RM250 Carb 98 vs 99

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May 15, 2007
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I have a 1999 RM250 that has a 1998 RM250 carb on it. I have searched the parts diagrams and part numbers and I can see that the carbs have different jetting and a different slide part number although both slides are #7.

Does anyone know if there is any difference in the 98 vs 99 carb other than the jets?

Here is what they have stock
98
162 main
60 power jet
45 pilot jet
niei needle

99
158 main
55 power jet
45 pilot jet
nieg needle

Both Bills and FMF suggest a 152 main on the 1999 and a 160 to 162 main on the 1998. Are the engines that different or is it the carb flow?

I'm want to install a FMF Gnarly and don't know where to start with the jetting. OR should I say don't want to start too lean. The stock pipe is damamged and cannot be used as a reference to begin jetting so I will have to pick something to start.
 
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