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jetting RM250

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Hi, im new here and to two strokes ive had my 00' rm250 for about 3 months and it runs good at wot and it will idle all day long but it seems rich from 1/4 trottle untile the power band comes in. the hotter the engine gets the better it seems to run. For ex. in first gear it dont seem to want to clear out and run wide open it just stutters but if i shift up to second and lug a little it will clear out and run. I ride around 3000 ft its about 70 to 80 degrees it has a twin air filter and a fmf sst header pipe and a fmf twin turbin core2 silencer with a usfda spark arrestor. The N3WK needle is in the 2nd position it has the stock 42 slow jet and 158main the air screew is 2 1/4 turns out and the bypass is 2 turns out not sure what the bypass is for though?? i guess im wondering if i should just try moveing my needle or do i need to change my main to somthing smaller? Any help would be great thanks. Oh and i do mostly trail riding but im working on a track near my house but dont plan on raceing just playing. there is also a some sludge comeing out of the exuast im useing klotz super techniplat at about 40:1 ratio. plug is always wet and black but never fouls. thanks again!

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Two things, one is your pilot needs to go up to a 45, and your main needs to go to a 155. Also the air screw needs to go in about another 3/4 turns, to 1 and 3/4 turns out. These specs are from FMF Racing's jetting chart, and you should be REALLY close on the jetting, a little rich for 3000 feet, but it sounds like your bike likes to run rich so no worries 👍

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thanks man i'll give it a try! were's a good place to buy jets or jet kits on the net? 👍

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bigd270,

Here’s a jetting chart I put together for your bike that should help to clarify how jetting needs to be adjusted for different temperatures / elevations. For you current conditions I would drop the main down to a 150, keep the needle in the #2 (from the top) position and drop the pilot to a 40. Make sure you start with a clean air filter. Set the airscrew @ 1-1/2 turns out from fully seated position and you will be within 3/8 of a turn + or - from the ideal setting. I hope this helps out.

2000RM250Jetting.jpg

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Hi, im new here and to two strokes ive had my 00' rm250 for about 3 months and it runs good at wot and it will idle all day long but it seems rich from 1/4 trottle untile the power band comes in. the hotter the engine gets the better it seems to run. For ex. in first gear it dont seem to want to clear out and run wide open it just stutters but if i shift up to second and lug a little it will clear out and run. I ride around 3000 ft its about 70 to 80 degrees it has a twin air filter and a fmf sst header pipe and a fmf twin turbin core2 silencer with a usfda spark arrestor. The N3WK needle is in the 2nd position it has the stock 42 slow jet and 158main the air screew is 2 1/4 turns out and the bypass is 2 turns out not sure what the bypass is for though?? i guess im wondering if i should just try moveing my needle or do i need to change my main to somthing smaller? Any help would be great thanks. Oh and i do mostly trail riding but im working on a track near my house but dont plan on raceing just playing. there is also a some sludge comeing out of the exuast im useing klotz super techniplat at about 40:1 ratio. plug is always wet and black but never fouls. thanks again!

if u r a short shifter and do not rev the bike hard for the majority of time drop the r-50 for starters,.

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Vetmxrider!!!!!!!! Can u do one of those for a 2004 KX 250. Been pulling my hair out. I know they r different bikes, but they are probably close.

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gaskillkfx, i hope your not trying to tell me what i can or can't ride here i just wanted some carb help. i love my rm i would keep it wide open all the time if i could but i got to stop everynow and again to rest and sometimes its hard to get it back in the powerband because of the rich spot at 1/4 to 1/2 trottle. i know everyone around here says get a four stroke and i would have if thats what i wanted but i always wanted a two stroke bike so i got one and have no regrets! there is nothing like it when it gets into the powerband and i cant get enough of it. i would ride it everyday if i could, oh wait i do ride it everyday lol 👍

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Vetmxrider!!!!!!!! Can u do one of those for a 2004 KX 250. Been pulling my hair out. I know they r different bikes, but they are probably close.

gaskillkfx,

I just completed a jetting chart for your bike. Start with the airscrew at 1-1/2 turns out from fully seated. Wait until you have the motor fully up to operating temperature and then adjust the airscrew in 1/8-turn increments until you find the best throttle response. Please let me know how this works out for you.

2004KX250Jetting.jpg

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Bigd 270! Iwas only saying if u r riding in the woods alot, and you are short shifting and lugging the bike, It seems like the Klots R-50 likes to load up. That was my carb advise FWIW.

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VetMXRider! Thank you for that info. I owe u one. Greatly thankfull!!!!!!!!!!! Them r awesome charts.

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oh ok i thought you were refering to my rm-250 as r-50 my mistake sorry about that! so your saying i may sould try a differnt oil? what kind do you use?

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