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Fuel Mixture

Joined
Jun 4, 2007
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#1
Hello All,

In a previous post, I had a problem with my 01 CR250r bogging when giving it a full throttle twist.
I pulled apart my carb and it was gummed up pretty bad (the bike had sat for 6-7 months). The jet that was in it was a 390, stock jetting should be a 420. I have an FMF pipe and silencer, they recommend a 400 jet. After cleaning the carb and putting a 400 jet in, the bike ran like it was new (tons of low end power).

After repacking my silencer, I still noticed some oil coming out of it.
Do you think I should lean my gas mixture out a little? I currently run the HP2 Honda oil at 32:1. (1) 16oz bottle to 4gal 93 octane gas.

If you have a CR, let me know what mixture you run. Or anyone else is welcome to chime in.
Thanks in advance!
 
Joined
Jun 12, 2007
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#3
Normally ppl on a 250 run 40-50:1 although the mixture isnt the real problem your jetting is. U can jet to any mixture but remember that you have to rev high with a 2 stroke. Even a perfectly jetting bike running a low rpms may foul a plug after a while.

Sounds like its rich, spooge is unburnt oil that comes outta the exhaust. I had that problem too, sometime it would bog cause it was so rich. I would say do a plug chop test, this is test to see if your jetting is rich or lean, To test your main jet, get on a long straight and full throttle through all the gears. When it tops out pull the clutch in and kill the engine and coast to a stop, or just let off the gas and brake. Pull out plug to see what it is like using a plug reading guide. Too rich is when its oily and you can foul plugs by this. Go down a size in the main and do the test again. CHeck plug. etc keep doing this till you find that perfect size when the plug is a chocolate brown colour.

Although your main jet may not be the only culprit. Use a jetting guide that you understand to get your jetting sorted. Spanky's jetting guide is the best in my opinion.

Have fun and I hope you get it workin.
 

_JOE_

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May 10, 2007
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#4
Read the oil bottle. Engine temp will greatly effect spooge. Low temps=spooge.