1998 yz250 surging done a ton of tests

hey guys

motor was rebuilt 28 hours ago

the motor ran great for 20 of those hours

 

it surges from idle to 1/4 throttle.

 

if I put a crazy fat PJ 65 then it almost goes away.

the bike runs great with the choke on

 

 done a leak down test and it does not show anything

 

checked crank seals

 

swapped carbs with another great running bike so its not a plugged PJ or anything

 

done compression check. 190 psi

 

no leaks of coolant or tranny oil

 

I have sprayed the entire motor area with starter fluid and no changes. 

 

took the bike to a shop and they did the same tests.

 

the shop wants to spilt the cases to look round inside..

 

with the bike running better with a crazy fat PJ 65 .... and or with the choke on ,,, it would scream air leak or lean.

 

anyone ever had this before??????????????

 

 

 

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