ESE's works engine tuner

[wobbly]

Avgas,or any leaded hi octane race gas runs best with hi com and lean mixtures.
Pump gas or no lead gas makes better power when running richer, with less com and generally more advance.
But in some applications ( like KZ2 ) we need to run lean with pump gas to get pipe temp,its a trade off between outright peak Hp and rev ability.
So pump gas " can " use the same TuBmax numbers as Avgas in EngMod, it depends upon the end use and mechanical setup of the engine.

[Grumph]

The Hinson spring clutch for the Banshee is way heavy and way expensive.
I have changed the csk cap screws on the cush drive plate from 6mm to 8mm and used 12.9 grade plus i have ordered some
Lurethane rod that is used in race car suspension bushing to make the cush drive buttons,its way denser and much stronger than the soft " rubber " originals.
Hinson say the 8 plate billet clutch is good for 100 Hp,but i think constant speed shifting creates big shock loads that simply smash the stock cush drive.
I hope what i have done for now will work.
Rekluse do clutches for later model big Yamaha MX bikes, so i am researching if Yamaha has done as they always do, use very similar shafts and splines from model to model.

For years Kawasaki used rubber inserts in the clutch cush drives. The 550 to Z750 all used the same setup - which collapses when you get more HP.
I've made up urethane bushes with good results. If you find the stuff you've ordered is too harsh, just make them give a little more with a hole in the center...

[richban]

plus i have ordered some
Lurethane rod that is used in race car suspension bushing to make the cush drive buttons,its way denser and much stronger than the soft " rubber " originals.
Hinson say the 8 plate billet clutch is good for 100 Hp,but i think constant speed shifting creates big shock loads that simply smash the stock cush drive.
I hope what i have done for now will work.


Not sure that machined Urethane would last better. Unless you cast them maybe. The rear wheel cush drive ones we ran on the buckets split quite quick. faster than stock rubber.

[husaberg]

Husa, I must admit that I do not understand what you mean by this. (sorry...)
Could you please explain what you are aiming for ?

Unlikely i could explain but a picture might help?
Okay its clearly not to scale and a pretty lazy ass attempt at a picture.:innocent:
328650328651
It would clearly only work with an engine that had no ancillaries on the disc side of the crankshaft.
Thus the clutch and the ignition would have to be on the other side.
Throw in Flettners variable inlet port timing as well.

[husaberg]

The Hinson spring clutch for the Banshee is way heavy and way expensive.
I have changed the csk cap screws on the cush drive plate from 6mm to 8mm and used 12.9 grade plus i have ordered some
Lurethane rod that is used in race car suspension bushing to make the cush drive buttons,its way denser and much stronger than the soft " rubber " originals.
Hinson say the 8 plate billet clutch is good for 100 Hp,but i think constant speed shifting creates big shock loads that simply smash the stock cush drive.
I hope what i have done for now will work.
Rekluse do clutches for later model big Yamaha MX bikes, so i am researching if Yamaha has done as they always do, use very similar shafts and splines from model to model.

Ages ago on the foundry thread i posted a engineering drawing of a YZF450 and YZ250 gearbox i will see if i can find it.
i couldn't on KB but here is the thread it has the part numbers for the baskets.
https://www.thumpertalk.com/forums/topic/927076-yz450f-transmission-gear-upgrade-close-ratios/
plus the cluster drawings.
people were making up straight cut primaries for the rd and rz using stock yamaha parts

One i think was a YZ490 (looks like it was SR500)with a gear from another bike.
http://www.2strokeworld.com/forum/index.php?topic=4903.0

[jamathi]

Unlikely i could explain but a picture might help?
Okay its clearly not to scale and a pretty lazy ass attempt at a picture.:innocent:
328650328651
It would clearly only work with an engine that had no ancillaries on the disc side of the crankshaft.
Thus the clutch and the ignition would have to be on the other side.
Throw in Flettners variable inlet port timing as well.

It would cause a lot of friction....

[husaberg]

It would cause a lot of friction....

likely i am sure it would but in my defense so do bevel gears.
Is there a rule of thumb for disc friction?
I considered some of those narrow thrust bearings like these.
328652
As it sealed on the outer oring housing i thought it might get away with a little leak arround the disc as it can't go anywhere or is this a big issue as well?
Anyway making it work is the R&D departments issue, i work in the silly ideas department;)

[eldog]

Never finished.... is actually my middle name:weep:

Come on, pull the other one.

you can do it.
choose something and tackle it until you finish.:niceone:

dont be like me.

[Peter1962]

Unlikely i could explain but a picture might help?
Okay its clearly not to scale and a pretty lazy ass attempt at a picture.:innocent:
328650328651
It would clearly only work with an engine that had no ancillaries on the disc side of the crankshaft.
Thus the clutch and the ignition would have to be on the other side.
Throw in Flettners variable inlet port timing as well.

Thx for the explanation. Very interesting. And I hope Flettner is hearing your hint. By the way, I think his idea for a variable inlet disc is a marvel.

[Yow Ling]

Instead of driving a disk valve off the end of the crank or the cross shafts like the RSA, would it be possible to put the disk on the end of an AC 3 phase servo, and run it off an encoder on the crank, you could locate it anywhere, front back top bottom side etc 15000 rpm might be a bit out of the reach of the servo but 3 or 4,000 is doable just put a 1:4 gear train on it. How much power does the disk take to run. Needs a good high voltage winding to power the drive, an added bonus would be variable timing

To give you more of an idea what Im talking about there is a demo video on this page https://www.teknic.com/products/clearpath-brushless-dc-servo-motors/ watch from about the 4 minute mark will give you an idea of the accuracy and speeds etc.

All this is everyday stuff in the CNC world

[Flettner]

Instead of driving a disk valve off the end of the crank or the cross shafts like the RSA, would it be possible to put the disk on the end of an AC 3 phase servo, and run it off an encoder on the crank, you could locate it anywhere, front back top bottom side etc 15000 rpm might be a bit out of the reach of the servo but 3 or 4,000 is doable just put a 1:4 gear train on it. How much power does the disk take to run. Needs a good high voltage winding to power the drive, an added bonus would be variable timing

I guess my variable housing has a servo anyway. just not a high speed one.

[husaberg]

Instead of driving a disk valve off the end of the crank or the cross shafts like the RSA, would it be possible to put the disk on the end of an AC 3 phase servo, and run it off an encoder on the crank, you could locate it anywhere, front back top bottom side etc 15000 rpm might be a bit out of the reach of the servo but 3 or 4,000 is doable just put a 1:4 gear train on it. How much power does the disk take to run. Needs a good high voltage winding to power the drive, an added bonus would be variable timing

To give you more of an idea what Im talking about there is a demo video on this page https://www.teknic.com/products/clearpath-brushless-dc-servo-motors/ watch from about the 4 minute mark will give you an idea of the accuracy and speeds etc.

All this is everyday stuff in the CNC world

At highspeed it doesn't even have to rotate at all. As long as it stops in the open position. Its only needed at lower speeds isn't it?

[Yow Ling]

At highspeed it doesn't even have to rotate at all. As long as it stops in the open position. Its only needed at lower speeds isn't it?

Very very good point !

[F5 Dave]

Rotate? Why not just open and close guillotine?

[Yow Ling]

Rotate? Why not just open and close guillotine?
Health and Safety prevent us from doing that

[husaberg]

Very very good point !
with 8000 odd posts i had to have one once, eventually.


Rotate? Why not just open and close guillotine?
Thats a step away from Diesel talk and poppet valves :msn-wink:

[Tim Ey]

...
people were making up straight cut primaries for the rd and rz using stock yamaha parts
...


I am at the moment working on my Aprilia RS250 (= Suzuki RGV engine). I allready came to the clue that Suzuki uses the same design for clutch parts on RGV 250, GT250, GT380, DR400... So I modified the original clutch to one frictionplate more using a few GT250 steel plates.
Also the inner hub of the clutch has the same dimensions in these bikes - except for the height. Here the RGV is highest.

I wonder if anyone has done the same thing and may tell me if there is an other Suzuki which straight cut primary gears suit the RGV?!
Cheers to everyone
Tim

[husaberg]

I am at the moment working on my Aprilia RS250 (= Suzuki RGV engine). I allready came to the clue that Suzuki uses the same design for clutch parts on RGV 250, GT250, GT380, DR400... So I modified the original clutch to one frictionplate more using a few GT250 steel plates.
Also the inner hub of the clutch has the same dimensions in these bikes - except for the height. Here the RGV is highest.

I wonder if anyone has done the same thing and may tell me if there is an other Suzuki which straight cut primary gears suit the RGV?!
Cheers to everyone
Tim

No idea re the clutch and primaries for the RGV
But i have seen a SP or F3 RGV parts list posted on the net, have you tried to cross reference the parts numbers?
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Murphys law the one you want to see iis the blurry one.
Vincent Crabtree did a nice piece on using a RG250 crank in one for a 54mm stroke with some Snowmobile cylnders that are a bolt on.
They shared the same primary gear. or the spline from memory (RG250)
Lozza (2Tinstitute)brought a crank to do the conversion but i never heard anymore.
The best way to find what clutch parts fit others is to cross reference EBC cataloges and such like.
Honda and Suzuki seem to use the same plate parterns and baskets ove ran over again
For instance pretty much all the up to 250 hondas share 2 types of plates.

[Neal]

I am at the moment working on my Aprilia RS250 (= Suzuki RGV engine). I allready came to the clue that Suzuki uses the same design for clutch parts on RGV 250, GT250, GT380, DR400... So I modified the original clutch to one frictionplate more using a few GT250 steel plates.
Also the inner hub of the clutch has the same dimensions in these bikes - except for the height. Here the RGV is highest.

I wonder if anyone has done the same thing and may tell me if there is an other Suzuki which straight cut primary gears suit the RGV?!
Cheers to everyone
Tim

The tunning works do trick clutch and primary gear parts

[Martin1981]

Jan and/or Frits,

can you please tell me the Big End Pin and Crank Web Diameter of the RSA 125?

Thank You!

[Frits Overmars]

Jan and/or Frits, can you please tell me the Big End Pin and Crank Web Diameter of the RSA 125?I think the pin was 24 mm but I don't remember the web diameter. Can't look it up either; at the moment me and my files are not in the same country. Jan should know.

[jamathi]

I think the pin was 24 mm but I don't remember the web diameter. Can't look it up either; at the moment me and my files are not in the same country. Jan should know.

The RSA big-end pin was 22mm
On the RSW 21,3 was tried, with one roller more.
It gave slightly less power.
This may have been caused by less crankshaft stiffness or by more friction.
So I don't think 22mm was the best solution....
And the RSW's 20mm never gave trouble!
A 22mm big-end does not guarantee a stiffer crankshaft.
The outside diameter of the crank wheels is just as, or even more, important.
Sorry, I don't remember the RSA crank web diameter.
But I do remember they seriously disturbed inlet flow.
So we had to use a longer connecting rod of 120mm
With hindsight, I consider the RSA a mistake.....
At the time I was too obsessed with the RSW's bad inlet flow, disturbed as it was by the connecting rod...
When the first RSA crankcase arrived at Derbi I immediately did an inlet flow test, of course.
It flowed less than the RSW, I remember feeling VERY disappointed....

[wobbly]

Jan could you elaborate a bit on the inlet flow of the RSA.
I know you tested the kart engine with the shields over the wheels, as these have the inlet flow in the opposite direction
to the top of the flywheels - and that made more power when reversed.
But the RSA had the wheels rotating into the case at the top - ie the same direction as the rear inlet flow.
And I would have thought that the rod would have alot less bad effect on the inlet when moving forward and backward, unlike the RSW
where it moved across the flow direction.
Do you think the shape directly after the rotary valve was " wrong " or was something else interfering with the rear inlet flow into the case.

[jonny quest]

Why did RSA make more power than RSW if inlet flow was down?

[jonny quest]

How did you measure inlet flow? Flowbench, head off, 3 different transfer openings... then averaged

[jamathi]

How did you measure inlet flow? Flowbench, head off, 3 different transfer openings... then averaged

If you do it this way you would only be measuring transfer flow....

[jamathi]

Why did RSA make more power than RSW if inlet flow was down?

There are many more factors in an engine determining power!

[jamathi]

Jan could you elaborate a bit on the inlet flow of the RSA.
I know you tested the kart engine with the shields over the wheels, as these have the inlet flow in the opposite direction
to the top of the flywheels - and that made more power when reversed.
But the RSA had the wheels rotating into the case at the top - ie the same direction as the rear inlet flow.
And I would have thought that the rod would have alot less bad effect on the inlet when moving forward and backward, unlike the RSW
where it moved across the flow direction.
Do you think the shape directly after the rotary valve was " wrong " or was something else interfering with the rear inlet flow into the case..

Yes Wobbly, the 'other side' of the cylinder was now like a wall the flow collided with.
Of course many shapes of the duct after the valve should have been tried, but it was not done....
Directing the flow towards the transfer ducts, like in a read valve engine.

My task at Aprilia after I returned from Derbi was cylinder development.
To use a cylinder on the RSA the rear side had to be cut off as much as possible.
As it stood in the way of the inlet flow.
After this cutting such a cylinder gave less power on a RSW and 250
So we did this as least as possible....

And I was not very happy to return to Aprilia, after 1.5 year at Derbi, but had no choice.
So I lost interest, worked very little, and retired the year after.

When I was gone they saw their change to try a 'Honda'-type exhaust duct and port.
They lost 1,5HP, because they had to make the A-ports narrower I think.
What are your thoughts about 'Honda type' vs triple ports?
Have you ever been able to make a honest comparison?
At Derbi I had cylinders with triple ports cast and nikasil plated, they were ready to try when I had to leave....
Still I have some regrets about this.

[F5 Dave]

Life is but so long. I have experiments as yet uncomplete. At this stage unlikely.
But so be it.

Be sure that your sage words are like 20 years just happened in our collective experience.

[husaberg]

Life is but so long. I have experiments as yet uncomplete. At this stage unlikely.
But so be it.

Be sure that your sage words are like 20 years just happened in our collective experience.

An't that the truth.



A friend in Holland has made a 50cc twin-disc.
For the moment it is inferior to the single-disc.
Maybe because of the unequal inlet duct length, caused by the primary drive.
2 22mm carburetors are used.

A few things just occurred to me.
The RSW125 with its single sided entry way have been compromised with its asymmetric flow pattern, but it was also not hampered by the possible slowing down of two opossing intake steams colliding and losing velocity either. Which I assume would happen in a dual sided disc valve set up.
Is a collision of intake streams in a crankcase and slowing down a likely hindrance?
Given the transfers hold enough mixture to fill the cylinder anyway?
I muse maybe for a twin sided disc valve to make a lot more power than a single it would require an intake track with a very large updraft that way some of the airflow would go directly up the transfers on the same side rather than colliding and thus losing velocity in the middle an into the conrod?
I note the kreidler 50 with 2 discs had the intakes facing steeply towards the crankwheels rather than being straight a well. packaging?
328685328686

In regards to honda percevering with the bridged ex port. (ie old eyebrows)
Cameron wrote in the early 80's that Yamaha knew there flat roofed and colliding stream transfers and reed valve made less power than Aprilia style layout used by Suzuki on the RG500,
but they used it as it gave them greater acceleration and a wider power band within the limitations of their layout, They actually developed a power valve to maximise this effect.
I guess the marketing and corporate gods dictated the use of reed valves as it was a current Yamaha branded product.
I see parallels with the Honda use of the bridged exhaust. It could be said that it was almost a corporate trrademark. used as far back as the Mtr125 and likely further, plus it fitted in with their own patented powervalve design.
It may have ultimately made less power than a triple port, but it might have given a broader power within the confines of what was dictated as a layout Honda was to use.
The same might be said for its much shorter rods.
Ie reed valve single crank.

[adegnes]

Can you go smaller on stinger restriction/venturi size with cooler running fuels like e85?

I'm currently doing sims of my Spx on e85.
50cc, about 27hp with a 15mm diameter, 10mm long stinger restriction. Tubmax peaking at 940.

With Gasoline, 27hp and 15mm stinger restriction does not compute, but how about with e85?

[41juergen]

So based on the output of the EngMod simu I made a first "test" cylinder. The timings are : main ex 198°, aux ex 195° start open, A port 129°, B port 131°, C port 131° CA. That all as a road going bike with the (nozzle) modified stock exhaust (not too bad in the dimensions) at 11000 rpm peak. The question is: are the large aux ex ports the right way to go? Or shall I better use the "tear drop" shape getting a potential better flow with compromising on the (at that engine setup with 56,0mm bore and 50,7mm stroke) already hard to get blow down TA?
The first pic shows the stock setup, the other pics the current status of my porting.

328681 328682 328683

[wobbly]

If you crank up the TuBmax to the same level as petrol, this by inference means that the fuel in the header, and thus the bulk pipe temp
will also change back toward petrol levels - making the pipe wave speed faster.
Alcohol fuels do not loose power when running rich, and being rich allows way higher com without deto.
But this scenario also lowers the pipe temp, due to excess unburnt fuel in the header.
In your video it shows the peak return wave coming back too early ( pipe to short as you said ) but if you run it richer ( and then also try increased com as well )
then the pipe will cool, and make the TL closer to correct - plus it should add some power.

[wobbly]

The big square Aux port will not work well at all.
It will promote bad short circuiting from the A port, and this will also lower the header temp - then trying to lean it down will loose more power.
You have to re arrange the main Ex upper width,or increase the Aux top width to get back the STA without ruining the scavenging regime.
Also,you cannot know for sure that the "reverse stagger " will work in this engine,as the scavenging pattern is heavily dependent upon the B port duct
geometry.
Remember Jans B port duct in the Aprilia was very small in entry area, and you cannot just ignore this when trying to replicate his results.

[adegnes]

If you crank up the TuBmax to the same level as petrol, this by inference means that the fuel in the header, and thus the bulk pipe temp
will also change back toward petrol levels - making the pipe wave speed faster.
Alcohol fuels do not loose power when running rich, and being rich allows way higher com without deto.
But this scenario also lowers the pipe temp, due to excess unburnt fuel in the header.
In your video it shows the peak return wave coming back too early ( pipe to short as you said ) but if you run it richer ( and then also try increased com as well )
then the pipe will cool, and make the TL closer to correct - plus it should add some power.

Thanks!
I'm going to do a few baseline runs on e85 with the unmodified engine, play around with jetting/timing. I'm curious to see how it compares to pump gas on the dyno!

[TZ350]

Page 1670......:wacko:


Chairs, the latest ones i see are are digital now though, so they will have a curve i hope.
They are still a neat little set up, and cheap as chips.
328749328750
Price:$299.00 + $4.49 shipping
https://www.amazon.com/DIGITAL-IGNITION-CONVERSION-2009-2013-SXS12050039/dp/B00CFL5QLU

http://www.ktm-parts.com/mm5/graphics/00000001/SXS12050039.pdf

For an idea just how big they are for those unfamilar with the little KTM's
328751



Was thinking about this and wondered that, instead of having the two disc valve passages being coaxial or on a plane, have them enter the under cylinder volume semi tangentially.

A very good idea, I was thinking about that too..


The problem with grinding a cylinder is that the main exhaust will then not have the plating going around the corner from the bore into the port.

As the ring bulges outward, and the top/bottom port radi with a chamfer help to guide it back into the groove,eventually the plating will be worn thru to alloy - or chipped away.

You can smooth the edge with a cotton mop to help the situation, but for sure it will last long enough to test the porting results.

The transfers don’t give any problems, as they don’ need a chamfer at all.


As you have gone 1/2 way and put in the bore/duct radius you may as well go all the way and epoxy fill the B port front wall as Jan did as a successful test on the Aprilia.

328855


I notice Yamaha regressed in that detail. Compared to the earlier reverse cylinder
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=326858&d=1481884812


The problem with grinding a cylinder is that the main exhaust will then not have the plating going around the corner from the bore into the port.

As the ring bulges outward,and the top/bottom port radi with a chamfer help to guide it back into the groove,eventually the plating will be worn thru to alloy - or chipped away.

You can smooth the edge with a cotton mop to help the situation,but for sure it will last long enough to test the porting results. The transfers dont give any problems, as they dont need a chamfer at all.



The transfers dont give any problems, as they dont need a chamfer at all.Even if it's not needed to guide the rings back into place, isn't there still some benefit to airflow? I had always thought sharp edges were the enemy of good aerodynamics.


Jean or Frits indicates that the chamfered intake ports were harmful. It helps the exhaust gases to come in when the intake ports open.


Transfer ducts with what is called "exit " flow benefit far more from the sharp edges at the bore as the gas that forms the scavenging regime maintains a much better coherent stream.

With bore chamfers the column edges break up, and eddies or tiny turbulent swirls are formed that compromise the directional control.

Jan tested this at Aprilia, and i have done a direct back to back on a KZ10B, dynoing at 47.8 Hp with no chamfers, then immediately loosing near on 1 Hp everywhere after chamfering all the transfer ports - creating a ruined cylinder in about 10 minutes .


Wob, do you have any comment / recommendation on the height of the aux ex ports?


Re the height of the Aux ports.This is a simple case of swings and oundabouts - the higher you go the better the peak power ( more STA at opening ) but this comes at the expense of power at the low end, and in the overev ie it creates a narrower band of peakyer power.

So, to get the best of both, once the width has been maximized, and that seems to be limited to around to bore center,then the height is dictated by the power needed and the width of the powerband.

This is helped of course in the bottom by a PV, but the Aprilia had around 2mm of height difference on a 54.5 stroke,and thus was biased somewhat toward band width, allowing good overev capability.

KZ2 engines have no PV and need plenty of bottom and overev,but the width is nowhere near bore center ( no piston plugs ) but have around 1.5mm stagger, so i believe there is a lot to be gained in tests with plugs and much wider/lower Aux.

FCR carbs were designed for 4T, and the biggest issue on a 2T is that the slide is set at a 1.5,whereas a normal 2T Keihin would be a 5.

This gives very rich transition response,and cant be tuned out - but on Meth this may not matter. For simple gravity feed you need at least a 4.2 float jet,and I believe that Meth needles are available, but the tube is fixed,so will have to be drilled or be part of an alky kit to get sufficient flow at 1/4 to WOT with a thin point on the needle tip.


re the 75% cylinder exit area rule of thumb,this area is just a by product of the desire to reduce the volume of the whole exit duct.

The other guide is that this area is most effective if it occurs at around 1.5x the bore diameter,thus many cylinders are way too short.

I have added extra ,smaller area ,duct length to many cylinders, by extending the bolt on spigot plate, or making a female spigot on the cylinder into a male one.

Then the header that sits after the oval to round transition, starts at 2x bore.


Hi All,
Thought I’d drop by to share the findings of my YZ250 EFI project. It has a 2009 CRF450R 50mm throttle body, 3D printed polyurethane throttle boot to a Boyesen RAD valve. Fuel system is returnless with a Walbro GSL-414 pump controlled by a Madhu PWM pump controller/pressure sensor. Fuel filter is a Sytec mini bullet. Injector is the CRF450R 12 hole injector (440cc/min @ 4 bar). It’s controlled with a Microsquirt V3 running MSextra code, triggered by a 20-1 tooth wheel welded to the ignition rotor and a crank sensor from a YFM350.

It’s tuned in Alpha-N strategy (TPS vs. RPM table), with barometric pressure sensor and intake air temp sensor for compensation. It uses a Wideband O2 and logs either EGT or Fuel pressure.
First start was about a month ago, have put 3 tanks of fuel through it so far. Most of the tuning has been automatic based on AFR targets, except idle, light throttle and overrun where it needs to be tuned manually. 50mm throttle feels just as linear as the 38mm carb. I haven’t used any accel pump fuelling yet, so I’m hoping that will sharpen the throttle up a bit more.

Throttle transition at high rpm has been the main tuning issue. When closing and reopening the throttle, the motor would flood and not refire until the revs dropped, so I figured the airflow must drop off at some throttle value. I tried tuning a ledge into the fuel map, it was better than before but still hit and miss, fast roll on was ok, slow roll on or steady part throttle would still flood.
Then I figured that the airflow wasn't just related to the throttle, but when the engine is firing, the airflow is significantly higher than when it isn’t firing, due to the exhaust vacuum after blowdown pulling charge through the engine.
Therefore the fuel required for a cycle can be predicted by whether or not the engine fired on the previous cycle, in addition to engine speed and throttle position.
So my solution is to check whether the cylinder has fired, then adjust the fuel table for the next cycle. The throttle body MAP sensor is connected to the exhaust port and samples the pressure during blowdown. I’ve set up a 2nd fuel table in the ECU with a multiplier for when the pressure is above a threshold, corresponding to the cylinder firing. When the exhaust pressure is high, the main fuel table is unchanged, when low, it is reduced by 50% (will need to be dialled in for various RPM, but seems to work so far). The main fuel table is tuned with the wideband when the motor is firing, then extrapolated into the non-firing low throttle/overrun area. On closing the throttle, once the motor stops firing, fuel flow drops to match the airflow, so the motor doesn’t flood. On opening the throttle, the mixture is correct to initiate firing, then after the first fire fuel flow goes back to the main table value.

I think with some tuning I should be able to get the transition pretty much seamless. At the moment I'm working on getting the fuel table just right around the transition area, then I'll work on the switch threshold and multiplier values. That said, it's pretty decent already, but I'm a perfectionist.

Nathan

https://www.youtube.com/watch?v=4Zsz26QmfAU

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Throttle transition at high rpm has been the main tuning issue. When closing and reopening the throttle, the motor would flood and not refire until the revs dropped, so I figured the airflow must drop off at some throttle value.

Then I figured that the airflow wasn't just related to the throttle, but when the engine is firing, the airflow is significantly higher than when it isn’t firing, due to the exhaust vacuum after blowdown pulling charge through the engine.Great stuff, TeeZee will be very interested.My thought too. Waiting for TeeZee now.

Yes, very interested. Thanks Nathan, for the great idea of using a MAP sensor to measure the pressure changes in the exhaust system so as to see the changes in bulk air flow through the engine, I wish I had thought of that ages ago.



Overun over fueling, Cagiva had the same issue. Yours is a bloody neat set up though.

https://www.kiwibiker.co.nz/forums/album.php?albumid=4842&attachmentid=301602
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The Cagiva used to keep pumping in fuel on over run, then bog with its rich mixture and then chime in with a potential highside causing burst, when the unburned fuel finally cleared out of the crankcase.
Pumper carbs can do the same thing, not an issue on karts as they tend to keep on the gas.
I think What you have done is you have compensated for lower airflow and incomplete combustion on over-run, which was creating a richer mixture in the crankcase, which is what a conventional vacuum metered carb does.I found with my system it would never clear once it bogged, just 100% dead until the revs dropped. They must have been using some method of clearing it.
I guess that's why injected snowmobiles and boats don't have the issue, as soon as the throttle is cut the revs drop.
Nice article on the Cagiva too, I hadn't seen that one.



I found with my system it would never clear once it bogged, just 100% dead until the revs dropped. Exactly my problem too.


Same problem everyone else, from Cagiva through to Suter last year at the IOM the longer time at full throttle the worse it will be.That overlay from the ECU on the video is uber cool


Measuring the blowdown pressure pulse rather than the negative (since they should be proportional) gives you a head start on getting the fuel in. I have the pressure sample window set to 140-170° ATDC. The peak moves with RPM, because of the delay along the hose to the MAP sensor, so best to keep it as short and close to the port opening as possible. I have the injection start 10° after the sample window, so the latest pressure value is used to calculate the injector pulsewidth.

I suspect the pulses develop to full strength over a few cycles, as the return wave strengthens the combustion, so probably no need to get all the fuel in on that first cycle after measurement.

I am measuring through the powervalve vent, so my pressure values are only indicative for firing or not. With a proper exhaust port measurement you could adjust fuelling based on the pressure rather than just firing/not-firing..


Not likely; the 125 cc KTM GP-bike already had an injector in the crankcase that injected through a port below the exhaust port.
They used it instead of a powerjet and it would only have been logical to use the same setup for full EFI.
328804 328805 328806


Neels describes in "Using Post2T to investigate Detonation" TUBmax should be lower 950° for AV Gas.
Is there any temperatur recommendation for unleaded 95/100 Fuel?


Avgas,or any leaded hi octane race gas runs best with hi com and lean mixtures.

Pump gas or no lead gas makes better power when running richer, with less com and generally more advance.

But in some applications ( like KZ2 ) we need to run lean with pump gas to get pipe temp,its a trade off between outright peak Hp and rev ability.

So pump gas " can " use the same TuBmax numbers as Avgas in EngMod, it depends upon the end use and mechanical setup of the engine.


At max.torque rpm the transfer event is not even on full song by BDC; the transfer flow is still accelerating.
About 20° after BDC the crankcase pressure has dropped to atmospheric level; then it is time to connect the case to the outside world.
If you open the inlet earlier, you will lose case pressure. If you open it later, the case pressure will drop more than it would need to, slowing down the transfer flow.

There is a reason that the disk opened later on many rotary road bikes: if you let the case pressure drop lower before opening the disk, there will be a stronger suction signal to the carburetter, making carb. setting more responsive. But hey, you've got EFI.

[peewee]

The big square Aux port will not work well at all.
It will promote bad short circuiting from the A port, and this will also lower the header temp - then trying to lean it down will loose more power.
You have to re arrange the main Ex upper width,or increase the Aux top width to get back the STA without ruining the scavenging regime.
Also,you cannot know for sure that the "reverse stagger " will work in this engine,as the scavenging pattern is heavily dependent upon the B port duct
geometry.
Remember Jans B port duct in the Aprilia was very small in entry area, and you cannot just ignore this when trying to replicate his results.

ya i dont like the square aux either. with the teardrops you lose alittle area in the lower rear corner but gain some area in the upper rear, where its needed most. so the pressure drop can be faster through the first few initial degrees of opening, atleast that's what I think happens

[richban]

Hi Guys.


I did a quick thread search and could not find anything discussed on smartcarb. Anyone running one? I have had a little experience with Lectron and they seam really good. Is smartcarb as good?

[wobbly]

One other small point about the square Aux, is that this exposes a huge area enabling interconnection to the A port via the small end piston hole.
With a teardrop the port exposes less than 1/2 the area where the linking can occur, and separates them height wise.

[husaberg]

Hi Guys.


I did a quick thread search and could not find anything discussed on smartcarb. Anyone running one? I have had a little experience with Lectron and they seam really good. Is smartcarb as good?

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130842057#post1130842057
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130255542#post1130255542
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130812466#post1130812466
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130437168#post1130437168
there is more but KB search is not working properly maybe due to the thread being split a few times. poll etc

[richban]

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130842057#post1130842057
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130255542#post1130255542
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130812466#post1130812466
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130437168#post1130437168
there is more but KB search is not working properly maybe due to the thread being split a few times. poll etc

Thank you kind sir. Very Keen on a smart carb for the 50.

[bjorn.clauw.1]

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130842057#post1130842057
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130255542#post1130255542
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130812466#post1130812466
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130437168#post1130437168
there is more but KB search is not working properly maybe due to the thread being split a few times. poll etc

google search just for this thread:
https://cse.google.com/cse/publicurl?cx=009468122799118164990:5pd9xdluxce

only downside is that the google indexing robot passes by every 5 days, so the last 5 to 10 pages are not included.

[husaberg]

google search just for this thread:
https://cse.google.com/cse/publicurl?cx=009468122799118164990:5pd9xdluxce

only downside is that the google indexing robot passes by every 5 days, so the last 5 to 10 pages are not included.

I ended up doing that, but the thread search is generally very good, as long as you use the advanced option and seach for posts, but not so much lately.

[F5 Dave]

I've only ridden one bike with a smartcarb. About 2 weeks back. Ran nice. But I know a lot of people on gg forum that were ccustom sanding the needles. Seemed supercritical, not as they set out one needle fits all. I question how they would wear.
Heavy to hold.

[41juergen]

The big square Aux port will not work well at all.
It will promote bad short circuiting from the A port, and this will also lower the header temp - then trying to lean it down will loose more power.
You have to re arrange the main Ex upper width,or increase the Aux top width to get back the STA without ruining the scavenging regime.
Also,you cannot know for sure that the "reverse stagger " will work in this engine,as the scavenging pattern is heavily dependent upon the B port duct
geometry.
Remember Jans B port duct in the Aprilia was very small in entry area, and you cannot just ignore this when trying to replicate his results.

Thank's for the feedback Wob and PeeWee. As the rear of the aux port is already at the bore centerline I need to give up a bit of the (theoretical) blow down. Re the short circuiting I will use a piston plug, but that will not really solve the problem, right? So I will follow the tear drop shape...
Re the stagger: the Yam cylinder has indeed a different transfer entry as Jan's RSA cylinders. I thought with the 3 ex port design the reverse stagger would be the way to go. Also the Yam engineers had the idea to let the A port going flat into the cylinder were the B port has a 15° upward angle. Need to think about to fill up the A port top with JBweld...

328716328717

[jamathi]

Thank's for the feedback Wob and PeeWee. As the rear of the aux port is already at the bore centerline I need to give up a bit of the (theoretical) blow down. Re the short circuiting I will use a piston plug, but that will not really solve the problem, right? So I will follow the tear drop shape...
Re the stagger: the Yam cylinder has indeed a different transfer entry as Jan's RSA cylinders. I thought with the 3 ex port design the reverse stagger would be the way to go. Also the Yam engineers had the idea to let the A port going flat into the cylinder were the B port has a 15° upward angle. Need to think about to fill up the A port top with JBweld...

328716328717

We used piston plug AND teardrop shape!
And with a triple port the A-port must be lower to reduce short circuiting with the aux-ports.
The Yam engineer's ideas seem VERY outdated.
Later they copied Honda 100%, and even published an SAE paper about that......were proud of it.....
They even didn't do the copying themselves, Yamaha-France's famous head mechanic Guy Coulon did it for them.

Our A-port was at least 25° inclined upwards, maybe a bit more.....
When I reduced the B-duct entry the reverse stagger was already there.

[Frits Overmars]

Alcohol fuels do not loose power when running rich, and being rich allows way higher com without deto. But this scenario also lowers the pipe temp, due to excess unburnt fuel in the header.True, an overly rich mixture will yield a low exhaust gas temperature. But even with a correct mixture strength such an engine will loose revs because a high compression ratio doubles as a high expansion ratio, dropping the EGT even before the exhaust port opens.


The Yam engineer's ideas seem VERY outdated. Later they copied Honda 100%, and even published an SAE paper about that... were proud of it...
They even didn't do the copying themselves, Yamaha-France's famous head mechanic Guy Coulon did it for them.And let's not forget Harald Bartol. Our beloved friend Cees van Dongen showed the way by putting a Honda RS125 cylinder on his son's Yamaha TZ125, and Bartol first copied Van Dongen's idea and subsequently developed 'special' cylinders, financed by Yamaha. I hear that Yamaha were not amused when it became clear that their money had been used to carbon-copy Honda cylinders.

[jonny quest]

41j you seem to have room to bring the aux exhaust ports closer to main exhaust, instead of just making them wider outwards.

The bridged exhausts like Honda 125's, open up to wristpin. Has Honda ever used closed wristpins? Any time I've tried widening a bridged exhaust on a dirt bike into wristpin area it ruined the power. Couldn't get it to work.

[jonny quest]

Forgot to mention I've had really good luck widening bridged exhaust port next to transfers. This goes against the RSA results... but has always worked for me on bridged ports

[190mech]

Very late reply!Husa asked in Nov 15,2011(page 360) if anyone tested the ignition curve from a KTM 50SX iggy,well I did today,,planning to use it on a one off Minarelli scooter engine,so I built a test rig.Sorry to say its a "flat liner",no curve at all!Back to the drawing board...:brick:

[husaberg]

Very late reply!Husa asked in Nov 15,2011(page 360) if anyone tested the ignition curve from a KTM 50SX iggy,well I did today,,planning to use it on a one off Minarelli scooter engine,so I built a test rig.Sorry to say its a "flat liner",no curve at all!Back to the drawing board...:brick:

Chairs, the latest ones i see are are digital now though, so they will have a curve i hope.
They are still a neat little set up, and cheap as chips.
328749328750
Price:$299.00 + $4.49 shipping
https://www.amazon.com/DIGITAL-IGNITION-CONVERSION-2009-2013-SXS12050039/dp/B00CFL5QLU

http://www.ktm-parts.com/mm5/graphics/00000001/SXS12050039.pdf

For an idea just how big they are for those unfamilar with the little KTM's
328751

[wobbly]

As you have gone 1/2 way and put in the bore/duct radius you may as well go all the way and epoxy fill the B port front wall
as Jan did as a successful test on the Aprilia.

[41juergen]

Thank you guys for the feedback.
Currently I have 3,0 mm distance from the main to the aux ex port, can I go narrower, let's say to 2,0 mm (I remember the 5KE TZ cylinders had a problem there with cracking walls)?
Ok Wob as you say, now I'm already not too far from a good setup I will do that too. The front of the B port has already the right direction at the outlet to the cylinder, but to minimize the lost of energy I will correct also the complete wall.
BTW: when cutting so much on a cylinder is a re-plate a must? As that is my first attempt my idea was to test that setup let's say for about 2-3000 km on the road and then put in all the new stuff (like piston, crank, etc.).

[ken seeber]

I muse maybe for a twin sided disc valve to make a lot more power than a single it would require an intake track with a very large updraft that way some of the airflow would go directly up the transfers on the same side rather than colliding and thus losing velocity in the middle an into the conrod?
I note the kreidler 50 with 2 discs had the intakes facing steeply towards the crankwheels rather than being straight a well. packaging?


Was thinking about this and wondered that, instead of having the two disc valve passages being coaxial or on a plane, have them enter the under cylinder volume semi tangentially.
One could enter under the A passage entry point on one side and the other, on the opposite side, enter under the B passage. This would eliminate any direct collision of the streams, but dunno about the connecting rod impeding the flow over the cycle.
Also, the possible resultant swirl motion above the crank might create some asymmetry to the flow entry into the transfer passages.

[jamathi]

Was thinking about this and wondered that, instead of having the two disc valve passages being coaxial or on a plane, have them enter the under cylinder volume semi tangentially.
One could enter under the A passage entry point on one side and the other, on the opposite side, enter under the B passage. This would eliminate any direct collision of the streams, but dunno about the connecting rod impeding the flow over the cycle.
Also, the possible resultant swirl motion above the crank might create some asymmetry to the flow entry into the transfer passages.

A very good idea, I was thinking about that too..

[wobbly]

The problem with grinding a cylinder is that the main exhaust will then not have the plating going around the corner from the bore into the port.
As the ring bulges outward,and the top/bottom port radi with a chamfer help to guide it back into the groove,eventually the plating will be worn thru to alloy - or chipped away.
You can smooth the edge with a cotton mop to help the situation,but for sure it will last long enough to test the porting results.
The transfers dont give any problems, as they dont need a chamfer at all.

[shnaggs]

was having some fun with my computer these past few days. Still trying to figure out the Ryger and how this design software works:brick:

Trying to figure out how to animate the damn thing!

[Michael Moore]

Very late reply!Husa asked in Nov 15,2011(page 360) if anyone tested the ignition curve from a KTM 50SX iggy,well I did today,,planning to use it on a one off Minarelli scooter engine,so I built a test rig.Sorry to say its a "flat liner",no curve at all!Back to the drawing board...:brick:

Could you post a photo on your test rig? I need to run a 2015 KTM 250SX ignition as I can't find anyone who has any idea of what the map in it looks like and I don't know if it will be suitable for RR use instead of MX.

thanks,
Michael

[peewee]

was able to finally start it today so thnx to everyone on this site who offered assistance along the way :niceone: . wasn't tuned real well since I had to steal the carb from my Honda but never the less it runs and there were no immediate mechanical failures. ill put the methanol carb back on and run it again after the mud dries up in a few weeks. probly do alittle more work to the head like install a mechanical compression relief so the crankcase doesn't break at the kickstart area and may lower the com ratio a bit


https://www.youtube.com/watch?v=NCfLIXlK-6c

[190mech]

Here is my backyard(bucket) method,machined a shaft(read bolt) to match the crank profile,install it into cases,add iggy,TrailTech tach,spark plug and timing light,degree wheel or protractor on stator to read curve at different RPMs(not used in my case)Spin it with a DoAll dental drill motor attached to the shaft 328769328768328767

Wobbly has a vid of his rig somewhere in this thread that uses a vacuum cleaner motor,waay more hi-tech than my rig!

https://www.youtube.com/watch?v=pA6kjjEMiaw&feature=plcp

[d2t]

The transfers dont give any problems, as they dont need a chamfer at all.

Even if it's not needed to guide the rings back into place, isn't there still some benefit to airflow? I had always thought sharp edges were the enemy of good aerodynamics.

[jfn2]

was able to finally start it today so thnx to everyone on this site who offered assistance along the way :niceone: . wasn't tuned real well since I had to steal the carb from my Honda but never the less it runs and there were no immediate mechanical failures. ill put the methanol carb back on and run it again after the mud dries up in a few weeks. probly do alittle more work to the head like install a mechanical compression relief so the crankcase doesn't break at the kickstart area and may lower the com ratio a bit


https://www.youtube.com/watch?v=NCfLIXlK-6c

You gotta love those paddle tires! Sounds pretty good.

[Michael Moore]

Here is my backyard(bucket)

thanks, that's pretty much what I had in mind though making a dedicated housing rather than using the crankcase.

cheers,
Michael

[41juergen]

Even if it's not needed to guide the rings back into place, isn't there still some benefit to airflow? I had always thought sharp edges were the enemy of good aerodynamics.
But you want the flow in the desired direction, that would be (a least a little) influenced by the grinding....
One other point came back into my mind: Wob I think you mentioned some when before that the aux ex ports shall be some °CA lower as the main ex port, otherwise one would loose some significant power in the lower power band. Is that valid also for aux ex ports which are connected to the PV (as the Yamaha drum type is)? If not I can get some more blow down there...

[wobbly]

Transfer ducts with whats called "exit " flow benefit far more from the sharp edges at the bore as the gas that forms the scavenging regime
maintains a much better coherent stream.
With bore chamfers the column edges break up, and eddies or tiny turbulent swirls are formed that compromise the directional contol.
Jan tested this at Aprilia, and i have done a direct back to back on a KZ10B, dynoing at 47.8 Hp with no chamfers, then immediately loosing
near on 1 Hp everywhere after chamfering all the transfer ports - creating a ruined cylinder in about 10 minutes .

[husaberg]

As you have gone 1/2 way and put in the bore/duct radius you may as well go all the way and epoxy fill the B port front wall
as Jan did as a successful test on the Aprilia.

I notice Yamaha regressed in that detail. Compared to the earlier reverse cylinder
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=326858&d=1481884812

[41juergen]

But you want the flow in the desired direction, that would be (a least a little) influenced by the grinding....
One other point came back into my mind: Wob I think you mentioned some when before that the aux ex ports shall be some °CA lower as the main ex port, otherwise one would loose some significant power in the lower power band. Is that valid also for aux ex ports which are connected to the PV (as the Yamaha drum type is)? If not I can get some more blow down there...

Wob, do you have any comment / recommendation on the height of the aux ex ports?

[philou]

Even if it's not needed to guide the rings back into place, isn't there still some benefit to airflow? I had always thought sharp edges were the enemy of good aerodynamics.

Jean or Frits indicates that the chamfered intake ports were harmful. It helps the exhaust gases to come in when the intake ports open.

[Frits Overmars]

Jean or Frits indicates that the chamfered intake ports were harmful. It helps the exhaust gases to come in when the intake ports open.Philou, we must be careful with our terminology here. I was talking about the transfer ports: the ports that transfer the mixture from the crankcase to the cylinder.
For me, intake ports are the ports that allow the mixture to enter the crankcase.

[philou]

Yes Frits, you're right. I'm sorry.

My English is not yet very good :cri:

I want to participate in the discussions.

Not only take information

[SwePatrick]

Is there someone that have successfully converted an Keihin FCR carburetor for use on Twostroke?
I´ve got an FCR 41 tapered bored from 43.4 and upstreams to 46mm then a short nice velocitystack.

If so, what were your mods?

I plan to use this with methanol.
And one idea i have is to modify the throttle.
As is, it has a big cavity from underside and up inside instead of viceversa as normal on twostrokes.
This will lead to modify the 'venturi' to look as an normal twostroke carb like PWK/PWM.
And ofcoarse delete the pumper.

Rgds
Patrick

[Frits Overmars]

Yes Frits, you're right. I'm sorry. My English is not yet very good. I want to participate in the discussions. Not only take informationYou are very welcome Philou. And don't worry about languages; I suppose that your English is a lot better than my French :msn-wink:.


Is there someone that have successfully converted an Keihin FCR carburetor for use on Twostroke?Yep, 25 years ago, so I don't remember many details Patrick.
328778 328779

[jfn2]

Has anyone tried this setup from Yoshimura yet? They are using TMR, FCR's,TM's and YD's for their setup.
http://www.bikebros.co.jp/vb/sports/sfeat/yoshimura-carburetor-en/
MJN stands for 'Multiple Jet Nozzle'
Also check out their Dual Stack Air Funnel setup.
Comments?

[peewee]

You gotta love those paddle tires! Sounds pretty good.

i dont normally ride in dirt with that tire , i just wanted to see if the engine would run so i went just barely out of city limits. it did get good traction as the front tire lifted up rather quickly :laugh:

[Grumph]

Is there someone that have successfully converted an Keihin FCR carburetor for use on Twostroke?
I´ve got an FCR 41 tapered bored from 43.4 and upstreams to 46mm then a short nice velocitystack.

If so, what were your mods?

I plan to use this with methanol.
And one idea i have is to modify the throttle.
As is, it has a big cavity from underside and up inside instead of viceversa as normal on twostrokes.
This will lead to modify the 'venturi' to look as an normal twostroke carb like PWK/PWM.
And ofcoarse delete the pumper.

Rgds
Patrick

My experience with FCR's on methanol is on fourstrokes but I hope some of it will help.
Float needles and seats - standard petrol sizes will work - but only with a pump supply. I used around 1.2lb pressure with good results. If you're gravity feeding, you'll need bigger float needle and seat assemblies.
Pilot/slow run jets - with a bore size that big, petrol slow runs would be around .50mm bore. Meth, I'd start around .65mm bore.
Needle and needle jet - You can get Methanol needles i believe but a rich petrol needle will do. Needle jet should go to around 3.2- 3.5mm bore.

I wouldn't modify the slide. try it as it comes first. The pump is adjustable, if you do have response problems, it's worth trying a small pump shot.
Remember that you can happily run Methanol up to 20% rich and never notice...This fills in a lot of holes in the jetting, LOL.
Wob's already said quite a bit about EGT's for Meth, he knows that side better than me.

[oldjohnno]

Has anyone tried this setup from Yoshimura yet? They are using TMR, FCR's,TM's and YD's for their setup.
http://www.bikebros.co.jp/vb/sports/sfeat/yoshimura-carburetor-en/
MJN stands for 'Multiple Jet Nozzle'
Also check out their Dual Stack Air Funnel setup.
Comments?

I can't help but think all this has as much to do with marketing as it does with engineering. The late great Harry A Miller was producing progressive multi-hole-discharge carbs in the 1920s. And there were no 4 into 1 exhausts before Yoshi "invented" them in the 70's?

[wobbly]

Re the height of the Aux ports.This is a simple case of swings and roundabouts - the higher you go the better the peak power ( more STA at opening )
but this comes at the expense of power at the low end, and in the overev ie it creates a narrower band of peakyer power.
So,to get the best of both, once the width has been maximized,and that seems to be limited to around to bore center,then the height is dictated by the power needed and
the width of the powerband.
This is helped of course in the bottom by a PV, but the Aprilia had around 2mm of height difference on a 54.5 stroke,and thus was biased somewhat toward band width,allowing
good overev capability.
KZ2 engines have no PV and need plenty of bottom and overev,but the width is nowhere near bore center ( no piston plugs ) but have around 1.5mm stagger, so i believe there is
alot to be gained in tests with plugs and much wider/lower Aux.

FCR carbs were designed for 4T, and the biggest issue on a 2T is that the slide is set at a 1.5,whereas a normal 2T Keihin would be a 5.
This gives very rich transition response,and cant be tuned out - but on Meth this may not matter.
For simple gravity feed you need at least a 4.2 float jet,and I believe that Meth needles are available, but the tube is fixed,so will have to be drilled or be part of an alky kit
to get sufficient flow at 1/4 to WOT with a thin point on the needle tip.

[peewee]

patrick have you checked ebay for used kiehin, mikuni or lectron ? these may be easier options

juergon i left my aux about 3* lower than the main. seems like standard 250cc cylinders such as ktm were about 8* lower if i remember correct

[SwePatrick]

My experience with FCR's on methanol is on fourstrokes but I hope some of it will help.
Float needles and seats - standard petrol sizes will work - but only with a pump supply. I used around 1.2lb pressure with good results. If you're gravity feeding, you'll need bigger float needle and seat assemblies.
Pilot/slow run jets - with a bore size that big, petrol slow runs would be around .50mm bore. Meth, I'd start around .65mm bore.
Needle and needle jet - You can get Methanol needles i believe but a rich petrol needle will do. Needle jet should go to around 3.2- 3.5mm bore.

I wouldn't modify the slide. try it as it comes first. The pump is adjustable, if you do have response problems, it's worth trying a small pump shot.
Remember that you can happily run Methanol up to 20% rich and never notice...This fills in a lot of holes in the jetting, LOL.
Wob's already said quite a bit about EGT's for Meth, he knows that side better than me.

Thanks, Yes i´ll wait with modifying throttle then. :)
And yes, the rich situation is one of the parameters why i want to go methanol.
'Less adjusting at the tracks as it still produces power slightly rich'

As is, the engine it will sit on is 211.6cc and produces at this point quite well already on Avgas100ll.
I have to redesign the pipe a bit i guess thou, the powerpeak is very high(73.29hp, corrected), but very short.(i got a quite hard angle on the end converging cone)
Peakpower is at ~12400rpm and roughly 500rpm wide :(
The powerband is average ~40hp as is(9000-13000rpm), quite sad actually.
Made an powerjet the other day to try to widen the curve a bit, i need a carb that is a bit leaner just before and after the torquepeak, i figure the powerjet will do just that(not fully tested in dyno yet)
But on Methanol this would play a minor part i guess ;)
At this point(on avgas100ll) i run an bored out(41mm) Keihin PWM.
It screams for a bigger carb also as just boring the carb 0.5mm gave me 3hp

And Frits, Try to remember ;)

[Nath88]

Hi All,
Thought I’d drop by to share the findings of my YZ250 EFI project. It has a 2009 CRF450R 50mm throttle body, 3D printed polyurethane throttle boot to a Boyesen RAD valve. Fuel system is returnless with a Walbro GSL-414 pump controlled by a Madhu PWM pump controller/pressure sensor. Fuel filter is a Sytec mini bullet. Injector is the CRF450R 12 hole injector (440cc/min @ 4 bar). It’s controlled with a Microsquirt V3 running MSextra code, triggered by a 20-1 tooth wheel welded to the ignition rotor and a crank sensor from a YFM350.

It’s tuned in Alpha-N strategy (TPS vs. RPM table), with barometric pressure sensor and intake air temp sensor for compensation. It uses a Wideband O2 and logs either EGT or Fuel pressure.
First start was about a month ago, have put 3 tanks of fuel through it so far. Most of the tuning has been automatic based on AFR targets, except idle, light throttle and overrun where it needs to be tuned manually. 50mm throttle feels just as linear as the 38mm carb. I haven’t used any accel pump fuelling yet, so I’m hoping that will sharpen the throttle up a bit more.

Throttle transition at high rpm has been the main tuning issue. When closing and reopening the throttle, the motor would flood and not refire until the revs dropped, so I figured the airflow must drop off at some throttle value. I tried tuning a ledge into the fuel map, it was better than before but still hit and miss, fast roll on was ok, slow roll on or steady part throttle would still flood.
Then I figured that the airflow wasn't just related to the throttle, but when the engine is firing, the airflow is significantly higher than when it isn’t firing, due to the exhaust vacuum after blowdown pulling charge through the engine.
Therefore the fuel required for a cycle can be predicted by whether or not the engine fired on the previous cycle, in addition to engine speed and throttle position.
So my solution is to check whether the cylinder has fired, then adjust the fuel table for the next cycle. The throttle body MAP sensor is connected to the exhaust port and samples the pressure during blowdown. I’ve set up a 2nd fuel table in the ECU with a multiplier for when the pressure is above a threshold, corresponding to the cylinder firing. When the exhaust pressure is high, the main fuel table is unchanged, when low, it is reduced by 50% (will need to be dialled in for various RPM, but seems to work so far). The main fuel table is tuned with the wideband when the motor is firing, then extrapolated into the non-firing low throttle/overrun area. On closing the throttle, once the motor stops firing, fuel flow drops to match the airflow, so the motor doesn’t flood. On opening the throttle, the mixture is correct to initiate firing, then after the first fire fuel flow goes back to the main table value.

I think with some tuning I should be able to get the transition pretty much seamless. At the moment I'm working on getting the fuel table just right around the transition area, then I'll work on the switch threshold and multiplier values. That said, it's pretty decent already, but I'm a perfectionist.

Nathan

https://www.youtube.com/watch?v=4Zsz26QmfAU

328790
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328793

[SwePatrick]

FCR carbs were designed for 4T, and the biggest issue on a 2T is that the slide is set at a 1.5,whereas a normal 2T Keihin would be a 5.
This gives very rich transition response,and cant be tuned out - but on Meth this may not matter.
For simple gravity feed you need at least a 4.2 float jet,and I believe that Meth needles are available, but the tube is fixed,so will have to be drilled or be part of an alky kit
to get sufficient flow at 1/4 to WOT with a thin point on the needle tip.

Nice, Thanks!,
I´ll check that slide issue if having problems.
Yes i figure the needle need some job, as is it almost has no taper at all. :sick:
The carb came from a big KTM 4t.
And i plan to use a mikuni fuelpump from a snowmobile.
I have also designed the fueltank to give slighty higher gravityfeed during hard acceleration.
Will measure the floatjet later today, my first impression is that is is quite huge already as std.

Rgds.

[Flettner]

[QUOTE=Nath88;1131031730]Hi All,
Thought I’d drop by to share the findings of my YZ250 EFI project. It has a 2009 CRF450R 50mm throttle body, 3D printed polyurethane throttle boot to a Boyesen RAD valve. Fuel system is returnless with a Walbro GSL-414 pump controlled by a Madhu PWM pump controller/pressure sensor. Fuel filter is a Sytec mini bullet. Injector is the CRF450R 12 hole injector (440cc/min @ 4 bar). It’s controlled with a Microsquirt V3 running MSextra code, triggered by a 20-1 tooth wheel welded to the ignition rotor and a crank sensor from a YFM350.

It’s tuned in Alpha-N strategy (TPS vs. RPM table), with barometric pressure sensor and intake air temp sensor for compensation. It uses a Wideband O2 and logs either EGT or Fuel pressure.
First start was about a month ago, have put 3 tanks of fuel through it so far. Most of the tuning has been automatic based on AFR targets, except idle, light throttle and overrun where it needs to be tuned manually. 50mm throttle feels just as linear as the 38mm carb. I haven’t used any accel pump fuelling yet, so I’m hoping that will sharpen the throttle up a bit more.

Throttle transition at high rpm has been the main tuning issue. When closing and reopening the throttle, the motor would flood and not refire until the revs dropped, so I figured the airflow must drop off at some throttle value. I tried tuning a ledge into the fuel map, it was better than before but still hit and miss, fast roll on was ok, slow roll on or steady part throttle would still flood.
Then I figured that the airflow wasn't just related to the throttle, but when the engine is firing, the airflow is significantly higher than when it isn’t firing, due to the exhaust vacuum after blowdown pulling charge through the engine.
Therefore the fuel required for a cycle can be predicted by whether or not the engine fired on the previous cycle, in addition to engine speed and throttle position.
So my solution is to check whether the cylinder has fired, then adjust the fuel table for the next cycle. The throttle body MAP sensor is connected to the exhaust port and samples the pressure during blowdown. I’ve set up a 2nd fuel table in the ECU with a multiplier for when the pressure is above a threshold, corresponding to the cylinder firing. When the exhaust pressure is high, the main fuel table is unchanged, when low, it is reduced by 50% (will need to be dialled in for various RPM, but seems to work so far). The main fuel table is tuned with the wideband when the motor is firing, then extrapolated into the non-firing low throttle/overrun area. On closing the throttle, once the motor stops firing, fuel flow drops to match the airflow, so the motor doesn’t flood. On opening the throttle, the mixture is correct to initiate firing, then after the first fire fuel flow goes back to the main table value.

I think with some tuning I should be able to get the transition pretty much seamless. At the moment I'm working on getting the fuel table just right around the transition area, then I'll work on the switch threshold and multiplier values. That said, it's pretty decent already, but I'm a perfectionist.

Nathan

https://www.youtube.com/watch?v=4Zsz26QmfAU

That goes alright! There has certainly been a lot of thought put into this project, thank you for sharing this.

[peewee]

So based on the output of the EngMod simu I made a first "test" cylinder. The timings are : main ex 198°, aux ex 195° start open, A port 129°, B port 131°, C port 131° CA. That all as a road going bike with the (nozzle) modified stock exhaust (not too bad in the dimensions) at 11000 rpm peak. The question is: are the large aux ex ports the right way to go? Or shall I better use the "tear drop" shape getting a potential better flow with compromising on the (at that engine setup with 56,0mm bore and 50,7mm stroke) already hard to get blow down TA?
The first pic shows the stock setup, the other pics the current status of my porting.

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maybe your aware already but take care not to make the aux window too big if there isn't sufficient material around the passage to make it appropriate size also. I see a lot of amateur guys make this mistake on other websites. what happens is their aux port looks like a hour glass shape. the window is large but the passage gets small then it gets large again where it intersects with the main passage

[Frits Overmars]

I figured that the airflow wasn't just related to the throttle, but when the engine is firing, the airflow is significantly higher than when it isn’t firing, due to the exhaust vacuum after blowdown pulling charge through the engine.
Therefore the fuel required for a cycle can be predicted by whether or not the engine fired on the previous cycle, in addition to engine speed and throttle position. So my solution is to check whether the cylinder has fired, then adjust the fuel table for the next cycle. The throttle body MAP sensor is connected to the exhaust port and samples the pressure during blowdown. I’ve set up a 2nd fuel table in the ECU with a multiplier for when the pressure is above a threshold, corresponding to the cylinder firing. When the exhaust pressure is high, the main fuel table is unchanged, when low, it is reduced by 50%I like your approach very much Nathan.
But looking at your third picture, I wonder how much radiator heat will be picked up by the fuel. Some fuel components have a boiling point around 50° C ....

[husaberg]

Hi All,
Thought I’d drop by to share the findings of my YZ250 EFI project. It has a 2009 CRF450R 50mm throttle body, 3D printed polyurethane throttle boot to a Boyesen RAD valve. Fuel system is returnless with a Walbro GSL-414 pump controlled by a Madhu PWM pump controller/pressure sensor. Fuel filter is a Sytec mini bullet. Injector is the CRF450R 12 hole injector (440cc/min @ 4 bar). It’s controlled with a Microsquirt V3 running MSextra code, triggered by a 20-1 tooth wheel welded to the ignition rotor and a crank sensor from a YFM350.

It’s tuned in Alpha-N strategy (TPS vs. RPM table), with barometric pressure sensor and intake air temp sensor for compensation. It uses a Wideband O2 and logs either EGT or Fuel pressure.
First start was about a month ago, have put 3 tanks of fuel through it so far. Most of the tuning has been automatic based on AFR targets, except idle, light throttle and overrun where it needs to be tuned manually. 50mm throttle feels just as linear as the 38mm carb. I haven’t used any accel pump fuelling yet, so I’m hoping that will sharpen the throttle up a bit more.

Throttle transition at high rpm has been the main tuning issue. When closing and reopening the throttle, the motor would flood and not refire until the revs dropped, so I figured the airflow must drop off at some throttle value. I tried tuning a ledge into the fuel map, it was better than before but still hit and miss, fast roll on was ok, slow roll on or steady part throttle would still flood.
Then I figured that the airflow wasn't just related to the throttle, but when the engine is firing, the airflow is significantly higher than when it isn’t firing, due to the exhaust vacuum after blowdown pulling charge through the engine.
Therefore the fuel required for a cycle can be predicted by whether or not the engine fired on the previous cycle, in addition to engine speed and throttle position.
So my solution is to check whether the cylinder has fired, then adjust the fuel table for the next cycle. The throttle body MAP sensor is connected to the exhaust port and samples the pressure during blowdown. I’ve set up a 2nd fuel table in the ECU with a multiplier for when the pressure is above a threshold, corresponding to the cylinder firing. When the exhaust pressure is high, the main fuel table is unchanged, when low, it is reduced by 50% (will need to be dialled in for various RPM, but seems to work so far). The main fuel table is tuned with the wideband when the motor is firing, then extrapolated into the non-firing low throttle/overrun area. On closing the throttle, once the motor stops firing, fuel flow drops to match the airflow, so the motor doesn’t flood. On opening the throttle, the mixture is correct to initiate firing, then after the first fire fuel flow goes back to the main table value.

I think with some tuning I should be able to get the transition pretty much seamless. At the moment I'm working on getting the fuel table just right around the transition area, then I'll work on the switch threshold and multiplier values. That said, it's pretty decent already, but I'm a perfectionist.

Nathan

https://www.youtube.com/watch?v=4Zsz26QmfAU

That goes alright! There has certainly been a lot of thought put into this project, thank you for sharing this.
Overun over fueling, Cagiva had the same issue. Yours is a bloody neat set up though.
https://www.kiwibiker.co.nz/forums/album.php?albumid=4842&attachmentid=301602
https://www.kiwibiker.co.nz/forums/album.php?albumid=4842&attachmentid=301601
https://www.kiwibiker.co.nz/forums/album.php?albumid=4842&attachmentid=301600
https://www.kiwibiker.co.nz/forums/album.php?albumid=4842&attachmentid=301599
https://www.kiwibiker.co.nz/forums/album.php?albumid=4842&attachmentid=301598
https://www.kiwibiker.co.nz/forums/album.php?albumid=4842&attachmentid=301597

The cagiva used to keep pumping in fuel on over run, then bog whth its rich mixture and then chime in with a potental highside causing burst, when the unburnt fuel finally cleared out of the crankcase.
Pumper carbs can do the same thing, not an issue on karts as they tend to keep on the gas.
I think What you have done is you have compensated for lower airflow and incomplete combustion on over-run, which was creating a richer mixture in the crankcase, which is what a conventional vacum metered carb does.
Neat solution.

[41juergen]

OK, so will start with the 2°CA lower aux ex ports... And thank's for the head up peewee, I believe the passage is currently big enough as it has more than half of the overall aux ex port area...

[peewee]

OK, so will start with the 2°CA lower aux ex ports... And thank's for the head up peewee, I believe the passage is currently big enough as it has more than half of the overall aux ex port area...


your doing good job :2thumbsup. will your exh exit be 75% of exh area at bore face ?

[FastFred]

Throttle transition at high rpm has been the main tuning issue. When closing and reopening the throttle, the motor would flood and not refire until the revs dropped, so I figured the airflow must drop off at some throttle value.

Then I figured that the airflow wasn't just related to the throttle, but when the engine is firing, the airflow is significantly higher than when it isn’t firing, due to the exhaust vacuum after blowdown pulling charge through the engine.

Great stuff, TeeZee will be very interested.

[oktrg500]

Great stuff, TeeZee will be very interested.
My thought too. Waiting for TeeZee now.

[lodgernz]

At highspeed it doesn't even have to rotate at all. As long as it stops in the open position. Its only needed at lower speeds isn't it?


Rotate? Why not just open and close guillotine?

Guillotine implies reciprocating, i.e. back and forward or up and down, the killer motion.
Rotate is better than reciprocate, even in stop/start stepper motion, and the stepper only needs to have two positions: Opened and closed, being 90° apart.
Or, the disk could have a number of "fingers", each a bit wider then the port, and the stepper could just move however many degrees required to move to the next open or closed position.
If there were, say, six such fingers (and six gaps, obviously), the stepper would only need to move 30° per step (open to closed or closed to open), or 60° per rev.

Such demands might be within the reach of a stepper motor at 15000 RPM. I don't know.
The load on the motor wouldn't be huge: discs don't weigh much although the starting friction (stiction) could be high with the disk surface stationary against the port, with pressure in one direction or the other.

Having the port completely open and unobstructed for its full duration sounds ideal, but I wonder if the very sudden closing and opening would have repercussions down the tube?

[Nath88]

I like your approach very much Nathan.
But looking at your third picture, I wonder how much radiator heat will be picked up by the fuel. Some fuel components have a boiling point around 50° C ....

As it turns out, a not insignificant amount... :( The fuel starts to boil in the pump when water temp exceeds 70°C, and the fuel pressure drops, it can be awkward in traffic. I am installing a return line to the tank, bleeding off about 8L/hr to move fuel through the pump. The pump will draw extra power and the fuel in the tank will be heated, but it should do the job until I redesign the system. Fitting the parts on the bike cleanly is most of the battle. In-tank pump would be ideal!

[TZ350]

Throttle transition at high rpm has been the main tuning issue. When closing and reopening the throttle, the motor would flood and not refire until the revs dropped, so I figured the airflow must drop off at some throttle value.

Then I figured that the airflow wasn't just related to the throttle, but when the engine is firing, the airflow is significantly higher than when it isn’t firing, due to the exhaust vacuum after blowdown pulling charge through the engine.
Great stuff, TeeZee will be very interested.
My thought too. Waiting for TeeZee now.

Yes, very interested. Thanks Nathan, for the great idea of using a MAP sensor to measure the pressure changes in the exhaust system so as to see the changes in bulk air flow through the engine, I wish I had thought of that ages ago.

[Nath88]

Overun over fueling, Cagiva had the same issue. Yours is a bloody neat set up though.
https://www.kiwibiker.co.nz/forums/album.php?albumid=4842&attachmentid=301602
https://www.kiwibiker.co.nz/forums/album.php?albumid=4842&attachmentid=301601
https://www.kiwibiker.co.nz/forums/album.php?albumid=4842&attachmentid=301600
https://www.kiwibiker.co.nz/forums/album.php?albumid=4842&attachmentid=301599
https://www.kiwibiker.co.nz/forums/album.php?albumid=4842&attachmentid=301598
https://www.kiwibiker.co.nz/forums/album.php?albumid=4842&attachmentid=301597

The cagiva used to keep pumping in fuel on over run, then bog whth its rich mixture and then chime in with a potental highside causing burst, when the unburnt fuel finally cleared out of the crankcase.
Pumper carbs can do the same thing, not an issue on karts as they tend to keep on the gas.
I think What you have done is you have compensated for lower airflow and incomplete combustion on over-run, which was creating a richer mixture in the crankcase, which is what a conventional vacum metered carb does.
Neat solution.

I found with my system it would never clear once it bogged, just 100% dead until the revs dropped. They must have been using some method of clearing it.
I guess that's why injected snowmobiles and boats don't have the issue, as soon as the throttle is cut the revs drop.
Nice article on the Cagiva too, I hadn't seen that one.

[TZ350]

I found with my system it would never clear once it bogged, just 100% dead until the revs dropped.

Exactly my problem too.

[2T Institute]

Throttle transition at high rpm has been the main tuning issue. When closing and reopening the throttle, the motor would flood and not refire until the revs dropped, so I figured the airflow must drop off at some throttle value. I tried tuning a ledge into the fuel map, it was better than before but still hit and miss, fast roll on was ok, slow roll on or steady part throttle would still flood.

Same problem everyone else, from Cagiva through to Suter last year at the IOM the longer time at full throttle the worse it will be.

That overlay from the ECU on the video is uber cool :drinknsin

[2T Institute]

I found with my system it would never clear once it bogged, just 100% dead until the revs dropped. They must have been using some method of clearing it.
I guess that's why injected snowmobiles and boats don't have the issue, as soon as the throttle is cut the revs drop.

A prop will never drive the engine once the throttle is chopped, sleds have a CVT so the engine is always in band. The other thing in common is on/off throttle no trailing no feathering no half off pipe throttle.

[Nath88]

Thanks Nathan, you have shown me a very different approach. Use a 2 bar MAP sensor to measure the pressure changes in the expansion chamber to determine bulk changes in air flow through the engine. Good idea, wish I had thought of that ages ago.
Measuring the blowdown pressure pulse rather than the negative (since they should be proportional) gives you a head start on getting the fuel in. I have the pressure sample window set to 140-170° ATDC. The peak moves with RPM, because of the delay along the hose to the MAP sensor, so best to keep it as short and close to the port opening as possible. I have the injection start 10° after the sample window, so the latest pressure value is used to calculate the injector pulsewidth.

I suspect the pulses develop to full strength over a few cycles, as the return wave strengthens the combustion, so probably no need to get all the fuel in on that first cycle after measurement.

I am measuring through the powervalve vent, so my pressure values are only indicative for firing or not. With a proper exhaust port measurement you could adjust fuelling based on the pressure rather than just firing/not-firing.

You could even use a firing/not-firing approach based on the sound from the combustion chamber to switch maps... More time to sort the fuel for the next cycle.

Will be complicated on a multi-cylinder when one cylinder kicks on before the other... Will have to separate the signals from each cylinder, two switched map sensors?! Maybe have the spark output for each cylinder activate the MAP input for that cylinder? So it flips back and forth? Ughh.

Will you try it?

[TZ350]

Will you try it?

Yes.........

[husaberg]

I found with my system it would never clear once it bogged, just 100% dead until the revs dropped. They must have been using some method of clearing it.
I guess that's why injected snowmobiles and boats don't have the issue, as soon as the throttle is cut the revs drop.
Nice article on the Cagiva too, I hadn't seen that one.


Exactly my problem too.


Same problem everyone else, from Cagiva through to Suter last year at the IOM the longer time at full throttle the worse it will be.

That overlay from the ECU on the video is uber cool :drinknsin

My initial thoughts would be Auto blip throttle control, MGP bikes have it.
Ages ago I posted something Jennings wrote that came from John Brooks who was the macolloch pumper carb guru.
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131005018&highlight=jennings#post1131005018
From memory they fixed the pumper carb by closing off the circuit when there was i think no air pressure on the upstream side of the venturi
maybe that’s what the Fuel injection needs the Air pressure sensor on both sides of the throttle body and the truth table to compare them.
I don't think the Microsquirt could react fast enough to the sudden decrease in revs to control it that way.

Cagiva alluded it could be tuned out, but not sure if that actually involved GPS mapping which was one the cusp widespread use at that time.


Foggy refused to ride it at the Brit GP due to its behaviour.

I have never heard it mentioned as being a problem with either the fuel injected NSR500 or the EXP400 Honda that were also throttle body injected.
Riley Will was having some good results last time i looked with a kart motor.

[Flettner]

That overlay from the ECU on the video is uber cool :drinknsin

Yes I like that too.

[41juergen]

your doing good job :2thumbsup. will your exh exit be 75% of exh area at bore face ?

Yes, at least best as I can. The Problem is that I can't make a real oval as I would get into the water jacket, so I try to make the aux tunnel as far and "wide" as I can... Also I will put the stinger nozzle in, EngMod predicted a nice power increase behind peak. So let's see what the dyno will tell :)

[TZ350]

328803

Well, for something different, Paul and I spent the last few evenings playing with a Bucket EFI 4T, as you do, playing with motorbikes instead of spending time with family and loved ones. We found extra hp by advancing the cam 6 deg, and carefully shortening the inlet 10mm at a time. Anyway 151 runs latter, 23 hp. In the end there was still a cyclic series of humps, interesting, no idea how to smooth them out.

Really looking forward to getting back to my 2T EFI project and exploring Nath88's idea of using the strength of the exhaust suction pulse on over run to adjust the strength of the next injection cycle.

[shnaggs]

I just read that KTM was going to run EFI on their 125 gp right when the moto 3 rule went into play. Wonder if that was TB injected???


Here: https://www.motomatters.com/analysis/2017/02/22/our_most_hated_rival_ktm_s_long_feud.html

[jonny quest]

Are there any pics out there of KTM'S parallel twin 250 gp engine? I tried searching with no luck

[Martin1981]

Does anybody know if there is a good heat and fuel/oil resistant liquid rubber a carburetor insulator boot could be made of?

[senso]

Silicone, or RTV?

[190mech]

Polysulfide compound,its used as fuel tank sealant in the aviation world,search for PRC PR 1422 or 3M corp EC801,its a 2 part system that dries tuogh and flexible.Sold at Aircraft Spruce..

[Frits Overmars]

I just read that KTM was going to run EFI on their 125 gp right when the moto 3 rule went into play. Wonder if that was TB injected?Not likely; the 125 cc KTM GP-bike already had an injector in the crankcase that injected through a port below the exhaust port.
They used it instead of a powerjet and it would only have been logical to use the same setup for full EFI.
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[Frits Overmars]

Are there any pics out there of KTM'S parallel twin 250 gp engine? I tried searching with no luckHere you go Jonny.
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[mr bucketracer]

don't know about fuel but at work we made soft stuff out of rotomoulding pvc , here is a small clip of baby heads been made https://www.youtube.com/watch?v=TSyZY6aFJZ0

[F5 Dave]

RZ slipping clutch; I've never looked at this sort of thing as assumed a drag thing, but Wob was posting of issues and the night before my RZ started slipping on the dyno at anything approaching 90hp (its a CPI 496cc).

So what is having a lockup clutch like? It applies pressure, but does it change the action so it feels weird?

Wonder if it needs a spacer.

http://m.ebay.com/itm/NEW-Yamaha-Banshee-LOCK-UP-clutch-kit-lock-out-finger-BILLET-BLACK-ANODIZED-/141972896541?hash=item210e3e7b1d%3Ag%3AMgsAAOSwYmZ XH8Vw&_trkparms=pageci%253Ab85d3ac4-f9f5-11e6-bc71-74dbd18007b2%257Cparentrq%253A6c3a498515a0a786ca68 02b2ffedd4f1%257Ciid%253A11

[adegnes]

An idea I've been playing with for a while now:

As I'm not restricted by any rules or regulations, how about a supercharged "hyprid" two stroke?
Blower connected directly to the transferports, a relatively small exhaust port, a pipe designed to retain as much energy as possible before the convergent cone(a pure "port blocker"), and an electric motor for bringing it into the powerband.

The point being to blow huge amounts of fresh mix through the cylinder, eliminating any possibility for mixing with spent gases, and at the same time (due to the small exhaust port/blocking pipe) build considerable pressure before exhaust port closing.

Stupid?

[peewee]

Yes, at least best as I can. The Problem is that I can't make a real oval as I would get into the water jacket, so I try to make the aux tunnel as far and "wide" as I can... Also I will put the stinger nozzle in, EngMod predicted a nice power increase behind peak. So let's see what the dyno will tell :)

I understand. sometimes you just do the best you can and leave the rest to compromise. to get down to 75% i ended up needing to do a lot of welding on the floor and roof of the main passage. was pain in the ass :laugh:. the cylinder was designed sometime in the early 80's and really there was nothing good about its design. sometimes i wonder if it was just a big waste of time. hopefully your adventure is less grief than mine :niceone:

[adegnes]

sometimes i wonder if it was just a big waste of time.

No way! Think of all the experience and knowledge you've gained from it!

[peewee]

Not likely; the 125 cc KTM GP-bike already had an injector in the crankcase that injected through a port below the exhaust port.
They used it instead of a powerjet and it would only have been logical to use the same setup for full EFI.
328804 328805 328806

ktm been using 3exh port configuration in the motox engines for 30yrs now. wouldn't you think that experience would carry over to the road going sector ? ive really gotten to dislike the center bridged exh after bad experience with it chewing up rings :laugh:. luckily ive sold off nearly every bike i had with a center exh bridge :laugh::laugh::laugh:

[richban]

328803
Anyway 151 runs latter, 23 hp. In the end there was still a cyclic series of humps, interesting, no idea how to smooth them out.


Looks like your classic 4 banger Exhaust reversion. Was it there with the old cam timing? I can't find my old Graph from your dyno. Mine might have had it as well. Fix should be all in header length and muffler size.

[teriks]

Silicone, or RTV?
Would be good for alcohol fuels, but silicons doesn't like gasoline at all.

[jonny quest]

Here you go Jonny.
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Thank you! Did that have a 180 firing order?

[Frits Overmars]

Thank you! Did that have a 180 firing order?Nope. It was 90°/270°, rather unusual for a parallel two-stroke twin.

[husaberg]

Are there any pics out there of KTM'S parallel twin 250 gp engine? I tried searching with no luck


Here you go Jonny.


Here is a few more, Internals are pretty much race Kit NSR/RS Honda. AS are the pipes
https://www.kiwibiker.co.nz/forums/album.php?albumid=4901
Pipe spec courtesy of Frits Overmars bottom.
https://www.kiwibiker.co.nz/forums/album.php?albumid=4854&attachmentid=310144

[Nath88]

Does anybody know if there is a good heat and fuel/oil resistant liquid rubber a carburetor insulator boot could be made of?
I have a 3D printed TPU (Thermoplastic Polyurethane) boot on my bike at the moment. Printed by Duckhive3D. He's done a few for bikes and karts, it might be an easier option. Or possibly cast it using TPU.

[TZ350]

328803 In the end there was still a cyclic series of humps, interesting, no idea how to smooth them out.
Looks like your classic 4 banger Exhaust reversion. Was it there with the old cam timing? I can't find my old Graph from your dyno. Mine might have had it as well. Fix should be all in header length and muffler size.

Worse at the beginning, got better with each positive change to cam and inlet tract length. It has a tapered and stepped header. If there is another time on the dyno with this bike, we will follow your suggestions.

[richban]

Worse at the beginning, got better with each positive change to cam and inlet tract length. It has a tapered and stepped header. If there is another time on the dyno with this bike, we will follow your suggestions.

Cool yeah sounds like you just need to match up the exhaust. I ended up chucking out the stepped header in favour of a more 2 stroke style header. The size increase was with a steady cone instead to hard steps. My engine was very sensitive to any hard pipe transitions. Stupid things anyway to many moving parts.

[crbbt]

Just curious what happened to all of ktms 125gp bikes? Can not say I recall seeing any at club level. were they only a factory effort?

[SwePatrick]

RZ slipping clutch; I've never looked at this sort of thing as assumed a drag thing, but Wob was posting of issues and the night before my RZ started slipping on the dyno at anything approaching 90hp (its a CPI 496cc).

So what is having a lockup clutch like? It applies pressure, but does it change the action so it feels weird?

Wonder if it needs a spacer.

http://m.ebay.com/itm/NEW-Yamaha-Banshee-LOCK-UP-clutch-kit-lock-out-finger-BILLET-BLACK-ANODIZED-/141972896541?hash=item210e3e7b1d%3Ag%3AMgsAAOSwYmZ XH8Vw&_trkparms=pageci%253Ab85d3ac4-f9f5-11e6-bc71-74dbd18007b2%257Cparentrq%253A6c3a498515a0a786ca68 02b2ffedd4f1%257Ciid%253A11


Yes, clutching it in high rpm will be harder, sometimes impossible.
You need a shiftcut with that. ;)

[SwePatrick]

An idea I've been playing with for a while now:

As I'm not restricted by any rules or regulations, how about a supercharged "hyprid" two stroke?
Blower connected directly to the transferports, a relatively small exhaust port, a pipe designed to retain as much energy as possible before the convergent cone(a pure "port blocker"), and an electric motor for bringing it into the powerband.

The point being to blow huge amounts of fresh mix through the cylinder, eliminating any possibility for mixing with spent gases, and at the same time (due to the small exhaust port/blocking pipe) build considerable pressure before exhaust port closing.

Stupid?

Like an old diesel twostroke ;)

https://www.youtube.com/watch?v=xTQvM1cXOyc
https://www.youtube.com/watch?v=mA7l3dpx6t0

[TZ350]

As I'm not restricted by any rules or regulations, how about a supercharged "hyprid" two stroke? Blower connected directly to the transfer ports, a relatively small exhaust port, a pipe designed to retain as much energy as possible before the convergent cone(a pure "port blocker"), and an electric motor for bringing it into the powerband. Stupid?

Nothing stupid about that, or maybe everything but if the engine capacity was right and started life as a non competition motorcycle engine then it would be totally go for Buckets. I like your thinking.

[husaberg]

Nothing stupid about that, or maybe everything but if the engine capacity was right and started life as a non competition motorcycle engine then it would be totally go for Buckets. I like your thinking.

There is a company in the states that make very small supoerchargers suitable for 50CC.
https://www.oguraclutch.co.jp/e/product/supercharger/type.html
https://www.oguraclutch.co.jp/e/product/supercharger/size.html
The nanufacturer is known for its high end racing clutches so it should be very well made and likely priced accordingly.

[adegnes]

Like an old diesel twostroke ;)

https://www.youtube.com/watch?v=xTQvM1cXOyc
https://www.youtube.com/watch?v=mA7l3dpx6t0

Yep! BTW, did you find any more info on that small supercharged two stroke you posted a while back?


Nothing stupid about that, or maybe everything but if the engine capacity was right and started life as a non competition motorcycle engine then it would be totally go for Buckets. I like your thinking.
:yes: Thanks!


There is a company in the states that make very small supoerchargers suitable for 50CC.
https://www.oguraclutch.co.jp/e/product/supercharger/type.html
https://www.oguraclutch.co.jp/e/product/supercharger/size.html
The nanufacturer is known for its high end racing clutches so it should be very well made and likely priced accordingly.

Nice!
I'll contact them, maybe I can persuade them into sending me a unit for testing purposes...

I'll make a video further explaining what I have in mind.

[41juergen]

I understand. sometimes you just do the best you can and leave the rest to compromise. to get down to 75% i ended up needing to do a lot of welding on the floor and roof of the main passage. was pain in the ass :laugh:. the cylinder was designed sometime in the early 80's and really there was nothing good about its design. sometimes i wonder if it was just a big waste of time. hopefully your adventure is less grief than mine :niceone:
Yep, know what you mean. Attached a first try for the next set of cylinders... :shit:
328842

[peewee]

RZ slipping clutch; I've never looked at this sort of thing as assumed a drag thing, but Wob was posting of issues and the night before my RZ started slipping on the dyno at anything approaching 90hp (its a CPI 496cc).

So what is having a lockup clutch like? It applies pressure, but does it change the action so it feels weird?

Wonder if it needs a spacer.

http://m.ebay.com/itm/NEW-Yamaha-Banshee-LOCK-UP-clutch-kit-lock-out-finger-BILLET-BLACK-ANODIZED-/141972896541?hash=item210e3e7b1d%3Ag%3AMgsAAOSwYmZ XH8Vw&_trkparms=pageci%253Ab85d3ac4-f9f5-11e6-bc71-74dbd18007b2%257Cparentrq%253A6c3a498515a0a786ca68 02b2ffedd4f1%257Ciid%253A11

like Patrick said it may be difficult or impossible to use the clutch at high revs ( youll be trying to push the pressure plate open while the fingers are trying to keep it clamped shut). the whole assembly bolts on top of the pressure plate. no spacer needed. but it makes the engine wider so you need a special clutch cover. its mostly for drag racing as you never use the clutch but on take off http://www.ebay.com/itm/BANSHEE-CLUTCH-LOCK-UP-COVER-Anodized-Lock-Up-BANSHEE-QUICK-CHANGE-COVER/222410241509?_trksid=p2047675.c100623.m-1&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%2 6asc%3D41402%26meid%3D043daf1b5c7f4d4b9af13f31678f 4188%26pid%3D100623%26rk%3D4%26rkt%3D6%26mehot%3Dl o%26sd%3D141972896541

I think they have one that fits under standard clutch cover. uses ballbearings in ramped grooves. not sure how well the clutch would work on this as its function is the same as the finger style. says its good for 140+HP :laugh: http://www.ebay.com/itm/New-Yamaha-YFZ350-Banshee-Lock-Up-Ball-Bearing-Clutch-Kit-140-HP-Fit-1987-2006/142234731083?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%2 6asc%3D41402%26meid%3Dc9c4daea263a4f909e7ccc3c9a9c 38b6%26pid%3D100005%26rk%3D4%26rkt%3D6%26sd%3D1519 68425953

what about stiffer springs and hydraulic setup ?

[SwePatrick]

Yep! BTW, did you find any more info on that small supercharged two stroke you posted a while back?



No nothing.
I googled for a couple of hours, nothing :(

[husaberg]

No nothing.
I googled for a couple of hours, nothing :(
Challange accepted
Post a link or the picture.;)

[TZ350]

""Well its been awhile!!, but the bike hit the dyno!!, and it turns out I have alot of tuning to do.........running pig rich in boost it seems. Its funnny because on the street it always seemed pretty good into and above 20psi. Anyways at 10.5 psi boost the bike is making a solid 70hp at the wheel at 10200rpm, anything over 11psi and afr's go to around 8:1. hopefully in the next few weeks I can work on the tune and get the afrs perfect into the 25psi range. It takes alot of load to spool the turbo, the pulls were done in 6th gear. I have a gt12 I might try and see if I can get a bit faster spool. I expect to be well over 100hp soon""

328843 .... http://supermotojunkie.com/showthread.php?144672-Turbo-Banshee-motor-in-a-yamaha-yzf-cafe-chassis!!!

Turbo RZ project.

[41juergen]

""Well its been awhile!!, but the bike hit the dyno!!, and it turns out I have alot of tuning to do.........running pig rich in boost it seems. Its funnny because on the street it always seemed pretty good into and above 20psi. Anyways at 10.5 psi boost the bike is making a solid 70hp at the wheel at 10200rpm, anything over 11psi and afr's go to around 8:1. hopefully in the next few weeks I can work on the tune and get the afrs perfect into the 25psi range. It takes alot of load to spool the turbo, the pulls were done in 6th gear. I have a gt12 I might try and see if I can get a bit faster spool. I expect to be well over 100hp soon""

328843 .... http://supermotojunkie.com/showthread.php?144672-Turbo-Banshee-motor-in-a-yamaha-yzf-cafe-chassis!!!

Turbo RZ project.

Interesting project, as the English man would say. Wob gets the 70HP out of 1 cylinder..... :not:

[Frits Overmars]

Just curious what happened to all of ktms 125gp bikes? Can not say I recall seeing any at club level. were they only a factory effort?The ones with the injector were works bikes, but the 125 cc KTM production racers were used in the Red Bull Rookies Cup for years, so there must be dozens around.
I too wonder where they all went.

[sispeed]

The ones with the injector were works bikes, but the 125 cc KTM production racers were used in the Red Bull Rookie Cup for years, so there must be dozens around.
I too wonder where they all went.

I know a person in Austria who ownes one.
https://www.facebook.com/christopher.eder.7?fref=ts
Hope you can see this without an account

[wobbly]

I have some 30 % uprated springs to use in Yamaha/Hinson RZ/Banshee clutches,just use 3 of them and the lever isnt too stiff.
PM me if you want some,they are good for the 130RWHp I got in Makrs Landspeed RD400.
The lockup clutch is no good for a 2T in roadracing,where many riders use the clutch on downshifting to keep the back stable under brakes.
And yes you must use a speedshifter on the upshift.

Just a small point re the 75% cylinder exit area rule of thumb,this area is just a by product of the desire to reduce the volume of the whole exit duct.
The other guide is that this area is most effective if it occurs at around 1.5x the bore diameter,thus many cylinders are way too short.
I have added extra ,smaller area ,duct length to many cylinders, by extending the bolt on spigot plate, or making a female spigot on the cylinder into a male one.
Then the header that sits after the oval to round transition, starts at 2x bore.

[F5 Dave]

Thanks. I have uprated springs and new oem FZR plates. I'll go have a fish around might have only fit 3 could try all 6. Lever arm is lengthened, Ido have a cheapo hhydraulic cable conversion Iwas ggoing to try out.

[speedpro]

Depending on how many plates you have, what about thinning all the steels a small amount and taking small amounts off the alloy clamping faces. If you can fit an extra pair of plates that is a useful increase in clutch surface area.

[F5 Dave]

Indeed, the 100 clutch you did for me was great.

Bit concerned they would warp with 100hp going through them. But heck might be worth measuring up when I'm in there.

[breezy]

not sure my pm thing is working.. so tz350 can you tell me what size hole is required in the crank wheels/ webs to fit a 22mm crank pin. i had a suzuki gp 125 crank machined a few years ago which renderd it useless in its present form. thanks .

[41juergen]

Just a small point re the 75% cylinder exit area rule of thumb,this area is just a by product of the desire to reduce the volume of the whole exit duct.
The other guide is that this area is most effective if it occurs at around 1.5x the bore diameter,thus many cylinders are way too short.
I have added extra ,smaller area ,duct length to many cylinders, by extending the bolt on spigot plate, or making a female spigot on the cylinder into a male one.
Then the header that sits after the oval to round transition, starts at 2x bore.

Yep, I remember you pointed that out a longer time ago. So I verified that with the sim ending with approx. 85mm length for the 75% area place. As you mentioned also the TZR exhaust duct is too short, so I replaced the stock 33mm cylindrical pipe in front of the header by an cmc machined part. Of course that will be not as good as a real oval to round transition, but at least I will give it a try...
For the other set of SP cylinders I welded the floor of the duct and the spigot... The rear cone will also get a stinger venturi...

328861328862328864 328863

[adegnes]

Challange accepted
Post a link or the picture.;)

Here ya go Husa, work your magic!


328640328639328638

How about this one?
anyone got info?
it´s an supercharged twostroke from what i can see.
No crankcase like an old diesel twostroke?



""Well its been awhile!!, but the bike hit the dyno!!, and it turns out I have alot of tuning to do.........running pig rich in boost it seems. Its funnny because on the street it always seemed pretty good into and above 20psi. Anyways at 10.5 psi boost the bike is making a solid 70hp at the wheel at 10200rpm, anything over 11psi and afr's go to around 8:1. hopefully in the next few weeks I can work on the tune and get the afrs perfect into the 25psi range. It takes alot of load to spool the turbo, the pulls were done in 6th gear. I have a gt12 I might try and see if I can get a bit faster spool. I expect to be well over 100hp soon""

328843 .... http://supermotojunkie.com/showthread.php?144672-Turbo-Banshee-motor-in-a-yamaha-yzf-cafe-chassis!!!

Turbo RZ project.
Nice find!

My idea! After doing some more research(lots of info here:
http://www.elsberg-tuning.dk/supercharging.html)
I realized it's not that unique.
You think the crankcase vent valve and pipe thing is necessary?


https://youtu.be/8HaDroJAuQI

[peewee]

Yep, I remember you pointed that out a longer time ago. So I verified that with the sim ending with approx. 85mm length for the 75% area place. As you mentioned also the TZR exhaust duct is too short, so I replaced the stock 33mm cylindrical pipe in front of the header by an cmc machined part. Of course that will be not as good as a real oval to round transition, but at least I will give it a try...
For the other set of SP cylinders I welded the floor of the duct and the spigot... The rear cone will also get a stinger venturi...

328861328862328864 328863

what kind of chassis do you have ? my passage was far to short. to get it any where near 1.5x it would of needed to be 135mm. this was not possible because the front tire would of smashed the header during suspension travel

[Frits Overmars]

https://www.youtube.com/watch?v=8HaDroJAuQI#t=4m05s Maybe this picture will help you on your way Alex:
328865


You think the crankcase vent valve and pipe thing is necessary?Nah. KISS, remember?


I also ordered an RC remote needle valve which I will use as an adjustable power jet.These valves, used by some of my model airplane buddies, allow in-flight mixture leaning in the pursuit of that final rpm. And final is often the correct description;
those RC remote needle valves are also known as remote engine killers because their operators tend to get too rpm-greedy.

[adegnes]

Maybe this picture will help you on your way Alex:
328865
Now that's something in my "style", what's the story here?




Nah. KISS, remember?
That would simplify things alot!



These valves, used by some of my model airplane buddies, are very effective. They allow in-flight mixture leaning in the pursuit of that final rpm.
And final is often the correct description; those RC remote needle valves are also known as remote engine killers because their operators tend to get too rpm-greedy.

The valve I've ordered is just ment to move the needle away from the prop area(I think TZ used a similar one on the beast at some point) I looked at those servo operated "really" remote valves you are talking about too tho, being rpm-greedy I steered away...

[TZ350]

Not likely; the 125 cc KTM GP-bike already had an injector in the crankcase that injected through a port below the exhaust port.They used it instead of a powerjet and it would only have been logical to use the same setup for full EFI.

328868328869



328871328870

The Artic Cat injected above and inside the piston.

328866328867

On my two stage EFI air cooled motor I tried to cool the under side of the piston crown by having the second stage main injector firing up inside it (center injector). Unfortunately I did not get the piston cooling I was hoping for because this arrangement did not fuel well on full load when I maximized the fuel being injected under the piston, I think it just drowned things.

But with the smaller primary injector in the middle it did fuel very well on part throttle and off the pipe. The engine was at its best with the small low load first stage injector in the middle and the second stage main power injectors on the sides in the transfer ports.

I put the good low load throttle response down to good mixing of the central low load injectors fuel charge into the transferred air by the piston movement.

The Artic Cat's method of injecting above and below the piston might have given me the piston cooling I was looking for if the low load injection cycle was timed to be below the piston for low loads and extending the injection cycle to above the piston for direct crown cooling when the load and RPM got up and the pipe's trapping efficient positive pressure pulse was working hard plugging the exhaust port to stop air/fuel escaping.

The Ecotrons two stroke EFI software comes with only the Alpha-N table active but if I can get Ecotrons to turn the VE table back on then I could try using the pressure at the exhaust port from the returning wave to fine tune the fueling at over run, like Nath88 suggested.

I like the Ecotrons EFI system because it is accessible and affordable enough for beginners to experiment with.

[Sketchy_Racer]

Indeed, the 100 clutch you did for me was great.

Bit concerned they would warp with 100hp going through them. But heck might be worth measuring up when I'm in there.

For what its worth, we laser cut 1.5mm steel plates to replace the 2mm plates in the NSR dry clutches and get an extra steel and fiber plate. I thought that they may warp badly but mines been in there for two seasons now and still works a charm.

[husaberg]

Here ya go Husa, work your magic!


it might be easier if youhad have posted them as an image
the pictures actually say turbo on the side of the engine.
While looking i found this though.
http://s-charger.com/50cc-supercharger/
If i was going to supercharge a small two stroke i would prefer to use a small wankel compressor just like NSU did.

[adegnes]

it might be easier if youhad have posted them as an image
the pictures actually say turbo on the side of the engine.
While looking i found this though.
http://s-charger.com/50cc-supercharger/
If i was going to supercharge a small two stroke i would prefer to use a small wankel compressor just like NSU did.

I'm not sure I understand about posting them differently?
Funny that it says "turbo"...
That s-charger could work! I actually sent them a mail earlier today saying something like "Me need blower, you need publicity, let's talk!".

[Frits Overmars]

The Artic Cat injection above and below the piston might have given me the piston cooling I was looking for if the low load injection cycle was timed to be below the piston for low load and the injection cycle extending to above the piston for direct crown cooling when the RPM got up and the pipe was working to block the exhaust stopping air/fuel escaping.They do it the other way around TeeZee: late-starting direct injection at low load to avoid fuel losses, and indirect injection at high load, stirring the mixture in the crankcase in order to create a homogeneous mixture.


Here ya go Husa, work your magic! Attachment 328640Attachment 328639Attachment 328638

it might be easier if you had have posted them as an image. the pictures actually say turbo on the side of the engine.Yes, it says Turbo but in this case it is merely a promotional term because turbos are hot these days.
Technically speaking it's not a turbo: the centrifugal compressor is not driven by an exhaust gas turbine but it is geared to the crankshaft.
The gear ratio is 8 to 1 and for now that is all I am allowed to say about it by the man behind the engine, my mate Roland Holzner.
328899 328900

[wobbly]

My understanding of the KTM injector was that it was only used to supply some extra mixture on the overun into corners on closed throttle.
Apparently the engine seized several times in testing when run with very high rpm downchanges, with no throttle opening.

[adegnes]

Yes, it says Turbo but in this case it is merely a promotional term because turbos are hot these days.
Technically speaking it's not a turbo: the centrifugal compressor is not driven by an exhaust gas turbine but it is geared to the crankshaft.
The gear ratio is 8 to 1 and for now that is all I am allowed to say about it by the man behind the engine, my mate Roland Holzner.
328899 328900

Ok. Just as I've started war on the Dutch 25whp Zundapp guys then this pops up! What kind of power are we talking here? I'll double it!
Don't make me pull out the green flames!

But seriously, the engine looks very interesting, can't wait to hear more about it!

[adegnes]

Yes, it says Turbo but in this case it is merely a promotional term because turbos are hot these days.
Technically speaking it's not a turbo: the centrifugal compressor is not driven by an exhaust gas turbine but it is geared to the crankshaft.
The gear ratio is 8 to 1 and for now that is all I am allowed to say about it by the man behind the engine, my mate Roland Holzner.
328899 328900

Looks like there's some kind of separate exhaust timing thing going on, clever!

[Frits Overmars]

Looks like there's some kind of separate exhaust timing thing going on, clever!You noticed, didn't you? But you didn't hear it from me :msn-wink:.

[TZ350]

They do it the other way around TeeZee: late-starting direct injection at low load to avoid fuel losses, and indirect injection at high load, stirring the mixture in the crankcase in order to create a homogeneous mixture.

Thanks for that, maybe they got their better results by pointing the injector down, I must try that.

[ken seeber]

Looks like there's some kind of separate exhaust timing thing going on, clever!

Alex, thinking about your supercharged engine thoughts and your concern re crankcase contamination with fuel.
Years ago I was with Orbital, developing both our 2 stroke engines for auto use and the 2 fluid DI injection system for various applications.
Of the auto engines, we commenced with the mainstay 3 cyl crank scavenged X engine but also a 3 cyl (1 litre) and 6 cyl (2 litre) externally scavenged engines. These were wet sumped with pressure fed crank.
All scavenging was done by an engine driven Roots style blower. Interestingly this allowed us to have a common manifold on either side of the engine. From these we had vertical passages. In between each pair of adjacent cylinders, these were bifurcated at the top, such that one side feeding the two adjacent A ports, the other side feeding the two B ports. Probably not ideal in terms of flow due to the bifurcations, but certainly allowed us to maintain tight bore centres. Obviously these only transferred air, as these were DI.
Bit of a long story to get to the pistons. To prevent (uncontrolled/copious) oil entry up the bore and into the combustion area, the piston had an oil scraper ring at the base of the piston skirt, this being situated low enough to not uncover the exhaust or transfer ports. Obviously the piston was full skirted and longer (by a bit) than the engine stroke. Lubrication of the piston skirts and compression rings was achieved by oil being carried up the bore via the honing. A bit uncontrollable maybe, but I don’t remember any concerns with excess oil consumption and certainly no smoke or smell. Maybe not so suited to your max power only requirement, as these will necessarily be heavy. I think I might have one kicking around work, so will post a pic if I can find something.
These engines featured an exh power valve which allowed the exh timing to be very considerably lowered, providing the opportunity to pressurise the trapped volume to a degree.
So, I reckon that whatever cylinder you use, get one with a power valve that can go quite low.
As you might be aware, I am personally keen on having the exhaust drawing in air (or mixture) directly from the atmosphere, bypassing all the reed/crankcase/transfer passage losses, ideally on a wet sump bottom end.
There is another site: https://www.facebook.com/groups/105572222948183/?ref=bookmarks where various things are discussed, one being the concept of a small electric motor providing enough flow to get the engine started There is also a range of other engine scavenging thoughts.

[JanBros]

Alex, why would you still put reads in the intakes, when there is only flow in one direction ;)

[F5 Dave]

For what its worth, we laser cut 1.5mm steel plates to replace the 2mm plates in the NSR dry clutches and get an extra steel and fiber plate. I thought that they may warp badly but mines been in there for two seasons now and still works a charm.
Choice, sounds like a plan. Must get that lamba sensor back to you. Cheers.

[breezy]

not sure my pm thing is working.. so tz350 can you tell me what size hole is required in the crank wheels/ webs to fit a 22mm crank pin. i had a suzuki gp 125 crank machined a few years ago which renderd it useless in its present form. thanks .

thanks TZ, not sure if im doing something wrong but my pm messages are disappearing into space still... https://youtu.be/PU5xxh5UX4U

[41juergen]

what kind of chassis do you have ? my passage was far to short. to get it any where near 1.5x it would of needed to be 135mm. this was not possible because the front tire would of smashed the header during suspension travel

As said, I will replace the constant diameter part with the cnc machined one, so no further space needed. The bike is a TZR250R type 3XV. I bit similar like the TZ250 4DP ones...
328943

[TZ350]

thanks TZ, not sure if im doing something wrong but my pm messages are disappearing into space still.:no:

Sketchy_Racer is your man for crank mods.

[adegnes]

You noticed, didn't you? But you didn't hear it from me :msn-wink:.
:msn-wink: Can you tell me how far it is in development?
Getting second thoughts about my port blocker pipe...


Alex, thinking about your supercharged engine thoughts and your concern re crankcase contamination with fuel.
Years ago I was with Orbital, developing both our 2 stroke engines for auto use and the 2 fluid DI injection system for various applications.
Of the auto engines, we commenced with the mainstay 3 cyl crank scavenged X engine but also a 3 cyl (1 litre) and 6 cyl (2 litre) externally scavenged engines. These were wet sumped with pressure fed crank.
All scavenging was done by an engine driven Roots style blower. Interestingly this allowed us to have a common manifold on either side of the engine. From these we had vertical passages. In between each pair of adjacent cylinders, these were bifurcated at the top, such that one side feeding the two adjacent A ports, the other side feeding the two B ports. Probably not ideal in terms of flow due to the bifurcations, but certainly allowed us to maintain tight bore centres. Obviously these only transferred air, as these were DI.
Bit of a long story to get to the pistons. To prevent (uncontrolled/copious) oil entry up the bore and into the combustion area, the piston had an oil scraper ring at the base of the piston skirt, this being situated low enough to not uncover the exhaust or transfer ports. Obviously the piston was full skirted and longer (by a bit) than the engine stroke. Lubrication of the piston skirts and compression rings was achieved by oil being carried up the bore via the honing. A bit uncontrollable maybe, but I don’t remember any concerns with excess oil consumption and certainly no smoke or smell. Maybe not so suited to your max power only requirement, as these will necessarily be heavy. I think I might have one kicking around work, so will post a pic if I can find something.
These engines featured an exh power valve which allowed the exh timing to be very considerably lowered, providing the opportunity to pressurise the trapped volume to a degree.
So, I reckon that whatever cylinder you use, get one with a power valve that can go quite low.
As you might be aware, I am personally keen on having the exhaust drawing in air (or mixture) directly from the atmosphere, bypassing all the reed/crankcase/transfer passage losses, ideally on a wet sump bottom end.
There is another site: https://www.facebook.com/groups/105572222948183/?ref=bookmarks where various things are discussed, one being the concept of a small electric motor providing enough flow to get the engine started There is also a range of other engine scavenging thoughts.

That sounds like an ideal setup if one could keep the piston weight down. Yep some kind of exhaust valve is probably necessary, this Neg engine looks like it uses a secondary piston, maybe spinning at 2x crank speed. Too complicated for my "prototype", maybe a drum valve could work?
Your exhaust as intake idea is interesting!
Thanks for the link, I'll check it out!


Alex, why would you still put reads in the intakes, when there is only flow in one direction ;)

Good point... :facepalm

[Frits Overmars]

:msn-wink: Can you tell me how far it is in development? :shutup: . . .

[adegnes]

You noticed, didn't you? But you didn't hear it from me :msn-wink:.

I thought he'd just left the spark plug out in the picture, but word on the street says it's a diesel. Phew, can rest my shoulders again...

[tjbw]

They do it the other way around TeeZee: late-starting direct injection at low load to avoid fuel losses, and indirect injection at high load, stirring the mixture in the crankcase in order to create a homogeneous mixture.


Yes, it says Turbo but in this case it is merely a promotional term because turbos are hot these days.
Technically speaking it's not a turbo: the centrifugal compressor is not driven by an exhaust gas turbine but it is geared to the crankshaft.
The gear ratio is 8 to 1 and for now that is all I am allowed to say about it by the man behind the engine, my mate Roland Holzner.
328899 328900

Is it a supercharged diesel two stroke uniflow engine, with a single side valve for exhaust?

The exhaust is not controlled by a poppet valve, but by a little piston, with asymmetric timing?

[Michael Moore]

the piston had an oil scraper ring at the base of the piston skirt,

Laverda 125/150 singles had a piston like that. I found it interesting that every one I took apart had the bottom of the piston broken off at the ring groove.

cheers,
Michael

[breezy]

I thought he'd just left the spark plug out in the picture, but word on the street says it's a diesel. Phew, can rest my shoulders again...

dont let the big boys hold you back.. theyll be scratchin their arses most of the time..

[adegnes]

dont let the big boys hold you back.. theyll be scratchin their arses most of the time..
:2thumbsup Too bad that's what I do most of the time too...

[breezy]

Sketchy_Racer is your man for crank mods.

thanks Glen....

[ken seeber]

OK, couldn’t find an actual piston from the engines I was referring to, but this is another similar research piston we did for a company when they were investigating DI for various applications, nearly 20 years ago. It was an Ø86 * 86 size.

328951

Funny though, it looks a lot like this one http://www.lotuscars.com/engineering/case-study-omnivore-research-engine
This piston in the pic was just an early off tool sample and was used for refining the casting and Molykote D10 spraying process.
I reckon that if I was going down this road I’d go for an oversquare engine to reduce piston length and weight. I know it goes against all the port area/STA stuff, but my thoughts are more towards a utilitarian application, not needing to rev the tits off it as perhaps Alex is considering.

[shnaggs]

OK, couldn’t find an actual piston from the engines I was referring to, but this is another similar research piston we did for a company when they were investigating DI for various applications, nearly 20 years ago. It was an Ø86 * 86 size.

328951

Funny though, it looks a lot like this one http://www.lotuscars.com/engineering/case-study-omnivore-research-engine
This piston in the pic was just an early off tool sample and was used for refining the casting and Molykote D10 spraying process.
I reckon that if I was going down this road I’d go for an oversquare engine to reduce piston length and weight. I know it goes against all the port area/STA stuff, but my thoughts are more towards a utilitarian application, not needing to rev the tits off it as perhaps Alex is considering.

Funny, I was just thinking about the Lotus 2 stroke the other day and wondered if any of the guru's on this site knew anything about its life/demise.

[adegnes]

OK, couldn’t find an actual piston from the engines I was referring to, but this is another similar research piston we did for a company when they were investigating DI for various applications, nearly 20 years ago. It was an Ø86 * 86 size.

328951

Funny though, it looks a lot like this one http://www.lotuscars.com/engineering/case-study-omnivore-research-engine
This piston in the pic was just an early off tool sample and was used for refining the casting and Molykote D10 spraying process.
I reckon that if I was going down this road I’d go for an oversquare engine to reduce piston length and weight. I know it goes against all the port area/STA stuff, but my thoughts are more towards a utilitarian application, not needing to rev the tits off it as perhaps Alex is considering.

Nice, thanks! And, yes I like rpm more than most!

[tjbw]

Funny, I was just thinking about the Lotus 2 stroke the other day and wondered if any of the guru's on this site knew anything about its life/demise.

Interesting engine, would also be good for research work.

I also liked their rotary valve engine idea.

http://www.aqpl43.dsl.pipex.com/MUSEUM/POWER/unusualICeng/RotaryValveIC/RotaryValveIC.htm#lotus

[shnaggs]

Interesting engine, would also be good for research work.

I also liked their rotary valve engine idea.

http://www.aqpl43.dsl.pipex.com/MUSEUM/POWER/unusualICeng/RotaryValveIC/RotaryValveIC.htm#lotus

Never saw that ^^^ one before. Although the rotary valve head designed by McLaren for their F1 engine was a pretty neat one. I cant find pics of it, but If I remember, the FIA banned it the first time it showed up to competition.

[teriks]

Never saw that ^^^ one before. Although the rotary valve head designed by McLaren for their F1 engine was a pretty neat one. I cant find pics of it, but If I remember, the FIA banned it the first time it showed up to competition.
Here you go, Bishop rotary valve, Australian stuff:
http://home.people.net.au/~mrbdesign/PDF/AutoTechBRV.pdf

[shnaggs]

Here you go, Bishop rotary valve, Australian stuff:
http://home.people.net.au/~mrbdesign/PDF/AutoTechBRV.pdf

That's the one! Thanks, been a while since I've looked at that concept.

I once had a Coates rotary valve engine sitting in my shop while a legal investigation was taking place. Neat concept, but with obvious faults.

Of coarse my lack of rotary valve 2 stroke experience will shine through, but it always seemed that the rotating window of the RV would be problematic to inlet flow...causing a "sprinkler" effect, I don't know how else to describe it.

[JanBros]

I reckon that if I was going down this road I’d go for an oversquare engine to reduce piston length and weight. I know it goes against all the port area/STA stuff, but my thoughts are more towards a utilitarian application, not needing to rev the tits off it as perhaps Alex is considering.

but all that "port area/STA stuff" is for normaly aspirated 2-strokes.
so for supercharged engines surely the STA-stuff is way less important or maybe totaly different numbers will be the optimum. my (not so educated) guess :msn-wink:

[chrisc]

I don't run a det counter and I really want to understand my 98 RS125 better so I got an EGT. It's a standard engine, ignition, pipe, carb, etc. Only changes are a VHM head with a standard profile 10.4cc insert, and a reed block stuffer (stock reeds).

How far down the header should I be putting this probe? and how far into the header should it be?

I've searched the ESE thread and saw some comment on jetting to certain Fahrenheit temps at wide open throttle. Are these temps pretty universal across race 2 strokes? Any other advice on how I should get my own base line and at what point this stock 125 of mine might lunch itself is greatly appreciated.

One of these:
http://www.scooter-center.com/medias/sys_master/NewProductImagesFolder/8885954379806/TNT164044R(1).jpg

Other discussion in the thread:



In any badly tuned 2T you can easily get readings over 1300*F and survive,ONLY if the setup is not optimal.
If the com is too low for the fuel, or if the timing is overly retarded, then the excess heat produced late in the combustion cycle is dumped into the pipe
and thus alot less is soaked into the piston.

If a correctly setup engine cannot be held under 1200*F by the jetting, then it should be richened immediately so that it can be.
THEN, go down one size at a time and approx 50* rise should occur for each change, shooting for a max on AvGas of 1250*F.
If the change produces less than 50* delta in egt then that indicates that you are approaching deto rather than making more power from the extra heat of combustion.
The opposite is true as well, if more than 50* is seen with 1 jet leaner, then you can be sure the setup is not correct for the fuel and a heap of unused heat is being dumped into the pipe.
But, using excess fuel to cool the combustion process will not make anywhere near the actual power available ,if the ignition and com was optimised.
This means as a general rule for a fast watercooled 125 cylinder on AvGas that the com is close to 16:1 and the peak power timing is close to 15* - any numbers alot less than that
then you dont need AvGas,and or you do need to rethink the tuning.

[breezy]

Sorry https://youtu.be/OnLMIMiXoR8

Katinas, did the engine feel tight when you first started the engine... feeling like high compression? have you any breather system for the crankcase now that its sealed? have you had to increase the pilot circuit in the carb for it to start ? thanks , breezy:sherlock:

[F5 Dave]

Chris. Had wondered if you had disappeared. Guage instructions usually say 5-6" down header (note bung on your 50). But I've read Wob quote much shorter. Don't shorten sensor lead but that made for intolerable length on my kit as car based. Your kit looks much shorter.
Just mounted it on the 500 but not reading stable when engine running. Been suggested that I run an earth from the sensor to the gauge earth. I should know that shit.
Slip joint. Rubber mounts. Yeah can see that being a ground issue.

Probe needs to be exposed type. Mine claimed to be superb but I doubt it.
Run it up on the dyno with bung fitted and then with probe to see that it isn't influencing. Played havoc on the 50. The 500 doesn't seem to care.

I see a clamp type of wire splice in that kit. Quickly stamp on it and throw it in the bin. Preferably on fire.

[emess]

How far down the header should I be putting this probe? and how far into the header should it be?



From Wobbly on page 562 he suggests 150mm

That was in 2012 . . .

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130362060#post1130362060

[DoldGuy]

Have a Digatron Gauge, instructions say 5-6 inches from the face of the piston, mounted mine at 6. Just remember it's your temp readings, they can be higher or lower readings based on placement. It's a great tool gathering data & can save you from a melt down.

My gauge has the RPM pickup from the spark plug coil & instructed to keep the EGT/Temp leads away from the RPM lead as there can be interference if too close, giving erratic readings on other data.

[adegnes]

Run it up on the dyno with bung fitted and then with probe to see that it isn't influencing. Played havoc on the 50. The 500 doesn't seem to care.



Great you mentioned this, I had forgoten that you talked about it earlier. Have only run my Spx with the probe, will test without it.

[TZ350]

Page 1680 ......:Police:

Building a F4 water cooled two stroke Bucket racing engine.

328983

Sleeving a RGV250 or RG150 cylinder down to 50mm used to be the hot ticket for making water cooled F4 2T's, a lot of work, and you had to admire the engineering effort that went into them.


Have a look at this thread. http://www.fxr150.co.nz/forum/showthread.php?947-New-Barrel-for-RG100

then this one. http://www.fxr150.co.nz/forum/showthread.php?863-Sleeving-a-NSR250-Barrel-for-F4-100cc

then this one. http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page3

John Tice actually covers the sleeve build for the NSR100 http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page46

328986

This is a very successful bike with a sleeved RG cylinder. It dominated racing at Mt Wellington for quite some time.

328987

This is another sleeved RG that has been very successful down South.

Now that the capacity limit has been relaxed a bit constructors can take a different approach.

This is Team ESE's formula for a reliable 110cc water cooled Bucket racing Engine.

It's very simple, NSR cylinder, de stroke crank, long rod, to give enough room for a thick spacer plate to marry the NSR cylinder to the GP100 crankcase, can't get any easier than that.

329020

The Suzuki GP crank was de-stroked to 48mm.

To marry the NSR cylinder to the GP cases, the original stud holes in the GP cases were plugged with threaded aluminium rod glued and screwed into the original stud holes. And the stud holes relocated to suit the NSR cylinder. The forth GP stud hole is used to hold the spacer plate down while the fourth stud for the NSR cylinder is located in the spacer plate itself.

The cylinder needs to be positioned by the spacer at a height that has the exhaust port opening at 80 deg ATDC (power valve fully up), transfers will then be 115 ATDC, our spacer plate was 15mm thick and we cut our rotary valve to open 145 BTDC and close 85 ATDC.

The top of the cylinder was turned down 2mm and the head was spigot'd 2mm into the cylinder, total adjustment 4mm. When you turn the top of a plated cylinder it pays to grind a chamfer around the top of the bore so the turning tool does not pick up and chip the plating. There are two areas in the crankcase just below the cylinder that need to be relieved for rod clearance.


Some more detailed pictures here.

Basic parts.

NSR250 cylinder

Wiseco 15x20x17.8 top end bearing part number B1038

Wossner Suzuki RM125 00-03 part number 8061DA (54mm bore, 1mm ring, gap at 6 o'clock and 15mm L/E pin).

Yamaha RD400 Pro X Connecting Rod Kit 03.2070 OEM # 2T2-11651-00

RGV250 big end bearing.

2 of 20x20 Mallory metal slugs. Franklin Engineering can help you here, pricey but. http://www.franklinengineering.co.nz/

Recoverable cylinder from a Honda NSR250 , Suzuki RGV250 or Aprilia RS125. In fact the complete top end cylinder, head, power valves, cables and power valve servo.

De stroke crank to suit re bored cylinder diameter. 48mm stroke for 54mm cylinder and 44.5mm stroke for 56mm cylinder.

Honda RS125 expansion chamber or your own copy of one or maybe something more exotic.

Some 15mm plate big enough to make a base gasket shaped spacer out of.

OKO 24mm carb. OKO because they machine very well when you want to make a 24mm legal super flow carb.


With my so called diffuser carburetors the idea was to move the 24mm high velocity area away from the disruptive metering area around the slide.

As a base for their Bucket racing projects Team ESE use the old 70/80's Suzuki GP100 rotary valve engine. The Suzuki TF or TS100 is also a good choice, maybe a very good choice for pairing with the Aprilia RS125 cylinder. The GP,TF, TS all have 19mm big end pins that can be bored out on a CNC machine for the 22mm RD400 pin and easily offset to reduce the stroke.

From memory, on the Suzuki GP/TF/TS the B/E pin needs moving in 1.25mm for a stroke of 48mm for the Honda NSR250 and Aprilia RS125 cylinder, the RGV needs 2.75mm, anyway best double check that and anyway it could be a little different depending on how re bored your cylinder is.

328972

We are all used to raising the exhaust port for more power but great news, no porting required. The thing is, you get the same result by shorting the stroke. Because the crank has to turn further (more degrees) from the top of the exhaust port opening to the transfer port when you shorten the stroke.

Shortening the stroke means you get more blow down time area and improved performance but still have standard cylinder like reliability. A win win.

328973

On the 110cc GP engine we built we used a salvaged NSR250 cylinder. The cylinder was mounted on a spacer plate who's thickness was adjusted so the exhaust port opened at 80 deg ATDC and by good fortune the transfers then opened at 115 deg ATDC. So perfect performance port timing from a standard cylinder all because we shortened the stroke from 50.5 to 48mm.

You don't have to go the six speed conversion, dry sump, gear spray oil and straight cut primary gears rout unless you really want too. It is probably much better to stick with five gears and arrange the power spread to allow the bike to run corner to corner with the minimum number of gear changes. At Mt Wellington a very twisty tight track my air cooled engine could get away with only two changes, per lap, one up, one down.

The GP has a bit of a gap between 2nd and 3rd. The early five speed TS125 gear box can be modified to fit the GP.


Making progress with the six speed Suzuki GP110cc engine. Spent my evenings after work for the last couple of weeks test assembling everything to make sure that they fit and the clearances are correct. Lots and lots of detail work has been required to get things right.


The good news is that after months of work I have finally given Mr.Bigglesworth a thrashing on the dyno. The bad news is that there is still a reluctance to come back on the throttle.


The oiler lubricates the clutch hub gear through a small hole near the end of the spray bar and the end of the tube sprays oil onto the outside of the clutch hub itself, some of it will hopefully dribble down to the output shafts plain bush bearing. There is a new hole in the input shaft to lubricate the clutch hub bearing.

The whole build can be seen by following the backstory posts like a trail of bread crumbs.

From here posts of the builds progress link back to each other and you can follow them like a trail of bread crumbs.

[TZ350]

Page 1680 ...... B


Farmer Ken had his new engine on track today, a few nice home made goodies in this baby, NSR250 pot on TF bottom end, stroked crank, power valve, quick shifter, it's fully loaded

328988

This bike has a de stroked Suzuki TS100 engine fitted with a NSR MC18 cylinder and custom full case reed block, it runs really well.

328989 ... 328990

The good old piston port semi case reed Suzuki TF/TS100 engine looks like a very good candidate for a Aprilia RS125 cylinder.

The Suzuki range of TF engines from the 80's are still being made new so there must be a few old engines floating about.

328992

Electric water pump, 45 deg bypass thermostat from Wobbly, radiator off Trademe, I think it is from a Kawasaki.


I see flow should be 1 L/min/hp. The Mercedes/Bosch pump falls well short. The pumps I found that get somewhere close to 30L/min draw 4A plus. The Prius pump at 19L/min draws under 2A. This video shows current draw at the 3.45 minute mark https://www.youtube.com/watch?v=1ojNID2jDz4 You can buy the Prius pump from ebay for about $55NZ.


My $50 intercooler pump has been the bastion of reliability. Wish I'd found it earlier

Bit like this. . . golly that's got expensive. Still. . .

http://m.ebay.com/itm/CXRacing-12V-DC-Water-Coolant-Pump-For-Radiator-Intercooler-SuperCharger-/271976332382?hash=item3f530d7c5e%3Ag%3AyTYAAOSw0Jp V6Sqj&_trkparms=pageci%253Ae9ba059c-dee8-11e6-a8c4-74dbd1805048%257Cparentrq%253Abaf3def81590a7854edb c630ffb0e7b2%257Ciid%253A4

328994 CXM-WP-50-40

CXRacing Manufacturer Part Number: 1076106001997 ... 30l/min . 3 amps



329027

How to make a decent light weight racing 12 Volt generator stator for the Suzuki GP/TF/TS from a Lifan after market magneto kit. We have spun these to 14,000 rpm plus on the dyno and they have proved reliable on the track.

Follow the link back to the original post to see more details about the generator.

[TZ350]

Page 1680 ...... C

Modifying an early five speed Suzuki TS gear cluster to fit the GP.

329065

Anneal both TS and GP input shafts.
Drill the center through the TS shaft for the clutch push rod.
Spigot the TS shaft with a press fit into the cut off end of the old GP shaft.
Weld the two shafts. Be careful to tack in several places to pull and hold the shafts straight.
Clean the weld and polish the shaft until the input shaft bearing slips on easily.
Case harden to a depth of 0.005" or so.

The two left hand output shaft forks need building up with bronze.
They must be built up on the inner face only, ie the center line of the original fork is offset.
Top and bottom forks are offset towards each other, ie the center lines are closer together.
And the fork ends are thicker for the wider grove in the TS output shafts sliding dogs .
The input shaft fork on the right does not need any bronze but it needs to be opened up a bit to fit the slightly larger diameter TS sliding dog.

The GP box has a big gap between 2nd and 3rd, the TS is much better.


329028

Team ESE use these. Ignitec Sparker DC-CDI-P2 Race digital CDI, this unit is powered by 12 Volt DC, ie battery powered. http://www.ignitech.cz/en/vyrobky/dccdip2_race/dccdip2_race.htm

Bucketracer posted how he sets up Team ESE Ignitec ignitions. You will need to go to the original post, to read all the details.


I got the job of setting up NedKellys IgniTech programmable Ignition.

This is how we went about it with one of Team ESE's bikes and Mt Eden Motorcycles dyno. Chambers is friendly with Mike and was able to get a bit of a deal on some dyno time.

The IgniTech software is very clever as changes to the ignition curve can be made on the fly and the Ignition itself re-programed while the engine is still running............


Chairs, the latest ones i see are are digital now though, so they will have a curve i hope.
They are still a neat little set up, and cheap as chips.
328749328750
Price:$299.00 + $4.49 shipping
https://www.amazon.com/DIGITAL-IGNITION-CONVERSION-2009-2013-SXS12050039/dp/B00CFL5QLU

http://www.ktm-parts.com/mm5/graphics/00000001/SXS12050039.pdf

For an idea just how big they are for those unfamilar with the little KTM's
328751


Det buttons ...

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130263736#post1130263736

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130792235#post1130792235

328563328564


http://www.greencarcongress.com/2016/08/20160805-anltribo.html


Researchers at Argonne National Laboratory have discovered an ultra-durable, self-lubricating tribofilm that regenerates in the presence of oil, heat, and pressure—meaning that it will not wear away over the life of an engine. The film, reported yesterday in the journal Nature, develops when a new catalytic coating that can be applied to engine parts interacts with lubricating oil to create an extremely tough coating that almost eliminates wear.

Tests revealed the diamond-like carbon (DLC) tribofilm reduced friction by 25-40% and that wear was reduced to unmeasurable values. The discovery could have implications for the efficiency and durability of future engines and other moving metal parts that can be made to develop self-healing DLC tribofilms.

This is a very unique discovery, and one that was a little unexpected. We have developed many types of diamond-like carbon coatings of our own, but we’ve never found one that generates itself by breaking down the molecules of the lubricating oil and can actually regenerate the tribofilm as it is worn away


I reckon this is a good way to get very close. http://www.underdogsracing.com/fospipe/ And you get a pipe as a bonus.

Input all the relevant bits and it will recommend the exhaust port diameter for the engine. The 2 engines I have at the moment use the crab size that this calculator recommends as exhaust port dia. Good please to start I reckon.


I don't run a det counter and I really want to understand my 98 RS125 better so I got an EGT. It's a standard engine, ignition, pipe, carb, etc. Only changes are a VHM head with a standard profile 10.4cc insert, and a reed block stuffer (stock reeds).

How far down the header should I be putting this probe? and how far into the header should it be?

I've searched the ESE thread and saw some comment on jetting to certain Fahrenheit temps at wide open throttle. Are these temps pretty universal across race 2 strokes? Any other advice on how I should get my own base line and at what point this stock 125 of mine might lunch itself is greatly appreciated.

One of these:
http://www.scooter-center.com/medias/sys_master/NewProductImagesFolder/8885954379806/TNT164044R(1).jpg

Other discussion in the thread:


In any badly tuned 2T you can easily get readings over 1300*F and survive,ONLY if the setup is not optimal.
If the com is too low for the fuel, or if the timing is overly retarded, then the excess heat produced late in the combustion cycle is dumped into the pipe
and thus alot less is soaked into the piston.
But just the mere fact the engine did survive that insane abuse, points to the fact that the setup is nowhere near correct.
It still amazes me though that people have gauges on the bike, skid around the track, see death numbers on the screen then ride back to the pit and tell everyone about what just happened.
Why is the gauge there ? To help tune the engine,but what if the com was perfect and the timing dialled in correctly on a dyno.
The same rider would then do several laps - watching the temps scream past 1250, lock it up at the end of the straight - THEN come in and say " I saw 1300 and shit ive siezed it, bastard thing".
If a correctly setup engine cannot be held under 1200*F by the jetting, then it should be richened immediately so that it can be.
THEN, go down one size at a time and approx 50* rise should occur for each change, shooting for a max on AvGas of 1250*F.
If the change produces less than 50* delta in egt then that indicates that you are approaching deto rather than making more power from the extra heat of combustion.
The opposite is true as well, if more than 50* is seen with 1 jet leaner, then you can be sure the setup is not correct for the fuel and a heap of unused heat is being dumped into the pipe.
But, using excess fuel to cool the combustion process will not make anywhere near the actual power available ,if the ignition and com was optimised.
This means as a general rule for a fast watercooled 125 cylinder on AvGas that the com is close to 16:1 and the peak power timing is close to 15* - any numbers alot less than that
then you dont need AvGas,and or you do need to rethink the tuning.

[wobbly]

The only simple position guide I can give is to say about 3 X Bore down the header from the port face.
You are trying to get out of the unburnt air/fuel zone that sits in the header - but not so far down as to see the gradual temp drop from wall heat radiation.
As far as depth into the header, do what ever you can to get it as close to the middle as possible.
The short,capped end 5mm probes some suppliers sell are useless for reliable use as a tuning tool.
This makes a HUGE difference , believe it or not.

In a 125 kart engine at the Nationals, I got completely lost for 2 days practice trying to get it tuned.
The egt said it was on the limit at 660*C, but the piston and plug were nowhere near,and we were 3/10 sec off the pace.
Luckily on the morning of the final I noticed from the outside that the probe seemed to be pushed in along way.
It was a long exposed tip Stinger type from EGT Industries ( the best and only guaranteed probe you can buy ) with a 90* bend just above the ferule and locknut.
And sure enough, it was 10mm too far in ,past center-line.
I pulled it back up to on center and in the warmup, what was 660*, now read as 610*.
At least an easy 2 jet sizes too rich.
We won, having been second all thru qualifying and the heat races.

As you are running a 10.4 cc head, you will be on Avgas, so in F you are looking for a minimum of 1220 and a max close to 1280.
Start rich, and go down a jet at at a time,you should see around 30 to 40* F increase in temp each change.
If you go down a jet and only see a 20*F increase ,or even worse it stays the same ,or real BAD it drops - then Mr Deto is in the house - go back one, or two in size.
Just remember that ignition timing affects the reading as well,+2* will drop the temp around 2 jet sizes in a RS125 - so then the delta temp change rule becomes even more important.

[TZ350]

328996328997

Supercharged 2T with twin rotary valves. http://www.elsberg-tuning.dk/supercharging.html#turbos more 2T stuff towards the bottom of their page.

[WilDun]

Supercharged 2T with twin rotary valves. http://www.elsberg-tuning.dk/supercharging.html#turbos more 2T stuff towards the bottom of their page.

Good stuff! we don't hear a lot (from Denmark?) on bikes with superchargers these days, but this has sure made up for that!

[F5 Dave]

RGV sleeved has been a bit variable. Nigel's bike for sure has been successful but largely because of the useless old old fat fart (a mate) riding it. Its fast but my MB has past it. He needs to increase peak power past 12000 rpm.(pussy) .but hes too ghey. Diesels bike has never been close. But one ride of it at Ruapuna motivated me to get my RS MB going again.

Skinny kid not afraid of braking more bones could have won the battle of the buckets once I'd sorted it, easy. Useless fat old prick winning the sprint races showed that if it could keep together itcould (pin fixed that).

[husaberg]

RGV sleeved has been a bit variable. Nigel's bike for sure has been successful but largely because of the useless old old fat fart (a mate) riding it.

er...i always thought Nigel has no mates.:lol:

[F5 Dave]

Nah, he's a good prick. But don't try come around the outside and expect to eat anything but grass.

[Frits Overmars]

Good stuff! we don't hear a lot (from Denmark?) on bikes with superchargers these days, but this has sure made up for that!Well.... 'these days' was 52 years ago, in 1965.
Here are some more pics of this blown 12-speed Kreidler engine, the latest version with 2-speed hand x 6-speed foot operated gearboxes (riders lost count when downshifting with the previous 3-hand x 4-foot setup).

[lohring]

The Roots blower is very inefficient at any but the lowest pressure ratios because it has no internal compression. Screw type compressors are used where moderate pressures are needed and piston compressors are still the choice for high pressures. Axial and centrifugal compressors are used where high volumes and moderate pressures are needed.

The problem with simple two strokes is the cylinder pressure is hard to raise much even if the exhaust is closed during intake because of the short time possible. A very long time ago it was realized that raising the exhaust pressure along with the intake pressure was the solution. That's what turbochargers do. The problem is that turbochargers are more efficient in larger sizes. I think that the latest small turbochargers (http://turbochargerspecs.blogspot.com/2013/03/garrett-gt06-gt0632sz-32-trim-80-hp.html) might work better than tuned pipes alone in as small as 50 cc engines. There's no question that turbochargers are the answer in larger sizes. See the snowmobile engine below.

Lohring Miller

329014

[Frits Overmars]

The Roots blower is very inefficient at any but the lowest pressure ratios because it has no internal compression. Screw type compressors are used where moderate pressures are needed and piston compressors are still the choice for high pressures. Axial and centrifugal compressors are used where high volumes and moderate pressures are needed.The supercharger on the above Kreidler engine may look like a Roots blower but it was in fact an excentric vane compressor. Here are some details.

329015 329016 329017



The problem with simple two strokes is the cylinder pressure is hard to raise much even if the exhaust is closed during intake because of the short time possible.Some coincidence; I just wrote a few words on the subject here Lohring: https://www.kiwibiker.co.nz/forums/showthread.php/171300-Oddball-engines-and-prototypes/page82

[philou]

Interesting concept for development

http://iffitech.com/project/p2-cylinder/

[Frits Overmars]

Interesting concept for development http://iffitech.com/project/p2-cylinder/
The P2 was an internal project where we developed a novel porting scheme.... we developed cylinders with fully CNC machined ports so that small changes in torque could be discerned...iffi's novelty claim may be more iffy than they realize. Below are some pictures published by German Ernst Ansorg in 1965. No, he didn't use CNC. But he did apply some tricks of the trade that iffi may yet have to discover.
Ansorg smoothed the small gaps between his exchangeable transfer inserts and the cylinder sleeve with lead solder. If the blowdown time.area was too small, the hot spent gases that entered the transfer ducts, would round off the soldered edges; a nice indication.
329019

[eldog]

Interesting concept for development

http://iffitech.com/project/p2-cylinder/

Was very surprised this is in NZ

interesting.

[breezy]

can anybody help me with this question?. if there was a increase in atmospheric pressure what impact would it have on a 2 stroke engine? would it be a positive impact or a negative one?

[TZ350]

329021

How to make a decent light weight racing 12 Volt generator stator for the Suzuki GP/TF/TS RG50 from a Lifan after market magneto kit. We have spun these to 14,000 rpm plus on the dyno and they have proved reliable on the track.

The Lifan back plate and modified flywheel fits perfectly into the Suzuki GP/TF/TS and RG50 cases.

329025

Basically the conversion involves transferring the center from a Suzuki flywheel to the Lifan.

329023 ... 329024

Chambers starts by spinning the heads of the rivets off of the Suzuki flywheel. He then punches out the rivets of the Suzuki fly wheel to free the Suzuki's center boss.

He then bores the Lifan boss out to suit the Suzuki boss, a close fit is required here, basically size for size, with minimal clearance. And then he spins the heads of the rivets off the Lifan flywheel.

The next move is to orientate the Suzuki boss and Lifan flywheel so that there is an appropriate gap between the heal of the trigger tooth and trigger coil at TDC, usually 20 deg.

329026 ... 329022

The last move is to secure the Suzuki boss to the remains of the original Lifan boss left inside the Lifan flywheel. Chambers drills and taps through the Lifan flywheel and the remains of the original Lifan hub and rivet's. If a rivet turns, he gives it a little touch with the TIG, just a small tack weld is all that is needed to hold a loose rivet while it is drilled and tapped.

We cut the two Lifan high Voltage winding's off and re wind the three empty stater polls for extra 12 Volt current capacity. Although you can get away with using just the three original 12 Volt coils for powering an Ignitec but if you want a water pump too then you need to rewind the empty three polls.

Use a Lifan voltage rectifier/regulator and a 36V 2200uF capacitor for powering an Ignitec CDI ignition. If you do try winding on extra coils remember they are wound in alternating directions, ie; the first clockwise the second anti clockwise, the clockwise again and so on around the stater.

We use the Lifan stater assembly to power our Ignitec ignitions. We have not tried it but you may get away with using the complete Lifan racing ignition package and CDI. The Lifan CDI is probably better for engines that don't rev much past 10k or so.

[Frits Overmars]

if there was a increase in atmospheric pressure what impact would it have on a 2 stroke engine? would it be a positive impact or a negative one?When in doubt, exaggerate, Breezy. And if that doesn't help, reverse the situation. What impact would zero atmospheric pressure have on a two-stroke engine?

[husaberg]

can anybody help me with this question?. if there was a increase in atmospheric pressure what impact would it have on a 2 stroke engine? would it be a positive impact or a negative one?


When in doubt, exaggerate, Breezy. And if that doesn't help, reverse the situation. What impact would zero atmospheric pressure have on a two-stroke engine?
I haven't actually read it but i am sure its rad.:shifty:
http://www.intercompracing.com/documents/Understanding_Air_Density.pdf


When the air temperature drops the engine will run leaner and more fuel will have to be added to compensate.
Altitude affects jetting since there are less air molecules as altitude increases. A bike that runs good at sea level will run rich at 10,000 ft due to the thinner air.
As humidity increases, jetting will become richer. http://www.iwt.com.au/mikunicarb.htm

[F5 Dave]

Hey good timing Rob, a mate just bought that TF in the NSR frame from Auckers and I'm inevitably going to get pulled into it and finding CR setups is expensive and getting harder. Maybe Ican get him to ssubcontract the ign out so I don't have to do more than set it up. Then he just needs to find some money for an ignitech.

[jasonu]

RGV sleeved has been a bit variable. Nigel's bike for sure has been successful but largely because of the useless old old fat fart (a mate) riding it. Its fast but my MB has past it. He needs to increase peak power past 12000 rpm.(pussy) .but hes too ghey. Diesels bike has never been close. But one ride of it at Ruapuna motivated me to get my RS MB going again.

Skinny kid not afraid of braking more bones could have won the battle of the buckets once I'd sorted it, easy. Useless fat old prick winning the sprint races showed that if it could keep together itcould (pin fixed that).

I heard No mates (nigel) bike seized every time he tried to ride it on any track bigger than a kart track.

[diesel pig]

Diesels bike has never been close. But one ride of it at Ruapuna motivated me to get my RS MB going again.

version you rode a couple or three years ago may not have been close with sub-optimal pipe and crack in the cylinder head but by doing all the welding the head needed in one go with very careful heating and cooling we got around the cracking problem in the cylinder head. Using Frits's formula for pipe design and a beautifully made but cheap Tyga pipe as a base we have got a pipe alot closer to optimal. It now go's past Tuned FXR150's down the front of straight ruapuna and back straight at levels like they are stuck in fifth gear.

[mr bucketracer]

I heard No mates (nigel) bike seized every time he tried to ride it on any track bigger than a kart track.Don't Mention the War!, i think i got away with it last time :facepalm:

[mr bucketracer]

version you rode a couple or three years ago may not have been close with sub-optimal pipe and crack in the cylinder head but by doing all the welding the head needed in one go with very careful heating and cooling we got around the cracking problem in the cylinder head. Using Frits's formula for pipe design and a beautifully made but cheap Tyga pipe as a base we have got a pipe alot closer to optimal. It now go's past Tuned FXR150's down the front of straight ruapuna and back straight at levels like they are stuck in fifth gear.yes , mine jumps back to fifth gear because i'm to fat lol, good old tyga pipes work well

[husaberg]

version you rode a couple or three years ago may not have been close with sub-optimal pipe and crack in the cylinder head but by doing all the welding the head needed in one go with very careful heating and cooling we got around the cracking problem in the cylinder head. Using Frits's formula for pipe design and a beautifully made but cheap Tyga pipe as a base we have got a pipe alot closer to optimal. It now go's past Tuned FXR150's down the front of straight ruapuna and back straight at levels like they are stuck in fifth gear.

It sure is pretty though.

[breezy]

When in doubt, exaggerate, Breezy. And if that doesn't help, reverse the situation. What impact would zero atmospheric pressure have on a two-stroke engine?

oh right, thanks. well no atmospheric pressure i assume would be no air flow? therefore no airflow into the engine would be a negative impact. i would then suppose that if the engines airflow was subjected to/lived in a higher than our average 14.96 psi atmosphere then this would be increased airflow in and a positive impact? like turbo charging, maybe?

please put me right, if i am wrong:sweatdrop:bash:

Frits, if a 2 stroke engine was mechanically run, completely sealed off, with only air trapped inside when sealed up , would there be an increase in air pressure trapped within ?:sherlock:

[breezy]

I haven't actually read it but i am sure its rad.:shifty:
http://www.intercompracing.com/documents/Understanding_Air_Density.pdf

husaberg, so is air pressure the same as atmospheric pressure?:sherlock:

[husaberg]

husaberg, so is air pressure the same as atmospheric pressure?:sherlock:

Atmospheric pressure varies, that why they invented barometers, The atmosphere is made of air.:laugh:
I just assumed that was what you are asking about, It seems what you are actually asking about is Pressure above relative amospheric pressure.

[breezy]

Atmospheric pressure varies, that why they invented barometers, The atmosphere is made of air.:laugh:
I just assumed that was what you are asking about, It seems what you are actually asking about is Pressure above relative amospheric pressure.

Yes, sorry my fault:wacko:

[lohring]

Increased atmospheric pressure helps in my experience. I race 26 cc gasoline engine powered model boats as well as smaller boats with nitro fueled engines. Our straight line speed trial boats always ran 2 to 3 mph faster at around 100 mph in Los Angeles than at our 500 foot elevation pond. Gasoline engine boats won't pull sea level size propellers at 2500 foot elevation. Nitro fueled engines have no problem at that altitude but need to run a little leaner. At 5,000 feet even the nitro boats need to prop down and gasoline fueled boats run much smaller propellers with much leaner carb needle settings. The 100 degree summer temperatures didn't help either. We probably needed to change the tuned pipe lengths at higher altitudes, but I run fixed length pipes on gasoline engines

Lohring Miller

[Frits Overmars]

oh right, thanks. well no atmospheric pressure i assume would be no air flow? therefore no airflow into the engine would be a negative impact. i would then suppose that if the engines airflow was subjected to/lived in a higher than our average 14.96 psi atmosphere then this would be increased airflow in and a positive impact? like turbo charging, maybe? please put me right, if i am wrong:sweatdrop:bash:
Frits, if a 2 stroke engine was mechanically run, completely sealed off, with only air trapped inside when sealed up, would there be an increase in air pressure trapped within ?:sherlock:You're on the right track with 'no atmospheric pressure i assume would be no air flow' but you could say it even shorter: ''no atmospheric pressure would be no air'.
And no air = no combustion = no power at all.
I'm not sure where you're going with your second question. Motoring a sealed engine requires some energy, even if the seals are free of friction, because the air inside is pumped from one corner to another and back. And this energy raises the air temperature, which in turn raises the air pressure inside the engine. But if you stop motoring the engine and allow it to cool down, the internal air temperature and pressure will return to their initial values.

To answer your initial question: increased atmospheric pressure augments engine power, as Lohring described.

[jasonu]

Don't Mention the War!, i think i got away with it last time :facepalm:

hahahahahahahahhaha!!!!!

[WilDun]

The microlight and homebuilt aircraft boys (and Flettner) might be able to give a lot of info on this subject - their engines are subject to constant atmospheric pressure variation!

[oldjohnno]

Worth remembering too that as the air pressure increases so does its density, so the engine is ingesting a greater mass of air and that's probably of much greater importance than the increased pressure differential between bellmouth and crankcase.

[jasonu]

https://www.kiwibiker.co.nz/forums/showthread.php/178625-Could-2-smokes-make-a-comeback/page2

[jamathi]

I think it comes down to the higher speed at which the smaller "crankcase" volume attains its peak efficiency.
With the conventional style engines reducing the primary comp to anywhere near the same level had required the crankcase airflow and transfer flow to become so hugely stifled it became irrelevant, I believe it was because it created huge boundary friction in the areas around the crank wheels. plus other flow airflow restrictions.Thus I muse separating the crankcase might be the difference.
Also it would seem the ryger benefits from modern transfer control and durations. As devloped over the last 40 years.



or it might just be overhyped horse poo.

Maybe it is...

Ryger finally bought a dyno....
Those 70HP were just calculated as I always thought.
The new dyno is very 'unfriendly', as it indicates far less HP than expected.
A really big disappointment after some years of work, but we must have patience!
How many years I don't know......
The 50cc version gives 14HP I heard
So the world record attempt will have to be postponed a little bit!
As about 30HP would be needed...


All time and money spent in this project looks wasted to me, I am sorry to say!
How so many people were fooled, I still don't understand.......

[wobbly]

Here is a jetting chart for a KZ2 engine, showing Density Altitude and RAD Vs Jet size in a 30mm Dellorto carb.
One point on the graph was best power on the dyno with egt at 660*C - so the other 2 points used to plot the line were really widely varying density days
but with the tuning done to achieve that 660 result.
All this is doing is replicating the bsfc number at best power, with widely varying air conditions - be they affected by temp, baro pressure or humidity %.

[peewee]

Worth remembering too that as the air pressure increases so does its density, so the engine is ingesting a greater mass of air and that's probably of much greater importance than the increased pressure differential between bellmouth and crankcase.

i dont know much about this stuff but at high atm pressure there would be more oxygen i believe. some you guys live near the ocean. im near 7000' :bleh:

[ken seeber]

i dont know much about this stuff but at high atm pressure there would be more oxygen i believe. some you guys live near the ocean. im near 7000' :bleh:

Peewee,
At 7000 ft, the density would be around 1.0 compared to 1.225 kg/met^3 at sea level.
If you come down from that stratosphere, you might get 20% more power. :niceone:

329048

[jasonu]

[QUOTE=jamathi;1131033456


The 50cc version gives 14HP I heard
...[/QUOTE]

But we were getting 11 and 12hp (Dynojet 100) out of crappy old Suzuki RG50's 20 years ago.

[TZ350]

329051


... a mate just bought that TF in the NSR frame from Auckers ...

Great looking bike, all the basic stuff, should make a great Bucket when you have finished fettling it for him.

[speedpro]

A really big disappointment after some years of work, but we must have patience!
How many years I don't know......
The 50cc version gives 14HP I heard, I still don't understand.......

Darren Gosper's Pete Sales tuned RG50 was making 14hp a long time ago, and was a tractor to boot, unlike his flatmate's 50

[jasonu]

Darren Gosper's Pete Sales tuned RG50 was making 14hp a long time ago, and was a tractor to boot, unlike his flatmate's 50

Me and Gossamer did a Mt. Welli 2hr on that bike. What a sweetie, able to out drag a lot of the 100 2t's and 125 diesels up the main straight.

[husaberg]

Maybe it is...

Ryger finally bought a dyno....
Those 70HP were just calculated as I always thought.
The new dyno is very 'unfriendly', as it indicates far less HP than expected.
A really big disappointment after some years of work, but we must have patience!
How many years I don't know......
The 50cc version gives 14HP I heard
So the world record attempt will have to be postponed a little bit!
As about 30HP would be needed...


All time and money spent in this project looks wasted to me, I am sorry to say!
How so many people were fooled, I still don't understand.......

14HP well that should be competive with 1965 Kreidlers.........
They will have to watch out for the Honda 1966 RC116 though that had 2 more HP
329052

[jasonu]

14HP well that should be competive with 1965 Kreidlers.........
They will have to watch out for the Honda 1966 RC116 and several shitter RG50's too.
329052

Fixed for accuracy.

[Niels Abildgaard]

Peewee,
At 7000 ft, the density would be around 1.0 compared to 1.225 kg/met^3 at sea level.
If you come down from that stratosphere, you might get 20% more power. :niceone:

329048

But You will need more power for same speed due to more air-resistance

[ken seeber]

But You will need more power for same speed due to more air-resistance

Correct if you were going for a LSR where aerodynamic drag is the dominant load.
However, if you were in a kart or on a motocross bike where the aero load is small in relation to the % of time accelerating, then doing this at sea level would be better.

[breezy]

You're on the right track with 'no atmospheric pressure i assume would be no air flow' but you could say it even shorter: ''no atmospheric pressure would be no air'.
And no air = no combustion = no power at all.
I'm not sure where you're going with your second question. Motoring a sealed engine requires some energy, even if the seals are free of friction, because the air inside is pumped from one corner to another and back. And this energy raises the air temperature, which in turn raises the air pressure inside the engine. But if you stop motoring the engine and allow it to cool down, the internal air temperature and pressure will return to their initial values.

To answer your initial question: increased atmospheric pressure augments engine power, as Lohring described.

i had been trying to seal the crankcase from beneath the barrel with a nitrile rubber boot set up.. trying to determine why katinas engine had a burst of high rpm ..could it be the piston crank set up or the sealed crankcase. .. the experiment was a disaster due to to both boots i made being torn to pieces very quickly. on my first attempt to start the enginei almost broke my wrist using my old clutch-less high torque drill it seemed i had maybe some kick back or massive build up of compression when cranking the engine over.... the bike did fire up.. but to keep it running i had to have the throttle more than half way open. it sounded dull and tight, but on blipping the throttle a couple of times it did rev out... then the seal broke and drew oil out the crankcase filling the garage with dense smoke... this happend twice... no real conclusions... the crankcase wasnt vented, i wonder if the pressure inside the sealed crankcase had risen high enough to turn the nitrile boot into a balloon destroying it by the descending piston. could such pressure be vented elswhere for some benificial use.At this point having not destroyed my cagiva barrelled bantam engine i called it a day.. another way of sealing the crankcase in mind for another day and another less precious engine.....thanks to all for answering my, vague at times, questions:sherlock:

[F5 Dave]

Darren Gosper's Pete Sales tuned RG50 was making 14hp a long time ago, and was a tractor to boot, unlike his flatmate's 50
Yeah, he was a turkey that guy, esp when blowing on the internet after a few drinks, like a few pages back:shutup:

[F5 Dave]

But we were getting 11 and 12hp (Dynojet 100) out of crappy old Suzuki RG50's 20 years ago.
And to be fair they were originally supplied to customer with a natty little packrack for tieing your sandwich box to, on your way to school or work.

[jasonu]

esp when blowing on the internet after a few drinks, like a few pages back:shutup:

and prolly later this afternoon too...:drinkup:

[monkeyfumi]

Yes, very interested. Thanks Nathan, for the great idea of using a MAP sensor to measure the pressure changes in the exhaust system so as to see the changes in bulk air flow through the engine, I wish I had thought of that ages ago.

https://www.hpacademy.com/technical-articles/mass-air-flow-sensors-vs-manifold-air-pressure-sensors/

A car and fourstroke based article, but I found this a good comparison of Mass Airflow vs Manifold Air Pressure sensors and their various benefits/drawbacks.

[SwePatrick]

About barometric pressure.

If the pressure is 'low' and oxygenlevel is 'high'
The engine gives the 'same' power as if the pressure is 'high' but oxygenlevel is 'low'.
The thing to measure is the density of air.
To do that with simple tools you calculate with moisture and temprature.
The moisture is complicated enough relativly to temp and pressure.
Thereby there´s an formula to calculate with relativitly moisture.
You can all find this info in dynocorrection standards, they calculate from different 'origos' but they do about the same job all of them.

To set things in perspective:
If a raise in atmosphere pressure is double, but density is half.(from originally situation)
The engine will not produce any more power.
Probably it will loose power as that situation only accurs in bad boostsetups.
(heatproblems)

Rgds.

[husaberg]

about barometric pressure.

If the pressure is 'low' and oxygenlevel is 'high'
the engine gives the 'same' power as if the pressure is 'high' but oxygenlevel is 'low'.
The thing to measure is the density of air.
To do that with simple tools you calculate with moisture and temprature.
The moisture is complicated enough relativly to temp and pressure.
Thereby there´s an formula to calculate with relativitly moisture.
You can all find this info in dynocorrection standards, they calculate from different 'origos' but they do about the same job all of them.

To set things in perspective:
If a raise in atmosphere pressure is double, but density is half.(from originally situation)
the engine will not produce any more power.
Probably it will loose power as that situation only accurs in bad boostsetups.
(heatproblems)

rgds.
rad.......
using your swede
http://www.swedetechracing.com/techtips/How-To-Create-A-Jet-Chart/63165

i haven't actually read it but i am sure its rad.:shifty:
http://www.intercompracing.com/documents/understanding_air_density.pdf
http://www.dtec.net.au/Air%20Density%20&%20Tuning.htm


Re LSR attempts on the salt.
I built the pipes for Kiwi - Cory Bertelson's records on a Honda RS250 at Bonneville and as far as tuning is concerned with a
two stroke there are two important factors.
You must run a flat line advance thru the area used from peak Hp into the overev region.
This is to prevent the natural cycle of more retard = more heat = more power = more rpm = richer jetting needed when sitting at your peak speed due to aero and friction.
Once the motor/pipe temp stabilizes, the pipe heat remains constant, as does the fueling then needed for that power level.

Second thing, is to get on the pace as fast as possible,as the weather changes during the day, you should already have a RAD jetting chart done with a load control dyno
so you can do constant rpm at peak power - long enough for the power and egt to stabilize.
If you jet for peak power on a specific day,this will translate into a specific egt number, at a specific RAD.
Do this twice with very different weather combinations, and you can then draw up a chart with a straight line relationship between RAD and jet size.

Here is one for a KZ10 kart engine ( that also has by the way, a straight line ignition ) that was generated using 3 different days, but hitting the same egt on
each day of 640*C ,that was also the peak power egt, before deto, on a constant accelerating inertia dyno - exactly the conditions the kart engine runs under.
This has been used for probably a dozen completely differing RAD days, and I usually change jets every heat race to stay exactly on 640*C, no guessing at all involved.
It has won every race meeting except one second place last year, when we fucked the good motor by leaving all its water on the track.
https://srgclub.org/Jet_BL.html
http://www.tz250.com/forums/archive/index.php/t-4295.html
http://www.everything2stroke.com/forums/attachment.php?attachmentid=3020&d=1140811026.
https://wahiduddin.net/calc/calc_hp.htm

[chrisc]

The only simple position guide I can give is to say about 3 X Bore down the header from the port face.
You are trying to get out of the unburnt air/fuel zone that sits in the header - but not so far down as to see the gradual temp drop from wall heat radiation.
As far as depth into the header, do what ever you can to get it as close to the middle as possible.
The short,capped end 5mm probes some suppliers sell are useless for reliable use as a tuning tool.
This makes a HUGE difference , believe it or not.

In a 125 kart engine at the Nationals, I got completely lost for 2 days practice trying to get it tuned.
The egt said it was on the limit at 660*C, but the piston and plug were nowhere near,and we were 3/10 sec off the pace.
Luckily on the morning of the final I noticed from the outside that the probe seemed to be pushed in along way.
It was a long exposed tip Stinger type from EGT Industries ( the best and only guaranteed probe you can buy ) with a 90* bend just above the ferule and locknut.
And sure enough, it was 10mm too far in ,past center-line.
I pulled it back up to on center and in the warmup, what was 660*, now read as 610*.
At least an easy 2 jet sizes too rich.
We won, having been second all thru qualifying and the heat races.

As you are running a 10.4 cc head, you will be on Avgas, so in F you are looking for a minimum of 1220 and a max close to 1280.
Start rich, and go down a jet at at a time,you should see around 30 to 40* F increase in temp each change.
If you go down a jet and only see a 20*F increase ,or even worse it stays the same ,or real BAD it drops - then Mr Deto is in the house - go back one, or two in size.
Just remember that ignition timing affects the reading as well,+2* will drop the temp around 2 jet sizes in a RS125 - so then the delta temp change rule becomes even more important.

Thank you Wob!

[oldjohnno]

Anyone have any rules-of-thumb for carb sizing with reed valve engines? Working back from some existing engines I get something like throat dia = √(hpx32), though there's a lot a variation. Does this sound like a reasonable place to start?

[husaberg]

Anyone have any rules-of-thumb for carb sizing with reed valve engines? Working back from some existing engines I get something like throat dia = √(hpx32), though there's a lot a variation. Does this sound like a reasonable place to start?

There is a rule of thumb per the reed valve vs Carb area i think it was .8.
Pretty sure Frits and wob have both mentioned it.
Ages ago i posted an old graph for carb size per HP.
329170
I do know that a 24mm carb will flow 30HP (TZ350's bucket)
Plus a 28mm carb will flow 35HP (Numerous RD yamahas)
But i doubt that means they are the optimal size.
why not scale the carb size by area from a known well developed engine.

[richban]

Anyone have any rules-of-thumb for carb sizing with reed valve engines? Working back from some existing engines I get something like throat dia = √(hpx32), though there's a lot a variation. Does this sound like a reasonable place to start?


I reckon this is a good way to get very close. http://www.underdogsracing.com/fospipe/ And you get a pipe as a bonus.

Input all the relevant bits and it will recommend the exhaust port diameter for the engine. The 2 engines I have at the moment use the crab size that this calculator recommends as exhaust port dia. Good place to start I reckon.

[shnaggs]

Was thinking this afternoon (I know I shouldn't do such a thing), about CFM vs HP and how this may correlate to the 2 stroke. Now I am NO engineer, scientist, etc. so most of my research is the search button on Google:facepalm:

according to a website, you need 33.31 cfm to make 48hp...now I know there are multiple variables that you need to take into account before assuming such a number, but doesn't 33 cfm seem rather low? I mean a 38mm carb can flow a shit tone more air then that (obviously the test pressure would need to figured). So what am I missing??? Why don't we run smaller carbs and smaller intake ports and ramp up velocity? It would appear from my untrained eye that everything seems to be on the big size.

Please educate me!

[wobbly]

Re carb and reed size for a race engine.

Here is a note I had Neels add to the help file of EngMod


" For high performance, high BMEP, applications a quick check through the areas generated by the software will give a good indication of the engines overall efficiency, and thus a in pointer as to where to devote time with changes to an input.

In these cases the carburettor inlet area, the reed effective area, and the total exhaust and transfer areas will converge to equality, as each of these elements is optimized. Using this technique a "too small a reed" for example will quickly become evident – and a change to improve this, will immediately give a power increase when the simulation is re run. "

The reed block port dimensions are more important than the petal curtain area, as small petals will self compensate somewhat by staying open longer.

[adegnes]

Was thinking this afternoon (I know I shouldn't do such a thing), about CFM vs HP and how this may correlate to the 2 stroke. Now I am NO engineer, scientist, etc. so most of my research is the search button on Google:facepalm:

according to a website, you need 33.31 cfm to make 48hp...now I know there are multiple variables that you need to take into account before assuming such a number, but doesn't 33 cfm seem rather low? I mean a 38mm carb can flow a shit tone more air then that (obviously the test pressure would need to figured). So what am I missing??? Why don't we run smaller carbs and smaller intake ports and ramp up velocity? It would appear from my untrained eye that everything seems to be on the big size.

Please educate me!

Because the intake doesn't flow all the time, and some of the time is does flow, it does it in the wrong direction.
Sorry, no time for a real answer(and someone will probably soon chime in with a better explanation than I can provide anyway...)

[oldjohnno]

why not scale the carb size by area from a known well developed engine.

Using figures from eight engines from Yamaha, Honda and KTM gave an average carb size constant of 33, ie. Throat diameter = √(hpx33). The individual numbers varied from 29.5 to 40, but even after eliminating these two the average remained at around 33, so I think this would be a safe starting point.


I reckon this is a good way to get very close. http://www.underdogsracing.com/fospipe/ And you get a pipe as a bonus.

Input all the relevant bits and it will recommend the exhaust port diameter for the engine. The 2 engines I have at the moment use the crab size that this calculator recommends as exhaust port dia. Good place to start I reckon.

This seems to result in an awfully big carb.


Re carb and reed size for a race engine.

The reed block port dimensions are more important than the petal curtain area, as small petals will self compensate somewhat by staying open longer.

Interesting you should say that - when you look at the evolution of Japanese MX engines from the early days of reeds in the 70's to the current day many of them started off with smallish reeds that grew much bigger in the 80's before reducing in size again later on. The later engines had a much cleaner flow path though.

[wobbly]

One big issue with all the MX engines is that the carb is severely angled ( in both planes ) and this gives hugely asymmetric flow thru the petals.
Thus technically the reed blocks are way too big, but due to this flow limitation,in reality the situation is very complex.
I can pick up 4 Hp ( in 36 ) from a SKUSA CR125 simply by changing the petals and backups, to help even out the flow pattern into the case.
If we were allowed a straight manifold off say the RS125, then another 2 Hp is gained instantly,then another 2 with petals to suit that setup.
So going from 36Hp to 40 then to 44 just by changing the petals and manifold.

[oldjohnno]

...So going from 36Hp to 40 then to 44 just by changing the petals and manifold.

Bloody hell, who wouldn't kill for an easy 22% increase?

Interesting that the engine is so sensitive to the incoming flow bias - I picture the conditions in the crankcase as being like a tornado of turbulence, what with the crank and rod whizzing around so quickly, and would've thought the turbulence would make it relatively indifferent to flow direction. Obviously not...

[wobbly]

Regarding flow bias, there is around 2 Hp in 48 in a KZ10 kart 125 engine by utilizing a reed cage that is angled up toward the piston.
All of the manufacturers use reed petals that are softer on the top, to get this bias to point the incoming flow directly at the transfer entry area.
I have tested this and got an ICC engine over 50 Hp for the first time - with the same petals/backups top and bottom.
Not allowed to use it in the current homologation engine, but that reed block is going with me to the TM factory.
If an RS125 tuner is looking, the first thing you should be into is differing petals and rev plates/backups top and bottom - free Hp in a few minutes, or should I say days,
to get it right.