Posts
194
Joined
6/26/2008
Location
FR
Edited Date/Time
5/19/2022 8:43am
Hello,
I just finished to rebuilt a '01 250 CR, engine is basically new : replated cylinder, new piston, spark plug, gaskets, bearings, reeds, cleaned carb, etc.
Here is the rebuild post :
https://www.vitalmx.com/forums/Bike-Builds,46/250-CR-2001-Reborn,1399018
Compression is excellent, bike starts perfectly but does not rev from mid to full throttle.
When I go full throttle, the bike is shutting off just like when I press killswitch button.
My bike is smoking considerably considering every friction and rotating parts have been oiled before rebuild.
No air leak or gear box oil leak, seals and gaskets are new.
SO... I assume my carb jetting is way off and problem certainly comes from :
- Low float level
- Small main jet
- Too much air mixture screw
What are your opinion please ?
Thanks a lot, have a great day.
I just finished to rebuilt a '01 250 CR, engine is basically new : replated cylinder, new piston, spark plug, gaskets, bearings, reeds, cleaned carb, etc.
Here is the rebuild post :
https://www.vitalmx.com/forums/Bike-Builds,46/250-CR-2001-Reborn,1399018
Compression is excellent, bike starts perfectly but does not rev from mid to full throttle.
When I go full throttle, the bike is shutting off just like when I press killswitch button.
My bike is smoking considerably considering every friction and rotating parts have been oiled before rebuild.
No air leak or gear box oil leak, seals and gaskets are new.
SO... I assume my carb jetting is way off and problem certainly comes from :
- Low float level
- Small main jet
- Too much air mixture screw
What are your opinion please ?
Thanks a lot, have a great day.
Could be electrical. CDI--Stator
Hope it's not electrical.
The Shop
thank you for your help.
During the rebuild, the only part I did not checked or cleaned was my gas tank and fuel petcock.
It is stupid from me since I don't know how old was the fuel.
I started by draining my tank and removed the petcock.
There is probably dirt in my jet as well, I'll check everything tonight.
Also, the two vent tubes near the sprocket were pinched.
My main jet came loose and fell in my carb bowl, I havn't torqued it enough during rebuild I guess.
Engine was flooded with fuel at full throttle actually.
Now the bike starts first kick, revs perfectly and sounds crisp. I noticed the jetting was quite lean compared to OEM specs.
I live and ride at 900/1000 feet elevation. Bike runs with unleaded 98 fuel, 32:1 oil ratio.
Except a DEP pipe, PC silencer, engine is full stock and brand new.
Current jetting :
Main jet : 400
Slow jet : 30
Needle : 6BEH1-74
Clip : 3rd groove
Air screw : 1 3/4 turn
OEM jetting :
Main jet : 420
Slow jet : 35
Needle : 6BEH1-73
Clip : 3rd groove
Air screw : 1 3/4 turn
I'll ride the bike on a track this weekend, I cannot wait to test it.
Then it bogged on a big table, almost died so took it home. The main jet had backed itself out and was sitting in the bottom of the bowl, lol.
It almost devoured 1/2 liter of fuel and silencer was spraying oil everywhere
My car is white, it was parked 5 meter behind the bike. It has black oil stains everywhere.
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