ESE's works engine tuner

[J.A.W.]

Bam Bam is a baby dear I thought! Give us a picture Hussa please.

Google Flintstones TV show for Bam Bam.. he was a baby character, but def' violently humanoid.. & named as such, onomatopoeically, of course..

[wobbly]

Left16, the answer is yes - easy.
The best KZ2 engine I have done ( 125cc-30mm carb ) is nearly 48 Hp/13000rpm at the sprocket where most all manufacturers measure these.
Its easy enough to go over 50 Hp but with no PV and straight line analogue PVL ignition,there is too much loss of bottom end and overev power when the ports
and other tuning elements are biased toward peak only.
We regularly use 15200 rpm when deleting between corner gearchanges as its way quicker.
This engine is quicker on track than any TechSav or other Euro tuned World Cup engines.
But all that is now irrelevant as Mr Ryger has blown ours and everyones tuning efforts to hell in a handcart.

[J.A.W.]

But all that is now irrelevant as Mr Ryger has blown ours and everyones tuning efforts to hell in a handcart.

Hmmm, Xmas is coming, are we there yet? This waiting tease-game is.. bloody killing me..

[TerraRoot]

Hmmm, Xmas is coming, are we there yet? This waiting tease-game is.. bloody killing me..

everyone's flaming sick of me talking about it.. so for their sake I hope it get released soon.

[Frits Overmars]

the photo below is from a kart engine brochure. 54x54.5 They claim that this engine has 43hp at 13900(25.2m/s)...is this possible from a 125cc engine?Or 23.6m/s is the redline?
Attachment 315631

The claim is possible. What surprises me though is that your engine has a cast iron cylinder liner. All six-speed KZ-engines I know of have linerless nikasil-coated cylinders while only the single-gear engines have cast iron liners. So what brand is yours?
There is no general redline for piston speed; it depends on the reliability of each engine. You may have missed the Ryger discussion here.
The Ryger is a KZ kart engine just like the one you were inquiring about, but it revs past 20.000 rpm; the prototype Ryger even revved past 30.000 rpm; that equals an average piston speed of 54,5 m/s.

[Lef16]

Frits,I'm talking about conventional 2 stroke engines and not about the ryger.
The engine is a rok shifter by vortex.
At Aprilia the max power is at 23.6m/s and I thought that this was the upper limit for any hi-performance 2 stroke.I thought the power could not be achived at higher revs because of the blowdown ange.area.
So you are telling that is it possible that a conventional 2 stroke can have it's max power at greater piston speed than 23.6,but with sacrifising bottom and mid range power?
Cheers

[adegnes]

Frits,I'm talking about conventional 2 stroke engines and not about the ryger.
The engine is a rok shifter by vortex.
At Aprilia the max power is at 23.6m/s and I thought that this was the upper limit for any hi-performance 2 stroke.I thought the power could not be achived at higher revs because of the blowdown ange.area.
So you are telling that is it possible that a conventional 2 stroke can have it's max power at greater piston speed than 23.6,but with sacrifising bottom and mid range power?
Cheers

Much lower bmep for 43hp@13900 than 56hp@13500.

[Lef16]

Yes,but it uses a flat line ignition curve and an 30mm carburetor.
Can this engine-and any engine-achive 16-16.5bar BMEP at 13000rpm if it is tuned properly?

[Frits Overmars]

...They claim that this engine has 43hp at 13900(25.2m/s)...is this possible from a 125cc engine?Or 23.6m/s is the redline?

At Aprilia the max power is at 23.6m/s and I thought that this was the upper limit for any hi-performance 2 stroke.I thought the power could not be achived at higher revs because of the blowdown ange.area. So you are telling that is it possible that a conventional 2 stroke can have it's max power at greater piston speed than 23.6,but with sacrifising bottom and mid range power?

You're mixing up two things. The rpm redline is not the rpm where an engine delivers its maximum power but the maximum rpm that an engine will sustain without flying apart. Hence my reference to the Ryger that refuses to fly apart even at 54,5 m/s.
Of course a conventional two-stroke can have its maximum power at greater piston speed than 23,6 m/s but that maximum power will probably be lower than that of the Aprilia RSA because, as you rightly say, the blowdown and scavenging time areas will become too small.

[Grumph]

Of course a conventional two-stroke can have its maximum power at greater piston speed than 23,6 m/s but that maximum power will probably be lower than that of the Aprilia RSA because, as you rightly say, the blowdown and scavenging time areas will become too small.

Hmmm, I seem to remember you saying, Frits, that the Ryger had changed your opinion of what was possible in time/areas....

But of course, here you qualify the statement by prefacing it with "a conventional two-stroke". Leaves a lot of questions about just what the Ryger would be described as...

[nine-thirtysix]

Hi 936 welcome. Thinking your misfire could have been voltage drop? Try a meter taped to the tank and over the power and ground. Some 125s were 4 pole alternators but thought 04. Failing that coil, plug lead etc worth swapping out.

Thanks for your answer.
I changed for the Ignitech from the 06 generator to a 04 one with cap and rectifier. I measured today 16,5V at idle and 15,9V at about 12000rpm (at the moment one capacitor to the coil).

Has anyone an idea why less advance below the pipe makes more power (probably just in my case and the YZ I don't know)?

If someone is interested in, a KTM SXS 125 ECU retards till 3,5degree!

[F5 Dave]

Either you meter is suspect or you have a queer regulator. My CR setup doesn't go above 14.5 from memory. That's the typical limit for most 12v systems. Not to say they haven't cranked the 4 pole one up in voltage and its not running sensitive equipment n the cct.

About now Wobbly will ask what plug you are running and your loom layout. There is a little bit on ignitechs on this thread.

[nine-thirtysix]

I don't know but I thrust the meter. It's old but was quite good equipment then. I just tried to test the capacitor and this was unsatisfying because the Voltage droped from 14 to 1V in about 1s. Don't know if it's normal but my feelings says longer should work better mainly during kicking since it slightly kicks back frequently.

Plug: I'm running either R7376-9 or R7433-8 since they deliver a different powerband....the R7376 is not so rought (because of the slightly changing compression ratio???) and makes more power now with the ignitech but looses a little bit from the low to middle transition. R7433 makes more power with the stock ignition and always in the transition.

Loom: it's completely new from ground up and I wired everything what I could probably use in the future...

[wobbly]

43 Hp at 14,000 is only 11 Bar bmep, simple to do but be careful about where the power is measured.
Most calculation programs show crank power, wheras most manufacturers quote power at the sprocket.
If you talk about crank power then 16 bar at 13,000 is 58Hp, and we know the Aprilia did around 54 sprocket power at 13,000
so that is achievable using every tiny advantage that a huge R&D effort could produce.
In the case of the KZ2 engines,the best as I said make 47+ sprocket power at 13,000, so this would translate to just over 50 at the crank
= near 14bar.
But those engines when tuned to make 50Hp at the sprocket loose too much bottom end and more importantly the overv capability.
No free lunch in physics as usual.

[marsheng]

I set the rev limiter soft and hard at 15000 since I thought I will never hit that. But found out that it misfires at about 11500 to 12000! After that I changed for 16000rpm and it reved more...now it is at 20000rpm and hopefully will never distract again. I don't know what happend there in the ignitech...

The reason is the crank does not turn at a uniform speed. The speed varies with crank position. So, your ignition is seeing the crank at the higher section and setting the RPM limit.