port rear wall hook when testing the BSL cylinders.
Honda at the time had a steep hook, but Aprilia and the cylinders from SA Design for the 500 GP flying web engine had smooth radi pointing to 1/2 way
between bore centre and the rear wall.
The smooth radi made better power up to the peak.
I also re-angled the front wall of the B port to perpendicular to the bore, as is done by Aprilia.
Although I didnt have the flat entry to the septum ( the angle changed smoothly down the duct ) this made more power everywhere.

[NAR RG500]

I experimented with the B port rear wall hook when testing the BSL cylinders.
Honda at the time had a steep hook, but Aprilia and the cylinders from SA Design for the 500 GP flying web engine had smooth radi pointing to 1/2 way
between bore centre and the rear wall.
The smooth radi made better power up to the peak.
I also re-angled the front wall of the B port to perpendicular to the bore, as is done by Aprilia.
Although I didnt have the flat entry to the septum ( the angle changed smoothly down the duct ) this made more power everywhere.

Hey Wobbly,

Sorry to Hijack thread but could you please PM me regarding RG cranks.

Thanks a lot,

Neil

[Muciek]

Guys I want to tune my engine right but I have few questions (Engine 70cc 44s x 45b 21mm carb reed valve ). How should I calculate window in cylinder for reed valve , and how big should be transfers from crankcase (I want to use 230* open inlet (power porting from bell book)).I heard about a ratio that area of the ports feed from crankcase should be 1.2/carb area (in my case it is 21mm carb 346,19mm2 area). But I have seen cylinders with much bigger windows and small carbs and it was working good. What should I do? Greetings

[chrisc]

http://www.motorcycle.com/manufacturer/honda/quick-take-honda-exp2-15170.html


Honda plan to campaign the EXP-2 again next year. The company says it has no plans to make a production engine right away, but from the success so far, we'd predict that the world's cleanest two stroke motorcycle will be in production before the year 2000.

Cough :Pokey:

[husaberg]

Cough :Pokey:

Blame Yamaha for that one with the YZ400F. Husaberg as well played a part

Honda have a long history of doing something grand just because they can. Corporate masturbation i guess.........

Look at the NR500 once Freddie (yes freddie was pretty special)proved it could be near competitive.It even won a non GP race against Kenny's Yamaha.(Luguna Seca 1981) So the next year they started building what they could/should have all a long.

[bucketracer]

281897

The CVT has pretty much the same gear ratio range as the GP gear box.

So one possibility is to run the variator of a modified gear box input shaft and run the rear pulley on a shaft through the engine mounting plates with the front chain sprocket behind it. Effectivly replacing the GP's gearbox with the CVT.


281917

TeeZee if you move the engine forward there looks to be plenty of room for the CVT.

281918 281919

With new shafts and the CVT you might even be able re arrange the GP gear box like this.

[FastFred]

<iframe width="420" height="315" src="http://www.youtube.com/embed/4vAw1CC4A3g" frameborder="0" allowfullscreen></iframe>

How's this for a 2.5cc two/stroke doing over 300km/hr at 30,000 rpm?

<iframe width="420" height="315" src="http://www.youtube.com/embed/u0MN6NHChZI" frameborder="0" allowfullscreen></iframe>

and a 5cc 2/stroke breaking the world record - 335.8 km/h - insane rpms

[Frits Overmars]

While we're on the subject of record breaking: http://www.youtube.com/watch?v=FTmg1tq031A
Here's a 35,000 rpm MB40 engine doing a bit of radio-controlled(?) flight at over 400 kmh, breaking...every bone in the fuselage :laugh:.

[husaberg]

While we're on the subject of record breaking: http://www.youtube.com/watch?v=FTmg1tq031A
Here's a 35,000 rpm MB40 engine doing a bit of radio-controlled(?) flight at over 400 kmh, breaking...every bone in the fuselage :laugh:.

The warm up is a little brutal. how do the starters work direct onto the cone in front of the prop?
Any landing that the pilot can walk/run away from is a good one i guess.

[Frits Overmars]

The warm up is a little brutal. how do the starters work direct onto the cone in front of the prop?
Any landing that the pilot can walk/run away from is a good one i guess.The starter motor has a countercone that is pushed against the model's prop spinner. It's as simple as that.
A friend of mine, ex-world champion F3D flying, has a day job as a Boeing 737-captain (" I'm a bus driver, but I get payed better").
According to this pro "Any landing from which the passengers can all walk away, is a successful landing. And if the plane is still usable afterwards, it was a véry successsful landing".

[RomeuPT]

I experimented with the B port rear wall hook when testing the BSL cylinders.
Honda at the time had a steep hook, but Aprilia and the cylinders from SA Design for the 500 GP flying web engine had smooth radi pointing to 1/2 way
between bore centre and the rear wall.
The smooth radi made better power up to the peak.
I also re-angled the front wall of the B port to perpendicular to the bore, as is done by Aprilia.
Although I didnt have the flat entry to the septum ( the angle changed smoothly down the duct ) this made more power everywhere.

Thanks for this info.

So, the type 2 angle is mostly like that, half way between bore center and rear wall.

Front wall of b-ports in the Honda cylinders are slighty aimed to the rear.

NSR and CRM cylinders came exacly with the Type-1 angle, both sides, maybe because they use 2 rings...

Were, some pics, Honda would arrest me if they were still on 2 strokes XD

A-Kit in picture 4!?

[dinamik2t]

Measuring the primary DC resistance of a coil does not tell you much about its inductance, burn time or the energy release.

A way of evaluating different coils is by measuring their stored energy.

http://www.dtec.net.au/Ignition Coil Energy Testing.htm

Ignition coil stored energy is measured in milli Joules (mJ) and is relatively easy to measure with some simple DIY equipment. Coil energy encompasses time, current and voltage characteristics. Stored energy is a very important factor, it relates directly to spark intensity and burn time. Very few people seem to realise how simple it is to measure and what an important aspect of an optimum ignition system it is, electrical engineers dealing with automotive ignition systems certainly do!
This tester does not measure coil voltage output of the coil, it is for measuring stored energy which, as stated, is extremely valuable information.

Has anybody used the setup described by Dtec to measure any coils/ignitons?

I am in the process of trying to extract some timing data from a cdi, but found a few difficulties, so I measured the coil energy along the way, which is simpler.
I set up a triggering arrangment with the porting motor (up to 15kRPM), a 2.5mm thick iron sheet, cut proportionately to the rotor's dimensions, and an SCR voltage regulator.

The thing is I measured an unexpected signal from the stock cdi, compared to Ignitech or the signal in Dtec's pdf. Second pic is Ignitech Race, third is a stock CDI.

281986281987281988

Does this signal means there are minor "positive" and "negative" sparks after the first one?

Furthermore, energy seems low in comparison with Dtec value. The stock coil is ~0.5Ω Rprimary. Haven't tested a selettra and an RGV250 coil yet to compare.
Would anybody have any numbers from tests?

[speedpro]

The "stock CDI" doesn't lok like a CDI output. It looks like a standard Kettering or points/coil output. The oscillation is the coil resonating with the capacitor once the points open. Nowadays the points are replaced with a transistor but the principle is the same. The rise time of the voltage is a clue as well. CDIs are quick and kettering systems are slow which is why CDIs came along. The slow rise time of the voltage allowed time for energy leakage on a fouled plug. So much so on a badly fouled plug that the voltage never reached the point where it arced over before the coil ran out of energy.

[Flettner]

http://i1056.photobucket.com/albums/t380/uniflow/IMG_0886_zps603a65ff.jpg

You don't need a CNC to make a ball valve.

[speedpro]

and the housing for it?? So that's what you have been busy with all week.

[husaberg]

Not going to let you get away with that one. We have plenty of big tracks mate. We are just lucky we have some great short ones as well. For hard, mental, crazy racing you just can't go past a Kart track.

No need to bite Rich, it was only an observation. I pm'd Rich the old pics of the smallest tightest track. here is the updated one.
It about 2 km away, but on the wrong side of the river.

[Flettner]

I will be making the housing on the CNC ( already have the program) but you could also make the housing by tilting the dividing head at 45 degrees, turn the tool around and generate the inside shape.

[dinamik2t]

The "stock CDI" doesn't lok like a CDI output. It looks like a standard Kettering or points/coil output. The oscillation is the coil resonating with the capacitor once the points open. Nowadays the points are replaced with a transistor but the principle is the same. The rise time of the voltage is a clue as well. CDIs are quick and kettering systems are slow which is why CDIs came along. The slow rise time of the voltage allowed time for energy leakage on a fouled plug. So much so on a badly fouled plug that the voltage never reached the point where it arced over before the coil ran out of energy.

It looked strange for a plain capacitor discharge signal, but I have been wrong many times so I stopped making assumptions -publicly- about things I cannot explain.
Still, the manufacturer reports a "DC-CDI" ignition control... :pinch:

281998

Would you have any bibliography on ignition systems to suggest me speedpro?
Cheers

[Ocean1]

I will be making the housing on the CNC ( already have the program) but you could also make the housing by tilting the dividing head at 45 degrees, turn the tool around and generate the inside shape.

You can make almost a full hemisphere on a lathe by making a tierod/link arm and pinning it between the locked tailstock and the cross-slide. Pays to address whatever backlash issues you've in the topslide feed first. I've got an adjustable length one somewhere around here...

[speedpro]

Still, the manufacturer reports a "DC-CDI" ignition control... :pinch:

281998

The DC part would suggest battery powered rather than stepping up the AC from a generator and the CDI part suggests exactly what it says. Could be the marketing guys got a hold of it before it went out the door though. I think the late '70s when CDIs and transistorised ignitions were coming in that there was some confusion with labelling. I seem to recall seeing something similar on Kawasaki electronic ignitions for the Zs where a quick measure of the coil primary resistance indicated it wasn't CDI at all. I pissed with this quite a bit and built my own battey powered CDI which was triggered off the points on my AC50 bucket racer. At max spark rate using a signal generator to trigger it the current draw was about 10A but it threw a 10mm FAT blue spark. That was about 40,000 sparks/min with absolutely no loss of output.

[Flettner]

I made one of those too, melt tar seal at 10 Km's! Not to be touched. I put more capacitors in it.

[speedpro]

Me and a mate built one each. We upped the voltage from the inverter to the capacitor from 300V to 400V and fitted 2 capacitors for good luck. It wouldn't have been a good idea to touch the primary let alone the secondary. My Ignitech throws a good spark, better than Rob's from memory, but it isn't close to the one I made.

[fatbastd]

Minor point to remember when going to a better ignition (for those to whom it applies): bigger spark = more torque (compared to a crap ignition) = more fuel required. Jet up.

[Flettner]

http://i1056.photobucket.com/albums/t380/uniflow/IMG_0887_zpsb8d0a697.jpg
http://i1056.photobucket.com/albums/t380/uniflow/IMG_0888_zpsbeceacac.jpg

A 32mm ball valve inner, 8mm shafts, ball dia 68.

The home made CDI I built now is used to strobe my injectors. I've coupled a spare coil the the injectors power wire and zippy tied this coil to the coil that triggers the CDI. So when we get an inductance change ( injector powered up or down ) there is enough inductance to trigger the CDI and run a strobe light. Interestingly by changing the polarity on the trigger coil I can " see " injector on, or injector off. Crude but it works great!

[TZ350]

http://www.ecotrons.com/2_Stroke_Small_Engine_EFI_kit.html

I have been trying to figure out how to go about the initial mapping of my 2-Strokes EFI as I want something that is at least close to the ball park, to kick the whole EFI tuning process of with.

First up I need to build the Speed Density map which plots VE (volumetric efficiency) against RPM and MAP (manifold absolute pressure). The big problem is, VE data is not all that easy to get.

But they say you can determine VE from dyno data which is handy because I have a virtual dyno, EngMod2T.

282009

Not to sure about what I am doing, so rightly or wrongly, this is how I have gone about it.

At the moment EngMod2T does not give a VE (volumetric efficiency) vis MAP graph but it does plot DR (delivery ratio) which is basically VE at atmospheric pressure. So I simulated a whole lot of runs at various atmospheric pressures to simulate changes in MAP to see if the engines VE (DR) changed with changes in pressure.

It didn't much, which is no surprise really as the DR or VE is just a ratio between whats theoretically possible at that pressure and what happens in reality. As the pressure changed the proportion of inside air to outside air remained much the same.

282015

But of course the Power dropped of with decreasing atmospheric pressure (simulated MAP).

282008 282014

Because the Speed Density map is more about the lower RPM range I broke the standard atmospheric pressure DR graph into two parts and maximized the scales so I could see them better.

I made up a spread sheet using the DR values at Standard Pressure (1013) and proportioned them across the pressure range from 300 to 1050.

This is the Formula I formulated. (Actual Pressure / Standard Pressure) * Delivery Ratio ... for each RPM/MAP point.

282010

And entered the values into the EFI's 16 x 12 Speed Density map.

282011

Nice picture, I have no idea what the colors mean. But if you look along the blue edge you can see it pretty much mimics the DR (VE) EngMod2T graph. Hopefully that means I have got something right.

Only Lambda, Load, and Alpha-N maps to go.

[TZ350]

http://i1056.photobucket.com/albums/t380/uniflow/IMG_0887_zpsb8d0a697.jpg http://i1056.photobucket.com/albums/t380/uniflow/IMG_0888_zpsbeceacac.jpg

A 32mm ball valve inner, 8mm shafts, ball dia 68.

Flettner that's very nice work.

282019

I am looking forward to trying the new Ball Valve, old Plenum, and modified OKO "24mm Carb Equivalent" and EFI combo with my new better Blow-Down STA cylinder designed using EngMod2T.

[bucketracer]

I am looking forward to trying the new Ball Valve, old Plenum, and modified OKO "24mm Carb Equivalent" and EFI combo with my new better Blow-Down STA cylinder.

Why???? ....... your making good power, why resurrect the old plenum idea again.

[Flettner]

Why not, now it will work without fuel entering the plenum chamber thanks to EFI. As I always say, if some is good, more must be better.

[dinamik2t]

...

...

...

Got to this http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXyzryy.pdf and this http://www.freescale.com/files/microcontrollers/doc/app_note/AN4006.pdf , which are very informative for a beginner.
About the spark duration on CDI's.. If two capacitors were to be discharged together, the second with a slight delay? To your knowlegde is this an already solved 'problem'?

p.s. TZ excuse me for intruding, eh..

[TZ350]

http://www.freescale.com/files/microcontrollers/doc/app_note/AN4006.pdf

About the spark duration on CDI's.. If two capacitors were to be discharged together, the second with a slight delay?

The freescale schematic is very interesting.

How does the two capacitor thing work extending the spark duration??, I am not sure but I don't think you would have to delay the discharge of the second capacitor.

This is what I think I understand, but would be interested in hearing more about it.

Its the flux change of the magnetic field in the coil as the CDI discharges into the coils primary windings that builds up the spark voltage but once the spark jumps the gap its duration is the length of time it takes to discharge the capacitors and the magnetic field to collapse.

There can only be spark voltage while the magnetic field is in a state of flux, either building up or falling down it doesn't matter, there just has to be change going on in the coils magnetic field for energy to be present at the spark plug gap.

The old 6-12V battery coils Flux was to slow building up (lack of driving voltage) to make a spark but when the points opened the change in Flux was fast enough for the collapsing (Fluxing) magnetic field to make 200 to 400V in the primary and that induced a high enough voltage in the secondary for a spark at the plug.

CDI's hit the coil hard with 200 to 400V driving a lot of current through the primary side of the coil and the magnetic field builds up so fast it induces a massive voltage in the secondary and the resultant spark and energy keeps flowing across the plug gap until the field has collapsed again.

The strength of a magnetic field is proportional to the current in the coil and its the CDI's voltage that drives the current. But the capacitors voltage fades away as the current is drained.

So maybe the current capacity of more or bigger capacitors could actually allow the CDI's voltage to drive the magnetic field even higher after the spark has jumped the gap. Unlike the poor old 6-12V battery coil where when the points opened and the current stopped there was only one way for the magnetic field to go, and that was down.

I would be interested in knowing more about this.

[Muciek]

For a good CDI spark you need to match the capacitor in the CDI module and coil. Here's my DC CDI https://www.youtube.com/watch?v=zNcA0oYLj1s using 12V source (battery was dead , so power was from stator) output 360V. I have also bulid 400v ( https://www.youtube.com/watch?v=OhG4M2WEM9w ) and 600v version but there was problem with cooling and coils were dying like flies. That one one video need about max 2A it's very high efficiency (over 90%) and compact it looks like a cigarette box.

[dinamik2t]

TZ, I was thinking of sending a second ignition pulse, say at about 1/2nd of the duration of the first, from a second capacitor.
Would it be possible coil wise though, as you say?

[TZ350]

I was thinking of sending a second ignition pulse, say at about 1/2nd of the duration of the first, from a second capacitor. Would it be possible coil wise though, as you say?

My understanding is limited to thinking in terms of coil flux, and nothing happening at the plug gap unless the magnetic field inside the coil is in a state of flux.

Are you looking for two spark events? its possible but you have to wait until the first spark is extinguished, ie the magnetic field has collapsed in which case the crank may have moved well beyond TDC.

You need to look at the time lines, I would be interested in how long a spark lasts and how many degrees of crank rotation that represents.

More research is required ... Google is our friend. try "spark burn time"

http://www.globaldenso.com/en/products/aftermarket/plug/basic_knowledge/spark/index.html

http://spdispark.com/pages/frequently-asked-questions-spark-duration

http://www.auroraelectronics.com/ignition_systems_-_basics_to_high performance.htm

Multi spark only effective at low RPM http://www.dtec.net.au/Multi Spark Ignition.htm

http://www.daytona-twintec.com/tech_ignition.html

Testing Plug Wires http://www.mr2.com/TEXT/DavidKucharczyk/ignition.html

http://www.acuravigorclub.com/Timely-Topics/Timely1104-2.htm

http://forums.turbobricks.com/archive/index.php/t-50682.html

http://www.not2fast.com/ignition/cap-dis-ignit-cdi.pdf

Plasma Spark ..... http://spdispark.com/pages/about-spdi-spark

Plasma ignition, now that looks interesting, by the look of it, its a real mans ignition that can weld 1/2" plate.

[TZ350]

Why???? ....... your making good power, why resurrect the old plenum idea again.

282074

This is a back to back test with a 24mm carb vis a 30, the 30 gave better over rev.

282073

Although I have been able to get 31 rwhp (35ish at the crank) it was hard work and finniky. So I am starting to feel hampered by the 24mm carb restriction.

In the past the plenum made about as much power as a carb could and I don't really expect things to be much different this time.

But now that I have an EFI kit to try I can run the plenum again without the fuel drop out problems of before and maybe this time I can get 31-32 rwhp consistently. One of the things I would like to try is an air chiller inside the plenum so the motor ingests really cold air.

[TZ350]

Posted because someone was asking me about it ....


Page 500 .....
No need to have a peaky engine. Here are Two Very useful Tools. EngMod2T a 2-Stroke simulation package and a handy (and cheep) Porting Calculator from:- http://www.porting-programs.com/ which is based on Blairs work.

Buckets post has links to detailed pictures of how we built the early engine.


Yep, hand drills are good, you can do some quite good work with basic hand tools.

We got most of our improvement by opening up the rear transfer ports. Nothing fancy, a 13mm drill or ball end long series milling cutter will do the trick. These two posts are worth a look to see how rough you can be and still get a good result.


Got me a nice new 10mm ball end milling cutter today. Its great for digging holes and leaves a nice radius on the back of the newly excavated transfer ducts

282142282141282140

STA's for the triple port show that with a bit of work reasonable numbers are possible from the old Suzuki cylinder.

282145282144282143

STA's for a single port Suzuki GP125 cylinder.

Avs bike is a single port with the Exhaust opening 80 degrees ATDC 72% wide, Transfers 114 ATDC and Inlet opening 145 BTDC and closing 80 ATDC. Its a very easy bike to ride with a smooth flat torque curve. The carb is a taper bored 24mm OKO and is 30mm at the engine end and the rotary valve port window area has an effective diameter of 36mm.

If we were doing it again we would probably pay more attention to widening the rear "B" transfers and opening them a little later, like in the EngMod2T data sheets above.

Remember to get those transfers low and wide to maximize specific blow down time area of the exhaust port.

[Frits Overmars]

One of the things I would like to try is an air chiller inside the plenum so the motor ingests really cold air.A fridge in that plenum won't do your total mass and your cornering clearance any good, TeeZee. And anything smaller will probably not have sufficient cooling capacity to make a difference. We're talking about 1300 liters of air per minute....

[TZ350]

.... probably not have sufficient cooling capacity to make a difference. We're talking about 1300 liters of air per minute....

I have a dinky little alluminium radiator that I had thought of running ice water through. The radiator could sit inside the plenum with a fan circulating plenum air through it while the radiator is being chilled by the ice water. Another option is an air/air inter cooler with dry ice or in a bath of ice water or an air/water intercooler with ice water pumped through it. The whole thing was to hinge around the latent heat of fusion of ice.

Yes I will have to run the numbers to see what the thermal requirements would be.

[Yow Ling]

I have a dinky little alluminium radiator that I had thought of running ice water through. The radiator could sit inside the plenum with a fan circulating plenum air through it while the radiator is being chilled by the ice water. Another option is an air/air inter cooler with dry ice or in a bath of ice water or an air/water intercooler with ice water pumped through it. The whole thing was to hinge around the latent heat of fusion of ice.

Yes I will have to run the numbers to see what the thermal requirements would be.

If you go down that route you may as well put the 36mm carb on it as it could be argued that you would be limiting yourself to 100cc.

[husaberg]

I have a dinky little alluminium radiator that I had thought of running ice water through. The radiator could sit inside the plenum with a fan circulating plenum air through it while the radiator is being chilled by the ice water. Another option is an air/air inter cooler with dry ice or in a bath of ice water or an air/water intercooler with ice water pumped through it. The whole thing was to hinge around the latent heat of fusion of ice.

Yes I will have to run the numbers to see what the thermal requirements would be.

At the risk of sounding like an industry insider, i are just not getting it Rob.

The Vehicles that i am aware of that run inter-cooling pressurize the intake, Thereby greatly heating the charge, prior to induction. I can't see how you could achieve a large drop in intake temp, with ambilent air temp without a lot of restriction or over complication.
Beer i mind, I am often wrong though. just mussing.

[chrisc]

Posted because someone was asking me about it ....

Avs bike is a single port with the Exhaust opening 80 degrees ATDC 72% wide, Transfers 114 ATDC and Inlet opening 145 BTDC and closing 80 ATDC. Its a very easy bike to ride with a smooth flat torque curve. The carb is a taper bored 24mm OKO and is 30mm at the engine end and the rotary valve port window area has an effective diameter of 36mm.

If we were doing it again we would probably pay more attention to widening the rear "B" transfers and opening them a little later, like in the EngMod2T data sheets above.

Remember to get those transfers low and wide to maximize specific blow down time area of the exhaust port.

Nice one Rob! I was looking through old posts and I came up with a new forum signature, thanks wob! you got a laugh out of me.

Time to hit the engineering shop for some new tools :ar15:

[TZ350]

OK I looked at some numbers.

Air 1300 L/min

Race duration 15 min

15 * 1300 L = 19500 L of air or lets say 20 cubic meters of air for a race.

At 300K the specific heat of air is nominally 1 kJ/kg K

So at 300 Kelvin (or 27 deg C) it takes 1 kJ of energy to heat (or cool) 1 kg of air 1 deg K (or C as C's are the same size as K's, its just that the K scale starts at absolute zero. The point where all thermal activity ceases and the C scale starts at the freezing point of water).

Now I want to cool the air by 25 degrees so its only 2 degrees C going into the engine. That means I have to have 25 times 1 kJ of energy per kg of air or 25 kJ per kg of air to drop the air temperature 25 deg C.

Now dry air is nominally 1.2 kg a cubic meter at standard temperature and pressure.

So we have 20 m3 of air times 1.2 kg or 24 kg of air consumed in a race.

24 kg of air times 25 kJ = 600 kJ of cooling energy (energy absorption if you like) required for a race.

Heat of fusion of ice is nominally 334 kJ/kg.

It looks like 600 kJ is required and I can get that from 2 kg of ice or two and a bit liters of ice water.

So long as I have not made any real mistakes and I am happy with the weight penalty then it looks possible and the result depends on the effectiveness of the radiator and fan inside the plenum.

[husaberg]

O

Now dry air is nominally 1.2 kg a cubic meter at standard temperature and pressure.

So we have 20 M3 of air times 1.2 kg or 24 kg of air consumed in a race.

24 kg of air times 25 kJ = 600 kJ of cooling energy (energy absorption if you like) required for a race.

Heat of fusion of ice is nominally 334 kJ/kg.



OK but those 24 liters of air what is the contact time the air would have with you medium?

Anyway my all time favourite dubious use of cooling intakes.

Peter Brock won pole position after the top 10 run-off but he had to face the stewards on Saturday afternoon. His team was charged with using an on-board fire-extinguishing system to direct super-cooled halon gas over the intercooler, thus boosting power for qualifying. The stewards found the charge unproven, but the Entrants Association imposed a $5000 fine on Brock for a moral infringement of the rules.

[TZ350]

Brock .... good thinking, deserved a medal.


OK but those 24 liters of air what is the contact time the air would have with you medium?

Unsure, but the plenum at 2.5L is 10 times the size of the engine and with a fan inside the plenum circulating the plenum air and blowing it through the radiator I expect that a lot of the air will get several passes through the radiator (heat absorber) before being inducted by the engine.

Anyway, whatever happens the air will be cooler and denser than it would have been.

[chrisc]

TeeZee has already talked about sleeves, use Thread Tools and View Images to see them.

Anyone who thinks they can win races against the current crop of 20-23 hp FXRs with a low 20's hp 2-stroke is likely to be dissapointed.


who had these 75 hp f3 bikes? but agree 22-24 hp 2 stroke with a good bike set up and rider is all it needs to win gp's


Put the same people on a 2 stroke and the same result me thinks.

Best of current crop is faster than the old dogs for sure. Young hard charging kids that can peddle a 600 fast as well as a bucket are the ones to watch out for. Us old dogs are getting put out to pasture.

I apologise for thread dredging here but it's amusing what is said on the internet then proven wrong. Then it's followed by some old bloke from down sound playing a very small violin only to come second in the 2013 Tokoroa GP

[TZ350]

Anyone who thinks they can win races against the current crop of 20-23 hp FXRs with a low 20's hp 2-stroke is likely to be dissapointed.

I have tried to win races against the current crop of 20-23 hp FXR's and was dissapointed .... :laugh:

[husaberg]

Brock .... good thinking, deserved a medal.

It was clever, i liked the Allan Moffit in your face rule flouting, it cost him points, but it got the rules changed. From memory he also did the same with dry sumps till they made them legal as well.

Round four - Sandown; Allan won the race on Sunday but was eventually disqualified. Both Moffat Ford Dealer cars and most of the other Falcon teams were using illegal roller rockers.


Unsure, but the plenum at 2.5L is 10 times the size of the engine and with a fan inside the plenum blowing plenum air through the radiator I expect that a lot of air will get several passes through the radiator (heat absorber) before being inducted by the engine.

Anyway, whatever happens the air will be cooler and denser than it would have been.

Yes but
30HP/85kg=.353kg/hp
34hp/95kg=.357kg/hp

If you were to pursue this path wouldn't a long thin intake give you a greater surface area for potential cooling like a RSW intake for instance.

[TZ350]

30HP/85kg=.353kg/hp
34hp/95kg=.357kg/hp


I see your point, luckily I have been on a diet.


If you were to pursue this path wouldn't a long thin intake give you a greater surface area for potential cooling like a RSW intake for instance.

How many passes did you say?

[RAW]

It was clever, i liked the Allan Moffit in your face rule flouting, it cost him points, but it got the rules changed. From memory he also did the same with dry sumps till they made them legal as well.




Yes but
30HP/85kg=.353kg/hp
34hp/95kg=.357kg/hp

If you were to pursue this path wouldn't a long thin intake give you a greater surface area for potential cooling like a RSW intake for instance.


The NASCAR guys would have a fire extinguisher filled with nitros oxide, they would release the extinguisher contents about the radiator support panel at a specified time when qualifying, this would be ingested through the appropriately jetted carburetor and wellar, pole position here we come


Some pro stock drag race guys had fitted nitros systems within the dry sump swirl pot, nitro lines would be inserted within the oil lines of the dry sump system to conceal them, once at the valley cover / under the intake manifold seperater plumbing and nozzles were hidden to feed each intake runner, this all came to the light when a system exploded, most likely a oil Vs pressure problem, shame these ideas men didn't understand how a diesel works

[husaberg]

I see your point, luckily I have been on a diet.



How many passes did you say?

Thats just mean, but it would also mean three potential heatings on its trip past the Ballvalve<_<

[TZ350]

... three potential trips past the Ball valve ...

I hadn't thought of that .... I must make a video clip of it. http://www.kiwibiker.co.nz/forums/images/smilies/laugh.gif

[Frits Overmars]

....the Entrants Association imposed a $5000 fine on Brock for a moral infringement of the rules.In my book there is no such animal as moral infringement. There are good readers and there are badly written rulebooks. Either something is laid down in writing, or it isn't.
Whenever someone mentions"'the intention of the rules" you can be sure that the rules are rubbish.

[husaberg]

In my book there is no such animal as moral infringement. There are good readers and there are badly written rulebooks. Either something is laid down in writing, or it isn't.
Whenever someone mentions"'the intention of the rules" you can be sure that the rules are rubbish.

Frits if i may, how does one go about designing a blance shaft and settling on the starting point for the weight?
Is there a simple formula or rule of thumb?

[Frits Overmars]

Frits if i may, how does one go about designing a blance shaft and settling on the starting point for the weight? Is there a simple formula or rule of thumb?You may, Husa. The picture below may give a first impression, and you'll find the whole story here: http://www.tonyfoale.com/Articles/EngineBalance/EngineBalance.pdf (http://www.tonyfoale.com/Articles/EngineBalance/EngineBalance.pdf)
282158

[FastFred]

OK I looked at some numbers.

It looks like 600 kJ is required and I can get that from 2 kg of ice or two and a bit liters of ice water.

It looks possible and the result depends on the effectiveness of the radiator and fan inside the plenum.

2kg of ice, that is not such a big fridge, the idea might be possible. :eek:

[crazy man]

I apologise for thread dredging here but it's amusing what is said on the internet then proven wrong. Then it's followed by some old bloke from down sound playing a very small violin only to come second in the 2013 Tokoroa GPand what did l say is wrong couse it just happen ( but agree 22-24 hp 2 stroke with a good bike set up and rider is all it needs to win gp's)

[jasonu]

Anyone who thinks they can win races against the current crop of 20-23 hp FXRs with a low 20's hp 2-stroke is likely to be dissapointed.


I have tried to win races against the current crop of 20-23 hp FXR's and was dissapointed .... :laugh:

Maybe you should try it on a 20hp 80...<_<

[chrisc]

and what did l say is wrong couse it just happen ( but agree 22-24 hp 2 stroke with a good bike set up and rider is all it needs to win gp's)

I added your quote not to say you were wrong, rather to point out you were right... I just forgot to write that part

[crazy man]

I added your quote not to say you were wrong, rather to point out you were right... I just forgot to write that part20 years and l get something right for once must be a record

[Ocean1]

2kg of ice, that is not such a big fridge, the idea might be possible. :eek:

Could be interpreted as stored energy in teh rules?

[Grumph]

Could be interpreted as stored energy in teh rules?

Unlikely i'd think - more likely to be described as water cooling...

What about liquid air if you want to push the boundaries - allow it to drip into the inlet tract....

[Ocean1]

Unlikely i'd think - more likely to be described as water cooling...

What about liquid air if you want to push the boundaries - allow it to drip into the inlet tract....

Was going to suggest dry ice in a slightly pressurised container, valved to flow at WOT through an intercooler.

But LOX and Liquid Hydrogen is a MUCH better idea!




Wonder if we've just popped a wee red flag at spook HQ...

[husaberg]

You may, Husa. The picture below may give a first impression, and you'll find the whole story here: http://www.tonyfoale.com/Articles/EngineBalance/EngineBalance.pdf (http://www.tonyfoale.com/Articles/EngineBalance/EngineBalance.pdf)


Dank u meneer:niceone:


Was going to suggest dry ice in a slightly pressurised container, valved to flow at WOF through an intercooler.

But LOX and Liquid Hydrogen is a MUCH better idea!

Wonder if we've just popped a wee red flag at spook HQ...

Not to mention contrvened the fuel regs lol.

[TZ350]

Unlikely i'd think - more likely to be described as water cooling...

Water cooling of what though?.....

[TZ350]

282172

I have been looking at where I can place the motor in the new frame, the forks are adjusted to represent maximum suspension travel. I could reverse the cylinder and move the motor quite a bit further forward. Also looks like plenty of room for the alternative CVT setup too.

[husaberg]

I have been looking at where I can place the motor in the new frame, the forks are adjusted to represent maximum suspension travel. I could reverse the cylinder and move the motor quite a bit further forward. Also looks like plenty of room for the alternative CVT setup too.
thats a sexy frame:msn-wink:
I still say it needs to meet Mr saw though.
but can you turn the forks? ps what is the castor at the Swingarm pivot height you have that packed to?
Fits or Wob might be able to explain how you might get more even cylinder cooling by reversing the Cylinder:psst:

[richban]

I apologise for thread dredging here but it's amusing what is said on the internet then proven wrong. Then it's followed by some old bloke from down sound playing a very small violin only to come second in the 2013 Tokoroa GP

Yes well the old dogs will go down fighting for sure. This one is in training for the BOB. A few mods to the bike also. Number one is a quick shifter.

Sorry you were not at the track TZ. Race day fry up will have to wait a while.

[TZ350]

thats a sexy frame:msn-wink: I still say it needs to meet Mr saw though.


This is not the realy good one you gave me, that one is at Gigglebuttons being modded for some special forks.


... can you turn the forks? ps what is the castor at the Swingarm pivot height you have that packed to?

Yes for turning but not sure about castor, need the rear end in place first.


Fits or Wob might be able to explain how you might get more even cylinder cooling by reversing the Cylinder:psst:

I have heard that, and would like to know more.

[TZ350]

Sorry you were not at the track TZ. Race day fry up will have to wait a while.

I am very much looking forward to the next chance we all get to meet at Tiffany's again.

[Kickaha]

http://2stroker.createforumhosting.com/resources/image/425

[RAW]

You may, Husa. The picture below may give a first impression, and you'll find the whole story here: http://www.tonyfoale.com/Articles/EngineBalance/EngineBalance.pdf (http://www.tonyfoale.com/Articles/EngineBalance/EngineBalance.pdf)
282158

Nice article, thank you Frits
Does anyone have any information and or suggestions with regards to an inline twin such as the Rotax, DEA, FPE Kart engines and the balance issues if the cranks were to be phased at 180* instead of the current phasing of both pistons at TDC at the same time

Thanks

[Flettner]

The torsional loads on the crank drive will be much higher with a 180 cranks ( I'm assuming you are talking tandem twin ). You WILL have to have a stronger gear to crank attachment. Rising and falling together pistons are even loads from crank to crank. I know I built one ( 180, same rotation ) and couldn't keep the joining gears from failure. But it did run smooth as far as balance went.

[husaberg]

Yeah i am no RV guru for sure the twin disk or rear would be neat but f-ing problematic i did see another design from another later motor that was similar but can't remember where it was Mirhindra or something i think



http://2stroker.createforumhosting.com/resources/image/425
Thats the one i think? where is the pics of the drive set up?


Nice article, thank you Frits
Does anyone have any information and or suggestions with regards to an inline twin such as the Rotax, DEA, FPE Kart engines and the balance issues if the cranks were to be phased at 180* instead of the current phasing of both pistons at TDC at the same time

Thanks


The torsional loads on the crank drive will be much higher with a 180 cranks ( I'm assuming you are talking tandem twin ). You WILL have to have a stronger gear to crank attachment. Rising and falling together pistons are even loads from crank to crank. I know I built one ( 180, same rotation ) and couldn't keep the joining gears from failure. But it did run smooth as far as balance went.

I am on to you RAW:bleh:

[Kickaha]

Thats the one i think? where is the pics of the drive set up?
No idea, stumbled on that looking for some ADM 500 stuff, that was a single he did for an RS chassis

http://2stroker.createforumhosting.com/honda-rs125-adm-t6505-15.html
http://www.adm-racing.ch/index.html

[husaberg]

Nice article, thank you Frits
Does anyone have any information and or suggestions with regards to an inline twin such as the Rotax, DEA, FPE Kart engines and the balance issues if the cranks were to be phased at 180* instead of the current phasing of both pistons at TDC at the same time

Thanks


The torsional loads on the crank drive will be much higher with a 180 cranks ( I'm assuming you are talking tandem twin ). You WILL have to have a stronger gear to crank attachment. Rising and falling together pistons are even loads from crank to crank. I know I built one ( 180, same rotation ) and couldn't keep the joining gears from failure. But it did run smooth as far as balance went.


No idea, stumbled on that looking for some ADM 500 stuff, that was a single he did for an RS chassis

http://2stroker.createforumhosting.com/honda-rs125-adm-t6505-15.html
http://www.adm-racing.ch/index.html

Must not be the one. i was thinking of then i think the exulted great leader was involved but i could be wrong.
Frits will know the one i mean. (pretty sure he and Jan had commented on it on the site) it was i think on the pitlane thread but i can't find it. It had beefy looking gears for the drive compared to the RSA. looked to be simpler set up but may have lacked the finesse of the RSA

[TZ350]

282184water cooled CPU radiator

This is the sort of thing I had in mind for inside the plenum. One or two of these with fans circulating the plenum air through the ice water cooled radiators. I am picking that because the plenum is ten times the engine size then some of the plenum air will be passed through the radiators and cooled before its ingested by the engine.

[Moooools]

282184

This is the sort of thing I had in mind for inside the plenum. One or two of these with fans circulating the plenum air through the ice water cooled radiators. I am picking that because the plenum is ten times the engine then some of the plenum air will be passed through the radiators before its ingested.

Are you aware that even with 10 times the cylinder capacity it still only takes 0.04 seconds to drain the plenum? But that doesn't really matter if you just look at an AVERAGE of how long a single charge of air has spent in contact with the rad. Which is the length of time between intake strokes (0.004s). It cannot possibly average out to any more as the amount of air coming into the plenum must match that leaving.

And with only a 20ish degree temperature differential cooling is going to be really slow.

Average as idea sorry. Not buying this one unless you start using liquid nitrogen or dry ice. Get a bigger temp drop between rad and air and you might see something happen.

[wax]

Do you think the extra weight will effect the power to weight and handling in more of negative way than the power gained

[husaberg]

At the risk of sounding like an industry insider, i are just not getting it Rob.

The Vehicles that i am aware of that run inter-cooling pressurize the intake, Thereby greatly heating the charge, prior to induction. I can't see how you could achieve a large drop in intake temp, with ambilent air temp without a lot of restriction or over complication.
Beer i mind, I am often wrong though. just mussing.


OK but those 24 liters of air what is the contact time the air would have with you medium?

Anyway my all time favourite dubious use of cooling intakes.


Yes but
30HP/85kg=.353kg/hp
34hp/95kg=.357kg/hp

If you were to pursue this path wouldn't a long thin intake give you a greater surface area for potential cooling like a RSW intake for instance.
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=239514&stc=1&thumb=1&d=1306135696

Are you aware that even with 10 times the cylinder capacity it still only takes 0.04 seconds to drain the plenum? But that doesn't really matter if you just look at an AVERAGE of how long a single charge of air has spent in contact with the rad. Which is the length of time between intake strokes (0.004s). It cannot possibly average out to any more as the amount of air coming into the plenum must match that leaving.

And with only a 20ish degree temperature differential cooling is going to be really slow.

Average as idea sorry. Not buying this one unless you start using liquid nitrogen or dry ice. Get a bigger temp drop between rad and air and you might see something happen.


Do you think the extra weight will effect the power to weight and handling in more of negative way than the power gained

:wait::lol:
there must be an echo

Liquid nitrogen is out but Dry ice now that goes solid to Gas no liquid its a rule bender's dream, plus its in the rules "that you must have a fire extinquisher in the pits "

[TZ350]

Do you think the extra weight will effect the power to weight and handling in more of negative way than the power gained

I would really need to test the idea on the dyno to see if its worth while.


Not buying this one unless you start using liquid nitrogen or dry ice. Get a bigger temp drop between rad and air and you might see something happen.

Thanks for the numbers, they make sense. I wanted to use ice as its readily available, dry ice is harder to organize and not available everywhere.

I do have an air to air turbo intercooler that could be modified to use dry ice and be plumbed into an inlet system that runs from the high pressure area just under the front number board to the plenum. So hopefully there would not be much pressure loss in the plenum from having to pass all the air through the intercooler.

[husaberg]

Thanks for the numbers, they make sense. I wanted to use ice as its readily available, dry ice is harder to organize and not available everywhere.

I do have an air to air turbo intercooler that could be modified to use dry ice and be plumbed into an inlet system that runs from the high pressure area just under the front number board to the plenum. So hopefully there would not be much pressure loss in the plenum from having to pass all the air through the intercooler.

For making Dry ice= bucket, towel.CO2 fire extinguisher
Marine cooler is more sexy and would be potentially less problematic to fit in as well
http://us1.webpublications.com.au/static/images/articles/i1127/112712_2lo.jpg
if you visit the site here it has the pressure drops through various intercoolers
http://www.autospeed.com/cms/article.html?&A=1931

[2T Institute]

Nice article, thank you Frits
Does anyone have any information and or suggestions with regards to an inline twin such as the Rotax, DEA, FPE Kart engines and the balance issues if the cranks were to be phased at 180* instead of the current phasing of both pistons at TDC at the same time

Thanks

Tried 90 and 180 deg phasing all you get is a numb bum. Back to twingle they go.




* Brock was fine by the Entrants Association which he was presumably a member, so he was judged by cheats and rule benders :msn-wink:

[TZ350]

Thought I should get the tape measure out and compare the RS and NSR chassis.

It turns out that the distance between the front axial and swing arm are pretty much the same at 800mm, so I probably wont shorten the chassis. But the NSR swing arm is 100mm longer than the RS. Shortening the NSR swing arm would take weight off the front wheel.

[richban]

Thought I should get the tape measure out and compare the RS and NSR chassis.

It turns out that the distance between the front axial and swing arm are pretty much the same at 800mm, so I probably wont shorten the chassis. But the NSR swing arm is 100mm longer than the RS. Shortening the NSR swing arm would take weight off the front wheel.

How are you planning on correcting the lazy steering angel of the NSR? Would also be interesting to measure a later RS. My nsr is 22.2 degrees on the front and it is solid as tipping in. That could be because it is long as well. Oh and heavy.

[TZ350]

How are you planning on correcting the lazy steering angel of the NSR?

Dropping the forks through the tripple trees and jacking the back up, not sure how much yet. I will have to wait untill I get the frame back from Gigglebutton who is modifying the top stearing head bearing so it can take a special front end that I have.

[husaberg]

Thought I should get the tape measure out and compare the RS and NSR chassis.

It turns out that the distance between the front axial and swing arm are pretty much the same at 800mm, so I probably wont shorten the chassis. But the NSR swing arm is 100mm longer than the RS. Shortening the NSR swing arm would take weight off the front wheel.

Rob that 800mm, Is that with the NSR's forks still compressed vs the NF4 rs125's in the normal position? the NF4 also has a good few kgs well forward with the radiator position.
Cause as it is . It looks way longer. I'm picking the NX4 is a Good 150mm shorter front axle to swing-arm pivot as well, as Rich hinted.

[TZ350]

Rob that 800mm, Is that with the NSR's forks still compressed vs the NF4 rs125's in the normal position?

Both compressed, I will have to check with the NSR back in the normal position and tomorrow I will measure up the later RS chassis too.

[TZ350]

Alpha-N EFI Map

282199

Finally got the Alpha-N Load map, mapped against TPS and RPM.

282200

Another colorful map. You can see the effect of the pipe going in and out of resonance as the RPM goes up.

282198

Delivery Ratio Graph of multiple runs done in EngMod2T at different TPS (throttle) positions. The colorful Alpha-N map pretty much follows the EngMod simulations.

282197

To get the resolution required I used the EngMod graphing options to expand selected sections of the graphs.

282201

[chrisc]

Posted because someone was asking me about it ....
Buckets post has links to detailed pictures of how we built the early engine.
We got most of our improvement by opening up the rear transfer ports. Nothing fancy, a 13mm drill or ball end long series milling cutter will do the trick. These two posts are worth a look to see how rough you can be and still get a good result.

STA's for the triple port show that with a bit of work reasonable numbers are possible from the old Suzuki cylinder.

STA's for a single port Suzuki GP125 cylinder.

Avs bike is a single port with the Exhaust opening 80 degrees ATDC 72% wide, Transfers 114 ATDC and Inlet opening 145 BTDC and closing 80 ATDC. Its a very easy bike to ride with a smooth flat torque curve. The carb is a taper bored 24mm OKO and is 30mm at the engine end and the rotary valve port window area has an effective diameter of 36mm.

If we were doing it again we would probably pay more attention to widening the rear "B" transfers and opening them a little later, like in the EngMod2T data sheets above.

Remember to get those transfers low and wide to maximize specific blow down time area of the exhaust port.

I take the "Effective port diameter (mm)" to mean the chord width of the cylinder? Please confirm

[RAW]

[QUOTE=2T Institute;1130539530]Tried 90 and 180 deg phasing all you get is a numb bum. Back to twingle they go.

Hmmmm, so are you saying just re-phasing was a poor option because of the vibrations ?
Or are you saying that it was a poor option because you lost power ?
Or are you saying after addressing the balance issue it still did not produce a desirable effect ?

I'm still looking into this concept as its embedded in my deepest darkest thoughts, I desire to understand the required balance scenarios so I therefore may make a decision upon weather to invest the time, money & effort

[TZ350]

single port with the Exhaust opening 80 degrees ATDC 72% wide, Transfers 114 ATDC and Inlet opening 145 BTDC and closing 80 ATDC. Its a very easy bike to ride with a smooth flat torque curve. The carb is a taper bored 24mm OKO and is 30mm at the engine end and the rotary valve port window area has an effective diameter of 36mm.


I take the "Effective port diameter (mm)" to mean the chord width of the cylinder? Please confirm

If its the inlet rotary valve window area you mean. Then a port window that has an effective diameter of 36mm, means that the area of the oblong inlet window shape if squeezed round the diameter of the equivalent area would be 36mm.

282211

The convention is chordal measurement.

For an exhaust port that is 72% wide, and 56mm bore the chord length across the port window is 0.75 * 56mm = 40.32mm

[chrisc]

If its the inlet rotary valve window area you mean. Then a port window that has an effective diameter of 36mm, means that the area of the oblong inlet window shape if squeezed round the diameter of the equivalent area would be 36mm.

282211

The convention is chordal measurement.

For an exhaust port that is 72% wide, and 56mm bore the chord length across the port window is 0.75 * 56mm = 40.32mm

Sorry, by quoting that original post I meant the exhaust port as below:
282212

[TZ350]

282218
"Effective Port Diameter in mm) means, a round tube of 36.2mm ID would have the same area as that exhaust port window.

"Flow Width at Top" and "Flow Width at Bottom" give the Chordal width of the exhaust port.

Below is the Width % and on the left side is another important number, "Passage End Diameter" which is the diameter of the exhaust passage at the exhaust pipe flange. As a tuning trick, the pipe itself is sometimes made bigger than this.

[2T Institute]

[QUOTE=2T Institute;1130539530]Tried 90 and 180 deg phasing all you get is a numb bum. Back to twingle they go.

Hmmmm, so are you saying just re-phasing was a poor option because of the vibrations ?
Or are you saying that it was a poor option because you lost power ?
Or are you saying after addressing the balance issue it still did not produce a desirable effect ?

I'm still looking into this concept as its embedded in my deepest darkest thoughts, I desire to understand the required balance scenarios so I therefore may make a decision upon weather to invest the time, money & effort

Made no more or less power and was basicaly impossible to stay on the bike even on the dyno. Would have had to spend a lot of time and effort just to get back to where it was with twingle firing.

[wobbly]

Been away at Tokoroa track for two weeks testing new junior class engines for Kartsport NZ, so havnt been on here for a while.
There are two questions that need answering , firstly, the reposting of my statement about free bowjobs to anyone that thinks they can get even close to 30Hp at 10500 from an Aircooled 125 bucket with 24mm carb.
This equates to a bmep at 12Bar , this is = to a 125 watercooled , full house Italian racing kart engine with 44Hp at 13,000 ( note the only slightly higher rpm, where all the wave action,both inlet and exhaust, is WAY stronger ).
So does anyone seriously believe that any bucket optimised at 10500 is going to get even close to a fully modern cylinder design with a 130 diameter pipe, that spins to 15000 rpm even with a 30mm carb and straight line ignition.
Thus the offer still stands.

The other is the possibility suggested about better cylinder cooling by reversing the exhaust port direction.
Unless I am missing something so obvious its invisible then the only thing possible to me would be less radiated heat from the header, a minimal advantage.
There is only one way to cool a racing cylinder, especially good if the case is cooled as well.
All of the coldest water should flow from the boost port,over the transfers toward the exhaust, with no exits above it into the head at all apart from an an air pocket bleed.
From there - the now warmer water should flow up into the head,from over the exhaust,and travel around the head insert to exit at the highest point to the rad.
This increases the volumetric efficiency by max cooling the inlet charge, as well as reducing the delta T across the inside and outside of the insert.
In a perfect world the head should have its own, much hotter circuit, such that the minimum of heat is extracted from the combustion space and sent - wasted - to the cooling stream.
Maybe Frits has a clevererererer idea.

[husaberg]

The other is the possibility suggested about better cylinder cooling by reversing the exhaust port direction.
Unless I am missing something so obvious its invisible then the only thing possible to me would be less radiated heat from the header, a minimal advantage.
There is only one way to cool a racing cylinder, especially good if the case is cooled as well.
All of the coldest water should flow from the boost port,over the transfers toward the exhaust, with no exits above it into the head at all apart from an an air pocket bleed.
From there - the now warmer water should flow up into the head,from over the exhaust,and travel around the head insert to exit at the highest point to the rad.
This increases the volumetric efficiency by max cooling the inlet charge, as well as reducing the delta T across the inside and outside of the insert.
In a perfect world the head should have its own, much hotter circuit, such that the minimum of heat is extracted from the combustion space and sent - wasted - to the cooling stream.
Maybe Frits has a clevererererer idea.

Mr Waynewright, the question for you and Mr Frits it was about air cooled cylinders with rear facing ex port.
I didn't word it that clear though, so my fault.
With air cooled (or water cooled for that mater)I can see how the straighter ex would be beneficial the weight distribution can be improved the sheilding of the exhaust pipe can be beneficial.

But i have often seen it written that the cooling of the cylinders is better and more uniform with the rear facing exhaust on a air cooled cylinder

Which is counter intuitive to me as the hotter part of the cylinder around the ex port would receive preheated air, so intuitively it seems that the cooling would be less uniform. With the cooler part of the cylinder getting better cooler airflow with this set up

But this isn't the case..... or is it?

[TZ350]

Thought I should get the tape measure out and compare the RS and NSR chassis.


Rob that 800mm, Is that with the NSR's forks still compressed vs the NF4 rs125's

With the forks compressed both the early RS 795mm and NSR 810mm from the front axial to the swing arm. With the forks at full extension the NSR was 860 and RS 810, there may be a hint right there about why the RS handles better tipping into and changing lines in a corner.

For good measure I made a quick and dirty measure up of a later model RS too.

Post 95 RS front axle to swingarm 730mm swing arm to rear axle 520mm total 1250mm
Pre 95 RS front axle to swingarm 810mm swing arm to rear axle 460mm total 1270mm
NSR front axle to swingarm 860mm swing arm to rear axle 525mm total 1385mm (All quick and dirty ball park figures.)

So it does look like up to 100mm could be cut out of the NSR frame if needs be.

[F5 Dave]

. . .
There is only one way to cool a racing cylinder, especially good if the case is cooled as well.
All of the coldest water should flow from the boost port,over the transfers toward the exhaust, with no exits above it into the head at all apart from an an air pocket bleed.
From there - the now warmer water should flow up into the head,from over the exhaust,and travel around the head insert to exit at the highest point to the rad.
. . ..

Thanks.

So it amazes me when one looks at an RZ350 or the aftermarket responce like my CPI 496 that the approach is more or less to treat it like a bucket of water, aim a hose at the back of the bucket & put an outlet at the other side.

[fatbastd]

Yep, my modest collection of old Yamaha road-racers is the same as the RZ - all this makes me wonder if there are practical gains to be made, while making the engine look like a plumber's nightmare.

[speedpro]

Excellent news about the preferred cooling circuit. I had thought about a separate circuit for the head and the cylinder. The only issue would be 2 of everything unless I do a tricky bypass thermostat system. 2 of everything would probably be easier using electric pumps like I have now. Of course it's only waterjacketed down to the top of the ports.

[wobbly]

The Yamaha TZ,LC,RZ,Banshee are all complete crap, as is the CPI clone setup.
All it needs is a fitting on the rear of the cylinder, below a plate that will be welded to the deck as this will accommodate the longer stroke as well as hold the water flow within the cylinder.
Then the coolant flows up over the exhaust, into the head, and out the stock entry at the back, the front thermo being blocked off.
No plumbing nigtmare at all, it even auto bleeds on startup.
This is what will be in the Frepin copy TZ400 to blitz the field at Philip Island next Jan.

No drama to arrange a hotter head circuit, just restrict the flow at the head exit, such that you can overcool the cylinder, but overheat the head, with parallel circuits entering and exiting.
Of course you will need two sensors, at the exits to home in on the correct flow regime - and thus temp exiting from each.

[Grumph]

Are you sure those reed boxes are big enough ? What'cha got in there ? 6 petal blocks maybe ?

Fred would be salivating....

[husaberg]

My money's on CR250 but what model are the rubbers? TRX?

[wobbly]

The reeds are 8 petal VF3 to suit a CR125 that have enough area to support over 50 Hp per cylinder.
Those rubbers are aftermarket units from England to suit CR250 as used in 250 National Karts over there, but I redrilled the stud pattern to the CR125 - same as RS125 etc.
These manifolds will have 40mm Lectron HVs fitted with solenoid powerjets - all perfectly legal in pre 82 Post Classic Junior here, but will have to run in class 5 - 500cc at PI.
A huge crossflow radiator is being made now in Taiwan, as well as a new pump impeller ( thanks Niel at Autoflight ) to hold the temp at 50C, unlike the idiot Yamaha system for the TZ350 that has the temp at around 70C, throwing away probably
8 Hp ( 10%) easily.

[senso]

First, good night everybody, what a great thread you guys have over here, been reading through it from page 300, already at page 568, and there is a thing that buggers me, OKO carbs are very common around here, and they have a major flaw, they dry the float bowl very easily, don't you guys have trouble with that?
Yes, you use your carbs straight, but none the less, my dead 65cc crm will dry my oko 24mm in a matter of seconds, can't haven pull into 3rd without having the bowl dried out.

Keep goind on.
Best regards from Portugal.

[F5 Dave]

First, good night everybody, what a great thread you guys have over here, been reading through it from page 300, already at page 568, and there is a thing that buggers me, OKO carbs are very common around here, and they have a major flaw, they dry the float bowl very easily, don't you guys have trouble with that?
Yes, you use your carbs straight, but none the less, my dead 65cc crm will dry my oko 24mm in a matter of seconds, can't haven pull into 3rd without having the bowl dried out.

Keep goind on.
Best regards from Portugal.

I was asked to fix a mates foul stroke running one at a race.

It was running out of gas in the race. We'd fooled around raising float levels & bending floats so they didn't rub against the sides (evidence they did). But it still did it.

Maybe this is what fixed it.

There apeared to be a burr on the inside of the float needle brass housing where they cross drill it. I sanded it out with some sand paper over a drill bit & problem solved. Well at least so far. Chinese crap.

[senso]

I usually either add two extra holes around the float needle, as the stock ones are very small and the clearance between the needle and the bore is to thigh and the small cuts that the needle has are way to small, or I grab my 90º hand piece with a small 1mm burr and make the stock holes oval, and set the float to close a little bit earlier so they dont mess up due to uneven terrain(forward tilting).

[F5 Dave]

I checked the PWK on my GasGas last night to see it didn't have a similar burring (sometimes running out of gas on steep inclines).

[husaberg]

267776

My OKO float jet/needle valve had a brass washer like seat that fell out and was lost now its just a rubber tipped needle in an alloy hole like the original Keihin. It was easy to re set the float height.


I

Whoops i may not have posted the OKO vs PWK 28. It was from a Aussie pitbike thread.
I will find it again the float valve i think was smaller than the PWK28 i think but fixable.

OK here it is..........http://www.miniriders.com/tech-talk/26815-keihin-pwk-copy-carb-mods.html





First, good night everybody, what a great thread you guys have over here, been reading through it from page 300, already at page 568, and there is a thing that buggers me, OKO carbs are very common around here, and they have a major flaw, they dry the float bowl very easily, don't you guys have trouble with that?
Yes, you use your carbs straight, but none the less, my dead 65cc crm will dry my oko 24mm in a matter of seconds, can't haven pull into 3rd without having the bowl dried out.

Keep goind on.
Best regards from Portugal.


This explains how some pwk copies may differ in detail re the Float needle and seat.
http://www.miniriders.com/tech-talk/26815-keihin-pwk-copy-carb-mods.html

I can't vouch if it holds true for all the pwk copies or all the sizes. Guess some copy carbs less equal than others maybe........

[TZ350]

<iframe src="http://www.youtube.com/embed/KcNfci9OruU" allowfullscreen="" frameborder="0" height="315" width="420"></iframe>

OKO 24mm carb making 30 rwhp. Watch the fuel line, sometimes the restriction can be upstream at the tap maybe.

282328

Added a fuel header tank to the system by getting a large inline filter and modifying it by gluing a air breather to the top so now when the fuel demand is heavy the is a ready supply close to the carb.

[Gazzza]

Just a quick question but I'm sure some one out there may know the answer.
With out gong into models and things is it possible to add height to a piston crown by welding? Just to head off one reply, for various reasons I can't work the head to get the required compression, really need it to be the piston being altered if possible.

[TZ350]

Can you skim the base of the cylinder.

[Gazzza]

No not really, its a fairly rare engine I'm working on and don't want to sacrifice any of its originality... Really the only option it to modify the low compression pistons I have or wait until the right ones pop up, and that's fairly unlikely.

[speedpro]

This could be a useful place for those contemplating fuel injection

http://www.efihardware.com/index.php