At my Wits End - Kasea 90 Starts Runs Good then Falls Flat?

[jrns281]

Hi Guys,

OK my sons bike blew a piston and did a new top end. The compression post top end was 110. So we test drive it around the yard and seems to run fine for maybe 10 minutes then just completely falls flat with no power whatsoever. Ok so I tried to diagnose the problem but at my wits end and seriously could use some expertise.

Things I attempted to resolve problem after top end.

1. Cleaned Carb and jets, float and it gets plenty of Fuel

2. New Spark Plug and bike fires right up and can stay idling until runs out of gas.

3. Got new Reeds

4. Checked compression and it is at 110 WOT

5. Checked Rollers and were in good shape.


Bike runs great for like 10 minutes or until the engine gets warmed up. Once warmed up if my son puts any load on the quad (going up a small hill) the quad just cannot climb it as if just has no power and even on flat surfaces just runs slow. I have reached the end of my expertise on these bikes and am frustrated I cannot seem to solve this for my son. The bike is a kick start only so no battery.

I am at this point maybe guessing it is an electrical issue? Coil, Stator, CDI?

If anyone knows of a reliable shop in Southern California I would be willing to drop it off.

Thank you for taking the time to read my post.

[LT80]

Heat is usually a coil/CDI.
Could the pipe be plugging up?

[lon]

Is the new piston the same style as the old one? The only reason I ask is because when we had our top end rebuilt the guy went from a flat top to a domed piston and we lost alot of power because of it.

[desratt]

check compression when its really hot. also when its hot check the crankcase for leaks. or a leak down test.

[jrns281]

Thank you guys for the kind advice. I have had the opportunity to get some local help on the matter and trying to figure out the problem. Will check the Comp and the piston was the same style (flat) as the original piston.

[jrns281]

Problem seems to be resolved and it was a couple of issues including the Torque Spring and jetting. I really want to thank Brian & Emily SAIEVA (ONTARGET RACING) for their generosity in helping us with the bike.

[ontargetracing]

No problem.. Glad I could help.

[desratt]

good PEEPs right there. ^^^^ and good luck back on the east coast

[oscarmayer]

Bryan and Em rock! great peps!
We miss seeing them at the races. :`(