RM 250 - reed / jetting questions

[turtle]

KDX nation,
I have issues (blaming it on jetting for lack of knowing better) with my 2001 RM250. It seems lean down low, and then rich almost immediately off idle. It is hard to start, especially warm. Idle is not stable and it likes to die, even with idle adjusted up a bit. Cruising along a trail (probably not this bike’s strong suit anyway) is a chore – it doesn’t want to. Otherwise though, it does run good. No bog, no sputter, strong power throughout, no backfiring. It just is hard to start, wants to die, and won’t run smoothly at steady speeds. I was also told it smokes a lot (just one time, on some very technical low speed single track when it was really hot out, if that matters). Spooge is reasonable.

Jets are 160/45 vs 162/48 stock. I don't remember what clip the needle is on. I can go look if need be.

The reeds were replaced several years back by the PO. I want to eliminate reeds as a variable so I am planning to replace them, even though I can’t see any cracks or chips and they look fine to me. They are a carbon reed but I don’t know what kind. I’ve been looking at Boyesen’s web site and the variety of reeds confuses me. Superstock Reeds, Power Reeds, Carbon Tech Reeds, Carbon Force Reeds (V-Force3), Pro-Series Reeds, … ugh. My head wants to explode.

I’ve done some searching on TT and have not seen the specific question asked … what reeds are best for a trail rider, or does it make much difference? I don’t do any motocross – it’s all woods riding for me, mostly fairly tight single track.

On the subject of jetting, what is a good baseline to start from? I was planning to start from stock, but I have a Moose reed block spacer, stock reed cage, fresh top end, clean carb, newer FMF Gnarly, and brand new FMF silencer. Is there a better starting point? I know each of these things has an effect, just not sure what the cumulative effect would be and what direction that would drive me on jetting. In the end I will follow the jetting guide, but for now I am just looking for a starting point.

Thanks for the help. Sorry for the long post.

[Actionman]

Just like a kdx, the rm has a pwk carb- and that stupid "jet block" gasket can go bad. My 96 rm has a torn jet block gasket and it stumble off idle but I didn't notice it until I actually just played around in my yard one day rolling on the throttle and lugging it. Start there, go ahead and replace reeds if they're old, check air filter, and make sure your rubber intake boots are in good shape. Also , take out your PILOT jet and make sure it's not clogged. If it is, check your in-tank filters to make sure their intact. When I got my kdx, the filter screens in the tank were gone, and every time I cleaned the carb itd run great until gunk went into the carb from the tank and clogged the pilot again. It took days before I got smart enough to take out my petcock and check those damned screens. Would've save me a ton of tone if I'd checked those first. BTW: make sure your power valve adjusters are set right!

[Actionman]

Reading your post again , it sounds EXACTLY like your pilot is getting clogged. Mine would run awesome when I got into the main jet, but it ran like **** on trails- burbling, smoking, etc.

[KDXrider1989]

I agree with Actionman, sound like your pilot circuit needs tweaking or, more than likely, your air screw. Id just go back to stock jetting and air screw setting and start from there, theres a really good jetting guide Indawoods put on here that I follow for every one of my 2-stroke bikes

[turtle]

..., theres a really good jetting guide Indawoods put on here that I follow for every one of my 2-stroke bikes

I can see through the pilot jet but I guess that doesn't mean it's clean. I will likely replace with stock anyway. My plan is to follow the jetting guide when it warms up. Just looking for a good starting point.

Thanks for the feedback!

Does anyone have input on the best type of reed? I am thinking of keeping it kinda simple, with a carbon superstock reed the most likely at this point.

[KDXrider1989]

I have the boyesen power reeds on my bike and I like 'em, I think you're good with the carbon reeds you have on there if they aren't worn out like you said. the reed petals themselves I believe won't make a HUGE difference, however the entire block will. Spacers will give a little more bottom end if I'm not mistaken