Kart gx200 mod skip at 6700rpm

[Yannickp]

Hi
I have gx200 kart.
Cam 285
Flat piston forged and long rod wisco
Roller 1.2
Big valve
Head 22cc port and milled to 0.070
S2 flywheel
Mikuni 24mm carb jet 140 pilot 20
Spring 37 lbs
Pushrods moly 5.5
That's what I have .. The engine start skip between 6500 and 7000 rpm
I don't know why ... Do you have any suggestion ??
I try my oem carb port and do the same thing
Thank for your help
I want go to 8000rpm

 

[88nightrider]

Valve float? Or ignition problems?

 

[mckutzy]

Hello and welcome...

What is skipping?

 

[Yannickp]

Thanks fire go out of exhaust when skip ..... It's like cut off .. Bug sometime it's happen at 6600 rpm sometime 7025rpm .
The valve I'd 37 lbs I don't think is float
Before I change everything I had 16 lbs valve and float at 7500 rpm ... And they never skip

 

[Yannickp]

When I crank for start sometime backfire happen ..... And it's hard to start....crank a lot

 

[itsid]

valve not sealing properly?
forgot to have them lapped in?
valve lash not properly set?
ignition advanced too far (like billet flywheel plus advance key)?

open it up and recheck EVERY single bit!
You wouldn't want a 7k revving GX in your back that decides to instantly turn 0rpm

'sid

 

[bad12jr]

Check the coil some have resistors in the boot. Can cause the skip.

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