Kawi2strokes.com Forum

Seems like the flatslides gives some extra power when correct tuned. Me like, since I am about to put them on. My dyno result with 2mm raised exhaust, vm34 and jollymoto was 84. 81 without the exhaust raise and same carbs and exhaust. But my butt dyno prefer the 81 hp version, it just felt quicker!!!

By the way: By 2mm raise, did you mean the cylinder or just the exhaust port?

If you ment the cylinder you have a lot more transfer angle.area, as the transfer floor is considerable lower than piston dome, but less blowdown angle.area than just raising the exhaust. On your 100rwhp H2, you did both did'nt you?

Jorgen

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

Arne bike: cylinders are raised 2 mm, so both ex and transfer ports are raised while skirt cutoff compensated for loss of inlet timing.
My bike: just ex-port is raised 2 mm, no cylinder lift. Port timing is stock, angles are changed slightly. Pistons with 1 pistonring, aluminum liners nikasiled. Found out yesterday my revcounter was reading 350 RPM too high so the whole graph should move to the left. Max torque was 90 Nm and should be 95 Nm@6900. Max RWHP stays the same obviously. This engine has been raced for three seasons by now, never missed a beat.
Ignition is standard H2 with Lush iggy box with retard past 6 K.

_________________
Speed is what’s life about.

Thanks for great info Leo.

I will "file" your info as I am searching for as much power as possible with 34mm set up.

Jorgen

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

.
On this occasion Leo, you are so VERY wrong, a couple of years ago I built 4 PERFECT stock H2's, a 1971, a 1972, a 1973 (yes, there were 2 versions of '73 cylinders) a 1975 H2c, I took them all to a newly installed just calibrated DYNO , and every bike was over 70 BHP without even running them in . . I was curious as to why the 1971 Cylinders delivered SO much more horsepower

_________________
Always remember, there will be greater and lesser people than yourself . . . you can learn from either!

Where are the dyno sheets?

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

What did you figure out?

_________________
Using a poorly conceived idea along with bad mechanical practice is not an upgrade but rather a recipe for disaster.

Maybe my dyno is one of the "tough ones" regarding hp.

Had a 100% stock H2 with second style cylinders, freshly honed and made exactly 60 rwhp. But that power was obtained some hundred rpm's prior to estimated peak power rpm at 6800 rpm, running rich I guess.

As said, just did 2 runs with stock cylinders and stock pipes but with vm34. Did not get more than 68 or something. I have a friend with the very early untouched 1971 cylinders where the transfer ports in cylinder steel liner is oriented at a complete different location than all the rest. Will try his bike on dyno spring time to see. This bike has stock VM30 today, but wanna upgrade to VM34. We will off course measure the bike with both 30 and 34 carbs. Bike gas fbg pipes though..

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

Leo what pistons have you fit with one ring only?
interesting me as we have try nickasil or exactly revaltec on the genuine kawasaki liners and we have trouble with genuine kawasaki pistons rings on a H1B - seized- but not on a H2A.

"As said, just did 2 runs with stock cylinders and stock pipes but with vm34. Did not get more than 68 or something. I uhave a friend with the very early untouched 1971 cylinders where the transfer ports in cylinder steel liner is oriented at a complete different location than all the rest. Will try his bike on dyno spring time to see. This bike has stock VM30 today, but wanna upgrade to VM34. We will off course measure the bike with both 30 and 34 carbs. Bike gas fbg pipes though.."


Why do you think Kawasaki changed the porting? I have seen cylinders that had very little material between the intake port and the transfer troughs, then Kawasaki lowered the liner cut outs for the transfers, looks like to keep from breaking cylinderss.

But you have to wonder why with the power of the original H2 they would change the porting so significantly.

If you had a completely stock H2A what are the best mods for a nice boost in performance, maintaining the most mid-range power and still with a nice jump in performance?

_________________
Using a poorly conceived idea along with bad mechanical practice is not an upgrade but rather a recipe for disaster.

A set of Jollymoto, VM34, untouched cylinders (even the latest ones) and you almost do 2.gear powerwheelies with stock gearing. With Aylor reeds, you do even better.
Amongst the oldschool pipes, I have heard Jims Dencoes is the best for peak power, and perhaps Higgspeed for best torque down low and in midrange. One gotta dyno to make sure.
81 rwhp with the jollys. Same configuration, but with 2mm exhaust raise gave 84 on same dyno same day.

BUT, and this is important: My butt dyno told me the 81 rwhp felt the quickest, so if I could choose between these 2 I'll take the 81

There are many many pipes I have not dynoed, like factory, fbg, specII, WalmsTriplenutsFatties, k2tec, lush etc. Fatties gives more power prior to pipes hit.
Dont have a clue about the earliest cylinders, will be interesting to dyno the bike mentioned earlier with those cylinders.

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