ESE's works engine tuner

[Drew]

search thread use a few words like psi injection pressure and results come up.
|I often search by pictures relating using view thread images.
I did find this though, out of pitlane I have posted it before.from memory robs and Neils was about 40psiCheers for the tip.

That alternating injector bizzo is the go.

[TZ350]

Ok, tonight I fitted two 89g/min injectors on the side transfers for starting and low speed running and a 360 g/min unit in the middle for squirting under the piston and ran it all up.

EngMod says that the 125 will consume about 260cc of fuel a minute and the big injector delivers 460cc (360 g/min) at 100% duty.

This data recorder is a pretty handy feature of the Ecotrons EFI system.

298349

RPM ... Brown line
Maximum Injection Time Possible ... Grey Line
Injector-1 ... Blue Line
Injector-2 ... Yellow Line

The second injector is coming in after the first 80 g/min injectors top out, the second 360 g/min injector still has some head room so that is a good sign and the EFI control system looks like its trying to do the right thing.

Still detonating though so I tried bigger map numbers but no real improvement, will check the line pressure next to see if its falling off with fuel demand.

[speedpro]

Their Lambda monitoring software is pretty good as well. If you connect the injector wiring into it you can map lambda against rpm. The response time of their WB lambda is near fast enough to see individual cylinder firings but there are other limitations.
Could be time to try the autotune function again.

[marsheng]

This is how I understand it.

As a 2T has only half the time of a 4T to get things done, my 2T at 13,000 is equivalent to a 4t doing 26,000rpm.


Not quite. The fuel is delivered over approx 220 degrees of crank shaft turn in a 2 St. That is much the same for 4 strokes. The inlet valve is open for maybe 280 degrees of crank ? Even though it is firing every second stroke, the valves are opening and closing fully in less than 1 stroke.

What I understand is that on a 4 St, fuel is pumped into the carb tract even when the inlet valve is closed. The fuel sits and waits there till the valve is opened effectively making for a longer time to do the necessary. However, some 4S rev very high so it must be possible.

Yes mechanical valves just don't work very fast.


Cheers Wallace

[TZ350]

Do you know if that value includes the amount of fuel leaving the cylinder unburned?"Fuelflow The fuel flow in cc/min". It can be found under Performance plots, you get a nice graph on fuel flow vs RPM.

298379298380

If I take the fuel flow vs RPM graph and divide the fuel flow by RPM I get the red line which looks like the BSFC line.

All my fuel maps have started low and increased as the rpm goes up like the fuel flow plot but after dividing the fuel by RPM (Red Line) it looks like the BSFC line.

I may have been doing it all wrong and maybe the numbers on my Alpha-N map should decrees as the RPM increases.?????

[teriks]

298379298380

If I take the fuel flow vs RPM graph and divide the fuel flow by RPM I get the red line which looks like the BSFC line.

All my fuel maps have started low and increased as the rpm goes up like the fuel flow plot but after dividing the fuel by RPM (Red Line) it looks like the BSFC line.

I may have been doing it all wrong and maybe the numbers on my Alpha-N map should decrees as the RPM increases.?????



http://ecotrons.com/files/Small%20engine%20EFI%20tuning%20guide%20-%20v2_4.pdf

“LOAD” by definition is the actual air mass charged into the cylinder divided by the ideal air mass that could be filled into the cylinder.
What is the ideal air mass?
When you have your cylinder fully filled with fresh air at sea level (barometric pressure = 1 bar), and at the temperature of zero degree C (air temperature = 32 F), the mass of the air in the cylinder is the ideal air mass.

“LOAD” tells the ECU how much fuel is exactly needed for the desired air-fuel-ratio. Because you can only calculate the fuel quantity, if you know how much air is in the cylinder.

Our system let you map the “LOAD” out of TPS/RPM table, and then the load is used everywhere else as the base inputs (fuel, ignition, lambda, etc). Why?
Because LOAD is the most representative physical variable for air charge in the cylinder. Throttle position is not even proportional to the air mass. It has a non-linear relation to the air mass (if you know some math).

LOAD is normalized against the air temperature, and altitude, and pressure. It is then multiplied by those factors with correct physical models.
The way to calibrate the LOAD mapping is similar to the “volumetric efficiency” table. The best way is to use an engine dyno. If not, use a wideband controller, and if not, use the narrow band O2 sensor to do “estimations”.
At certain throttle position, and RPM, tweak your LOAD output, until you have a good AFR.
This is what auto industry called “Alpha-N” method.

Note: again, do NOT tune your LOAD table when engine has not been warmed up! Only do that after the engine is fully warmed up (example,ECT >= 50C).

After a quick look in the ecotrons tuning manual Id say that the LOAD values should reflect your fuel flow graph.
Now, keep in mind that I have never fiddled with fuel injection, only been dreaming about a system small enough for my stuff...:blink:

EDIT: Newermind, its really late here, and the more I read the more confused I get... :facepalm:

[TZ350]

--“LOAD” by definition is the actual air mass charged into the cylinder divided by the ideal air mass that could be filled into the cylinder. “LOAD” tells the ECU how much fuel is exactly needed for the desired air-fuel-ratio. Because you can only calculate the fuel quantity, if you know how much air is in the cylinder. Our system let you map the “LOAD” out of TPS/RPM table,""--

Thanks Teriks, that actually makes sense...... it looks like I had become focused on fuel when in fact Ecotrons actually mean the numbers on their map is all about air and not fuel.

From EngMod ... ""CHARGING EFFICIENCY. The mass of fresh charge trapped in the cylinder during scavenging divided by the mass of atmospheric air which fill the entire cylinder volume when the piston is at Bottom Dead Center. It is equal to the Trapping Efficiency times the mass based Scavenge Ratio ( nearly equal to the Scavenging Efficiency ).""

But I think Ecotrons is expecting a 4T where its virtually direct injection into a trapped volume and not a 2T where there is a lot of scavenge air lost out the exhaust port. so I might be better making my map more like the delivery ratio.

From EngMod ... ""DELIVERY RATIO. Mass of fresh charge supplied to the cylinder during scavenging divided by the mass of atmospheric air which would be contained in the swept volume ( not the trapped swept volume ) of the engine.""

I think the delivery ratio better represents the air mass I need to mix fuel with, but if I had a direct injection system like Orbitals then I would only need to look at the charging efficiency curve. Because with Orbitals direct injection there is no need to waste fuel on the lost scavenge air.

298395 Red line "Charging Efficiency" ... Black line "Delivery Ratio" which I think is trapped air charge plus wasted scavenge air.

I will base my next Load Based (Alpha-N) mapping attempt on these air delivery ratio curves that I simulated using EngMod2T .

298392

The good thing is, the Beast more or less runs OK in the 2 to 8,000 rpm range, so I have a good starting point.

[RomeuPT]

Hello Everyone.

Sorry for a bit of offtopic, had a problem, and don't know the cause...

After riding my nsr engine with RS cylinder, piston and other mods for about a hour or two, the bike started to make a "cracking" noise when the engine stopped. Also does it sometime when on idle, it's scary, seem the engine is breaking apart :S
Also when pulling the bike by hand with the engine stopped in six gear It could be heard some sort of beating when the piston start's the compression stroke.

I checked everything and find nothing unusual, I quited for a weak, then changed for older piston and cylinder and the noise vanished. Then the old piston on the new cylinder, nothing wrong.
Inspected the piston and I did find the upper edge of the ring grove a little worn where the piston is exposed to the exhaust port mostly. Also the ring is slightly sticked at this side, but that happens frequently and does not cause scary noise.

What is happening?

A size domed top piston for Honda RS 125, and 97 Honda rs cylinder, the bike start's very wheel, and pulls fine

[TZ350]

Does the new piston have an offset piston pin (it can be 1-2mm) and if it has, is the crank rotating in the correct direction for the offset?

An offset pin among other things helps reduce the mechanical piston slap noise as it passes TDC and BDC but if its on the wrong side for the direction of crank rotation it amplifies the noise of the piston slapping over from/to the thrust side of the cylinder.

Get the piston pin offset wrong and the motor can sound very rough. Also the cylinder bore center line can be offset from the crank center for the same reasons as pin offset.

[TZ350]

... the more I read the more confused I get... :facepalm:

Yes ... me too. I knew the VE table was all about cylinder filling and I thought the cell values on an Alpha-N table were all about the volume of fuel to squirt but I have had to re-think that.

From the Ecotrons manual.


Volumetric Efficiency – VE table

Volumetric efficiency is probably the most important characteristics of an engine. It determines how efficient the engine is sucking the air into the cylinder.

"Volumetric efficiency, dependent on MAP sensor and RPM" ; this is the fundamental calibration map of an engine, also called "speed-density" method.

It determines the commanded fuel at different manifold pressure and RPM. Basically, the volumetric efficiency determines the fresh air amount in the cylinder, and therefore the fuel needed for optimized AFR.


LOAD based Alpha-N system

For two-stroke engines, the default fuel mapping is Alpha-N method, "RAM_MAP_LdTp_Tps_N", so if you want to calibrate the fuel quantity for a 2-stroke engine, you just modify the LOAD table only.

"LOAD" is not the throttle position, because you can have different air mass in the cylinder at the same throttle
position.

"LOAD" by definition is the actual air mass charged into the cylinder divided by the ideal air mass that could be filled
into the full cylinder.

"LOAD" is a relative value, in percentage, unit-less.

"LOAD" tells the ECU how much fuel is exactly needed for the desired air-fuel-ratio. Because you can only calculate the fuel quantity, if you know how much air is in the cylinder.

TPS based LOAD mapping

Once you know what the "LOAD" is, you can tune the TPS based load mapping. This is called "Alpha-N" model by the auto industry.

Our system do not let you map the fuel pulse width directly out of the TPS / RPM table, because it is too coarse, and it is affected by too many factors (temperatures, altitude, speed, AFR, etc.).

The way to calibrate the LOAD mapping is similar to the "volumetric efficiency" table. The best way is to use an engine dyno. At certain throttle position, and RPM, tweak your LOAD output, until you have a good AFR.


Some EngMod2T definitions.

DELIVERY RATIO.
Mass of fresh charge supplied to the cylinder during scavenging divided by the mass of atmospheric air which would be contained in the swept volume ( not the trapped swept volume ) of the engine.

CHARGING EFFICIENCY.
The mass of fresh charge trapped in the cylinder during scavenging divided by the mass of atmospheric air which fill the entire cylinder volume when the piston is at Bottom Dead Centre.

TRAPPING EFFICIENCY.
The ratio of mass of delivered charge which has been trapped to the total mass of delivered charge. Remember that some of the latter exits the exhaust port before combustion starts, ie during scavenging.

Dratio Black line: DELIVERY RATIO
Ceff Green Line : CHARGING EFFICIENCY
Teff Red Line : TRAPPING EFFICIENCY

298284

Now as you can see, not all the mixture that gets delivered actually stays in the cylinder long enough to be trapped there when the exhaust port closes. But with a carb all the "Delivered" air has had fuel mixed with it.

This is how I understand it. The black line is the air drawn through the motor by the pipe etc, some is lost out the exhaust port so the green line represents the amount left in the cylinder after the pipe has finished scavenging the cylinder and the red line is what has finally been trapped on the compression stroke with the help of the plugging effect of the pipe.

298414

From Ecotrons ... "LOAD" by definition is the actual air mass charged into the cylinder divided by the ideal air mass that could be filled into the full cylinder. "LOAD" is a relative value, in percentage, unit-less.

But Ecotrons definition looks more appropriate to a 4T as a lot of the inducted air mass (black line) in a 2T gets lost out the exhaust port. And for a 2T the Charging (green line) is not as useful for developing a Load based map as it would be for a 4T. If the 2T had direct injection then I imagine the Trapping Efficiency (red line) would be the one to use.

With a carburetor all the inducted (Delivery Ratio (black line)) air gets fuel mixed with it. So I guess that is where I have to start. I can refine it later by timing the injection end point (and hence its start point) to minimize the fuel lost with the wasted scavenge air.

298416

It looks like the Load-TPS (Alpha-N) map cell values should be an array of percentages that start by following the black line and at 8,500 rpm and TPS 100% the cell value would = 100% and for TPS 40% the cell value would = 80%.

[speedpro]

Is it possible to map the injection start or finish point or is it a single value? Being able to map it would seem ideal as you could avoid injecting fuel into air that is not trapped in the cylinder. Given that it seems likely the injectors could end up running at a high duty cycle it may be of little benefit as any air ingested at high load and rpm will have had fuel injected into it.

[TZ350]

Is it possible to map the injection start or finish point or is it a single value? Being able to map it would seem ideal as you could avoid injecting fuel into air that is not trapped in the cylinder.

Yes, with the Ecotrons system, on another map, its possible to map the injection end points and I think that will be very useful as Flettner has been able to reduce his fuel consumption that way. But first I have to just get the basics working and I am finding that harder than I thought it would be.

[Flettner]

This looks way complicated?
The YZ was tuned ( seat of the pants ) in about an hour ish riding around the yard. BUT now we have changed the YZ system to run a third injector ( in the crankcase, pointing at the bigend ) and we seem to have buggered up the settings. It's kind of staged but something is not happening as it should. I'm trying to convince Wayne to add extra wires at the injectors so we can " see " whats happening with my injector timing light.
The Link has it's limitations in 2T mode. I can set the ECU up as a 360 degree fourstroke twin and use two outputs ( joined to the same injectors, injectors will fire every 360 degree cycle ). This will need a cam sensor, I'll have to set up another trigger at half crank speed for this to happen but this will allow me to access ALL the settings available. A pain in the arse but Link will not finish the software needed to sort the 2T side out. Said there was no demand, might have a point there.
The F9 has been running a big fat carb this season ( on petrol ), but it's going back to EFI again this next season ( carb has been seen by all this year, no one will suspect a thing ) I'll be setting this up as above to test the system ( 360 degree fourstroke twin setting ).

[RomeuPT]

Does the new piston have an offset piston pin (it can be 1-2mm) and if it has, is the crank rotating in the correct direction for the offset?

An offset pin among other things helps reduce the mechanical piston slap noise as it passes TDC and BDC but if its on the wrong side for the direction of crank rotation it amplifies the noise of the piston slapping over from/to the thrust side of the cylinder.

Get the piston pin offset wrong and the motor can sound very rough. Also the cylinder bore center line can be offset from the crank center for the same reasons as pin offset.

Thanks for the reply.
The piston have no offset. The cylinder I don't know, but I think is not.

The thing is, this noise didn't start until I used this piston/cylinder combo for about an hour or two.
By hand the bike have compression going in front, going backwards have almost nothing. With the old piston feels the compression both ways...

I had an old RS cylinder running with a KX125 namura piston, that runned for a year playing around. Now that I really spended money with a real combo I got this :facepalm:

[Frits Overmars]

By hand the bike have compression going in front, going backwards have almost nothing. That happens when the piston ring is stuck in its groove, at the exhaust side. If you turn the crankshaft backwards, the con rod will push the piston against the bore opposite from the exhaust side, lifting the stuck side of the piston ring away from the bore.

[speedpro]

He did mention a stuck ring. The cause of the stuck ring could also be the cause of the noise. If the deck height of that piston is greater than the other pistons it may be just touching the head enough to flatten the edge of the piston enough to trap the ring. A look at the head and top of the piston should give us a clue. If the squish area adjacent to the ex port is clean compared to the rest of the squish that tells you it is closer. It wasn't mentioned but if the deck height is different and machining was required on the cylinder top surface maybe it wasn't machined square.

[F5 Dave]

Or the head not doweled to the barrel properly and head chamber offset in use. Bolt it up loosely off the cases and look up the bore and try move the head around. Should be unlikely to be a problem on RS parts but who knows their history?

[F5 Dave]

Ok my problem; along standing issue of ring seal and bore wear. MB100 running KT100 piston. Both steel bore std so ring are compatible.

There was an. Issue when the. Rod continued on its path extending the inlet port to the bottom. As I've case reeded it I've glued some ally in the hole to make a boost port fully formed. So I do have a question that this lack of support at the bottom could be affecting the bore at the top. But I've never had the ally crack it's epoxy or fall out and the barrel is complete for a cm below the ports so should be ok.

anyhoo I always get a polished bore above the ex and the boost port. Always wears there and a hone won't bring it back round easily. The area is scooped out above the exh the longer it runs. I'm also seeing scooping above the boost port. Running 20:1 castor oil. Ex port is 68% width , heavily chamfered and very oval and symmetrical. Ring seal has never gotten better than 25% (often much worse) despite using torque plates and heating to operating temp before honing. KT runs say 8% as comparison . Barrel is water cooled now.

so the KT piston runs it's ring peg centrally at the back over the open back boost port which we all knows works in many engines from where I first saw it in the 256. A difference I'm wondering is that the Rotax and everything more modern is plated. Contemplating one more go last oversize moving the peg to between boost and transfers. Thoughts?

[wobbly]

The rod angularity is at a max 1/2 way down the bore so if the lower skirt isnt supported properly the piston will cock over,dragging the ring edge into
the bore and creating the wear pattern.
Dump the 18th century fish and chip cooking oil and get something in there that has at least a modicum of film strength.

[TZ350]

I always get a polished bore above the ex and the boost port. Always wears there and a hone won't bring it back round easily. The area is scooped out above the exh the longer it runs. I'm also seeing scooping above the boost port.

Thoughts?

Sometimes I get this too and wonder if it could be bore wash from un vaporized fuel in the scavenge stream washing the oil away???? ... :scratch:

[F5 Dave]

Whiiir.CLICK. ok we'll get to that later.


Ahh Wob, you have a way with words that makes me laugh. . usually at myself.

I'd only changed to Castrol R30 in an attempt to get better ring sealing. I thought the old bean oils were supposed to have surprisingly good film strength esp when hot (& teh bike was air cooled not that long ago).

anyways..since it has a full reed conversion I trimmed the back of the piston from 56mm to 48 as it stuck down in the way at BDC. I'd noted the old aircoold YZs had most of the piston back missing and the KT100 .skirt was reasonably long and parralel. A few pages back you indicated that the most flow isn't happening at BDC. Perhaps I should go back to full length skirts (except on saturday nights when its dark).

[Ocean1]

If the deck height of that piston is greater than the other pistons it may be just touching the head enough to flatten the edge of the piston enough to trap the ring. A look at the head and top of the piston should give us a clue.


Or the head not doweled to the barrel properly and head chamber offset in use.

Plastigauge?

[peewee]

Dump the 18th century fish and chip cooking oil and get something in there that has at least a modicum of film strength.

why dont you like castor oil ?

[F5 Dave]

Makes the crumbed fillets soggy

[wobbly]

Most of the transfer flow IS at around BDC if the pipe is correctly designed to give max depression at this time.
Inlet flow occurs when the case starts to go negative ( and helped by the inlet length if its tuned correctly, as this goes positive )
due to the pipe suction pulling the mixture in the ducts into the cylinder,and this depression eventually opens the reeds via the case,near BDC as well.
Thus piston holes, Boyesens and short skirts all help the initial flow as the piston starts to rise.

Bean oil always has had crap film strength, what it does have is the ability to give a nice smooth wear surface - as you said when things get real hot it retains this superior
wear pattern, wheras a full synthetic disassociates into non lubricating shit chemicals.
But the new generation of oils based on esters that mimic castor but have the huge film strength of synthetics are way superior to both.
The best oil from much testing by many clever tuners for the air cooled KT100 now,is Elf 909, the most castor like of the new blends.
In my testing the best oil now for watercooled engines on pump gas that get close to being overheated by 640C in the header like we used to on Avgas, is Motul Kart at 20:1.
The super oils like Elf 927 were developed for unleaded race engines, as these run fastest when alot richer than a leaded setup and they never see the temps that killed full synthetics badly.

If you want to get the best cylinder surface on a new chromed bore, then slober R30 all over the place, mix it up at 16:1 and ONLY idle the new engine for 5 minutes.
This reduces the ring tension from high cylinder pressure, and the castor oil lets the ring/bore surfaces wear in to each other smoothly.
Once this is done, dump the castor and go racing hard on a semi synthetic.
Ive won dozens of titles with engines done this way.

[F5 Dave]

Most of the transfer flow IS at around BDC if the pipe is correctly designed to give max depression at this time.
Inlet flow occurs when the case starts to go negative ( and helped by the inlet length if its tuned correctly, as this goes positive )
due to the pipe suction pulling the mixture in the ducts into the cylinder,and this depression eventually opens the reeds via the case,near BDC as well.
Thus piston holes, Boyesens and short skirts all help the initial flow as the piston starts to rise.

Hmm ok so should I shorten the skirts but a little less both sides or just leave the dam things alone altogether?

[RomeuPT]

That happens when the piston ring is stuck in its groove, at the exhaust side. If you turn the crankshaft backwards, the con rod will push the piston against the bore opposite from the exhaust side, lifting the stuck side of the piston ring away from the bore.

Thanks, this is probably the case.

Squish deck is highly on the safe side. Rod is new....


The rod angularity is at a max 1/2 way down the bore so if the lower skirt isnt supported properly the piston will cock over,dragging the ring edge into
the bore and creating the wear pattern.
Dump the 18th century fish and chip cooking oil and get something in there that has at least a modicum of film strength.


I don't know what cause the wear at the piston top ring edge. I am not sure if this answer is for Dave or for me.
I am Using Castrol 2T stroke Racing, fully synthetic at around 3,25%.

[senso]

How is the exhaust bridge?
Seems like the problem that the gasgas has, pegging the ring in the bridge, solutoin was to drill 4 holes with 1.5mm chamfered to 2mm.

Or another note, what do you guys think about the shell racing M oil?
I can't run it on the 125, fouls plugs like there is no tomorrow, A747 doesn't do anything like that, but runs great in the cast iron 45mm crm liner.

[peewee]

has somebody tried this oil. says its good to 45,000 rpm :eek5:


http://i1081.photobucket.com/albums/j357/doddledo/_25_zps880fd692.jpg

[wobbly]

Well as I said, fully synthetics like 2T are not good when overheated in an engine that runs leaded race gas,where the normal running temp needed to
make the fuel work correctly, destroys the film strength - the only good reason to be running a full synthetic in the first place.
And at 30:1 it would struggle in any real race engine.
I had no idea you could still buy A747 - easily the best oil made for leaded fuel, many years ago.
Shell M was developed in the stone age,for use with Methanol fuels, so no reason to be using it for anything else, or at all really.
I wouldnt put Amsoil in a race engine if it was given to me, and it ran at only 5,000 rpm.
Last engine I saw on Amsoil, was a microlight that had crashed, due to a skirt dropping off.
The other piston was OK, except for the 0.012" bore clearance after 3 Hrs in the air - running 100:1 like it said on the bottle.

Every RS125 by Honda should have 2 bridge lube holes and 1 each side of the boost,unless you want to be freeing snagged rings all the time.
A T port is absolute hell on any oil trying to keep the ring off the bore, even with super trick piston shapes and properly relieved bridge geometry.

[peewee]

i wouldnt put amsoil in a lawnmower :laugh:

[senso]

A747 I can it locally for 22€, or from Spain at like 14€ for each pack of 12 liters, just under 200€ with shipping.
The Racing M is very cheap around here, about 10€ a litre.
Here is the still stock combustion chamber of the crm with like 1.2mm squish after burning 200l of 95 pump gas with the racing M.
298506

[husaberg]

A747 I can it locally for 22€, or from Spain at like 14€ for each pack of 12 liters, just under 200€ with shipping.
The Racing M is very cheap around here, about 10€ a litre.
Here is the still stock combustion chamber of the crm with like 1.2mm squish after burning 200l of 95 pump gas with the racing M.


I would say 1.2mm squish unless you have a elastic rod, or a huge bore and stroke (say 100mm by 100mm) is not squishing much at all.
It should be nearly half that I would have thought.

I have mentioned the early Cagiva injection before based on a similar set up based on the early 851 set up.
here is some pics harvested from facebook.

[husaberg]

some more Cagiva stuff

[husaberg]

I remember asking wob early on as I had heard tales of how close the Cagiva was to being a Yamaha clone looking at these crank pics gee coincidence I think not. Cagiva cranks of various years 3rd pic. The is rest Yamaha

bugger the links are dead for the Harris Yam cranks and I can't search for cached imaged on my browser (or I haven't figured out how yet ;) )
Anyway here is a couple that don't illustrate my point properly.........

[F5 Dave]

Well as I said, fully synthetics like 2T are not good when overheated in an engine that runs leaded race gas,where the normal running temp needed to
make the fuel work correctly, destroys the film strength - the only good reason to be running a full synthetic in the first place.
And at 30:1 it would struggle in any real race engine.
. ..

I run Av & if I change back to synth I'd have run 800 like in the 50. I know you've panned it for tests on aircooled engines but presumably ok for leaded WC use? I've tried 20:1 on the 50 & seen no changes on the dyno so I've been running 30:1 for forever. All it (the 50) gets is a ring every year & a new piston every 3rd & performance comes back to original but after 10 years the bore needs a replate. 800 is available & affordable(ish) but open to suggestions.

[TZ350]

Page .... 970


...not sure if this link has been put up already...pretty cool stuff, it's sucked a bit of my time... http://www.gt-rider.com/thailand-motorcycle-forum/showthread.php/38579-Early-Japanese-Motorcycles

Oil and EGT talk


has somebody tried this oil. says its good to 45,000 rpm :eek5:


http://i1081.photobucket.com/albums/j357/doddledo/_25_zps880fd692.jpg


How is the exhaust bridge? solutoin was to drill 4 holes with 1.5mm chamfered to 2mm.

Or another note, what do you guys think about the shell racing M oil? I can't run it on the 125, fouls plugs like there is no tomorrow, A747 doesn't do anything like that, but runs great in the cast iron 45mm crm liner.


Well as I said, fully synthetics like 2T are not good when overheated in an engine that runs leaded race gas,where the normal running temp needed to make the fuel work correctly, destroys the film strength - the only good reason to be running a full synthetic in the first place.
And at 30:1 it would struggle in any real race engine.

I had no idea you could still buy A747 - easily the best oil made for leaded fuel, many years ago.
Shell M was developed in the stone age,for use with Methanol fuels, so no reason to be using it for anything else, or at all really.

I wouldnt put Amsoil in a race engine if it was given to me, and it ran at only 5,000 rpm. Last engine I saw on Amsoil, was a microlight that had crashed, due to a skirt dropping off. The other piston was OK, except for the 0.012" bore clearance after 3 Hrs in the air - running 100:1 like it said on the bottle.

Every RS125 by Honda should have 2 bridge lube holes and 1 each side of the boost,unless you want to be freeing snagged rings all the time.
A T port is absolute hell on any oil trying to keep the ring off the bore, even with super trick piston shapes and properly relieved bridge geometry.


I run Av & if I change back to synth I'd have run 800 like in the 50. I know you've panned it for tests on aircooled engines but presumably ok for leaded WC use? I've tried 20:1 on the 50 & seen no changes on the dyno so I've been running 30:1 for forever.

All it (the 50) gets is a ring every year & a new piston every 3rd & performance comes back to original but after 10 years the bore needs a replate. 800 is available & affordable(ish) but open to suggestions.


Motul 800 a similar brew as Castrol 2T but as I said the much later Motul Kart product seems to be a very good imitator of castor - the 800 certainly wasnt, with every engine I pulled down being very "dry" unlike Kart where everything is covered in a slobbery wet film.

20:1 shows gains in the aircooled KT100, but not so much in a watercooled, except in reed engines where the richer mixture always helps reed cushioning and prevents incipient tip chipping.


Very good. Reeds are chipping a little even at modest revs with piles of oil.


ok i found something interesting. it says nothing about this in the ingredients on the data sheets

'Thanks to its high content in specially selected ricinus oil, ELF HTX 909 provides exceptional
protection against gripping.'

http://www.nkp-karting.com/uploads/products/files/HTX%20909%20EN.pdf

revised 2-20-2014 http://www.quickfds.com/out/16986-29245-27967-017784.pdf


The 909 oil mix seems to be specifically directed at the 20,000 rpm direct drive 100cc kart engines, and as I said its for sure the best oil today for the aircooled KT100 Yamaha, as I have done the direct testing for a customer who is one of the top tuners here.

Those guys are all die hard castor users, and it has taken several years to convince them the 909 is " better " but now they all use it.

Running the 976 full synthetic always lost power on the dyno when run very hard at 650 + in the header, as all top Yamahas do.

This was designed specifically for the unleaded GP engines, that dont run super hot like we did back in the day of full leaded rocket fuel, nor like they do in aircooled race engines.

Here is an old dissertation on how castor works.

asphttp://www.go-cl.se/castor.html


http://www.go-cl.se/castor.html


So as I read that if you're air cooled run Castor or ideally 909.

If yer watercooled run a decent synthetic ester oil. I'm assuming you don't consider Av as being a hot burning GP like rocket fuel, its just all that we can run vs pump fuel.


AvGas runs best exactly like the old leaded rocket fuel, if you dont have 650*C in the header you aint doin it right.

So yes 909 is for sure the best in an Aircooled running hot at 650*, but is equally fine in a watercooled on AvGas - just dont use a full synthetic in anything
that runs AvGas properly.

Find some old A747, or stick with Elf 909 or Motul Kart.
If you are running unleaded properly at rich ie cooler temps, then spend up large on Elf 927 full noise synthetic if you feel the need..


We used this castor mix oil for the first time when winning the KZ2 Nationals.
I havnt dynoed it yet, but will do soon after a rebuild is finished.

http://www.kartsport.org.nz/about-us/hot-topics/xeramic-kart-lubricants-now-available

Seems most top kart teams use this now, no one gets it free, so they must have tested it to death in Europe.


Huge EGT temps mean Jack Shit, I have seen idiots with a stock head TZ350 running 2 base gaskets that saw 1360 for 20 laps without seizing.

But funnily it was 5 seconds off the pace of a properly tuned one running 1245/1255 on AvGas.
Getting the max com and max advance possible for the fuel ,without deto is the key - and for AvGas or up to 110 race gas ,mid 1200s at max power means you are on the money.

One jet leaner , if it only sees around 20 to 30* hotter, means the optimum is back one jet richer, as the perfect scenario is 50 to 60* per jet change, as this always gets back to the max power available.

Sure the oil must be good with so many top teams running it, but telling me you have seen 1300 ( like some sort of red badge of courage ) just means the rider wasnt watching the gauges/and or ignored
the warning lights ( and should be shot ) or someone made a wrong tuning call on an engine that wasnt on the money to start with.

On unleaded it would be detoing unhappily around 100* richer at 1200 if tuned to the edge.
If it was really on the limit, it would have locked up at 1300 ,no matter what oil was on the bore.


That was a bit of a rant - but having riders tell me afterwards they saw over 1300 on the gauge, but dont understand why the bloody motor siezed because they didnt change the jets ,from coming off the dyno really piss me off.


No it's jetted on the money at 1250F each time it hits the track, but there is a certain amount of time it takes to get the carbs/airbox/fairing back on and be out on the dummy grid. Aand in that time 'something' changed and EGT's were regularly hitting 1300 at the end of the straight, the rider owns the bike, pays the bills and ultimately it is his decision what to do when the EGT starts flashing. He decided to go for it, taking T1 at full noise with his hand over the clutch each lap. Other oils hit 1300F once or twice in a race and the pistons show the deto or go bang. His opinion was the xeramic oil saved a seizure.


But its still my firm belief Lozza,that with another 1.5 degrees of advance or another 1/2 ratio of com the engine would have siezed when pushed to 1300.
With the jetting on the money at 1250, then logic dictates that it would also have been faster, running normally with the extra advance or com.

The only reason an engine doesnt sieze when running at 1300 is that its not maxed out at 1250.
Like I said running the TZ350 with super low com, it ran all day at 1300 + but was dead slow.
If the engine saw deto when running at 1300 before, I simply cannot see how changing the oil can make that deto go away - sure a super oil can prevent a lockup by simply being a better lube on the bores - but somehow killing deto .Na, that would mean the oil affects the octain rating of the fuel - making it illegal
and it certaily isnt in CIK.

As you say - something changed, to allow ( and cause ) that mental temp to occur, and whatever that issue was, it increased the thermal death limit of the
engine,and thus by inference,it must have reduced the performance level to allow that to temp happen as well.


With my egt sitting safely on the shelf as it has for last couple of years after a false start & loss of drive to re-experiment (I'd inserted the tip too far in on a tiny 50cc pipe and it was overheating the returning charge I believe as when I removed it the power returned),

annyhoo. You're stating the temps as constants. is this assuming that the position of the probe is i the correct place in the pipe? Or could you distort the readings required by placing in incorrect place or wrapping the pipe? perhaps they would only get cooler than danger zone.


I have had the probe anywhere from the flange face ( like Aprilia did ) to around 75mm from the cylinder.

The tip would normally be in the middle, but on the dyno I have done tests with it only 10mm inside the pipe.

Never seen any difference in the readings, as Robin Williams said " its hot, damn hot ".

But wrapping the header is a very bad idea, overheating the return gas slug causes deto, so no free lunch there.


But doesn't all premix oil effect the Octane? just some worse than others...... I guess you are meaning a positive effect? rather than a less of a negative one than previously was occurring?


Ok got it. I mentioned wrapping as a variable someone might be employing that might get different results. I I haven't wrapped my pipe since the 90s when I'd seen it on GP bike pics but a Cameron article sorted me out explaining the sled origins.


The egt readings converging to 1250* for Avgas or up to around 110 octain leaded, at peak power, is just another piece in the jigsaw of trying to optimize the com and advance of an engine to achieve the ideal BSFC for the fuel being used.

Not enough com and or advance and the egt will run hot, needing more fuel to lower the temp.
This energy carrying fuel mixture is then not being used to create power, but simply lower the egt.
As I have said before the synergy of fueling, com and advance can be detected easily on the dyno, and on the track.

If you progressively lean down and get to just on 1200, then go down another ( Keihin/Dellorto ) jet size, the egt will rise another approx 50* if everything is on the money.

If you only see 20* rise, you are operating on the cusp of diminishing returns due to too much advance, too much com, or too small a stinger.

An engine running in this zone will react badly to even small increments in RAD.
If by chance it then runs any leaner due to a drop in ambient temp say,it will sieze, any richer and power will drop.

Going the other way, if you see 1250 with the single jet change, and then the RAD makes it go leaner, and it jumps up to 1300, then the engine wasnt BSFC optimized in the first place.


Wobbly, Your acronym RAD, what is it? Really Awful Detonation, Replace After Detonation.....? Keep up the interesting flow of info, it's great Thanks Ken


Relative Air Density. Each 3% away from your dyno baseline of Air Temp, Humidity, and Pressure is a one jet change, and should get you back to your best power egt.

[Yow Ling]

All it (the 50) gets is a ring every year & a new piston every 3rd & performance comes back to original but after 10 years the bore needs a replate. 800 is available & affordable(ish) but open to suggestions.

Is your 50 nicasil bore?

[F5 Dave]

My RG was plated steel liner, made it last when it wore out on last over. Not many are (were) proficient at doing anything other than ally.

[wobbly]

Motul 800 a similar brew as Castrol 2T but as I said the much later Motul Kart product seems to be a very good imitator of castor - the 800 certainly wasnt, with every engine I pulled down being very "dry"
unlike Kart where everything is covered in a slobbery wet film.
20:1 shows gains in the aircooled KT100, but not so much in a watercooled, except in reed engines where the richer mixture always helps reed cushioning and prevents incipient tip chipping.

And I must throw some shit about the combustion chamber shown, it could not be a better example of what not to do in a modern race engine if you tried.
Crap surface finish, round corner into the bowl, flush plug tip with old fashioned heavy metal earth electrode, and 1.2 squish that wasnt working anyway.
Would have been perfect in Vespa riding Italian posties scooter during the war running 72 octain kerosene.

[Frits Overmars]

... I had heard tales of how close the Cagiva was to being a Yamaha clone Back then the Japanese factories were eager to keep the 500 class alive. Right after the 199x season Cagiva had the title-winning Yamaha 500-4 on loan for over a month. And Honda (picture) made its not-for-sale Keihin carb units available to Cagiva.

[husaberg]

Back then the Japanese factories were eager to keep the 500 class alive. Right after the 199x season Cagiva had the title-winning Yamaha 500-4 on loan for over a month. And Honda made its not-for-sale Keihin carb units available to Cagiva.

From what I understand a set magically appeared for Patton as well (care of burgess i think) rather than Honda direct, after they asked Honda how much they would cost for a set and were told $20000 and left rather disheartened......
I whish I could find the pics of the Harris cranks because they are pretty much exactly the same and I have heard most stuff was interchangable.
Wob mentioned the Yamaha boys used to help the Cagiva team.
Overall after studying a lot of pics My guess is the Honda NSR500 ends up not too much wider than the Yamaha/Cagiva Suzuki afterall due to the phasing and the gap the twin crank has to have for decent transfers as demonstrated by the Cagiva crank.

[F5 Dave]

Motul 800 a similar brew as Castrol 2T but as I said the much later Motul Kart product seems to be a very good imitator of castor - the 800 certainly wasnt, with every engine I pulled down being very "dry"
unlike Kart where everything is covered in a slobbery wet film.
20:1 shows gains in the aircooled KT100, but not so much in a watercooled, except in reed engines where the richer mixture always helps reed cushioning and prevents incipient tip chipping.

And I must throw some shit about the combustion chamber shown, it could not be a better example of what not to do in a modern race engine if you tried.
Crap surface finish, round corner into the bowl, flush plug tip with old fashioned heavy metal earth electrode, and 1.2 squish that wasnt working anyway.
Would have been perfect in Vespa riding Italian posties scooter during the war running 72 octain kerosene.
Very good. Reeds are chipping a little even at modest revs with piles of oil.

also my barrel is too worn to next over. Start again.

[RomeuPT]

I would say 1.2mm squish unless you have a elastic rod, or a huge bore and stroke (say 100mm by 100mm) is not squishing much at all.
It should be nearly half that I would have thought.

I have mentioned the early Cagiva injection before based on a similar set up based on the early 851 set up.
here is some pics harvested from facebook.

He is mentioning a stock engine.

IS funny that the namura does not get the ring stuck so easy at teh exhaust bridge. Maybe I need to check better the mixture strenght at peak power...

[RomeuPT]

Back then the Japanese factories were eager to keep the 500 class alive. Right after the 199x season Cagiva had the title-winning Yamaha 500-4 on loan for over a month. And Honda (picture) made its not-for-sale Keihin carb units available to Cagiva.

Looking at the pic, the exhaust flanges seem to be of some thick metal don't they? Woudn't this part of the pipe be made of thin mild steel or titanium sheet so it can heat faster and the pipe temp be more responsive to rpm changes? Or there is probably some different trick on them then we see with the 125cc?

[Frits Overmars]

Looking at the pic, the exhaust flanges seem to be of some thick metal don't they? Woudn't this part of the pipe be made of thin mild steel or titanium sheet so it can heat faster and the pipe temp be more responsive to rpm changes? Or there is probably some different trick on them then we see with the 125cc?The straight upper pipes of the Honda NSR500 are built-up titanium units (yes, for thermal reasons), but stamping titanium is extremely difficult, so the first, curved parts of the headers are separate castings. The lower headers are much more curved, so they are produced as stamped steel units.

[wobbly]

A couple of sets of Ti Keihins made it onto the Swiss Auto/Pulse team bikes as well, costing enough to pay most of the mechanics for a year ( which they werent )
Sadly they were shagged, and were so inconsistent in mid range jetting the riders were never sure what was going to happen next when rolling on/off the throttle - just a bit
disconcerting when the thing is trying to kill you on every corner.

[peewee]

hey guys you know of any specific sae papers with oil tests for synthetic ester and castor oil ? scoured the web but i havent found any legitimate tests or information. seems its mostly urban legend passed down the grape vine is all i see

wobbly i found alot of talk about htx909. people saying it has some percentage of castor. says no mention of castor in the data papers . whats wrong with these people ?

[peewee]

ok i found something interesting. it says nothing about this in the ingredients on the data sheets :blink:

'Thanks to its high content in specially selected ricinus oil, ELF HTX 909 provides exceptional
protection against gripping.'

http://www.nkp-karting.com/uploads/products/files/HTX%20909%20EN.pdf

revised 2-20-2014 http://www.quickfds.com/out/16986-29245-27967-017784.pdf

[wobbly]

The 909 oil mix seems to be specifically directed at the 20,000 rpm direct drive 100cc kart engines, and as I said its for sure the best oil today for the aircooled
KT100 Yamaha, as I have done the direct testing for a customer who is one of the top tuners here.
Those guys are all die hard castor users, and it has taken several years to convince them the 909 is " better " but now they all use it.
Running the 976 full synthetic always lost power on the dyno when run very hard at 650 + in the header, as all top Yamahas do.
This was designed specifically for the unleaded GP engines, that dont run super hot like we did back in the day of full leaded rocket fuel, nor like they do in aircooled race engines.
Here is an old dissertation on how castor works.

asphttp://www.go-cl.se/castor.html

[wobbly]

http://www.go-cl.se/castor.html

[F5 Dave]

So as I read that if you're air cooled run Castor or ideally 909.

If yer watercooled run a decent synthetic ester oil. I'm assuming you don't consider Av as being a hot burning GP like rocket fuel, its just all that we can run vs pump fuel.

[wobbly]

AvGas runs best exactly like the old leaded rocket fuel, if you dont have 650*C in the header you aint doin it right.
So yes 909 is for sure the best in an Aircooled running hot at 650*, but is equally fine in a watercooled on AvGas - just dont use a full synthetic in anything
that runs AvGas properly.
Find some old A747, or stick with Elf 909 or Motul Kart.
If you are running unleaded properly at rich ie cooler temps, then spend up large on Elf 927 full noise synthetic if you feel the need..

[peewee]

im not sure how flashpoint factors in but the article mentions 445 F. perhaps thats cator oil before any additives ? some brands like the klotz are 550 F flashpoint

[Gigglebutton]

I get Elf oils at distributor prices if any one wants some for T2 or T4 bikes

[speedpro]

Originally asked in my #6 thread but more people read this thread so . . . .

Been busy putting a new pipe together for Gary's MB. I've been grinding the welds inside with the Dremel tool, just where I've used a bit of filler rod and it's made a bump. After that I've used a flapwheel to clean it down properly. This has got me wondering if there is a finish that is better or worse on the inside of a chamber. A lightly ground finish might be good for creating a boundary layer. My thoughts were that it probably would not be a benefit with actual gas flow but that it might have some beneficial effects with the boundary layer acting as an insulator which might help the exhaust gas temperature jump back up after the throttle is reopened, rather than the pipe busily sucking heat out of the gas. Has anyone experimented with this?

[wobbly]

I tested a pipe set back to back, one with as you say the "bumps" ground off the other with every joint hammered flat.
This is easy if you are using gas with the very soft mild steel ferrox rods.
The hammering can be extended each side of the join line and makes a nice smooth transition, especially in a tight turn up near the cylinder.
Bottom line is that the hammered pipe made around 1.5 Hp more all the way up to the same power at peak, and same in the overev.
I tig every pipe now as its way cheaper consumables and faster, but the tig rod filler in small holes is too hard to hammer flat, you have to flap wheel the
bumps, but if I was going for the ultimate setup I would gas a pipe and charge a cheap more to do it.
Most people wont pay for this and wouldnt notice the difference anyway.

[wobbly]

We used this castor mix oil for the first time when winning the KZ2 Nationals.
I havnt dynoed it yet, but will do soon after a rebuild is finished.

http://www.kartsport.org.nz/about-us/hot-topics/xeramic-kart-lubricants-now-available

Seems most top kart teams use this now, no one gets it free, so they must have tested it to death in Europe.

[jasonu]

I tig every pipe now as its way cheaper consumables and faster, but the tig rod filler in small holes is too hard to hammer flat, you have to flap wheel the
bumps, but if I was going for the ultimate setup I would gas a pipe and charge a cheap more to do it.
Most people wont pay for this and wouldnt notice the difference anyway.

Get the heat right, purge the pipe with argon and the finish inside will look like you welded it from both sides.

[TZ350]

Recently we came by one of RMS Engineering's RG50 engines.

Very nice port work and the O ring head gasket and O ring around the water jacket are nice touches and the dowel pins for locating the head is real professionalism.

[TZ350]

Well, I rode in F5 at Mt Welly today, got good starts every time and managed a third in the prelim race.

In the first points race I dropped it in the infield and Gigglebutton fell avoiding me, there were a few frantic moments sorting ourselves out and racing to see who would get re started first. In the end I followed Giggles home in both points races. My personal best for the day was 35.5 sec (anti clockwise).

The 50cc 2T F5 bikes at the sharp end were doing 30.5 sec or a bit less laps, and that would be a good showing in F4 A grade.

The A grade F4 race I watched had Garry making a flying start on the MB100. The race order was 2T- 4T - 2T untill Garry dropped it then the 4T led for a while, eventually falling in the same corner. So it was a win for the 2T.

The pace during the day was pretty furious with the 4T lowering the F4 lap record.


298816 The results of the 1st round of the 14/15 season of AMCC bucket racing from today.
Tim will be updating the website. David Diprose


The results of Round 1 are now on Mylaps here: http://www.mylaps.com/en/events/1045407

The championship standings after 1 round are on Mylaps here: http://www.mylaps.com/en/championships/31443

Links to the above have been placed on the AMCC bucket racing news page here: http://amcc.org.nz/index.php/menu-bucketracing/bucketracingnews.html

On the AMCC page I have also mentioned that all 3 current anti-clockwise lap records were broken on Sunday. Well done Aaron (F4), Nathanael (F5) and Brenton/Kamil (Sidecar). What a meeting! Tim



Aaron Hassan put down a 28.806 on Darren's RSFXR F4 bike and Nathaniel Diprose did a 30.486 on their F5 RS bike on Sunday going anti clock wise at Mt Wellington. Blistering!


I noticed there are some records and results up on the AMCC page, here: CLICK LINK (https://flic.kr/p/nXXD9Z)

https://farm3.staticflickr.com/2929/14623226883_654ae07f60_b.jpg (https://flic.kr/p/ohcRTr)

https://farm4.staticflickr.com/3894/14416755557_31597a10ca_c.jpg (https://flic.kr/p/nXXD9Z)

[jasonu]

Recently we came by one of RMS Engineering's RG50 engines.

Very nice port work and the O ring head gasket and O ring around the water jacket are nice touches and the dowel pins for locating the head is real professionalism.

That looks like a motor we (Chris mostly I think I did the welding) built probably 15 or more years ago. It made a very rideable and competitive 11.5hp. The pipe was a mish mash of RG50 front section and hand made rear. Most if not all numbers came from Two Stroke Tuners book by a Graham Bell.

[2T Institute]

We used this castor mix oil for the first time when winning the KZ2 Nationals.
I havnt dynoed it yet, but will do soon after a rebuild is finished.

http://www.kartsport.org.nz/about-us/hot-topics/xeramic-kart-lubricants-now-available

Seems most top kart teams use this now, no one gets it free, so they must have tested it to death in Europe.

Only told you about that a year ago :lol:, the oil itself may not be the answer but we have had jetted to the limit and had RAD changes that saw 1300F regularly. Never seized pistons survived

[wobbly]

Huge EGT temps mean Jack Shit, I have seen idiots with a stock head TZ350 running 2 base gaskets that saw 1360 for 20 laps without seizing.
But funnily it was 5 seconds off the pace of a properly tuned one running 1245/1255 on AvGas.
Getting the max com and max advance possible for the fuel ,without deto is the key - and for AvGas or up to 110 race gas ,mid 1200s at max power means you are on the money.
One jet leaner , if it only sees around 20 to 30* hotter, means the optimum is back one jet richer, as the perfect scenario is 50 to 60* per jet change, as this always gets back to the max power available.
Sure the oil must be good with so many top teams running it, but telling me you have seen 1300 ( like some sort of red badge of courage ) just means the rider wasnt watching the gauges/and or ignored
the warning lights ( and should be shot ) or someone made a wrong tuning call on an engine that wasnt on the money to start with.
On unleaded it would be detoing unhappily around 100* richer at 1200 if tuned to the edge.
If it was really on the limit, it would have locked up at 1300 ,no matter what oil was on the bore.

[wobbly]

That was a bit of a rant - but having riders tell me afterwards they saw over 1300 on the gauge, but dont understand why the bloody motor siezed
because they didnt change the jets ,from coming off the dyno really piss me off.

[G Jones]

I tested a pipe set back to back, one with as you say the "bumps" ground off the other with every joint hammered flat.
This is easy if you are using gas with the very soft mild steel ferrox rods.
The hammering can be extended each side of the join line and makes a nice smooth transition, especially in a tight turn up near the cylinder.
Bottom line is that the hammered pipe made around 1.5 Hp more all the way up to the same power at peak, and same in the overev.
I tig every pipe now as its way cheaper consumables and faster, but the tig rod filler in small holes is too hard to hammer flat, you have to flap wheel the
bumps, but if I was going for the ultimate setup I would gas a pipe and charge a cheap more to do it.
Most people wont pay for this and wouldnt notice the difference anyway.Thanks for sharing the "gospel" - just curious about smoothing out the "bumps" - what do you do about the closing joint - or is there always one joint with some bumps ?....

[wobbly]

I always finish at the rear cone, and use a solid mandrel rod the same dia as the stinger hole, clamped in a vise.
I have several with a smooth long radius ground on one side of one end.
Sometimes I actually mark on the mandrel where the end of the cone should sit, to have the join
exactly over the rad, but you can always hear the sound change when hammering the pipe metal onto the flat mandrel surface
and juggle the pipe position as you move around the joint.

[speedpro]

I made the rear cones and welded that to the centre section on the new pipe for #3. This time I just spent a bit of time getting it pretty right tacking it on before I finished welding it and didn't bother with further finishing. Being the largest diameter portion of the pipe I figure it's the least critical joint. I really would have preferred to finish the header portion a bit better as there are definite "joints and sections" rather than a smooth curve.

[2T Institute]

Huge EGT temps mean Jack Shit, I have seen idiots with a stock head TZ350 running 2 base gaskets that saw 1360 for 20 laps without seizing.
But funnily it was 5 seconds off the pace of a properly tuned one running 1245/1255 on AvGas.
Getting the max com and max advance possible for the fuel ,without deto is the key - and for AvGas or up to 110 race gas ,mid 1200s at max power means you are on the money.
One jet leaner , if it only sees around 20 to 30* hotter, means the optimum is back one jet richer, as the perfect scenario is 50 to 60* per jet change, as this always gets back to the max power available.
Sure the oil must be good with so many top teams running it, but telling me you have seen 1300 ( like some sort of red badge of courage ) just means the rider wasnt watching the gauges/and or ignored
the warning lights ( and should be shot ) or someone made a wrong tuning call on an engine that wasnt on the money to start with.
On unleaded it would be detoing unhappily around 100* richer at 1200 if tuned to the edge.
If it was really on the limit, it would have locked up at 1300 ,no matter what oil was on the bore.

No it's jetted on the money at 1250F each time it hits the track, but there is a certain amount of time it takes to get the carbs/airbox/fairing back on and be out on the dummy grid and in that time 'something' changed and EGT's were regularly hitting 1300 at the end of the straight, the rider owns the bike,pays the bills and ultimately it is his decision what to do when the EGT starts flashing.He decided to go for it, taking T1 at full noise with his hand over the clutch each lap. Other oils hit 1300F once or twice in a race and the pistons show the deto or go bang. His opinion was the xeramic oil saved a seizure.

[wobbly]

But its still my firm belief Lozza,that with another 1.5 degrees of advance or another 1/2 ratio of com the engine would have siezed when pushed to 1300.
With the jetting on the money at 1250, then logic dictates that it would also have been faster, running normally with the extra advance or com.
The only reason an engine doesnt sieze when running at 1300 is that its not maxed out at 1250.
Like I said running the TZ350 with super low com, it ran all day at 1300 + but was dead slow.
If the engine saw deto when running at 1300 before, I simply cannot see how changing the oil can make that deto go away - sure a super oil
can prevent a lockup by simply being a better lube on the bores - but somehow killing deto .Na, that would mean the oil affects the octain rating of the fuel - making it illegal
and it certaily isnt in CIK.
As you say - something changed, to allow ( and cause ) that mental temp to occur, and whatever that issue was, it increased the thermal death limit of the
engine,and thus by inference,it must have reduced the performance level to allow that to temp happen as well.

[F5 Dave]

With my egt sitting safely on the shelf as it has for last couple of years after a false start & loss of drive to re-experiment (I'd inserted the tip too far in on a tiny 50cc pipe and it was overheating the returning charge I believe as when I removed it the power returned),


annyhoo. You're stating the temps as constants. is this assuming that the position of the probe is i the correct place in the pipe? Or could you distort the readings required by placing in incorrect place or wrapping the pipe? perhaps they would only get cooler than danger zone.

[wobbly]

I have had the probe anywhere from the flange face ( like Aprilia did ) to around 75mm from the cylinder.
The tip would normally be in the middle, but on the dyno I have done tests with it only 10mm inside the pipe.
Never seen any difference in the readings, as Robin Williams said " its hot, damn hot ".
But wrapping the header is a very bad idea, overheating the return gas slug causes deto, so no free lunch there.

[husaberg]

If the engine saw deto when running at 1300 before, I simply cannot see how changing the oil can make that deto go away - sure a super oil
can prevent a lockup by simply being a better lube on the bores - but somehow killing deto .Na, that would mean the oil affects the octain rating of the fuel - making it illegal
and it certaily isnt in CIK.
.

But doesn't all premix oil effect the Octane? just some worse than others......
I guess you are meaning a positive effect? rather than a less of a negative one than previously was occuring?

[F5 Dave]

Never seen any difference in the readings, . . .
Ok got it.

i mentioned wrapping as a variable someone might be employing that might get different results. I I haven't wrapped my pipe since the 90s when I'd seen it on GP bike pics but a Cameron article sorted me out explaining the sled origins.

[wobbly]

The egt readings converging to 1250* for Avgas or up to around 110 octain leaded, at peak power, is just another piece in the jigsaw of trying to optimise the com and advance of an engine
to achieve the ideal BSFC for the fuel being used.
Not enough com and or advance and the egt will run hot, needing more fuel to lower the temp.
This energy carrying fuel mixture is then not being used to create power, but simply lower the egt.
As I have said before the synergy of fueling, com and advance can be detected easily on the dyno, and on the track.
If you progressively lean down and get to just on 1200, then go down another ( Keihin/Dellorto ) jet size, the egt will rise another approx 50* if everything is on the money.
If you only see 20* rise, you are operating on the cusp of diminishing returns due to too much advance, too much com, or too small a stinger.
An engine running in this zone will react badly to even small increments in RAD.
If by chance it then runs any leaner due to a drop in ambient temp say,it will sieze, any richer and power will drop.
Going the other way, if you see 1250 with the single jet change, and then the RAD makes it go leaner, and it jumps up to 1300, then the engine wasnt BSFC optimised in the first place.

[ken seeber]

Wobbly,

Your acronym RAD, what is it? Really Awful Detonation, Replace After Detonation.....?

Keep up the interesting flow of info, it's great

Thanks

Ken

[wobbly]

Relative Air Density.
Each 3% away from your dyno baseline of Air Temp, Humidity, and Pressure is a one jet change, and should get you back to your best power egt.

[F5 Dave]

The egt readings converging to 1250* for Avgas or up to around 110 octain leaded, at peak power, is just another piece in the jigsaw of trying to optimise the com and advance of an engine
to achieve the ideal BSFC for the fuel being used.
Not enough com and or advance and the egt will run hot, needing more fuel to lower the temp.
This energy carrying fuel mixture is then not being used to create power, but simply lower the egt.
As I have said before the synergy of fueling, com and advance can be detected easily on the dyno, and on the track.
If you progressively lean down and get to just on 1200, then go down another ( Keihin/Dellorto ) jet size, the egt will rise another approx 50* if everything is on the money.
If you only see 20* rise, you are operating on the cusp of diminishing returns due to too much advance, too much com, or too small a stinger.
An engine running in this zone will react badly to even small increments in RAD.
If by chance it then runs any leaner due to a drop in ambient temp say,it will sieze, any richer and power will drop.
Going the other way, if you see 1250 with the single jet change, and then the RAD makes it go leaner, and it jumps up to 1300, then the engine wasnt BSFC optimised in the first place.

I better save that somewhere. Thanks for the insight.

Time to pull out the egt again. After finishing the triple port barrel. . .

and then theres that job in the bathroom. . .

[Frits Overmars]

and then theres that job in the bathroom. . .You talking about a daily occurrence? Like BYO (bring your own paper)?

[F5 Dave]

I'm only 46 so fortunately that's still a 5min operation. No a year ago I bought a section of acrylic sheet to make a moisture trap over the bath/shower above the shower curtain. It's been hiding and yesterday I dragged it out,clamped it to a table with a 200mm sewer pipe off cut for a radius and bent it slowly with a heat gun. Worked a treat. Re measuring to do the other side. But then I'd have to put it up. :(

Well winter's almost over,(with some poetic licence) don't really need it in summer. Won't store so well now. Better things to do in the garage.

[TZ350]

Ski-doo fuel injection animation. Looks to be quite a simple system.

http://www.ski-doo.com/technologies/engine-technologies/2-strokes

I like the voice coil style injector, and it looks like there is no air injected with the fuel and the fuel itself is delivered to the fuel injector body at quite low pressure. The injection pressure is developed by a plunger piston driven by the voice coil and as we all know from speakers the movement of a voice coil can be very accurately controlled.

299072

Orbitals air assisted fuel injection system.

With these clean technologies and the inherent power and simplicity of a two stroke its hard to imagine that strokers won't make a serious comeback sometime.

But I am not sure if trying to adapt 4T EFI car technology to a high revving 2T like I am trying to do is going to work.

Car technology EFI seems to work ok on a big single that tops out at 8 - 9K rpm and I can pretty easily get my engine to rev to 8 or 9K rpm OK too but much past that and the fuel injection time exceeds the transfer port window open time.

When the injection time exceeds the transfer port open time a portion of the fuel required is left floating in the transfer duct and I think the problem with that is that on the next cycle this slug of fuel is blown right around the scavenge loop and out the exhaust port leaving the trapped mixture that follows behind it on the lean side.

And no matter how much more fuel (longer) you try to inject into the transfers the trapped mixture in the cylinder is still lean. This could easily explain why I keep getting deto at high rpm no matter how much I increase the fuel injection map numbers.

299075299076

So with my transfer duct injection setup. Calling for more fuel is self defeating and I think the answer (if there is one) is in fast opening injectors, the balance between injector sizing and in timing the end point with width of the injection squirt so as to coincide as much as possible with the airflow in the transfer duct that is finally trapped in the cylinder and not the first slug of purging air that loops out the exhaust port and is lost, not much point in having that wasted air super fuel rich and the following trapped charge lean.

299074

For my bike, at 12k ish the delivery ratio is about 120% of the cylinder volume and the amount of air (charging ratio) in the cylinder at BDC is only about 80% of the delivered air and less than that actually gets trapped (trapping efficiency) at exhaust port closing, so you can see that a fair swag of air is lost out the exhaust port.

And my guess is that the bulk of the air that is lost is the first air entering the cylinder as the transfers start to open and if there was extra fuel already in the transfers that would be lost with it.

So unlike a 4T where you can get a head start by storing fuel behind the inlet valve ready for it to open you cant do the equivalent thing with a 2T's transfer port window without loosing it down the exhaust pipe.

It is looking like the moral of the story is to keep the transfer port injection time shorter than the real time that the transfer ports are open and at 12.5k that is about 1.5ms.

Transfer port injection has the potential to clean up the 2T's emissions as the first lot of purging air can be sent through with little fuel in it but if I can't get it to work on my bike above 8-9k rpm I will have to go to inlet injection and aim to get a more homogeneous fuel mixture in the crankcase just like a carburetor does.

[husaberg]

But I am not sure if trying to adapt 4T EFI car technology to a high revving 2T like I am trying to do is going to work.

Car technology EFI seems to work ok on a big single that tops out at 8 - 9K rpm and I can pretty easily get my engine to rev to 8 or 9K rpm OK too but much past that and the fuel injection time exceeds the transfer port window open time.

When the injection time exceeds the transfer port open time a portion of the fuel required is left floating in the transfer duct and I think the problem with that is that on the next cycle this slug of fuel is blown right around the scavenge loop and out the exhaust port leaving the trapped mixture that follows behind it on the lean side.

And no matter how much more fuel (longer) you try to inject into the transfers the trapped mixture in the cylinder is still lean. This could easily explain why I keep getting deto at high rpm no matter how much I increase the fuel injection map numbers.

So with my transfer duct injection setup. Calling for more fuel is self defeating and I think the answer (if there is one) is in fast opening injectors, the balance between injector sizing and in timing the end point with width of the injection squirt so as to coincide as much as possible with the airflow in the transfer duct that is finally trapped in the cylinder and not the first slug of purging air that loops out the exhaust port and is lost, not much point in having that wasted air super fuel rich and the following trapped charge lean.



For my bike, at 12k ish the delivery ratio is about 120% of the cylinder volume and the amount of air (charging ratio) in the cylinder at BDC is only about 80% of the delivered air and less than that actually gets trapped (trapping efficiency) at exhaust port closing, so you can see that a fair swag of air is lost out the exhaust port.

And my guess is that the bulk of the air that is lost is the first air entering the cylinder as the transfers start to open and if there was extra fuel already in the transfers that would be lost with it.

So unlike a 4T where you can get a head start by storing fuel behind the inlet valve ready for it to open you cant do the equivalent thing with a 2T's transfer port window without loosing it down the exhaust pipe.

It is looking like the moral of the story is to keep the transfer port injection time shorter than the real time that the transfer ports are open and at 12.5k that is about 1.5ms.

Transfer port injection has the potential to clean up the 2T's emissions as the first lot of purging air can be sent through with little fuel in it but if I can't get it to work on my bike above 8-9k rpm I will have to go to inlet injection and aim to get a more homogeneous fuel mixture in the crankcase just like a carburetor does.

Fuel in equals Pressure and duration can your pressure not be bumped up? before you give up on transfer injection.

[Frits Overmars]

Fuel in equals Pressure and duration.You wish. Raising the pressure may raise the fuel amount but the relationship is far from linear and above a certain pressure quotient it's simply not true at all.

[husaberg]

You wish. Raising the pressure may raise the fuel amount but the relationship is far from linear and above a certain pressure quotient it's simply not true at all.

I do wish everything was simple.... Frits but from memory Rob is only at 40 psi so would be pretty near the bottom of the curve.
I actually used to design the odd water reticulation systems so I know pressure isn't a get out of jail free card.

[wobbly]

The ETEC system is insanely clever technology and would easily keep up with the fuelling requirements of a racing 2T.
Its voice coil driven pump/injector enables stratified charge completely controlled as to timing and volume, but the issue is that its locked into a very
robust patent,and the owners want a fortune for the rights to use it.
Running on the big Rotax engines the mechanical/electrical system is hardly stressed at all, its dead reliable and enables those powerplants to completely kick any 4T
off the planet as far as light weight,fuel efficiency and emissions compliance are concerned.
It really is the silver bullet for 2T domination, but this simply wont happen while the technology is locked up.
The air over fuel systems are another step forward for direct injection, and that is also patented, but cant compete with ETEC for simplicity and pin point fuel control.
Evinrudes big 2T outboards are now considered the benchmark in every measurable category you can think of, so the swing has already begun,but whilst the technology
is strongly protected from general ( read cheap ) everyday use, we simply wont see 2Ts overunning the streets of Bejing any time soon.

[Ocean1]

You wish. Raising the pressure may raise the fuel amount but the relationship is far from linear and above a certain pressure quotient it's simply not true at all.

And Husa's example has reminded me that the relationship between flow and orifice size isn't linear either, double the size and you get roughly 4 times the flow at the same pressure.

More injectors.

[peewee]

hi guys on my piston underside its turning black. is this normal on a good tune or does it suggest a problem like stinger diam too small causing overheating of the piston ?

[pete376403]

"You can raise an engines compression ratio until the varnish ... underside of the piston crown turns as black as a race officials heart and if you've done everything else right you down have to worry until the varnish begins to char. That's the danger point" - Gordon Jennings
http://homepage3.nifty.com/penta2/bike/doc/race_preparation.pdf

[TZ350]

http://publications.lib.chalmers.se/records/fulltext/149154.pdf

A Masters Thesis on 2T direct injection. Evenrude Outboard.

[peewee]

"You can raise an engines compression ratio until the varnish ... underside of the piston crown turns as black as a race officials heart and if you've done everything else right you down have to worry until the varnish begins to char. That's the danger point" - Gordon Jennings
http://homepage3.nifty.com/penta2/bike/doc/race_preparation.pdf

compression ratio is moderate. noticed black on pistons with 2 different cylinders and heads using the same pipe. so if there is a problem im thinking it may be stinger diam holding in too much heat. im not even sure theres a problem though. do any of you guys get black undersides ?

[F5 Dave]

Heck yeah
.

[Flettner]

I like my pistons well done also.

[Frits Overmars]

German MotoGP live http://cricfree.eu/bt-sport-1.php

[wobbly]

My experience is that the higher the state of tune ie bmep, and the better the actual tuning is ie optimum advance and no more, the less the crown
darkens on the underside.
Running low bmep setup like say a TZ350, needs plenty of advance, as the dynamic com, even with very high static com, is low due to the compromised transfer and inlet ducts.
Thus running plenty of advance heats the piston during the expansion phase, and the crown gets hot enough to burn on the oil.
When you have a very high state of tune, with plenty of dynamic com being developed and have advances such as head inserts with plenty of water around the plug threads,
the piston crown doesnt see enough temp for long enough, as alot more of the fuel energy converted to heat release, is used to raise the gas pressure early in the cycle.
Then you have the case of KZ2 kart engines with straight line ignitions, and these put plenty of heat into the crown due to the excessive advance at high rpm.

[TerraRoot]

The ETEC system is insanely clever technology and would easily keep up with the fuelling requirements of a racing 2T.
Its voice coil driven pump/injector enables stratified charge completely controlled as to timing and volume, but the issue is that its locked into a very
robust patent,and the owners want a fortune for the rights to use it.
Running on the big Rotax engines the mechanical/electrical system is hardly stressed at all, its dead reliable and enables those powerplants to completely kick any 4T
off the planet as far as light weight,fuel efficiency and emissions compliance are concerned.
It really is the silver bullet for 2T domination, but this simply wont happen while the technology is locked up.
The air over fuel systems are another step forward for direct injection, and that is also patented, but cant compete with ETEC for simplicity and pin point fuel control.
Evinrudes big 2T outboards are now considered the benchmark in every measurable category you can think of, so the swing has already begun,but whilst the technology
is strongly protected from general ( read cheap ) everyday use, we simply wont see 2Ts overunning the streets of Bejing any time soon.

i feel your patent pain

[Flettner]

The uniflow scavenge system neatly accomodates cylinder filling with no fuel over spill, without electronic injection, or patent issues. Has been shown to work.

[wobbly]

Yea Flett, an Iron Horse " works " as well.

[Flettner]

But no where as well as a uniflow scavange engine. Where has there been any real study on the two piston, one cylinder, crank case pumped type engine?
Split singles don't count as they do have efficency issues.

[TZ350]

... Iron Horse ...

299220

Iron Horse ...

[lodgernz]

The wisdom on squish bands, if I understand it correctly from this forum, is that the area thereof should be 50% of the bore area.
My question for Frits or Wobbly, or anyone who knows these things is: Does this apply to small engines? I'm thinking of a 39mm bore 50, where I'm wondering if a 50% squish band might mean having quite a deep combustion space to avoid dangerously high compression ratio.
I'd appreciate any guidance on this.

[speedpro]

To be clear, the 50% figure is area, not diameter. Either way the chamber shape should be the same just scaled up or down depending on the size of the engine.

[Frits Overmars]

the chamber shape should be the same just scaled up or down depending on the size of the engine.I wanted to approve by just writing '+1' but the forum software reacted with:
"The message you have entered is too short. Please lengthen your message to at least 10 characters."
Well, that has been fixed now:shifty:.

[lodgernz]

Thank you Speedpro and Frits. Just what I wanted to hear.

[F5 Dave]

Which means it will be quite shallow to get the compression usefully high, which will depend upon which path you choose gas and ignition wise. Welcome to pop over and look at the 50 head- Roger I assume ?

[ken seeber]

Plus 1 for an interesting topic. Questions:

If the 50% rule is the go, then why do KZs come with heads that have squish bands of around 35% the area?

Is there something else going on?

Has anyone tried a 50% squish area in a KZ?

[wobbly]

I detailed everything you need to know about a KZ2 head design back a few pages, experience gained from literally hundreds of dyno runs.
The straight line ignition completely changes EVERYTHING you ever thought was correct in a 2T combustion chamber.
Running 16* at 9000 is 10* not enough, running 16* at 14000 is 10* too much,the chamber needed to deal with the deto caused by this, along with the shit
pump gas we are forced to use, throws all the squish theory out the window..

[lodgernz]

Which means it will be quite shallow to get the compression usefully high, which will depend upon which path you choose gas and ignition wise. Welcome to pop over and look at the 50 head- Roger I assume ?
Yes Dave, you've rumbled me. I'll call you, I have your number.

[TZ350]

If the 50% rule is the go, then why do KZs come with heads that have squish bands of around 35% the area?Is there something else going on? Has anyone tried a 50% squish area in a KZ?
I detailed everything you need to know about a KZ2 head design back a few pages, experience gained from literally hundreds of dyno runs.

It can be hard to find previous stuff so hopefully this link goes back to the start of the KZ2 head posts.


... easy question to answer.....

Follow the link back, others that will be on the following pages.

[SwePatrick]

It is looking like the moral of the story is to keep the transfer port injection time shorter than the real time that the transfer ports are open and at 12.5k that is about 1.5ms.

Transfer port injection has the potential to clean up the 2T's emissions as the first lot of purging air can be sent through with little fuel in it but if I can't get it to work on my bike above 8-9k rpm I will have to go to inlet injection and aim to get a more homogeneous fuel mixture in the crankcase just like a carburetor does.


You got one more problem at hand.
Due to reguested fuel amount you need big injectors, big injectors have longer 'deadtime', the time for opening the injector(time from pulse start, to when the injector acually flows any fuel)
Example, Bosch '465cc' injectors hav about 0.8ms of deadtime, that is about half of the time you got to inject it in.
so with simple calculation,, if you need 465cc, then you have to double the injectorflow or put two as the half actual time to squirt flow is occupied with 'deadtime'.
You can also go with bigger injectors.. but those tend to be more unstable at low openingtimes.
And not to settle with this, the deadtime varies with voltage and fuelpressure,,,,,and bonusproblem!!: backpressure! (crankhouse compression)

[Flettner]

On my Kawasaki I used a "sampler valve", solinoid with the same coil size as the injector that allowed the crank case to only be connected to the computer as the injectors were opperating.

You are talking about adding an extra injector at the inlet for over 8 / 9000 rpm?

[TZ350]

Due to requested fuel amount you need big injectors, big injectors have longer 'deadtime', the time for opening the injector(time from pulse start, to when the injector actually flows any fuel)Example, Bosch '465cc' injectors hav about 0.8ms of deadtime, that is about half of the time you got to inject it in.

Thanks for your tip SwePatrick, I have drawn myself a picture so I can visualize it.

For 12,500 rpm and a duration of 130 deg the transfers are open for 1.73ms (orange area)

The injectors I have are rated at 1ms to open and 0.5ms to close (dead time or at least poorly controlled fuel squirt, dark green area)

The 0-5ms close time can all happen after the transfers have closed. The 1ms can start before port opening.

299252

In initial runs with these injectors I have found the minimin useful pulse width (not including close time) is 1ms, so maybe not much but the start does inject some fuel.

Now the opening time can start before the transfer opens and the close time after so that leaves me a clear 1.5 to 1.7ms of full on injection time.

The start point can be early but it looks as if the timing of the injection end point is going to become critical if we are going to get the bulk of the injection happening towards the end of the transfer event.

Now to work out what the injection pulse width might be.

Base Engine Data

125cc or 0.125 l cylinder capacity
Weight of air at STP 1.275 g/l
Max 13,000 Rpm
120% VE from EngMod2T's delivery ratio simulation.
12:1 air fuel ratio.
Injector 1 is 80 g/min
Injector 2 is 496 g/min (actually two 248 units)
130 deg Transfer duration.

Calculations

Injectors ability
130 / 360 = 0.36 transfers are open 36% of the time.
(80 + 496) * 0.36 = 207 g/min possible while transfers are open.
207 / 60 = 3.45 g/sec.
3.45 / 1000 = 3.45 mg/ms

Fuel Requirements
13,000 * 0.125 = 1625 * 1.2 = 1,950 l/min of air
1,950 * 1.275 = 2,486 g/min of air
2,486 / 12 = 207 g/min of fuel.
207 / 60 = 3.45 g/sec.
3.45 / 1000 = 3.45 mg/ms

Time
13,000 / 60 = 217 rpm/sec
217 * 360 = 78,000 deg/sec
78,000 / 1000 = 78 deg/ms
130 / 78 = 1.7 ms available to deliver 3.45 mg

By luck the Injectors ability to deliver 3.45 mg/sec is just what the engine needs so in theory 1ms of full on injection time is all that is required and there is 1.7 ms available to get it done in.

So in theory I think its possible, but timing is going to be the real challenge.

[Frits Overmars]

Transfers 130 deg duration....130/360 = 0.36 transfers are open 36% of the time.Seems to me that "transfers are open 36% of the time" is a very generous definition of 'open'.
The transfers need some time to build up a decent open area just like the injectors do.

[TZ350]

Seems to me that "transfers are open 36% of the time" is a very generous definition of 'open'.
The transfers need some time to build up a decent open area just like the injectors do.

Yes true, good point and there will be other issues like the transfer flow stalling when there is insufficient blow down time, so not that straight forward. But not obviously impossible yet, just difficult.

[richban]

Hi Guys

In the constant quest for power on the NSR300's we are developing, We are now using and looking into ram air setups.

We have a proper NSR F3 box that is working well. It is massive. The volume has not been measured but I would guess almost 20 litres. Maybe more.

Frits / Wob I have a couple of questions if you don't mind.
Number one is. How big does it need to be. I can replicate the HRC one for my bike but it does make working on the bike a little bit of a pain. Also its not fully inclosed. It pushes up against the bottom of the tank. And looks like it could leak with vibration and movement of the rider pushing on the tank.

I was thinking of making one the connects to the bell mouths and is fully enclosed with no chance of leaking. But how do I figure out how big to make it?

Is there some rule of thumb that needs to be applied. 300cc / 11500rpm / 85hp = ??? litre box?. From playing around with 4 stroke airboxes / plenums its can really rob power when it is wrong. Usually to small form my experience.

Also i suppose the sooner the positive pressure is there the sooner the power increases. I wonder if this will work on a bucket. Maybe not on a Kart track but it could work on a big tack. Max speed on the bike would be close to 150 160 kph.

Also the intake leading edge on the faring is very important. As has been discovered.

Anyhow, not sure this has been covered lately. Thanks Rich.

[Frits Overmars]

You can hardly make the airbox volume too big; certainly not within the restrictions of a bike.
If you connect the airbox to the bellmouth, the carb hangs out in the open which will create all sorts of complications. Put the whole carb in the airbox.
At 160 kmh you may get about 10 mbar overpressure; that's just one percent of ambient pressure but it is enough to push the fuel down the emulsion tube, unless the pressure in the carb and the pressure in the fuel tank keep up with the airbox pressure. That is why you need a large breather hose between the airbox and the fuel tank (Or a pump. Or injection).
Is an airbox on a bucket worth bothering? Definitely, but not so much because of that 1% ram-air pressure; its main purpose should be to feed cold air to the carb.

[wobbly]

I would have thought 260Km/Hr , Trevs TZ350 was doing 232 at Hampton during the Sheene Challenge.
And Frits is right as usual, the Helmholts resonant frequency of the box vol and the intake length/area means that basically the bigger the box the better it works within
the forcing frequency range of the carb inlets.
The inlet from the front must be a divergent duct, to use the inlet flows decreasing velocity to increase the pressure, along with the velocity pressure of the air at the front of the bike.

[richban]

You can hardly make the airbox volume too big; certainly not within the restrictions of a bike.
If you connect the airbox to the bellmouth, the carb hangs out in the open which will create all sorts of complications. Put the whole carb in the airbox.
At 160 kmh you may get about 10 mbar overpressure; that's just one percent of ambient pressure but it is enough to push the fuel down the emulsion tube, unless the pressure in the carb and the pressure in the fuel tank keep up with the airbox pressure. That is why you need a large breather hose between the airbox and the fuel tank (Or a pump. Or injection).
Is an airbox on a bucket worth bothering? Definitely, but not so much because of that 1% ram-air pressure; its main purpose should be to feed cold air to the carb.


Nice one. Thanks Guys.

The bike running the ram air really starts to pull hard from WOT in 4th to the upper gears. However fast that is. We think its worth 5hp at the top.

Ok so I will replicate Mr hondas design. Nice one on the divergent duct. I was thinking the the other way around, as is so often the case.



Thanks again.

[Neal]

Rich , I use the soft adhesive foam to seal my tank against the air box . You can also put 2 small pieces on either side of the tank where the air box does not sit to help stabilise the tank on the frame . The air box helps , check the breather on the fuel cap ! And seal the cap as tank pressure is lost there

[lodgernz]

Rich, don't forget to also pressurise the float bowl, and block any breathers to it.

[Neal]

The ram air box for the nsr has the carbs inside it so they become pressurised , the breather for the tank gets in closed on the underside of the tank by the air box so all good there too . You just have to jiggle the powervalve cables and all good

[richban]

The ram air box for the nsr has the carbs inside it so they become pressurised , the breather for the tank gets in closed on the underside of the tank by the air box so all good there too . You just have to jiggle the powervalve cables and all good

Yeah quite a good setup. Seams to work really well.

[TZ350]

The transfers need some time to build up a decent open area just like the injectors do.

Graph of Transfer mas flow simulated using EngMod2T.

299283

I see what you mean, not only do the Transfer streams need a little time to get moving they can reverse before the port closes.

Because the engine is making good power here (peak torque 12,250 rpm) my guess is this reversal is because the cylinder is being pressurized by the rising piston and plugging pulse from the pipe.

The horizontal lines represent 1ms at the different rpm.

[Yow Ling]

the streams can also reverse when the port opens. I read here or somewhere the first port to open is the last port to flow, to do with blowdown.

[TZ350]

the streams can also reverse when the port opens. I read here or somewhere the first port to open is the last port to flow, to do with blowdown.

299286

Yes your right and I think residual pressure in the cylinder from insufficient blow down will show up here on the transfer port opening side of the graph.

[F5 Dave]

Perhaps you could reduce the reverse flow at the start of the phase by countering it with a larger pressure in the cases. Perhaps mount a sparkplug in there:msn-wink:

[Frits Overmars]

...not only do the Transfer streams need a little time to get moving they can reverse before the port closes.
Because the engine is making good power here (peak torque 12,250 rpm) my guess is this reversal is because the cylinder is being pressurized by the rising piston and plugging pulse from the pipe.There's more to this than meets the eye. The piston is playing a double role: it pressurizes the cylinder and at the same time depressurizes the crankcase.
But even if the piston didn't move at all, there will be flow reversal if the transfers do not close at the right moment. It's a Helmholtz thing: gas flows from one vessel to another, the pressure difference will change sign, and the flow will slow down and reverse.
This is even more striking in the inlet system. The inlet port pops open, the inlet flow will fill the crankcase and at low revs it may reverse direction while the piston is still moving upward!

[TZ350]

There's more to this than meets the eye. The piston is playing a double role:

There is nothing simple about this :facepalm: why can't it be easy.

I don't want much, all I want to do, is squirt just a little bit of fuel 210 times a second, how hard can it be????.

[Flettner]

Link has a new manager ( used to road race twostrokes ) so the twostroke side of their software has been fixed now! Great, just need the right people in the right places. He is interested in our injection projects.

[wobbly]

All 2Ts have some flow reversal when the transfers open, as the residual blowdown pressure is greater than the pressure in the case.
Bulk flow doesnt occur till closer to BDC if the pipe is correctly designed, and the diffuser depression holds the Ex port below atmospheric long enough
to promote a differential across the open transfers.
I discovered the flow reversal, and the idea that the port to open first/flows last when I first Beta tested the Dynamation 2T code done by Kurt Leaverton of HotRods fame.
You can see the pressure rise in the transfers, when they crack open, in the running screen of EngMod - see the sample screendump where the green transfer line jumps up at EPO.

[peewee]

I discovered the flow reversal, and the idea that the port to open first/flows last .

wasnt there some ASE papers suggesting the same thing ? thats what i heard anyways. havent seen the papers for myself however. ive opened the A ports first on engines. may of done more harm than good but i dont know. but if your statement is correct wouldnt it make more sense to open the B first ?

while im thinking of it, on a reed cage, do the petals actually open all the way and hit the metal stoppers ? engmod is saying goodnews if i can open the petals 2mm more. ive found a way to open them 1.5mm more and might try it. basically where the stoppers bolt on the cage ill just use a spacer between the stopper and petal which will lift the stopper and allow the petal to open farther. but if the petals dont even open to the stoppers in the first place, then it would be useless to bother with this idea. ya it would be easy to test if i had a dyno but i dont have one

[peewee]

i may have answered my own question. looked at the old stopper and seen significant wear about half way to the end. only very minor wear at the end. so the petals may not be getting completely forced against the full radius of the stopper but theyre definatly contacting the stopper at the half way point with a quit a bit of force it seems. so my idea should work if i lift the stopper 1.5mm it will allow the petals to open farther. and theyre .5mm boyesen fiber resin material so theyre rather flexible. what do you guys think ?


http://i1081.photobucket.com/albums/j357/doddledo/IMG_20140718_1940211_zpse8677beb.jpg

[wobbly]

Perfectly correct, Jan Thiels setup in the Aprilia engines does exactly that - open the B first.
The B is wider than the A as well, and the lower A port helps to reduce the direct short circuiting upwards into the Aux Ex ports.
This layout maximises the available transfer port STA and is great for peak power at high rpm levels.
The usual reverse stagger as seen in Honda T port engines, with the A port the highest, works better in the 3 port layout when you are looking for wider power bandwidth.
Best example would be the KZ2 kart engines, as with no power valve, and the need to be able to pull hard from around 9000 to 14000 + this layout gives better
bottom end and overev power, at the expense of outright peak.
I have dyno tested high B port KZ2 engines, and been just over 50 Hp at the sprocket, but no matter what I tried with pipe length and ignition advance I could never generate
enough power down at 9000.
So although the cylinder was very fast in outright terminal speed, it lost too much off every slower corner, fine as a qualifying engine but no good diving under someone entering
a corner - as it simply would not pull out hard enough when on the "wrong " line.

[peewee]

so whats most everyones preference around here ? open A first, B first or all at the same time ?

[F5 Dave]

I think Wob was giving you a choice to make and the reasons to make it.. Reed bends most in middle so will rub most where you show it so I don't think you've proved it isn't fully opening.

[wobbly]

Spacing the stopper away from the reed will in a way "work" but if the reed is hitting the plate too early then hardly touching at its end,
then that means the stopper radius is too tight.
You need too decrease the bend radius so that the middle of it isnt overbending the petal at full lift.

Normal and reverse transfer stagger both have their place, as I have explained.
Opening them all together was last used by Yamaha in GP racing prior to the end of the 90s when they then bought themselves a CNC anemometric flow machine.
Suddenly they changed to square bore/stroke and staggered transfers, obviously a big deal in swallowing corporate pride - following Honda and everyone else.
This sea change saw the 250 twin win 1st and 2nd ( Jaques and Nakano )in the title for the first time in an age ,with a hugely superior package at the time.
There was then and still is now, no technical advantage whatsoever to concurrent transfer openings.

[peewee]

i think your right. the petal contacts the center of the stopper and then bends upward as it continues its range of movement. thats what seems to be happening anyways from examining the wear marks on the stopper

about the port staggering, i understand what wobbly is saying. ive heard other people say opening A first can broaden the bandwidth. so i believe it to be true. ive tried it myself but had no way to test it other than seat of the pants, which is useless most of the time.

[TZ350]

Its not all about horse power.

299295

Ran a bike up on the dyno today and the conversation got onto tyre warmers and whether they should be banned from Bucket racing to keep the costs down and the playing field level and less daunting for people wanting to get involved in the sport.

At Mt Wellington, before gridding up the bikes are left to circulate for quite a few laps so that hopefully everything is properly up to working temperature.

Typically the tyres are run under inflated here (usually 16-18 psi cold) to get heat into them and the colder the day the more under inflated they are and I guess this practice is much the same on all the smaller tracks.

Anyway the Dyno conversation got onto tyre warmers because both tyres of the current lap record holder were showing an unusual wear pattern and the owner had emailed this picture of the rear tyre to the supplier to find out why.

299296

The Reply:- "Cold Tearing: The surface is overheating. Pressures need to be increased, try 25 rear 23 front and see what its like. Warmers will help heaps. Without them the surface gets hot but the carcass does not, overheated surface and cold carcase causes these tearing type ripples to occur."

So I did a bit of looking on the net and found one of the main points of tyre warmers is to get the carcase up to temperature and to be able to accurately set the "Hot" tyre pressure and thereby optimize the handling available from predictable tyre grip.

This looks like a much better way to optimize race long tyre grip and handling than running the tyres half flat and hope and pray you guessed at the correct cold tyre pressure for when its hot and that the under inflated carcase will flex enough to get the tyre up to working temperature and not overheat.

I think everyone agrees that hp is only part of the story and that after a certain point improvements in handling pays ever increasing dividends.

And with the pointy end of F4 getting so competitive and consequently setup and handling is becoming very important. I expect we will see more people who have already optimized the weight distribution, suspension and other handling aspects of their bikes moving on to getting the best out of their tyres too.

I don't care one way or the other myself about tyre warmers but after reading the stuff I scraped of the net I am becoming more open minded about people using tyre warmers to improve the potential and safety of their bikes.

Scraped this stuff of the net:-

299297

Set your optimum HOT Tyre Pressures in the Pits
Tyres will increase in pressure by about 20% on the track (e.g. increase from, let's say, 30 to 36 psi) which makes a huge handling difference. CHR Tyre Warmers will get your tyres’ surface AND carcass into the proper temperature range (the same as you’ll see on the track). Without Tyre Warmers 6-8 laps would be needed to get a tyre to its proper "hot pressure".

If you pre-set your Tyre Warmers to the optimum temperature you anticipate seeing on the track, then allow your tyres to "heat-soak" for an hour and then set the Hot Pressure, when you hit the track, there will be minimal pressure change - meaning your grip and handling will remain much more consistent.

Many of the current race compound tyres are "low pressure" tyres with psi recommendations of around 22-24 psi. These tyres are much more sensitive about needing to be at their hot pressure before they work properly.

Avoid "Cold Tearing" of your tyres. Taking a tyre at ambient temperature (i.e. 20-25 degrees) and carefully pushing it hard on the track to warm it up will undoubtedly increase the very outer surface temperature of the rubber in a couple of laps. However, the rubber 2-3 mm down from the surface will not yet be warm and not be as elastic and this causes the outer rubber to grip the track surface and underlying rubber to rip or tear away from it. This shredded look or graining once developed in the tyre almost never goes away and basically ruins the tyre’s surface - thus reducing grip. By pre-heating the rubber, cold tearing is - quite simply - avoided.

Taking tyres from ambient temperature and bringing them up to race temperature on the track may take from 3-6 minutes depending on the machine, track and rider. Aside from giving up speed during these opening laps, it is truly too fast to heat the tyre in an ideal manner. For example on a 25 degree day, the rider may get the tyre surface hot in, let’s say, 4 laps which typically takes 6 minutes. This increase of 100 degrees in such a short amount of time actually "heat shocks" the tyre. Race compound tyres contain "activator" chemicals in them which are set into motion with heat. Getting your tyre hot too quickly actually spends or wastes some of the chemicals and tyres will lose grip sooner than if warmed slowly on a warmer.

Avoid the damage caused by overheating your Tyres. Tyre makers are increasingly providing the specific maximum temperature their individual tyres should be heated to (different tyres from the same maker can need different temperatures). Also, specifically, intermediate or wet tyres require lower temperatures so being able to use the maker's exact recommendation is an important benefit of a higher-spec warmer and can avoid the inadvertent overheating which can completely ruin a tyre over a relatively short period.

When tyres are heated & then cooled - i.e. “Cycled” a change occurs that can often be seen, measured and felt. On some tyres you will actually see a blue haze form over its surface as some "oils" migrate to the outside and oxidation occurs. On other tyre compounds you may observe a much drier grayish haze depending on individual tyre composition. Either way, each time a tyre is put though these hot-to-cold cycles the tyre’s grip reduces as the rubber hardens at the end of each cooling cycle and the useful life of the tyre reduces too.

[marsheng]

Kr150 Pistons.

I've done some digging around but I can't seem to find any supplier of pistons. One place has 0.25 0.5 mm etc over bores but this is a nicasil bore so I'm not sure what bike that is . I need to use either a standard piston or a B or C if they make them that way.

Cheers Wallace

[Neal]

Kr150 pistons ? 59 bore and 15mm gudgeon pin ? Look at the tyga 300 pistons

[peewee]

anybody run their engine on methanol ? looking for setup and tuning advice if i add a splash of nitro in with it :laugh:

right now im using 100% methanol. pingel fuel valve, 48mm lectron with 2 powerjets, mikuni 65L/hour pump

[Grumph]

anybody run their engine on methanol ? looking for setup and tuning advice if i add a splash of nitro in with it :laugh:

right now im using 100% methanol. pingel fuel valve, 48mm lectron with 2 powerjets, mikuni 65L/hour pump

80/20 Methanol/Toluene was a very good base mix back in the day - on 4 strokes, you could run 20% Nitro,80% meth/tol base and get very good running characteristics - and good fuel life too. Bonus was approx 20% better fuel economy over straight Methanol - Not when adding Nitro obviously....

When varying the mix for 2 strokes, we found that using the meth/tol mix as a base, dissolve the oil - synthetic castor - in benzole of a quantity such to give a final mixture 80% base (meth/tol) and 20% benzole/oil. takes a bit of calculation but it is a very nice mix which starts easily and tunes readily. Never ran nitro in the 2 strokes sorry....

[richban]

Its not all about horse power.

299295

Ran a bike up on the dyno today and the conversation got onto tyre warmers and whether they should be banned from Bucket racing to keep the costs down and the playing field level and less daunting for people wanting to get involved in the sport.

At Mt Wellington, before gridding up the bikes are left to circulate for quite a few laps so that hopefully everything is properly up to working temperature.

Typically the tyres are run under inflated here (usually 16-18 psi cold) to get heat into them and the colder the day the more under inflated they are and I guess this practice is much the same on all the smaller tracks.

Anyway the Dyno conversation got onto tyre warmers because both tyres of the current lap record holder were showing an unusual wear pattern and the owner had emailed this picture of the rear tyre to the supplier to find out why.

299296




Yeah warmers are a good thing for sure. But! With bucket bikes especially its the spring rate that messes up your rubber. I have killed a rather good tyre in 10 laps on a hot day. The rear spring was way out. The one time I ran my bike at Mt wellington the cold tyre pressures were 26 front -27 rear. No issues with grip. Bridgstone's that is. Dunlop's don't seam to be as fussy and can be run quite low. When I ran the Bridgstones with low pressure they felt spongy on max lean.

It is so hard to get any real heat into the tyre as they are never really worked enough to get hot. If you ran warmers at 80c on a bucket bike running on a Kart track, I reckon they would come in 20 to 30 deg cooler. But you might win the warm up lap.;)

[F5 Dave]

Power is a bit of an issue at most tracks we use. Groan, people running generators. Nah, let's not go there.

[peewee]

Never ran nitro in the 2 strokes sorry....

ive only found 1 person to try nitro in a full size 2t engine but he couldnt get it to run well so he gave up. must be a secret to it

[koba]

When I ran the Bridgstones with low pressure they felt spongy on max lean.


I noticed that too, pretty sure the Dunnie's are stiffer.

You and Fish are the only people down our way that I have noticed a bad tyre wear issue.
Both of you guys made rear suspension changes with good results.

I'm yet to see any tangible scientific evidence of an improvement from using warmers, when I've raced in classes that used them I have gone without and still done most of my passing in turn one!


Power is a bit of an issue at most tracks we use. Groan, people running generators. Nah, let's not go there.

I'm totally keen to keep warmers out, keen enough to consider a rule submission...

TZ, are those things actually plugged in?
Or is that just a wind up?

[Henk]

I'm totally keen to keep warmers out, keen enough to consider a rule submission...

TZ, are those things actually plugged in?
Or is that just a wind up?

Plugged in with a generator around the corner.
Keen to have none of this carry on, noisy enough at the track as it is.

[Gigglebutton]

I think if it makes the tires work as they should do, it cant be a bad thing, for the guys at the front of A grade. It would possibly make things a bit safer for them to have a more predictable tire.
You should get longer use from your slick as well, as they would only go through one heat cycle in a days racing if kept warm. This could make for cheaper racing.
Why ban them, when the guys that are using them are not wasting the whole field.

[Sketchy_Racer]

Yep flag warmers, generators are the biggest pain in the ass at a track.

If you're tearing up tires on a bucket then you have something really really wrong. So either fix that (whether it be spring rate or geometry) or do the lazy fix and put some medium compound tires on.

Back to 2t tuning. I've recently had to make some replacement head inserts for an air cooled. The original plan for the head was to get it welded then machined back to a modern combustion chamber but the welding went bad so the bloke before me made inserts for the head, great apart from the thermal issues.

Now the interesting this was that the inserts had over a 75% squish area and a 4.2cc head on a 124.9cc cylinder.... I dont know how or why but just wow!

So i've had to stick to the inserts but now it has a 50% squish area and a 10.3cc volume. I have machined a taper for them to pull up on to try and maximise the contact pressure to aid with thermal transfer. I will also be using some thermal transfer paste that is good to 400*c so hoping to recover as much as possible.

Here's hoping!!

[TZ350]

TZ, are those things actually plugged in? Or is that just a wind up?

Plugged into a generator, seen warmers on Buckets at Taupo recently too, so a few people are starting to use them.

[TZ350]

299313

Got my 50 going tonight, as F5Dave predicted the angle was to steep for the Mikuni carb so I fitted the old pumper that I used on the Beast. It works a treat.

299314

Well 7hp so not much of a threat to the front runners or anybody else really.

Still it gives me my own bike to ride in F5.

[husaberg]

Yep flag warmers, generators are the biggest pain in the ass at a track.

If you're tearing up tires on a bucket then you have something really really wrong. So either fix that (whether it be spring rate or geometry) or do the lazy fix and put some medium compound tires on.

Back to 2t tuning. I've recently had to make some replacement head inserts for an air cooled. The original plan for the head was to get it welded then machined back to a modern combustion chamber but the welding went bad so the bloke before me made inserts for the head, great apart from the thermal issues.

Now the interesting this was that the inserts had over a 75% squish area and a 4.2cc head on a 124.9cc cylinder.... I dont know how or why but just wow!

So i've had to stick to the inserts but now it has a 50% squish area and a 10.3cc volume. I have machined a taper for them to pull up on to try and maximise the contact pressure to aid with thermal transfer. I will also be using some thermal transfer paste that is good to 400*c so hoping to recover as much as possible.

Here's hoping!!

Seen this the other day I am not sure where............

[Grumph]

Yeah warmers are a good thing for sure. But! With bucket bikes especially its the spring rate that messes up your rubber. I have killed a rather good tyre in 10 laps on a hot day. The rear spring was way out. The one time I ran my bike at Mt wellington the cold tyre pressures were 26 front -27 rear. No issues with grip. Bridgstone's that is. Dunlop's don't seam to be as fussy and can be run quite low. When I ran the Bridgstones with low pressure they felt spongy on max lean.

It is so hard to get any real heat into the tyre as they are never really worked enough to get hot. If you ran warmers at 80c on a bucket bike running on a Kart track, I reckon they would come in 20 to 30 deg cooler. But you might win the warm up lap.;)

Slightly different on the big tracks, Rich. Warmers in the winter series - and at Levels up to Xmas.... make sense to extend tyre life.
I hate the bloody generators too but pretty well all the big track meetings are shared with classes who use them so it's noisy anyway.

Those of you coming down for the BoB and going to greymouth should know that tyre warmers have been seen in use on riders at greymouth.....cold and usually bloody wet too.

[husaberg]

Slightly different on the big tracks, Rich. Warmers in the winter series - and at Levels up to Xmas.... make sense to extend tyre life.
I hate the bloody generators too but pretty well all the big track meetings are shared with classes who use them so it's noisy anyway.

Those of you coming down for the BoB and going to greymouth should know that tyre warmers have been seen in use on riders at greymouth.....cold and usually bloody wet too.
Tyre warmers are kind of useful in Greymouth as it only has one left hand corner.
I call BS on the Rain Grumph its only like rained all day 4 times or so in 20 years.....

[Frits Overmars]

..the inserts had over a 75% squish area and a 4.2cc head on a 124.9cc cylinder.... I dont know how or why but just wow! Wow indeed. (124.9 + 4.2) / 4.2 = a compression ratio of 30.7. Ever considered diesel fuel?

[wobbly]

That air cooled would have blown to pieces even on Methanol with that sort of com - insane.
I mentioned awhile ago a project I was doing for the Webco type RD series of heads, 250,350,400
The prototype has just been cut on the CNC, so I could be able to supply blanks, or a special design with precut toroidal chamber, quite soon.

[Grumph]

That air cooled would have blown to pieces even on Methanol with that sort of com - insane.
I mentioned awhile ago a project I was doing for the Webco type RD series of heads, 250,350,400
The prototype has just been cut on the CNC, so I could be able to supply blanks, or a special design with precut toroidal chamber, quite soon.

I'd be interested in a blank when they become available.

[tdc211]

[/QUOTE]Wobbly

With the reverse stagger giving better transfer area ( as the B,C ports being high with alot of width compared to the previously high A port ) the engine now made 2 Hp or more than the factory trick cylinder
but was now 8 Hp up at 14000 and gained 400 rpm of usable overev, as previously it dropped dead at 13800 on track.
This setup proved to be quite insensitive to jetting and timing changes, allowing alot more static advance giving much better off corner power without killing revs as this would normally do.
Thus the enhanced blowdown flow of the radius at low port openings,allowed those much lower timings to be used effectively, enhancing power everywhere, but most importantly in the overev,where blowdown is most needed.

[QUOTE] Wobbly

Perfectly correct, Jan Thiels setup in the Aprilia engines does exactly that - open the B first.
The B is wider than the A as well, and the lower A port helps to reduce the direct short circuiting upwards into the Aux Ex ports.
This layout maximises the available transfer port STA and is great for peak power at high rpm levels.
The usual reverse stagger as seen in Honda T port engines, with the A port the highest, works better in the 3 port layout when you are looking for wider power bandwidth.
Best example would be the KZ2 kart engines, as with no power valve, and the need to be able to pull hard from around 9000 to 14000 + this layout gives better
bottom end and overev power, at the expense of outright peak.
I have dyno tested high B port KZ2 engines, and been just over 50 Hp at the sprocket, but no matter what I tried with pipe length and ignition advance I could never generate
enough power down at 9000.
So although the cylinder was very fast in outright terminal speed, it lost too much off every slower corner, fine as a qualifying engine but no good diving under someone entering
a corner - as it simply would not pull out hard enough when on the "wrong " line.



I would imagine port stagger completly depends if your valved and what port timings ,ign you have to work with?
Or do the higher A ports still give a better off the corner drive?

[wobbly]

The high A port setup works well with no powervalve as its inherent characteristic is to give a wider ( though lower peak ) powerband.
Same issue with the KZ2 straight line ignition, with not enough advance in the bottom end, and way too much in the overev, this is again offset by the high A port stagger arrangement.
This works in cylinders such as the 8 port aftermarket Banshee things with no powervalve as well - but for outright top end the reverse staggered low A port gives a big boost
if you are fixated on ( or want ) dyno peak numbers.
Having the A port high is hamstrung somewhat in that it limits what size you can go to with the Aux Ex ports, and of course it also increases short circuiting from the top of the A port
direct into the Aux, so as I said you choose what limitations you are up against and port accordingly.

[wobbly]

The high B port KZ2 engine won the Nationals here in 2013 and was insanely fast down the shute.
But this year I went thru all the testing again with the newest iteration of the TM - KZ10 .
This had the casting changed by the factory that allowed much bigger Aux Ex ports, and proved in the final analysis to generate more bottom end than I could drag out of the older engine, no matter what.
It won the title again this year, proving to be faster in outright power terms than the very best World Cup winning engines by SavTech from Europe, due in part to the extra
off corner response - also down to the perfect jetting combo on the day.
A super proud day for me and the team, making the pass for the lead at the end of the main straight with 3 to go after getting a way faster straight entry speed and carrying it in the draft.

[pete376403]

Wow indeed. (124.9 + 4.2) / 4.2 = a compression ratio of 30.7. Ever considered diesel fuel?

Two stroke? Isn't real (as opposed to calculated) CR only start from where the ex port closes? So the swept volume is going to be maybe half of the (bore x stroke) volume. So 15:1 sounds quite reasonable on meth, all my speedway bike motors (4stroke, but anyway) ran cr around that on meth

[lodgernz]

Has anybody successfully adapted a piston that had too big a gudgeon pin?
For example, using a piston with 14mm pin holes on a rod with a 12mm pin? Is a sleeve on each side of the piston a recipe for disaster?

[speedpro]

Has anybody successfully adapted a piston that had too big a gudgeon pin?
For example, using a piston with 14mm pin holes on a rod with a 12mm pin? Is a sleeve on each side of the piston a recipe for disaster?

Been there, done that. On a CB360 running GSXR1100 pistons. Ran for quite some time but resulted in obvious wear on the bushes.

[Sketchy_Racer]

For shits and giggles, here's a pic of the insert I was talking about, along with the new replacement. Only a slight change.... :msn-wink:

299361

299362

[Drew]

Two stroke? Isn't real (as opposed to calculated) CR only start from where the ex port closes? So the swept volume is going to be maybe half of the (bore x stroke) volume. So 15:1 sounds quite reasonable on meth, all my speedway bike motors (4stroke, but anyway) ran cr around that on meth

Someone please tell me if this is correct. I was under the impression that the exhaust chamber is primarily design to force mixture back into the combustion chamber through the exhaust port just as it closes.

Or do I have the very basics fucked up as well as the details?

[wobbly]

Just some basic facts for those who try and compare 2T with 4T tuning, then confuse everything by thinking you can mix and match effective with full stroke com.
Look at the point where an exhaust valve closes on a racing 4T, then calculate what the " effective " compression is.
You will find that using that formulae is about as useful as it is using the same idea in a 2T - ie not at all - even though the numbers are remarkably similar.
As most all " racing " 2Ts run in a very small range of Ex port closing timing numbers, the effective compression idea has no real useful purpose in my opinion.
No one uses effective com in the 4T racing community for a reason,there is no valid reason for doing so.
Full stroke compression is way easyer and quicker to calculate, and tons of empirical data has made the actual compression used for a particular fuel also very easy to hone in on.
15:1 full stroke compression is low for pump gas in a small bore 2T,and super low for any 2T motor running methanol, comparing that data to the effective or full stroke com in a 4T is totally irrelevant.

[wobbly]

Yea Drew ya got it 1/2 right.
There are 2 reasons for having a chamber.

1 - to suck the chrome off a tow ball when the piston approaches BDC.
2 - to pump mixture back in as the piston approaches EPC.

So as you are alluding to - with a heap of extra mixture being pushed into the combustion space as the piston rises, this totally invalidates ANY reason to
be using effective com as some sort of set in stone measure of a 2Ts performance characteristics.
The efficiency of the chamber and its interaction with the Ex port timing, throw up so many variables that no effective compression number can have any real meaning at all.
We finally found something you are good at - whew.

[F5 Dave]

Has anybody successfully adapted a piston that had too big a gudgeon pin?
For example, using a piston with 14mm pin holes on a rod with a 12mm pin? Is a sleeve on each side of the piston a recipe for disaster?

Someone in the very page helped me make some very nice sleeves to run YZ piston with MB rod, 16 vs 14. I won't name them as they were well made, although it was Sketchy;). But yeah it didn't go well,twice. I don't know whether it was directly attributable to the sleeves. possibly it wasn't, and certainly not Sketches fault as I told him what to make, but it has made me shy of doing it again. Next time I'd rebuild the crank with another rod to suit the piston. I cheaped out of doing it for the cost & the boring of the crank required. But choosing the best piston is the foundation of a good engine.

[peewee]

The high B port KZ2 engine won the Nationals here in 2013 and was insanely fast down the shute.
But this year I went thru all the testing again with the newest iteration of the TM - KZ10 .
This had the casting changed by the factory that allowed much bigger Aux Ex ports, and proved in the final analysis to generate more bottom end than I could drag out of the older engine, no matter what.
It won the title again this year, proving to be faster in outright power terms than the very best World Cup winning engines by SavTech from Europe, due in part to the extra
off corner response - also down to the perfect jetting combo on the day.
A super proud day for me and the team, making the pass for the lead at the end of the main straight with 3 to go after getting a way faster straight entry speed and carrying it in the draft.

you have the C same height as B ?

[wobbly]

In the high B port engine yes.
In the high A port, the B is lower, the C lower again.

[peewee]

well maybe im fuked. the honda cylinder i have was 124 A and B. 127 C. so i put A at 128 and B/C 127. ill try it and see. if that dont work i can put B/C at 130 and leave A at 128 and try that

my concearn is not letting the transfers get to high but i think ill be ok

[Frits Overmars]

well maybe im fuked. the honda cylinder i have was 124 A and B. 127 C. so i put A at 128 and B/C 127. ill try it and see. if that dont work i can put B/C at 130 and leave A at 128 and try that. my concearn is not letting the transfers get to high but i think ill be ok128° for A and 130° for B and C sounds fine, provided the transfer timing doesn't take too much away from the exhaust blowdown angle.area.

[lodgernz]

I think I understand how to derive the time-area for the exhaust and transfer ports, but I'm not sure that my method for the blowdown STA is correct.
I think that, for example, if exhaust opens at 85º, then the mean exhaust area is that exposed at 132.5º.
Similarly, if the A transfer opens at 115º, then the mean open area is the area exposed at 147.5º.

For the blowdown mean area, I'm assuming this is the area of the exhaust port exposed when the crank angle is halfway between EO and TO, ie in the above case at 100º.

Please, anybody, correct me if I have that wrong.

[Frits Overmars]

I think I understand how to derive the time-area for the exhaust and transfer ports, but I'm not sure that my method for the blowdown STA is correct. I think that, for example, if exhaust opens at 85º, then the mean exhaust area is that exposed at 132.5º. Similarly, if the A transfer opens at 115º, then the mean open area is the area exposed at 147.5º. For the blowdown mean area, I'm assuming this is the area of the exhaust port exposed when the crank angle is halfway between EO and TO, ie in the above case at 100º.
Please, anybody, correct me if I have that wrong.There are no such animals as an exhaust mean area and a blowdown mean area. The uppermost millimeter of port height is open for much longer than the lowermost millimeter and you must take these various periods of time into account. That's what the angle.area and time.area concepts do.

[wobbly]

Why fuck about deriving anything - there are plenty of free, or even better "proper" software programs that give you computed STA or Angle Area directly
with simple inputs.

[lodgernz]

There are no such animals as an exhaust mean area and a blowdown mean area. The uppermost millimeter of port height is open for much longer than the lowermost millimeter and you must take these various periods of time into account. That's what the angle.area and time.area concepts do.

Hi Frits, thanks for responding.
I agree that Jennings method as I outlined above seems terribly flawed in its concept and assumptions, but if I want to use his published ranges of time-area, I have to use his methods.

I also used your method (as I understood it) of multiplying the area of each mm "slice" of the port by the number of degrees that slice would be open, and totalling those angle-areas for the whole port, then dividing that total by the cylinder capacity. The answer was 42 deg-cm2/cm3, which doesn't seem to agree with any published values I can find. Clearly I'm doing it wrong.
I've read this entire thread several times, along with all four pit-lane.biz GP125 threads several times, but I'm still missing something. Quite a lot as it turns out.

I know you're a busy man Frits, but I'd really appreciate some guidance here.

[lodgernz]

Why fuck about deriving anything - there are plenty of free, or even better "proper" software programs that give you computed STA or Angle Area directly with simple inputs.

Because I want to understand it.

[peewee]

128� for A and 130� for B and C sounds fine, provided the transfer timing doesn't take too much away from the exhaust blowdown angle.area.

im trying to figure out the exh blowdown. in the past ive tried tall 200* exh ports (500cc single) and i simply couldnt make it work, with low transfers (130) and high transfers (136), no matter what combination i couldnt make it work. a well tuned 300cc probly had more power and certainly a wider bandwidth.

so i went back to the drawing board with new cylinder and remebered some warning advice you had for over zelous tuners getting the exh to high. for that large of engine i think 192 exh is a good place to start so thats what ive done. since i already have the A at 128 and B/C at 127 im gonna try it this weekend. i have to admit ive never tried the B/C higher than A but i want to test it. next week i can pull the cylinder back off and easily raise the B/C to 130 and keep A at 128 then test again, all while leaving 192 on the exh atleast for now

why i couldnt get the high exh timing to work on this big engine im not sure. to much time*area for the speed the piston is traveling perhaps ? im not sure. what works on them small engines sure doesnt seem to be any good on the large engines

[senso]

For simple, durable engines I have been using 187º exhaust and 124-127º in the transfers with good results, paired with "low" compression heads(around 12:1 in 50-75cc engines), they are not power houses, but much better than stock.
Given that removing material is much easier than adding it(and plating the new material is even worse), I would point for 187-190º in the exhaust.

[Frits Overmars]

Why fuck about deriving anything - there are plenty of free, or even better "proper" software programs that give you computed STA or Angle Area directly with simple inputs.
Because I want to understand it.The best answer in the world :niceone:.


I agree that Jennings method as I outlined above seems terribly flawed in its concept and assumptions, but if I want to use his published ranges of time-area, I have to use his methods.Jennings' values are superseded now and his method was far from exact, but it served a purpose: it gave an impression of the angle.area and time.area concepts in an era when nobody had access to a computer.
I also used your method (as I understood it) of multiplying the area of each mm "slice" of the port by the number of degrees that slice would be open, and totalling those angle-areas for the whole port, then dividing that total by the cylinder capacity. The answer was 42 deg-cm2/cm3, which doesn't seem to agree with any published values I can find. Clearly I'm doing it wrong. I've read this entire thread several times, along with all four pit-lane.biz GP125 threads several times, but I'm still missing something. Quite a lot as it turns out. I know you're a busy man Frits, but I'd really appreciate some guidance here.I can't check your calculations because I know hardly anything about your engine. My advice would be to start by calculating the raw angle.areas without bothering about cylinder capacity and crankshaft rpm for now, and use millimeters, not centimeters. You can use the Aprilia values as reference; you'll find them in the Pit-Lane threads and I also posted them here somewhere. In case someone else is interested in this subject, here are a couple of links to some of those Pit-Lane threads:
http://www.pit-lane.biz/t3173p816-gp125-all-that-you-wanted-to-know-on-aprilia-rsa-125-and-more-by-mr-jan-thiel-and-mr-frits-overmars-part-2-locked
http://www.pit-lane.biz/t3173p969-gp125-all-that-you-wanted-to-know-on-aprilia-rsa-125-and-more-by-mr-jan-thiel-and-mr-frits-overmars-part-2-locked.


...for that large of engine i think 192 exh is a good place to start so thats what ive done. since i already have the A at 128 and B/C at 127 im gonna try it this weekend. i have to admit ive never tried the B/C higher than A but i want to test it. next week i can pull the cylinder back off and easily raise the B/C to 130 and keep A at 128 then test again, all while leaving 192 on the exh atleast for nowSpecific time.areas are supposed to be universal; the size of the engine doesn't matter. But remember that short-stroke engines need more exhaust timing in order to achieve their desired specific blowdown time.area. For the short-stroke Aprilia RSW500 (awful engine!) it was even necessary to limit the transfer timing (to something like 122° if I remember correctly) in order to get sufficient blowdown TA. So don't raise your transfers just yet...

[lodgernz]

The best answer in the world :niceone:.

Jennings' values are superseded now and his method was far from exact, but it served a purpose: it gave an impression of the angle.area and time.area concepts in an era when nobody had access to a computer.I can't check your calculations because I know hardly anything about your engine. My advice would be to start by calculating the raw angle.areas without bothering about cylinder capacity and crankshaft rpm for now, and use millimeters, not centimeters. You can use the Aprilia values as reference; you'll find them in the Pit-Lane threads and I also posted them here somewhere.

Thank you Frits. I do use mm, I only convert the answers to cm because those are the units of the most-published figures.
I'll look for those Aprilia figures.
Regarding my angle-area value of 42: I'm embarrassed to admit that I used the wrong column in my spreadsheet (where would we be without spreadsheets?) and my answer using your method should have been 5.966... , which is of the expected order of values, and not too far away from those calculated using Jennings method.
The time-area value of this cylinder at 12,000 RPM would therefore be 0.0000829, again, of the expected order. Clearly the engine is deficient, but I knew that already. Now I have a good method of quantifying port areas and timing that I actually understand. You've made an old man very happy.

[wobbly]

OK I get it about understanding how to derive the STA numbers, but to then apply those numbers to Jennings old assumptions makes no sense.
Since then due to QUB, to Tom Turner, to Kurt Leaverton and then leading to Vannicks EngMod2T we now have cheap accessible code that not only calculates easily the STA numbers but then relates
all the numbers to each other, and to a desired bmep at a desired rpm from a specific swept volume.
Thus you KNOW how much power each port is capable of in relation to the others.
In this day and age I personally see no sense in harking back to prehistoric writings about 2T technology when all the answers you need are available at the click of a mouse.
BUT - here is the kicker, just up the thread we have someone working in the dark - wondering why a certain transfer height didnt work with some arbitrary Ex port height.
Without ANY calculation, I can tell you straight off that having any set of reasonable transfers sitting at 130* or even worse 136* duration and combining that with
an Ex sitting at 192* will not even begin to work PROPERLY due to compromised blowdown.
130* transfers are EXTREMELY high, a 192* Ex is EXTREMELY low for any high performance application.
The transfers are set for an absolute full race Aprilia GP type tuning, and the EX is down where a low BMEP MotoX engine would be.
Running the ports thru any simple STA program would give you the answers immediately.
If you have that sort of powerful information you then dont even need to have the experience to look at the timings and say, it wont work, due to the huge transfer STA creating very low velocity
and thus uncontrolled transfer scavenging streams, combined with very low blowdown STA that then creates a huge positive pressure ratio across those excessive transfers - making the situation
even worse.
Rant over for today.

[peewee]

i have engmod but it takes aleast a week if not alittle more to input all the info since i have other obligations during the day. my ktm is loaded in engmod but i just havent got to the honda yet. the 136 trans engine was a mistake i did quit a while back. long before i had engmod or much common sense. of course i wouldnt do the same mistake today. our major holiday is here in a couple weeks and i simply dont have enough time to mess with engmod until after that.

since we're on the subject, how does engmod account for the kickers (hooks) in the ports ? on the transfer port layout page theres a section that says 'area ratio between window and passage exit'. i assume this is where it takes into account any hooks ? but i dont understand how it can calculate the rearward/forward angle at which the kickers aims, since there is no place to put that info, only the ratio of window to passage exit. my ktm doesnt have hooks so theres wasnt much difficulty inputting the required info but honda has hook in the A and B.

edit: ok i forgot about the 'transfer port cylinder entry design' page. that must be where it figures the hook angles ?

[lodgernz]

OK I get it about understanding how to derive the STA numbers, but to then apply those numbers to Jennings old assumptions makes no sense.
Since then due to QUB, to Tom Turner, to Kurt Leaverton and then leading to Vannicks EngMod2T we now have cheap accessible code that not only calculates easily the STA numbers but then relates
all the numbers to each other, and to a desired bmep at a desired rpm from a specific swept volume.
Thus you KNOW how much power each port is capable of in relation to the others.
In this day and age I personally see no sense in harking back to prehistoric writings about 2T technology when all the answers you need are available at the click of a mouse.
BUT - here is the kicker, just up the thread we have someone working in the dark - wondering why a certain transfer height didnt work with some arbitrary Ex port height.
Without ANY calculation, I can tell you straight off that having any set of reasonable transfers sitting at 130* or even worse 136* duration and combining that with an Ex sitting at 192* will not even begin to work PROPERLY due to compromised blowdown.
130* transfers are EXTREMELY high, a 192* Ex is EXTREMELY low for any high performance application.
The transfers are set for an absolute full race Aprilia GP type tuning, and the EX is down where a low BMEP MotoX engine would be.
Running the ports thru any simple STA program would give you the answers immediately.
If you have that sort of powerful information you then dont even need to have the experience to look at the timings and say, it wont work, due to the huge transfer STA creating very low velocity
and thus uncontrolled transfer scavenging streams, combined with very low blowdown STA that then creates a huge positive pressure ratio across those excessive transfers - making the situation
even worse.
Rant over for today.

...and a most articulate and erudite rant it is Wobbly.
I wouldn't use the "prehistoric" assumptions such as Jennings and Blair now that I have Frits' methods and his numbers for the Aprilia.
I'd love to be using classy software to avoid the brain work, and I guess the "cheap" software you're talking about is EngMod2T. It might be cheap for someone who makes a living from preparing engines, but USD400 is a bit of a hit for the average bucket racer. Any suggestions for more accessible software? I have bought one of the really cheap ones, but it appears to be using Jennings methods, so probably not that one.

[peewee]

there appears to be a free calculator here. never tried it but it might be handy http://www.x-h2o.com/index.php?threads/porting-program.43429/

[wobbly]

As its only single dimensional EngMod cant " account " for transfer hooks, but what it does have is a very accurate canned model of the scavenging regime of an RS125.
This type of setup would apply the flow and scavenge characteristics of any engine with similar port layout with hooks.
All you do is enter your accurate port geometry and click the RS125 Scavenging Model at the bottom of the transfer page.

Frits numbers for the Aprilia of course make the assumption that you are able to develop EVERY aspect of the engine whole , to be able to use those ports
at that level of finesse - be careful, or should I say err on the side of caution.

[lodgernz]

Frits numbers for the Aprilia of course make the assumption that you are able to develop EVERY aspect of the engine whole , to be able to use those ports
at that level of finesse - be careful, or should I say err on the side of caution.

Understood. Thanks Wobbly

[TZ350]

Page 980 .... :eek:

[fatbastd]

...and apologies if it should be elsewhere, though the 'brains trust' seems to look in here most often..

Anyway, a mate's son in the UK is at the sharp end of some mini-bike/pit-bike racing championship and keen to win it. Obviously. They are currently running pump Shell V-Power unleaded gas (the best pump available there these days, with no added ethanol). They are making 11hp in an air-cooled 39cc two stroke. They want to avoid an engine-induced DNF. They also need more off-corner grunt and are keen to try exotic racing fuels to achieve this. e.g.VP12 or 14 of some Elf rocket fuel. They are keen to go leaded.

Now, I've asked Wobbly this via email and he had some pointers, though I thought I'd pose the question here as to which fuel they might want to try - they are sceptical of all the makers claims. They don't want to up the compression (though I suspect that's the best option with better fuels) for fear of a DNF. Ignition is some nasty thing with all the adjustment you can get from the slack in the holes on the stator held in by 2 x 5mm screws. There's been no mention of other instrumentation.

Power loss after a few laps is a frustration, for which they are running a touch richer than best power on the dyno, costing 0.5hp. Oil is some Bardhal brew that seems to work and has not been beaten for power on the dyno by other brands. I've passed on the recent oil recommendations discussed here recently. In fact they are running the Bardhal at 25:1, though will be going richer, as the only effect of leaner was greater wear rates. The scuttlebutt in these circles is that some adventurous fools are running down at 15:1 with good results..where have I heard all that before! (Oh, it was me reading Jennings and running a two-stroke air-cooled twin at 15 or 16:1 on veggie oil and finding jennings was right about the effects).

Enough rambling. I was rather hoping someone in the 50 brigade (or any other thinker) might have some useful suggestions for the effects of better fuels on mid-range power, where little else is changed, or a fuel recommendation (not that these fuels are in use in buckets..

Thanks for reading this far.

FB

[F5 Dave]

Yeah
The most obvious one is-is it against the rules to water cool it? That would bring lasting power and aid reliability in spades.

[TZ350]

... a mate's son in the UK is at the sharp end of some mini-bike/pit-bike racing championship and keen to win it. They want to avoid an engine-induced DNF. They also need more off-corner grunt ...
... water cool it? That would bring lasting power and aid reliability in spades.

A simple way to water cool it would be to dribble water into the ducting directing air over the cylinder and head. That way the engine is getting extra cooling from the latent heat of evaporation of the water droplets splashing onto the cylinder and head.

If the rules allow, then some sort of digital ignition like a programmable Ignitec would help for off corner acceleration. But you need a TPS so that at lower rpm the ignition retards back to something more normal when the throttle is closed.

More oil for more power, TZ's could run down at 16 or even 12:1 ... 20:1 is normal. Team ESE runs 20:1 in everything.

[wobbly]

Bottom line here is that as I have stated many times the tuning regime for leaded is completely opposite to that of unleaded pump type gas.
To get ANY benefit from a good leaded fuel they need to increase the com, back out the timing and run lean as hell.
NFG at all without an egt.
Get some super well proven A747 to run with it at 20:1, but if they are so gun shy of the thing that they wont do the dyno time and do proper back to backs then
its probably not going to be much use simply changing fuel and jack shit else.

[koba]

Is more power going to be the best way to ensure a good finish in the championship?
It's possibly sacrilege to say so in here but I've noticed many will do better in the long run by keeping this stable and being consistent...

All depends on the situation of course but often the best change is none at all.

[TZ350]

Is more power going to be the best way to ensure a good finish in the championship?

Agreed .... consistency is a good thing and more hp may not help much.

[richban]

To get ANY benefit from a good leaded fuel they need to increase the com, back out the timing and run lean as hell.
NFG at all without an egt.


Yeah it seams the 300 loves running lean. egt was hitting close to 1300F but man she was angry and fast. I am running Motul @ 30:1 Gunna switch to elf or 747.


It will be interesting to play around with the ratios on the dyno. Do you think I could run the 300 that low. 20:1 that is? Its running straight Avgas with 15:1 comp. ignitech of course.

[wobbly]

1300 is too hot.
Means that the ignition is ramping out too much timing past peak power.
But just as likely that the com is a bit low at 15:1.
Try some more advance past peak, ie flat line it at say 10* ( depends upon what the peak power timing is - it should be around 15* )
then depending upon the result, chuck it some extra com up closer to 16:1.
Both things will reduce the temp at high rpm , without having to go richer to stop it.

20:1 is fine for best engine protection.
Only issue is that Elf 909 will settle out quite quickly in AvGas, but as we used to do in the old days with Castrol R just add a little Acetone
and that problem goes away.
I havnt actually tried Motul Kart without the Acetone, so that may be OK in AvGas.
A747 is fine in AvGas.

[fatbastd]

Thanks for the thoughts...Wobbly's right, again - I doubt changing the fuel won't achieve much, unless the setup wasn't right in the first place. The water-cooling idea is a lateral option, which may or may not be legal/feasible. Will mention it. They do the dyno time, but not sure how effective it is or how willing they are to change things, so all it might be telling them is what they've got.

No free lunch then.

[jasonu]

Is more power going to be the best way to ensure a good finish in the championship?
It's possibly sacrilege to say so in here but I've noticed many will do better in the long run by keeping this stable and being consistent....

Yep just ask any of the 30+hp bucketeers...

[richban]

1300 is too hot.
Means that the ignition is ramping out too much timing past peak power.
But just as likely that the com is a bit low at 15:1.
Try some more advance past peak, ie flat line it at say 10* ( depends upon what the peak power timing is - it should be around 15* )
then depending upon the result, chuck it some extra com up closer to 16:1.
Both things will reduce the temp at high rpm , without having to go richer to stop it.

20:1 is fine for best engine protection.
Only issue is that Elf 909 will settle out quite quickly in AvGas, but as we used to do in the old days with Castrol R just add a little Acetone
and that problem goes away.
I havnt actually tried Motul Kart without the Acetone, so that may be OK in AvGas.
A747 is fine in AvGas.


Nice one. I was wanting to try some more inserts.

It would be a shame to blow it up. She's looking rather swish.

[timg]

Nice one. I was wanting to try some more inserts.

It would be a shame to blow it up. She's looking rather swish. Very swish indeed. Nice :niceone:

[chrisc]

Interesting read from Luc Foekema on spark energy and timing as posted on facebook:
https://www.facebook.com/notes/4223470164094/

Conclusion:
More top power as shown in the graph [from decreasing spare energy to 50% from 11K rpm], indicates a not good combination of setup and the exhaustpipe. The setup is optimal for a higher rpm then the exhaustpipe is made for. Just to lower the sparkenergy, more heat will be available for the exhaustpipe, resulting in a higher rpm and in this case a higher power output.

Conclusion "when there is a gain in toppower by reducing spark energy, the temperature in the exhaustpipe is too low or the exhaustpipe is too long, otherwise a gain in toppower would be impossible".

[richban]

Can you even buy A747 in NZ?

[jasonu]

Can you even buy A747 in NZ?

I used to run my RS125 on it in the mid 90's and paid about $35 a liter for it. Hate to think what it costs now.

[F5 Dave]

Looks good Rich. Go team old man.

[richban]

I used to run my RS125 on it in the mid 90's and paid about $35 a liter for it. Hate to think what it costs now.

looks like 12 x 1 litre from Germany would land at about $26 a bottle. Might just go with the 909 and acetone.

Mr wobbly when you say a little acetone. How much per 5 litres is a little. Thank you sir. I think you mentioned runing actone with motul 800 and av aswell.

[2T Institute]

I used to run my RS125 on it in the mid 90's and paid about $35 a liter for it. Hate to think what it costs now.

$35 a litre

[wobbly]

About a cup full in 5 litres.
I dont run Motul 800 as its a full synthetic - I have used Motul Kart with Avgas and Acetone simply as I found that the 909 would settle out and
wanted to keep as much the same for tuning as I could, just change the oil as some was given to me.

[richban]

About a cup full in 5 litres.
I dont run Motul 800 as its a full synthetic - I have used Motul Kart with Avgas and Acetone simply as I found that the 909 would settle out and
wanted to keep as much the same for tuning as I could, just change the oil as some was given to me.

Well it seams you can get castrol R30 of the shelf in nz. I want to go to a castor blend so what one yah reckon. Castrol or the elf.

Its got to worth a second a lap just from the smell.

[jasonu]

$35 a litre

Funny it didn't look right but my spill chucker didn't complain...

[jasonu]

looks like 12 x 1 litre from Germany would land at about $26 a bottle. Might just go with the 909 and acetone.

Mr wobbly when you say a little acetone. How much per 5 litres is a little. Thank you sir. I think you mentioned runing actone with motul 800 and av aswell.

$26 a bottle isn't bad as long as you can off load what you don't need. Even if you used a full bottle each meeting it will certainly be far from your largest expense. Worth the money me thinks.

[richban]

$26 a bottle isn't bad as long as you can off load what you don't need. Even if you used a full bottle each meeting it will certainly be far from your largest expense. Worth the money me thinks.

1 litre a day. 20L of avgas seams about whats we are using each bike. Thirsty work for the 300.

[wobbly]

The new hybrid oils are light years better than yer fish and chip castor.
Yr racing a 2T missile not cooking up a storm.

[richban]

The new hybrid oils are light years better than yer fish and chip castor.
Yr racing a 2T missile not cooking up a storm.

Ah Yes good point. Might just buy some for the oil burner at home.

[Grumph]

Ah Yes good point. Might just buy some for the oil burner at home.

I'll give you a half container of Shell M if you come down for the BoB - just to clear shelf space.....

[Kickaha]

looks like 12 x 1 litre from Germany would land at about $26 a bottle.
Cheap, I was paying $38 a litre about 12 years ago for the TZ Superkart and I was getting it cheaper than retail

[jonny quest]

The RSA 125 uses roller bearing for crank mains. What is the advantage of rollers over ball?

[quallman1234]

I haven't seen a mention of Elf 976? I know you can still get that in NZ ;). Its recommended next to A747 in the RS125 manual, its what i used to use on my RS125, never had a issue!
Wasn't cheap though!

[Frits Overmars]

The RSA 125 uses roller bearing for crank mains. What is the advantage of rollers over ball?Roller bearings can take higher loads, but that is not the main reason. When fitted correctly the Aprilia bearings allow for 0,4 mm of axial play. Any less costs power.
You can't do that with ball bearings (unless you use a sloppy fit on the shafts, like many kart tuners used to do).

[wobbly]

976 is a full synthetic just like Motul 800,so is OK for unleaded fuel ( as they were designed for ) when run rich to prevent breaking down the oil
when it overheats.
I did hours of dyno oil testing for a customer using 909 and 976 in a KT100 to establish the best type and ratio.
As soon as you really wind in the needles the superior lubrication of the castor base made more power the hotter the egt got.
The 976 started to show marks on the skirts and lost power over around 620* in the header.

[quallman1234]

976 is a full synthetic just like Motul 800,so is OK for unleaded fuel ( as they were designed for ) when run rich to prevent breaking down the oil
when it overheats.
I did hours of dyno oil testing for a customer using 909 and 976 in a KT100 to establish the best type and ratio.
As soon as you really wind in the needles the superior lubrication of the castor base made more power the hotter the egt got.
The 976 started to show marks on the skirts and lost power over around 620* in the header.

Thanks for that, was curious :rockon:

Majority of 125GP bikes in NZ are running on the wrong oil in that case :).

[jasonu]

Majority of 125GP bikes in NZ are running on the wrong oil in that case :).

Probably because it is cheaper.... not that you could ever accuse a Kiwi motorcycle racer of skimping.

[quallman1234]

Probably because it is cheaper.... not that you could ever accuse a Kiwi motorcycle racer of skimping.

Its not that cheap!

You learn quickly that you should never skimp out on the RS125's Recommended Servicing life of a part (Or any two strokes for that matter)
It ends up costing you more otherwise! Obviously if you had the knowledge and experience of Wobbly it would be different! But i'm just a newb!
I am one of the lucky few who just followed the book, and never ever once had a issue. Apart from the bike keep falling over but i think that was more the rider ;).

[Drew]

Apart from the bike keep falling over but i think that was more the rider ;).It's an inherent design fault with bikes. Get a sidecar!

[F5 Dave]

how 'bout a nice sensible Austin Allegro. Suit you Drew.

[peewee]

The high B port KZ2 engine won the Nationals here in 2013 and was insanely fast down the shute.
But this year I went thru all the testing again with the newest iteration of the TM - KZ10 .
This had the casting changed by the factory that allowed much bigger Aux Ex ports, and proved in the final analysis to generate more bottom end than I could drag out of the older engine, no matter what.
It won the title again this year, proving to be faster in outright power terms than the very best World Cup winning engines by SavTech from Europe, due in part to the extra
off corner response - also down to the perfect jetting combo on the day.
A super proud day for me and the team, making the pass for the lead at the end of the main straight with 3 to go after getting a way faster straight entry speed and carrying it in the draft.

i can see why someone would use a high B. allows the aux to be just that much bigger by bringing the floor down alittle more. but some engines cant have the aux floor right on top of the A like aprillia because the side piston skirt is cut to high so the aux floor needs to be kept alittle higher or you get a shortcircuit. on a situation like this do you think the high B would still work better or is its only benefit to allow the aux floor to sit right on top of A ? basically what im wondering is does a high B only have the benefit on letting the aux floor be very close to the top of A (assuming the piston design will allow it without creating a shortcut) or does a high B also have some kind of scaveging benefit also ?

[wobbly]

No - the high B gives more total STA to the transfers, as in a well designed setup it is alot wider than any A port.
So you have the B and C ports combining to give a better total STA than is possible with a normal small A and progressively lower B and C ports.
But its always a compromise, it makes no sense to run a high B port with no powervalve, as this scavenging regime favours top end at the expense of below
pipe power.
As I detailed before I could, and did, make a very good attempt at matching the high A port setup in a KZ2 with the big B port situation -
but at the end of the day we needed the high A port to get natural drive off the bottom when passing in traffic.
But this was helped some by the factory catching up on the usual 3 year lag in technology when comparing GP125 with KZ2 and allowing me to grind really big Aux port top edges
to gain sufficient blowdown to match the rocket ship big B port engine I did the year before.

[jasonu]

Its not that cheap!


I said cheapER.
NZers are notorious skimpers.

[Drew]

I said cheapER.
NZers are notorious skimpers.
Naaaaaah. Second hand tyres were fine on a full power superbike.:(

[peewee]

what you guys think ? engmod is suggesting the reeds open 2mm more. i managed to get 1.5 more :Punk: . hard to say if its going to work but theres only one way to find out


http://i1081.photobucket.com/albums/j357/doddledo/IMG_20140729_1911041_zpsf354b885.jpg
http://i1081.photobucket.com/albums/j357/doddledo/IMG_20140729_2004031_zpse253c7d6.jpg

[wobbly]

What is limiting the tip lift ?
Is it that the plate wont fit when any higher into the reed box.
Could you could just add another 0.5mm piece of reed strip under the plate - but general rule is to keep lift under 0.3* reed free length = 27mm for 9mm lift.

[peewee]

nothing is limiting the lift. i had some spare stoppers around and cut the fingers off then used the end strip under the cage stoppers. didnt think of it but ya i can cut a strip from some old reeds and put that under the stopper also. i wonder if the pressure differentials will actually open the petals this much now ?

[peewee]

rode the bike today and it pulls 1000 times better below the pipe than the last cylinder. probly because the ports arent sky high i suppose. mostly the transfers probly. before it seemed to have 1000 rpm wide powerband. below that and it couldnt recover without down shifting 1 or 2 gears. now it pulls back to the pipe alot better without down shifting ( in most situations). i left some meat on the bone so i can make more cylinder adjustments if needed. any body got ideas how to get more power without the midrange dropping out, like the last cylinder ?

heres what i got

honda T port exh and no powervalve
exh 192 and about 90% width
A trans 128 and 20* upward
B trans 127 and 15* upward. piston dome is 15* also
C 127 and 62* if i recall

i did the best i could with the upward angles. honda had them backwards. 20* on the rear and 15* on the front so i did the best i could with what i had to work with. i even lifted the cylinder up slightly with thicker gasket to try and correct the floor angles.

didnt get the spacer installed under the reed stopper yet. should be able to get that done this week and tested next weekend. i think it will help as the current 7mm lift seems really small. still might not be enough lift with the spacer but atleast ill know if im going in the right direction

[F5 Dave]

204* on the ex. Don't be a pussy.


you might need to use the clutch.

[peewee]

ive tried 200*. with 132 A and 130 B if i recall. worked ok. but i want to find a good compromise with lower ports. at some point i think the ports get so high you gain nothing but overrev which is useless for me. i ride in sand so there needs to be some power slightly lower in the rpm otherwise the sand can pull the rpm down too easily. maybe 8spd gearbox is the answer :laugh:

[jasonu]

204* on the ex. Don't be a pussy.


you might need to use the clutch.

Like your old 50 with the power spike...

[F5 Dave]

Sorry I might have been being a bit silly. I think my grape juice might have fermented.

[wobbly]

You only need to fill in 3 pages of EngMod to get the full benefit of the STA readout page.
Just having the engine, Ex and transfer inputs will tell you where the ports are in relation to what you think you need.
You , and we, are simply guessing at what is happening until you can give us the STA printout.
Do that and we can help.

[TZ350]

<iframe width="560" height="315" src="//www.youtube.com/embed/mrnul6ixX90" frameborder="0" allowfullscreen=""></iframe>

Ok a Tesla Turbine is not a 2T, but whatever happened to this great invention from a 100 years ago. Supposedly better power to weight and energy conversion than any other motor.

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

[husaberg]

Ok a Tesla Turbine is not a 2T, but whatever happened to this great invention. Supposedly better power to weight and energy conversion than any other motor.

The tesla one way valve is even cleverer

[Ocean1]

Ok a Tesla Turbine is not a 2T, but whatever happened to this great invention from a 100 years ago. Supposedly better power to weight and energy conversion than any other motor.

If you've got shitloads of compressed gas handy and don't mind losing most of the HP converting all those rev's into something useful.

[senso]

If the only thing that provides torque is the viscous coupling between air flow and the polished discs, the torque values might be in the 0.0x kgm range?
And yes, something has to provide a high flow of pressurized air/gas, that is no free power, so use a combustion engine coupled to a air compressor to drive it?

[Drew]

If the only thing that provides torque is the viscous coupling between air flow and the polished discs, the torque values might be in the 0.0x kgm range?
And yes, something has to provide a high flow of pressurized air/gas, that is no free power, so use a combustion engine coupled to a air compressor to drive it?That's a mighty inefficient way of making something spin.

If you want big revs and few moving parts, gas turbine all the way.

[FastFred]

If the only thing that provides torque is the viscous coupling between air flow and the polished discs, the torque values might be in the 0.0x kgm range? And yes, something has to provide a high flow of pressurized air/gas, that is no free power, so use a combustion engine coupled to a air compressor to drive it?That's a mighty inefficient way of making something spin. If you want big revs and few moving parts, gas turbine all the way.

Intuitively you would think so, and yes something has to provide a high flow of pressurized air/gas, to drive a conventional turbine to, the same thing could be used to drive a Tesla. The Tesla was conceived in the days of steam but with modern materials it might have a place in the turbo jet age too.

The Tesla works on drag of the boundary layer so the gap between any two blades is adjusted to twice the boundary layer thickness and in this way the coupling between blade and driving medium is very closely coupled.

http://en.wikipedia.org/wiki/Tesla_turbine ""The turbine efficiency of the gas Tesla turbine is estimated to be above 60, reaching a maximum of 95 percent. Keep in mind that turbine efficiency is different from the cycle efficiency of the engine using the turbine. Axial turbines which operate today in steam plants or jet engines have efficiencies of about 60 - 70% (Siemens Turbines Data).""

[136kg136ps]

Turbines do not like shifting, better have a variator style tranny.The tolerances are very hard to maintain as well, having worked on them up to LM2500 25K' hp they are light and powerful but piss poor in small vehicles.

[jasonu]

https://www.youtube.com/watch?v=BgwmiQr_t8M

Interesting but a bit useless.

[Drew]

Fuck it, go jet then.

Pretty hard to quantify the engine 'size', but that's up to the protester to try and figure out.

[TZ350]

<iframe width="420" height="315" src="//www.youtube.com/embed/tnJIx98Xsfg" frameborder="0" allowfullscreen=""></iframe>

Someone elses Suzuki GP125 F4 racer on YouTube, I would love to know more about it.

<iframe width="560" height="315" src="//www.youtube.com/embed/HmOI7af1CPE" frameborder="0" allowfullscreen=""></iframe>

Not sure who or when but a bit of F4 action at Taupo.

[Pumba]

Someone elses Suzuki GP125 F4 racer on YouTube, I would love to know more about it.

http://www.fxr150.co.nz/forum/showthread.php?715-gp125-project-motor

[TZ350]

Great Thanks .... hope Bren gives us an update soon.

[jonny quest]

Just some food for thought. .. I don't know if the ignetech would be capable of this. ...

One revolution standard max power ignition curve

The next revolution a highly retarded ignition curve

Repeat.

This scenario before powerband.... then at powerband and above your standard max power curve.

Any guess my something to try it might work logic behind this?

[wobbly]

Using TPS controlled 3D map does the same thing in effect - but the curve retard value is continuously variable as the rpm changes.