ESE's works engine tuner

[TZ350]

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It sure as hell isnt the ignition system, but for the 10,000 th time, are you using a " proper " fine wire race plug that needs 1/2 the gap voltage to ionize.

I am a pensioner so No, not been but I have one and will try it. The NGK R7376-10 is so damned expensive.

First thing to look at is when the piston is at TDC, does the piston side cutaways expose a lump of Aux real estate , connecting the case to the Exhaust duct
thru the side port ducts. That will run like shit.

Looking at the old Suzuki piston in the single exhaust cylinder it looks very possible that the side exhaust ports may be opening into the crankcase at TDC.

I will have to take the good cylinder and piston off to check ........

Cylinder off will be the first move.

[wobbly]

The best place to buy the NGK plugs is JDM Planet - very reasonable shipping as well. But here is another idea I have been using for some time now.
A NGK R0373A is the 10mm version of the R7376 , and is cheaper, plus it enables a minimal boss intrusion into the chamber when using a Toroidal dome
to reduce the shadow or masking effect on the loop flow across the dome face.
This idea was proven ( though sworn to secrecy ) via a World Champ winning big bore snowmobile project.
The small resistor caps to suit are cheaper as well - I got a bunch from a British Bike parts place in ChCh I think.

And yea, if your Aux are linked to the case - the jetting goes completely to shit.
Same thing happened when I cut the skirts short on a " stock " World Champ Jetski with a 2: 1 pipe setup.
The fuel curve went out the window completely, and it was only due to having pumper carbs with Aux venturi's that allowed the thing to be dialed back in.
Made a shit ton of top end power, and won a title with zero chance of any tech seeing what had been done.

[Larry Wiechman]

Attachment 357296

FireBall PS92N

PS91 or PS92, 3 Ω or .82 Ω, which one is preferred?

[Hoebra]

About the dip in the powercurve: Maybe not thge spark is lost in this rpms, but AFR is crazy wrong? Looking at the curve it is about the rpm of maximum torque. Have you made any changes to your scavening or your diffusorcreation? Once your scavening is less stiff than before, or your main Depression pulse is much stronger so sthe scavening colapses as it hits, leaving a lot of burned gases inside, as the this maindepression pulse gets weaker scavening becomes stiff enough again and AFR gets back to normal.
Had such phännomena by testing diffusor dimensions on non full race cylinders. Got good good curves with mild diff anngles, by increasing them torque an power rised, until a point of 18°+ main diff angle, curve startet at the same RPM with even higher torque, dipped than completly around max torque rpm and after this again went on with more torque than before, but in the region of the heavy main depression pulse great dip in the torque/powercurve, so to much Depression for the stiffness of this scavening.

[wobbly]

The coil I used was a PS92N, built for Nascar CDI systems.