Kawi2strokes.com Forum

Jim (Fastfromthepast) had been running a Zeel for a while on his H2 roadracer. It might just be the adjustment variation, but he said you just have to advance the ignition plate all the way, and he got 25 degrees. Then the Zeel gives you the delays you want to plug in.

Most of us know the hotter the gasses/pipe in a expansion chamber, the faster the sound waves travel. With a given burn time of fuel, the later the ignition, more of the fuel burning is done later and the gasses in the pipe is hotter, thus gaining RPM from the faster return waves.

The stock ignition gives an advance purely through function of the electronics, and not out of design. Which is fine with a stock exhaust, as the is no super charging effect, so less chance of detonation. (with decent fuel)

It's really a personal decision if the added cost is worth the added power. But a good performance update.

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........

My point about modifying timing plate was to get more than 25 deg.
Is this worth the effort? I'm assuming you would want to play with both ends of the spectrum.

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http://kawatriple.com/wtf/

25 degrees??

I got more than 5mm as far as I remember, piston before TDC. Stock 23 is 3,13mm. That equals to a lot more than 25. But I also turned all 3 pick-ups, not just the plate.

So, 30 degrees static advance is within reach without doing ANY modifications. (5,26mm before TDC)
Then you can play all from 30 to 10 degrees ignition timing with your zeel.

Jorgen

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72 H2, 72 H1B, 74 H2, 74 H2 Cafê Racer, 71 F8 Bison

It's not a 4 stroke Andrew........

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........

Hey, I'm completely ignorant to this stuff man, ease up!
It's only logic to think that 25 deg at 4k is a compromise correct, so I would think you'd want to go higher than 25 but not exactly sure what the reasonable limit is. 30 is the limit without modification but maybe a benefit to go further?

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http://kawatriple.com/wtf/

Get one and dyno time!

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........

Or go riding with your friends...

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http://kawatriple.com/wtf/

H2B780........tell the kid's they will inherit the H2 one day when you old and grey......that you must buy parts now ! (do not do that)....that EBOS porting is crazy, huge exhaust port

Jorgen......That is a great explanation, I had to read it a couple of times.......you explain it very well and it makes total sense.

On my H2B (looks like a C), I just rebuilt the motor.....28 new bearings, IMS rods, R&D undercut trans, 15 plate clutch, Ralfs RLS and 160 miles on it.....runs's good and strong

John Aylor did the porting (nice work !), just stage 1, but widened Exhuast and Polished, matched and open up transfers, Intake cleaned up, etc.....He is doing squish heads at this time.......running VM34's with UFO's........I have FBG later style pipes (skinny compared to JollyMoto)

I do think I have enough MOD's that a Zeel could be an improvement to some degree, different Pipes would probably be the biggest gain (I do like the looks of the FBG pipes as they have good lines on the bike)........wonder what the best all around street pipes would be for my motor setup........It's just a street rod.

Always looking for improvement, reliability and good streetability

THX Phil




THX Phil

If you read the following once more, what does it tell you?

"But how do you slow the combustion speed down? Less squish? Mixture too rich? You do not want to do that...
Fortunately there is a simpler solution. We do not slow combustion down; we just start it later: we retard the ignition timing. As far as the exhaust gas temperature in the expansion chamber is concerned, the effect is the same: the engine runs better at high revs.
That is the reason for programmable ignition systems.
Below the power band the ignition advance can be more than 30° so that there is a whole lot of expansion; the burnt gas contains hardly any energy when it enters the exhaust pipe, so the exhaust pulses that arrive at the wrong moments at low rpm, are weak and will not disturb the scavenging too much."

That means, if you add a effective squish band head, the combustion speeds up. Hence colder exhaust gases, right? That's the same as advancing ignition timing, and the motor gives more power down low.

Then, if you add squish band head, (speed up combustion and the exhaust is volder) you better adjust ignition timings vs having the stock heads, right?

Because if you don't, the engine revvs less because non-squished heads leads to hotter exhaust gases as described. Because squish band heads leads to faster combustion, hense the start time if expansion of the gases starts earlier, hence the exhaust gases is colder.

That also means, in general, when adding a squish band head you will have a less revving engine if you do not retard ignition timing.
So, to gain power from squish band heads in the upper rpm part, you need a adjustable ignition unit. I got 5 hp, as said.

Jorgen

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72 H2, 72 H1B, 74 H2, 74 H2 Cafê Racer, 71 F8 Bison

[quote="BBP"]H2B780........tell the kid's they will inherit the H2 one day when you old and grey......that you must buy parts now ! (do not do that)....that EBOS porting is crazy, huge exhaust port]

Yes, wide exhaust port give better blowdown, the angle.area increases, which is important. I have tried low bd on my H2 test cylinders, and it did not work AT ALL!
But hey, stock H2 cylinders still works great, as we all know

By the way, GREAT looking bike you got there BBP. Love the pipes you got, and John Aylors work looks great. He makes me squished band heads for both my H2 caferacer and H1B "as we speak".

Jørgen

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72 H2, 72 H1B, 74 H2, 74 H2 Cafê Racer, 71 F8 Bison