cr250 engine running on

Joined
Dec 20, 2002
Messages
23
Likes
0
#1
my 99 cr250 engine has developed a problem of running on,when i shut the throttle off the engine keeps running on as if im stuck on half throttle and then after about 5 laps it seizes.the cable is free and shutting the carb off,i have changed the barrel and head and cant see any leaks.anybody got any ideas please?
 

darringer

Lifetime Sponsor
Joined
Dec 2, 2001
Messages
1,029
Likes
0
#2
Could be a lean condition from a possible crank seal leak on the magneto side.
 
Joined
Jan 2, 2002
Messages
30
Likes
0
#5
do a leak down test, you could have air leaks in the air boot, cylinder base gasket, cases not mating correctly, crank seals both sides or reed cage. on some bikes the clutch side crank seal can pull air. a leak down test is the only true way to find the leak. don't ride this bike until you fix it or you will be buying a new crank or worse cylinder, piston, crank and gaskets&seals. if you don't know how have a shop proform the test.