RM 250 Dead Again (Partially)

[boscoholic]

Hello again! Well the saga continues. I finally got my bike running (See the Dead RM250 post for details) and it seemed like all was good. It fired first kick, warmed up nice, so i took it out. About 30 minutes into my ride (and several miles from home) it sputtered a little down low, so I opened it up to clear out the cylinder/plug. About 5 minutes later it started to sputter again, so I twisted the throttle to clear it out, but it was giving up the ghost and finally sputtered and died. Now my initial thought was "Great, here we go again." Luckily, my neighbor was out 4-wheeling and spotted me, so they went to get the truck to pick me up. They also brought a brand new plug. I pulled teh plug out and it was definitely fouled (black and oily). I put the new plug in on a hunch and whammo! it fired right up. I suspect jetting, but here's the dilemma: When I run in the low range it has some hesitation, but still has no problem getting into the powerband. This has never been a problem before. The second part is this: I got it topped out and held wide open and after a few seconds hit a dead spot and hesitation, then it picked back up. I let of the gas and then hit it again but it acted like it ran itself out of fuel for a second and had to catch up. So, my logic (faulty as it may) says I'm running too rich and fouling plugs, but how do i explain the low end response and top end hesitation? You all provided some great assistance last time around and hopefully you can help me figure this out before I end up sending it to the scrap yard. If Psychojello reads this (also has a 96 RM 250), please let me know your complete jetting specs so i can compare.

[ossagp]

I can't remember what you have already done to it. Maybe teaching you to fish is a better plan than catching one for you (doing your own diagnosis in other words). Rich: Bad jetting, over delivery on fuel (that float thing again, bad float parts etc.) low compression. A bad crank seal on the transmission side can make that same symptom and make the other conditions worse.

Bad electrics can do it too. bad plug wire. bad spark cap. bad connections, weak ground can all cause plug fouling.

Someone else's numbers may not be your numbers, and if the bike was running right on the existing jetting at any time in it's life, has not been greatly modified since then, then look elsewhere than someone else's jetting, would be my advice.

[mxracr121]

Originally Posted by boscoholic

Hello again! Well the saga continues. I finally got my bike running (See the Dead RM250 post for details) and it seemed like all was good. It fired first kick, warmed up nice, so i took it out. About 30 minutes into my ride (and several miles from home) it sputtered a little down low, so I opened it up to clear out the cylinder/plug. About 5 minutes later it started to sputter again, so I twisted the throttle to clear it out, but it was giving up the ghost and finally sputtered and died. Now my initial thought was "Great, here we go again." Luckily, my neighbor was out 4-wheeling and spotted me, so they went to get the truck to pick me up. They also brought a brand new plug. I pulled teh plug out and it was definitely fouled (black and oily). I put the new plug in on a hunch and whammo! it fired right up. I suspect jetting, but here's the dilemma: When I run in the low range it has some hesitation, but still has no problem getting into the powerband. This has never been a problem before. The second part is this: I got it topped out and held wide open and after a few seconds hit a dead spot and hesitation, then it picked back up. I let of the gas and then hit it again but it acted like it ran itself out of fuel for a second and had to catch up. So, my logic (faulty as it may) says I'm running too rich and fouling plugs, but how do i explain the low end response and top end hesitation? You all provided some great assistance last time around and hopefully you can help me figure this out before I end up sending it to the scrap yard. If Psychojello reads this (also has a 96 RM 250), please let me know your complete jetting specs so i can compare.

I raced a '96 RM 250 back in '96. Great bike. They came jetted from the factory rich on the bottom, but lean on the top. I can't remember exactly what jetting I ran. But if I remeber right, I leaned the pilot one size, and went one size richer on the main. Try that, then try to dial it in with the airscrew. If it still feels rich on the bottom, drop the pilot jet one more size. But you should be okay on the main. Another thing, make sure your power valve isn't sticking, and is opening and closing smoothly. If you haven't cleaned it, and it has rich jetting, it could be all gummed up.

[RoostRM125]

That sounds all most exactly like what my '94 RM 125 is doing. The plug gets pretty wet when I can finally get it to run but I don't have a powerband.

[boscoholic]

Alright everyone. I think I have this thing figured out. After going through the carb thoroughly to make sure that was not the problem, and checking compression (about 210), I went back through the electrical system. I know it's not a CDI issue because I jsut put a brand new one on. I checked the coil, plug wire and cap and even took it to the Suzuki shop to confirm it was okay. So, I'm looking at the stator (which the previous mechanic said he checked and it was fine). The pickup coil checked out, but the stator itself showed an open leg, meaning one of the coils on the stator is likely shorted. I ordered up a new stator from Ricky Stator and it will be here in a few days. Once I get it on and check everything out, I'll let you know how it goes. I should ahve just done my own troubleshooting from the beginning and I might have had it running by now. The more I think about it, a bad stator makes sense since I wouldn't be getting a hot enough spark to completely burn the fuel thus causing fouled plugs and a false rich condition. Once It's running I'll set the jetting back to stock and adjust from there.

[boscoholic]

Well, I don't know where to go from here. I put the new stator in and I got a really nice blue spark. The bike fired 1st kick. I took it out this morning and it seemed to run a little rough kinda like it was backfiring or knocking a little, but the power was there. After about 20 minutes I rolled to a stop and the sucker just up and died. I pulled the plug and sure enough, it was fouled again and really black and oily. One I got it home, I cleaned the plug real good, checked spark (good) and put it back in. The bike fired first kick and after about 10 seconds just died again. The plug fouled again. I've really done about everything I can think of and at this point I'm stumped. If this keeps up there will be a lot of new 96 RM 250 parts available on ebay.

If anyone can please help I'd appreciate it

[mxracr121]

Did you try leaning the pilot and clip position like I mentioned above?

[jambo]

i dont now if you already checked but my rm had similer probs and it was a hole in the reeds changed them and all ok
but now i cant find neutral lol

[Rotorranch]

Check the reeds. Kinda sounds like it could be the problem.

Maybe clutch side crank seal? Are you loosing tranny fluid perhaps?

Rotor

[daniel_111]

it might be just that the timing is out on your powervalve....??

[farfromhome63]

Id check that coil again... I had the same problem last weekend and it turned out to be the coil..... it sparks but it doesnt stay lit

[SikspakD]

Im thinking its a stuck or carboned up powervalve also. That could explain the low end and top end hesitation that is. Don't know much about RM's though.