Kawi2strokes.com Forum

Great thread, this can be a learning experience for all that want to learn more or care about tuning. I will be making a few points myself, this is from actually studying porting with some of the best triple tuners around, for the last 20 years along with the more useful real life tuning experience.

Flat spots have been throw around a lot, and yes 2 and 4 strokes do have them. If you want to take a look, here are 2 dozen dyno sheets, a few from magazines, to all sorts of tuning levels, including PHR, myself, Ebos, Leo, Chris, a case reed motor, and Nev's pipes are in there somewhere too I think. And a few 4 stroke just for fun. Take a look, they all show some sort of flat spot in or around the 5252 rpm range, pipes and porting can move this around a bit. The stock h2 actually has a very nice curve, with just a very imperceptible dip, And you can see others with a very easily seen dip. You can also see how misfiring really screws up the graph, with sharp hills and valleys. Not like my Werges/Denco dyno sheet, where the waviness is from RF interference, not having any resistor in the iggy system, and that's why it is mph, as I couldn't use a iggy pick up for a torque graph.

http://s186.photobucket.com/user/johnbo ... t=3&page=1

The thing is, torque dips big or small, cannot always be felt on the butt dyno. Here is a vid of me testing my 750 for flat spots, and I could not feel one at all, or you can see on the vid there is nothing noticeable, but the dyno showed there is one. And this is at 5500ft. (22%) horsepower loss, 15/45 gearing (stock is 15/47) which should have really accentuated the flat spot.

https://www.youtube.com/watch?v=HsFCLqxF2Kg.

Empirical proof wins the day. Book guys can go on and on about flow this and flow that, and this is what is "supposed" to happen. The truth is it just doesn't always work in the real world. And that goes for many things, in life, not just tuning.

Andrew (Walms) has been doing testing on a new 500 stage II reed block design for me. With his high RPM pipe, and my old reed block design, there was a definite flat spot that could easily be felt, it was awful. One would think from some opinions, taking the reed tip and moving it from 22mm away from the piston, to right up to the piston (my new design) this would make the flat spot even worse. Well the flat spot almost totally vanished. Real world data, this is what is useful for tuning.

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

First off, Thank you Tuner for the kind words they mean a lot from someone with your pedigree!!

Second WOW! I love this forum ..really great stuff!
I have read Jorgens post several times and appreciate the way he explains things and I do get it.
And with Moo's last post I will be busy for a while looking it all over.
And once its back on the road of course I will be posting what happens, and probably looking for more advice.
And please keep adding to it!
And from what I am learning I may be looking for pipes soon, Jorgen I can't wait for your tests on the Spec II pipes.

Here is one dyno sheet..

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I am just a man working in a tin shed.

Not seeing a dip there Johnno.

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I am just a man working in a tin shed.

Just a minor one, Nev. Nice curve. Does the motor have one of your retard iggys?

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

Yes. That's a 17 year old graph. I can't see a dip at 5200 rpm. It pulled all the way thru. See the shape of the torque curve. I don't see one like that in any of the ninety. That's not the most powerful 500 I've done, but it was sweet to ride. Pulled 16/43 sprockets at Phillip Island. No reeds. Not my bike but a happy owner.

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I am just a man working in a tin shed.

Nice torque pipe on that graph Nev. After having both a torque and a race pipe on my bike, I'm happy to have it start and sign off early... So much easier to ride on both the street and the track.
The flat spot can be moved around with different pipes easily enough.

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http://kawatriple.com/wtf/

WOW.

That's extremely impressive work you have done on that 500 Nev. It's absolutely amazing getting those peak power numbers, still having almost 25 at 5000 rpm.

I see the powerband starts at 5900 rpm, (a bit hard to tell) a very smooth transition from mid range to powerband. If so, that is exactly at same rpm as Walms 500 with Clough pipes at RB bash. Isn't that correct Andrew? And same number for your torque pipes, 5700?

Jørgen

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

Yes, the power spread is very similar to my torque pipe, just a bit higher... Mine is 5300 - 8200

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http://kawatriple.com/wtf/

Ok, that low. I thought you got on pipes a bit after 5500, but I may remember wrong.

Can check it up though, as I have the converted torque /power curve back home.

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