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01 rm250 running rich

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i bought an 01 rm250 it had this setup stock pipe, with a pro circuit r304 shorty silencer, it ran good with that setup, but because i do all my riding at a state park i need a spark arrestor, so i bought a fmf turbine core 2 spark arrestor and installed it.

first ride with the spark arrestor sputtering up top, great low to mid (i think) but no top. eventually fouled a plug, went to my carb went down on the main jet from 160 to 155

rode it again same altitude and settings and it rode a bit better, but still sputtering and still fouled the plug (longer ride duration though)

im a beginner when it comes to jetting, what do you think i should do?

i dont want to go leaner on the main for fear of running too lean

what are some recommendations?

setup: 01 rm250, 40:1 premix ratio, stock pipe with turbine core 2 spark arrestor

i ride at carnegie OHV in northern california i think its about 100-600 feet above sea level. normally not humid at all.

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You have a 160 main jet? Stock is a 460. PC recommends using a 430 with their pipe. And the stock pilot jet, but change the clip position on the needle to the 2md position.

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Procircuit recommends a 160 mainjet over the 162 stock, and they do recommend raiseing the clip position to the 2nd position.

Stock RM250 jetting 162 main, 48 pilot, N3WK jet needle, 3RD clip position, airscrew 1 1/2 turns out

Pro Circuit recommended jetting 160 main, 48 pilot, N3WK jet needle, 2ND clip position, with the airscrew 11/2 turns out

You need to start from the pilot and wok your way through the needle and main jets, providing everything is fairly fresh motor wise(topend, reeds)Temepature/elevation and riding style will all play a part in jetting.

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What was I looking at? But yes yathump is correct.

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Hey I ride at carnegie too all the time :p

Suzuki jetted the bike for 32:1 premix. your running 40:1, it wont change much but it's still a "richer" premix fuel wise so jetting down a bit & adjusting the airscrew is not uncommon

switching from a 162 to a 155 is a big jump, put a 160 in and drop the needle to the 2nd clip from the top.

how fresh are your reed's? off spec reed's can give your big a false rich condition and foul plugs.

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cool thank you, i havent checked my reeds yet, i pulled my carb off, and am waiting on some new float bowl screws (3 of the 4 were stripped:banghead: idk what the previous owner was doing) before i work on it. im going to check my floats to make sure they are in spec, and thanks i will check my reeds too, FMF's site says a 158 main for my bike, but thats with a 32:1 premix, you think a 160 will be fine if i move the needle to the 2nd clip?

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or you could use a 32:1 mix. its better for your engine.

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or you could use a 32:1 mix. its better for your engine.

Some oldskoolers will run 24:1 !! better ring seal but you need to know your jetting for sure.

I run full synthetic at 40:1 but if I was to switch back it would be 32:1 with out a doubt.

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well peak hp is achieved at 15:1 and that is where you get better lifespan. 15:1 is unrealistic though. I go 32:1 with fully sythetic and 50:1 with natural oils.

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ok so my floats are in spec, and my reeds look fine, i raised the needle to the 2nd clip (it was at the 3rd) and put in a 158 main, took for a ride yesterday and it ran great!

took me a week because all the floatbowl screws plus the 2 screws on the top of the carb were all STRIPPID:foul: stupid previous owner!

so i had to wait for new ones

but its finally complete

thank you guys for the help:thumbsup:

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