1999 cr250 jetting problem

hey

i have a 1999 cr250 that has been running super rich. I ride at 700 feet above sea level and in 70 degree weather. bike currently has a size 45 idle jet and a size 160 main jet and the needle is set 1 clip below stock. Running a pro circuit platinum pipe to a fmf turbinecore silencer with 40:1 honda hp2 oil. I know stock main jet size is 190 correct? could it be a problem with the reeds? ive messed with the air screw multiple times and it doesnt help much. at this point im just really confused.

Edited by osten

Indeed, bad reeds will make the engine act rich.

Before ANY attempts at fine tuning the jetting, adjust your carburetor's float level to specs.

 

Not 'fuel' rich, but rather oil fouling,

despite no external leaks, if the gearbox oil level seems to drop frequently 

you could suspect a bad right hand side crank seal. (oil injested thru the crankcase)

Edited by mlatour
1 hour ago, mlatour said:

Indeed, bad reeds will make the engine act rich.

Before ANY attempts at fine tuning the jetting, adjust your carburetor's float level to specs.

 

Not 'fuel' rich, but rather oil fouling,

despite no external leaks, if the gearbox oil level seems to drop frequently 

you could suspect a bad right hand side crank seal. (oil injested thru the crankcase)

ok i will look into new reeds 

 

never have had a problem with the gearbox oil level dropping thank god

Low compression as well makes the engine 'act' richer that usual.

(in the event of a way overdue top end refresh)

 

The air screw is quite simple, it fine tunes the pilot jet circuit.

With the engine warmed up to operating temps you adjust it to obtain the highest idle and best throttle response. (daily)

Beyond it's adjustment range you need to switch to a either smaller or larger pilot jet.

Edited by mlatour

I have one of those bikes with stock jetting at sealevel. They have a real rich spot just off idle that is apparently best fixed by modifying or changing the slide.

Reeds got here today just waiting for new carb hose to get here and some warm weather 

I went ahead and ordered a JD jet kit too

What jet size should I start with? 

20180131_174818.jpg

JD kits come with instructions and a reccomended starting point for your model. (Worked well on my "06 250 following his specs)

Clean carb well when you do jet/reed change

Correct float level is very important as stated earlier.

There is a lot of jetting info on TT

 

 

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