Jetting 01 RM 250

[Suzuki175]

I have an 01 rm 250 and having trouble with jetting it. I ride at a low elevation in southern maine. I have an fmf fatty to shorty pipe set up no motor mods and run 32:1 premix running 91 octane fuel. I was wondering if anyone had any ideas on what I should be running? As of right now bike runs good but when I check my plug its always seems a bit on the rich side.

[Onesolidbarr]

What's your elevation exactly? An jets are in the carb currently?

[Suzuki175]

Around 300 ft and im not sure on pilot but I believe main is a 480. air screw is at 1.5 turns out.

[yamaha racing 230]

You believe ? That doesnt help anyone . Find out what size main and what clip the needle is on . If you have a 01 and stock carb it should be a 162 main .... Id start with a 155 main and the clip on the needle on the second notch. Than after that put a fresh plug in it and do a plug chop test

[Suzuki175]

I said believe because I don't have the carb apart infront of me. the clip is in the stock position. And with the pipe I would want to allow more fuel so that would be up in size?

[Onesolidbarr]

Suzuki175, sometimes, sometimes not. Jetting a carb is a very finicky thing to do and like women no 2 will like the exact same thing. There are plenty of entry's in here that you can read up on. The best advice I can give you if you've not jetted before is read as much as you can, although nothing beats first hand experience (butt Dyno). I can tell you on my 03 set up for woods racing I installed a new pipe and actually ended up jetting down for the pipe. So not all 2 bikes will be the same. Buy you plenty of jets in the smaller increments you can 5-10 sizes each way and a box of plugs. Keep the air filter clean, do a compression test make sure the bikes not sucking tranny oil in through the crank seals make sure your silencer packing is fresh. Set your float level first if you don't have a manual for that bike get one before you start. If its in the primary it will be your slower circuits pilot jet etc. there are a lot of things that go into jetting if you'd like to have people help take a few minutes drain the fuel pull the bowl and give us all the info you can float level, pilot, main, needle clip position, air mixture screw, altitude etc. and maybe someone has had the same experience and maybe able to help you more. Good luck and let us know what you find out.

[bikedad1]

If you want a quick intro to jetting, dive in to the carb and lower your needle  position one notch (raise the clip).  This will lean out your bike and give you an immediate change with no waiting for parts.  You can then play a bit and raise it just for fun.  Be careful as you start to lean stuff out.  Needle position will affect a pretty wide range of throttle.from about 1/4 right upto the power band (estimate).  Just be careful as you go leaner and watch the plug.  Also find the highest/smoothest idle with the air screw.  If spec says 1 and 1/4 and your at say 2 then this suggests that your piolet is a bit rich, reverse if your down to say 1/2 turn.  Should be able to kill then engine by turning screw all the way in, or out several turns.  But I have had some bikes that screw had less effect on.

[Suzuki175]

Thank you guys for the information. Sorry for late response, been getting situated into college. I will be trying some of this stuff this week or next. hope I can get it running spot on.

[bikedad1]

Still here for you!