ESE's works engine tuner

**TZ350** · 9th December 2025, 14:47

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Originally Posted by wobbly

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.

Originally Posted by wobbly

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.

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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** · 9th December 2025, 15:45

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** · 9th December 2025, 18:08

Originally Posted by TZ350

Attachment 357296

FireBall PS92N

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

**Hoebra** · 9th December 2025, 20:55

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** · 10th December 2025, 08:28

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

**ken seeber** · 10th December 2025, 18:23

The man says:

"Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one."

Just maybe it's true:

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**wobbly** · 11th December 2025, 12:56

Kentastic, that was a line from a Joni song - she's older than me, but I would hope some much younger ladies would like that version of me, due to obvious physical enjoyment.

**husaberg** · Yesterday, 10:17

**diesel pig** · Yesterday, 12:26

Damn you Husberg! I now know what I will be doing this Xmas.

I got a little weirded out when I check out the JDM Planet site it's a car parts site but they do have all types of NGK plugs for reasonable prices.

**crbbt** · Today, 13:47

Originally Posted by wobbly

I have removed the PJ in that carb by clamping s piece of square steel in the vise, hold the PJ end square on the bar, and tap the body directly next to the pressed in ball.
The PJ tube and the ball easily came out doing this.

Thank you!

this worked. Now to find your post about putting the 0.2mm hole into tube to atomize the fuel coming out of the PJ

**husaberg** · Today, 14:06

..............

Originally Posted by crbbt

Thank you!

this worked. Now to find your post about putting the 0.2mm hole into tube to atomize the fuel coming out of the PJ

Originally Posted by wobbly

Here's a mod I have done on many Yamaha racebikes with the electronic solenoid PJ - move the PJ to the top of the bellmouth and shorten the dump tube so it
only protrudes around 15mm into the bore . I cut the tube end at 45* facing the reeds as this atomizes the fuel stream much better than the stock small hole does.
The slide has to be well past the tube end for flow to begin , having a low down tube richens the fuel curve way too much in the midrange.

The only other way is to use a truth table in the ecu to switch the flow depending upon TPS and rpm , but this is problematic to tune , causing jerking response on part throttle , mid corner.
Cutting the tube short works on Lectrons as well , when having to use large PJ flow ( 50 + ) to get the top end tune correct without shagging the midrange jetting.

Originally Posted by wobbly

Re the tiny bleed hole in the TZ powerjet tube - I always thought that this was a good idea to emulsify the fuel as it exited the dropper.
But years ago i did some wet tests on the flowbench with a VCR video camera ( pretty trick shit stuff back then ).
The Mikuni was a horror scene when played back slo mo,with huge "gobbs" of fuel exiting the main and powerjet.
We then stuck on a Lectron - wow, lovely fine mist of fuel from the back of the flat needle face - and it flowed 12% more air - size for size with a venturi 2mm smaller behind the slide.

Next is the current state of TeeZees GP125, here is the latest dyno curve digitised with 16% added to simulate crank power.
Then there is the sim with an actual RS early model pipe.
Then there is the new pipe of my design.
Of most interest is that in this case the sim is giving slightly too much crank power - but the shape and peak point are all but perfect.
I would be confident now that any change in the sim, would be reflected in reality on the dyno.
In my experience the later Dynojets like a twin roller 168 with Eddy current load control to slow the acceleration rate down ,seem to read around 5 to 10% lower
so this would put the sim and the dyno reading very close, as the shape is spot on now.

Originally Posted by wobbly

When using a simple powerjet nozzle the tip position matters in that no flow will occur until the slide is well past the exit hole, and there is sufficient airflow
to drag fuel up the feed tube above the bowl level.
With the aftermarket add ons and the ones as used by Lectron you can shorten the dump tube so that the flow will only occur at high slide openings,as well as high air flow.
These also have a built in "lag "control in that it takes time for the fuel to rise up the tube and dump out the exit into the air stream.
With a solenoid controlled setup all this is pretty much irrelevant as the flow can only occur when the solenoid is not powered up, and this
is TPS as well as rpm dependant inside the ECU program..
The carbs as used on the MX bikes has the dump tube very low in the bore as they added and subtracted fuel at low slide positions in those bikes.
For a race engine I bend the tube up to around 1/2 bore, as this is where the exit is on the Kehin SPJ carb for RS125/RS250 Honda.
And the general setting is the solenoid is powered up ie no flow below 4000 and 60% TPS and is powered up again at around 12400 to lean off the mixture and increase revon.
This causes a problem with Ignitechs that are used with only a capacitor, as at startup the solenoid is powered up, dragging all the voltage out of the ECU, so I convert the ECU output
to a 3 step truth table, and have the setting such that below 1500rpm the solenoid isnt powered.

**crbbt** · Today, 16:01

Thank you Husa,

I gave up after an hour.
Not sure where I recall the 0.2mm hole from however

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