ESE's works engine tuner

[mr bucketracer]

I was thinking of resurfacing that RS disc with the flapper wheel if its still lying around. Apparently some pads give that pulsing with certain surfaces.

may try that , mine was fine until my mate used it and manfeild , came back pulsing even though in the lath and dail was fine

[41juergen]

For the pressure trace its clear to use the 0mm position. May be I was a bit naive to think that I can use the other position to get a reasonable number for the ex temp....
Now after getting the TUbMax numbers down with lower comp I tried to use the spigot infront of the header. I used a 28mm long transition from the 75% ex area to the 100% area diameters, rest of the pipe like before. With that the power in the predicton went down about 10% and TUbMax incerased again. Could that be a sign of a kind of "over scaveging" because of better depression after EPO?

[Peter1962]

A question for wobbly : The 250 & 300 mx engines like the KTM stil use mechanicaly operated power valves. And they do not make use of the modern programmable ignition systems like the ignitech, neither do they use a TPS or electronic powerjet. One could say that time stood still the last 10 years or so.
In your opinion, would it be possible to modify the ktm powervalve to a servo driven unit, and change the ktm ignition for a more modern Ignitech that could operate both the powervalve as well as the ignition curve ? I know that a servo to operate the powervalve is not expensive, but can the necessary modification be done ?

Peter

[Pumba]

bert gave that to the rubbish tip

You guys throw nothing out so you probably need to come up with an excuse that is believable

[Bert]

I can cut you off some if I ever see my PWK back.

Yip, dug it last weekend, so it's now in the kit bag to bring down next round.

may try that , mine was fine until my mate used it and manfield , came back pulsing even though in the lathe it Dailed fine

Two of the four were fine, the rest were odd...

You guys throw nothing out so you probably need to come up with an excuse that is believable

[F5 Dave]

Yeah might be worth resurfacing as pad contaminated grooves could be the queer issue.


Will try t get into the transfers this weekend.

[wobbly]

Near on everything that increases power will increase the end gas temp - as it needs temp to create more cylinder pressure.
You need to find the combination that has the least effect on the TubMax but the max effect on power out.
Dropping the static com will drop the temp, but then raising the dynamic com with an engine tune mod will just as easily increase it again.

Re the Mx bikes with simple PV mechanisms.
Most of the Jap companies changed to digital ignitions in the early 2000s and tried electronic PJ control etc but I think only one has recently
used electronic PV servo control.
I have done many KTM and Honda 250 kart engines with Ignitech, and servo PV works really well on these highly tuned units, easy to implement and tune.
But you would be surprised that the best PV curve is usually opening around 6000 to full open at 8000 with a straight line, pretty easy to implement with
modified springs in a mechanical actuator.

[Peter1962]

Near on everything that increases power will increase the end gas temp - as it needs temp to create more cylinder pressure.
You need to find the combination that has the least effect on the TubMax but the max effect on power out.
Dropping the static com will drop the temp, but then raising the dynamic com with an engine tune mod will just as easily increase it again.

Re the Mx bikes with simple PV mechanisms.
Most of the Jap companies changed to digital ignitions in the early 2000s and tried electronic PJ control etc but I think only one has recently
used electronic PV servo control.
I have done many KTM and Honda 250 kart engines with Ignitech, and servo PV works really well on these highly tuned units, easy to implement and tune.
But you would be surprised that the best PV curve is usually opening around 6000 to full open at 8000 with a straight line, pretty easy to implement with
modified springs in a mechanical actuator.

I do admit that i am a little bit surprised to hear that. But is there not measurable benefit with a servo controled PV on a typical Kart track like in europe (few straight lines, a lot of corners so a lot of "on" - "of" throttle ? I would have thought that the more linear servo actuated opening of the power valve would be beneficial , when compared to the more abrupt opening of the power valve on engines with a mechanical actuator. Don't you think that there is some benefit to the electronic type under such conditions ? (I am considering this for supermoto use)

[Bert]

Re the Mx bikes with simple PV mechanisms.
Most of the Jap companies changed to digital ignitions in the early 2000s and tried electronic PJ control etc but I think only one has recently
used electronic PV servo control.
I have done many KTM and Honda 250 kart engines with Ignitech, and servo PV works really well on these highly tuned units, easy to implement and tune.
But you would be surprised that the best PV curve is usually opening around 6000 to full open at 8000 with a straight line, pretty easy to implement with
modified springs in a mechanical actuator.

I do admit that i am a little bit surprised to hear that. But is there not measurable benefit with a servo controled PV on a typical Kart track like in europe (few straight lines, a lot of corners so a lot of "on" - "of" throttle ? I would have thought that the more linear servo actuated opening of the power valve would be beneficial , when compared to the more abrupt opening of the power valve on engines with a mechanical actuator. Don't you think that there is some benefit to the electronic type under such conditions ? (I am considering this for supermoto use)

- by no means am I remotely a good tuner but....
We thought the same thing Peter (playing with TZR and NSR300s). But found stepped and almost almost straight line transitions produced best results (as Wobs has pointed out to us).
The theory I'm kinda working to is that the pipe is generally designed for best performance / mid to high RMP (wide open power valve) get that working well: then work backward to optimise the transition between closed and open (on the dyno)... You can even hear it in the exhaust note when your getting close (that might be me imagining things??).
Don't forget the acceleration vs how quickly the ignitech&servo combo can actually respond-keep up.
And you still need to match the carb setup and advance curve along the way.
--- no magic solution just lots of runs when first setting up a new build.

[senso]

I have developed a profound hate towards mechanical power valves, the freaking actuator in the Gas Gas 125 engine is so good that when it closes the valves it jams them right against the exhaust bridge and has already claimed two cylinder, now its off the bike and the valves are locked wide open

[wobbly]

There is a huge amount of effort needed to get the mechanical actuator to do what you want - and even then you are
really hard pressed to put numbers to what its doing during a run on the dyno - apart from the obvious gain or loss in power.
Having the Ignitech run the ignition makes perfect sense to also run the PV as its super fast and easy to adjust.
Do a run with the PV up, do one with it down, do one with it locked at 1/2 way, then simply join the max power dots.
Job done.
PS,if the servo line ends up dead straight, the hysteresis time is minimised if you dont have any extra points doing nothing defining the line.
The microprocessor then easily ( and quickly ) interpolates the movement from min to max, extra points slow the response time quite alot.

[Martin1981]

Wobbly, i have a Question regarding the Crankcase Compression Ratio.

You said that you find no more power with a crankcase bigger than 1,30 on 125ccm reed valve engines.

i own a kawasaki kx 500 and i always wondered that the engine, having 4 times more cylinder volume than a 125ccm engine, is not 4 times bigger than a 125ccm engine. maybe i found at least one reason for that.

i was curious about the TDC crankcase volume of the KX 500 engine and if i have not make a huge mistake when measuring it indeed was a big surprise.

it seems that the crankcase is WAY too small. It is about 1500 ccm! that would mean a ccr of 1,5! heading for 1,30 would mean a 60(!)mm longer rod and a 60(!)mm spacer "plate" between the case and the cylinder to gain 650ccm more crankcase volume to achieve a ccr of 1,30 (and still 500ccm when taking in account that the transferports could be a little bit crappy and thus heading for 1,33). by the way this huge plate could easilie contain an intake port making a case reed engine out of it.

What do you think about that? what was the reason for the engineers making the crankcase so small? was there a reason at all? Does the 1,30 rule of thumb ccr that works for the 125ccm engines not apply for the big 500ccm engines?

On the other hand, i have heard from the honda guys that the shortrod cr 500 engines make more power than the longrod engines. so in this case it would be the smaller case that makes more power.

i am a little bit confused about that and like to hear your opinion (and of course also Frits`and all others)

[peewee]

hey guys can someone explain the purpose of the cross over tube on a yami twin ? im confused as to why its there or if it even needs to be there. is it because each crankcase isnt 100% sealed from each other ? if both crankcases are seperate and sealed then i dont understand why you cant just treat eash cylinder seperate and eliminate the crossover

[peewee]

martin i had one of them old ktm 550cc engines and if i recall i was only able to pour about 1600cc of oil in it. seems like the case ratio was around 1.5XX or so. seemed rather strange with such a small volume. installed a longer rod and 4mm spacer. never did a dyno run before or after so i couldnt say for sure if there was any power difference. on them big engines i think the manufacturer makes alot of compromises just so the engine can fit into the chassis without much trouble

[Martin1981]

thanks peewee, so you firgured about the same like me. yes, it might be a compromise. with a 60mm spacer i will indeed have trouble to fit the engine into the frame.