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99 RM250, I can’t get rid of exhaust spooge.

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I have an 1999 RM250 which is a spare bike that gets ridden mostly by a guy who does not ride it real hard at all and it smokes a spooges a lot. It doesn’t seem to foul plugs but they are defiantly wet upon inspection. It is pretty dark as well. My guess is that the combustion chamber temperatures are not high enough to burn off the premix oil. I considered dropping the plug to a number 7 instead of the stock number 8. I know that jetting would be the first suggestion by most tuners but the pilot and main jets are already one size smaller than stock. The needle is stock and the clip is in the 3 slot. I might move the clip down one slot before I change the plug number. Aside from the jets everything else is good except I will repack the silencer again. The compression is good and the top end is fresh with only about 6 to 10 hours of ¼ to ½ throttle only riding. I told him to open it up once in a while to clean the engine out a bit. I did a leak down test and it was super great. The air filer is spotless and oiled correctly. I don’t really want to use less oil since that would make it even richer. I don’t want to use more oil since that would make it run even cooler. I run 32:1 Amsoil Dominator. Also, all this spooge took place when it was 70 degrees out. It has not been ridden in the cooler temps but I would suspect the same would happen.

Any suggestions?

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Spend a little time on jetting, I recently purchased the same model year bike and was able to look up some recommended jetting on TT and a few other sites, I dont have the numbers in front of me, but the recommended sizes were pretty consistant.

Re-jetting will make the bike run better with less spooge, and it will actually make it easier to ride. If it is rich down low, then the hit will feel extra hard when it hits the mid-range/powerband making it more difficult to ride especially for someone with minimal experience. If you jet it properly, you should be able to smooth out the hit and make it easier to ride.

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Thanks. I just rejetted my 2007 YZ250 along with some other minor mods. I richend up the main by one step and moved the needle up one position by moving the clip down. It runs awsome now. I guess the RM needs to go the other way. I will probably just lean out the needle for now since the rider will never see the main jets working. Rather slow rider.

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From MXA:

1999 SUZUKI RM250

Jet...Stock...Recommended

MAIN...158...152

PILOT...45...42

NEEDLE...N1EG...stock

CLIP...3rd...2nd

AIR SCREW...1.5 turns...stock

This seems to be typical of what I have found for the 99 rm250, I have yet to try it yet.

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