Jump to content

2000 rm 250 - Tuning Help Needed

Recommended Posts

Just bought this bike. It's a 99 frame with a 00 engine in it. Has a gnarly pipe and some kind of fmf muffler, about a foot long with one mounting bolt (stickers are worn off so dont know exact model). Its jets are 172 main, 58 slow, and clip on 1st position. Elevation is 700 ft.

For this bike to idle, have to turn the choke knob 26 clicks out, way too many. Rode about 20 hrs so far and have fouled 2 plugs. Had spooge coming out the connection points at slip on and exhaust port, but put new gaskets and a cushion in and solved that problem. Haven't noticed spooge coming out of freshly packed muffler yet.

It runs great in the main (40% and above throttle range im assuming) jet range, i think so at least as this is my first two stroke so I really have nothing to compare it to, but doesnt feel so well at slow or needle range. I looked up the fmf recommended jets and it was 155 and 40. I didn't have those exact ones so I tried a 162 and 45, ran like crap, it felt a lot worse than what was in there. Would not idle at all. I'm not sure where to go from here as it seems going in the recommended direction is the wrong thing to do. It smokes a good bit with original jets, but again i'm not sure if its an abnormal amount or not.

I read about doing plug chop test, but it seems very wasteful to buy a new plug for every test and no telling how many jets until you find the right one. Any ideas where I should start with jets or things i should look for and try?

Share this post


Link to post
Share on other sites

Rokyholler,

I have a 2000 RM.

Stock jetting on that bike is:

Main 158

Needle N3WK-3RD

Slow jet 42

Air screw 1-1 1/2

The choke knob you're turning is not a choke if this is a carb for a 2000 RM. It is an adjustment much like the air screw for 0-3/8 throttle. Standard adjustment is 2 turns or 12 clicks out from closed. It's called the bypass or starter. The mixture will become leaner as it is turned out counterclockwise to open the system after the dial has been turned in clockwise all the way.

To me it looks way too rich. Could be the reason for all the spooge.

I'm a trail rider so my fuel/oil mix is a little leaner. For what it's worth KTM recommends 60 to 1 mixture.

I have a shop manual for the bike so if you have any questions give me a yell.

Doug

  • Like 1

Share this post


Link to post
Share on other sites

Well, I think I found the problem, the carb is a Keihin PJ38. The carb is from the '96 model. If I change the jets and needle to the 2000 engine needs, would that fix the problem? Or will the air fuel mix still be different and should get a different carb? Would a '99 or '01 carb work because I'm having trouble finding '00 for sale.

Edited by rokyholler

Share this post


Link to post
Share on other sites

I don't know if this will help or not but here r the specs on my 00rm 250 that's has an fmf fatty pipe and a pro circuit forestry approved silencer that is like a mile long an some boyeson power reeds ( that did require me to lean out my main jet 1 size but hope maybe this will give u a close point of jetting

900 ft above sea level

70 degree day

45 pilot jet

1-1/4 turn out on air screw

18 clicks out on the choke adjustment

152 main jet

2nd clip from down from the top on stock needle

Stock power jet

And I can go a whole season on one plug .. The 30 dollar one

Idles great an very little spooge

Share this post


Link to post
Share on other sites

the 2004-2008 rm250 needs are smoother then the needles of previous years 

these are the NECx , NEDx needles we talk about in ever forum on thumpertalk , if anyone wants some more info pm me

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×
×
  • Create New...