confused about tuning

Im tuning my 19mm phbg on an e-50 polini, with malossi four petal and I can get the idle setting quite right.

I have tried a 55,50,45 idle jet and the idle speed screw doesnt effect the idle at all. It idles high and fast and rpms dont drop right after hitting wot and releasing

No air leaks, and the plug keeps coming out semi wet.

I would guess the idle is too small due to the high idle?

Needle is on second notch and a uni filter for air.

Get bigger jets?



Re: confused about tuning

Стев Браун /

Have you checked the throttle cable to see how much it's pulling?

Re: confused about tuning

Jason Luther /

yeah, sounds like a throttle cable issue. loosen it all of the way, and then tighten it until the slide just starts to rise

Re: confused about tuning

went and checked and the throttle cable is sticking alittle when the slide comes down and if I am correct there shoudl be a little gap left after the slide is all the way down right? Like a quarter inch gap?

ps. If I jiggle the cable a bit the rpms die down. need some cable lube i guess

Re: confused about tuning

if the cable is the absolute right length, then <i>when the idle adjustment screw is screwed all the way out</i>, the throttle should be completely closed. also, the second you twist the throttle at all, it should open. then, by screwing the idle adjust screw in, you force the throttle to be open, even when you're not twisting it. the amount that you force it open determines the speed of your idle.

Re: confused about tuning

cool cable was a tiny bit short and now it idles better. got too dark but I will try the smaller idle jets tomorrow and see how that goes.


Re: confused about tuning

My bike is running pretty well now with a 50 idle and an 89 main jet however it four strokes around 18mph and then comes out of it.

Is this a needle issue? im in the middle setting right now and one notch down would be as lean as i can go. Does changing the needle affect the whole sprectrum or just mid throttle?

Re: confused about tuning

needle type and position effect the 1/4 to 3/4 throttle range. if you're bogging in that range, then you should lower the needle (i.e., raise the clip a setting or two). however, it sounds from your original post like you never tuned your air screw - thus, your pilot jet may be wrong, which could be effecting your mid-range too. read this post that elliot just put up for more info:

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