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90cc advice needed
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Posted by: medicallen

I am needing some advise, I have an 04 with some mods, hetrick pipe, 24mm carb, uni filter, it is a 52mm bore I just put a fresh piston and rings in it and now it will idle fine, but if you give it past 1/4 throttle it cuts out and backfires and won't hardly run, but it goes right back and idles fine. If you go straight to full throttle it bogs and dies? I've tried plug, reeds, and cleaned the stator. Anyone got any suggestions?

Posted by: Nick's #1 Fan

First thing I would try is checking the grounds. If they are in place add an extra one just to be sure.

We had a similar problem and added a ground wire and it seemed to solve the problem.

The not running part sounds like a fuel (Carb) problem but the back fire make me think it's electrical.

Posted by: 03bill

Are you are using the stock carb and airbox?

Posted by: medicallen

No I am not using the stock carb, It's a 24mm with uni filter. It was running good befor the top end rebuild. I looked at the wireing some, I will try the add a ground and see. where exactly did you add ground?

Posted by: Nick's #1 Fan

I went right from the coil to one of the bolts on the clutch cover. I can't remember which side of the coil I came off of so look and see where the ground is coming off now and add another one to the same side.

Are you still running the stock wiring harness on the bike?

Posted by: howmuchnow

Is the piston in correctly ?

Posted by: Nick's #1 Fan

Would it still idle if the piston was in upside down?

I heard that they don't run very long when they are installed upside down but don't know about idling.

Posted by: medicallen

The wiring harness has been stripped down to the bare minimum. piston is right..lol (I checked it) I think I will get a compression tester and just see what she has, Does anyone have a number on what stock compression psi is?

Posted by: howmuchnow

with a stock head around 120

Posted by: Livin4Real

jetting? You did just do a fresh topend.

Posted by: drr5

im gona say ground.