power problem

[roadrunnerian]

i have noticed with my stage 4 gp200 which has had 3mm cut off sometimes when you open it up it goes great but when i was overtaking some cars i had to shut off then open up it won't go give it 20 seconds and it goes. could the cut off the piston be the trouble any advice
would be gratefull thanks

[sean brady scooters]

your trouble is probably down to carb set up.....did you have it dyno,d after the tuning mods..?

[Dazza]

Fuel supply flow rate?

[roadrunnerian]

thanks for the quick replies no i have not had it dyno,d because the person who built the engine said it was all set up right.how much do you charge per hour? i live near chorley its not far

[lee b]

hello ian!!!

[Stampede]

would be the blowback, i think. perhaps go for a LTH manifold to sort it!

Longer inlet timing (shorter piston ) doesn´t make this problem better....

Which carb do you use? A big one, bigger than 25mm?

[roadrunnerian]

i have a 28mm carb on the scoot m8

[sean brady scooters]

your carb settings,irrispective of what carb or size it is will need setting up for the new stage 4 tune.....
your tuner should have advised you in that respect........

typically you may find the need for a smaller pilot jet,and maybe diffuser and needle changes....etc

perhaps post up your carb /engine details and then maybe we can give you some pointers

[soosh]

What pipe you running?

[chris2470]

Is it a PWK type carb by any chance ??