93-95 RM 250 owners..need advice.

[SpectraSVT]

I need to know how the Rm is supposed to run, powerband wise. I know its a midrange only bike but I need more info. My buddy has one and I don't know how its supposed to be so its hard for me to trouble shoot. I have searched a couple posts and the jetting seems to be similar to what a couple other people are running.

The powerband is short obviously but its inconsistent. Its either on the pipe or not. Even if the revs are similar, as soon as I let off on the throttle than get back on it immediately afterwards it has fallen off the pipe already. It takes only 1 second for this to happen. Its really hard to ride. Either its pulling crazy hard or not at all. No in between. If I'm steady on the thottle it won't ever get on the pipe. I have to open it up and clutch it to get it to take off.

Jetting is 178 Main with clip in 2nd...55 pilot with air screw at 3 turns out. It was originally at 3rd clip but it bogged if I let off the throttle. Also at 3 turns out I thought I would try leaning out the pilot but that made it run bigtime lean and rev out at 1.5 turns on airscrew. It won't idle either. It starts to settle in then all of a sudden it will bog and die. When its warmed up, if I chop the throttle it will bog first and only rev up if I hold it open a bit.

Its has new top end, new reeds and new silencer packing. I don't know what to do next. I've read 3 jetting guides and nothing is helping me out. My buddy oils the crap out of the air filter so I'm thinking that might be a problem. And I am unfamiliar with the powervalve. It lookes like its set at 1:00. I don't know which way opens or closes it.

PLS let me know how your 93-95 runs so I can figure out if something is wrong or if the bike is just a lightswitch...off or on.

 

[BIKEMAN111]

first of all try some carbon fiber reeds.then for a jetting baseline----us a cr needle part#r1368n,place clip in middle 185 on the main then bp7ev-ngk plug

 

[SpectraSVT]

Can u explain? What does any of that do? The reeds are brand new so why CF ones?

 

[BIKEMAN111]

your power should be a little lacking on the bottom pull hard at mid throttle then sign off at high revs the nature of these year rm`s.are you sure you have done your jetting correctly remember the main only handles 3/4 to wide open throttle,a plug gap to large could cause a very pronounced miss.have you checked your vent hose for obstructions?checked for air leaks?are your reeds installed correctly?how did bike run before the new reeds were installed?

 

[2-Strokes 4-ever]

Sounds to me like a clogged pilot jet. Gas these days can go bad in as little as a month, clogging-up jets and causing problems that sound very similar to what you're experiencing. I know it sounds all too simple, but it just may be. For me, to keep from spending a fortune and tons of aggravation, I'd clean carb., go with fresh gas, and find stock jetting specs. I am also very paranoid about dirty air getting into motor, a well-oiled filter is a GOOD THING, however...not dripping. I use a clean rag to lightly squeeze filter after oiling, to make sticky, but not drippy. All cheap, and you're starting from ground zero.

 

[SpectraSVT]

Carb has been cleaned at least 5 times in past week. Jets are clear. Reeds have no gaps. Vent lines are clear as well. Gas is only 3 days old. The bike has actually improved but it don't feel right. Jetting is what FMF recommends as starting point. I now know lean is not way to go as bike did not like a leaner pilot. I have not checked gap on the plug...I will do that. I am just trying to figure out if the bike is supposed to fall off the pipe when you let off. I know the powerband is real narrow but I just can't keep it on the pipe. I have to almost slip the clutch thru the whole powerband to keep it moving.

I'm mostly concerned about the bog when the throttle is blipped whether on the stand in idle or on the track. It doesn't feel like its going to die when I do blip it, just a hesistation. Is this actually a lean bog not a rich bog?

Bikeman: thx for info...the rm was running far worse. Bike would pull then cut out. It ran great in 4th and 5th though. 1st and 2nd were horrible and 3rd was ok but not satisfactory. Now 1st is ok, 2nd below avg, 3rd is ok when clutch is slipped and 4th and 5th have improved.

 

[steve.emma]

hi,
from the sounds of it you could have more than just a simple jetting problem,if the powerband is real narrow and hard to use there could be a problem with the powervalve assembly. maybe its seized or the spring has broken etc.. on the left hand side of the barrel there should be a powervalve return spring holder that can adjust the spring preload, check someone hasent wound this right around (std is 1.5 turns.)
i had a 94' rm250 and found it a great bike with good low end compared to some of the earlier rm's. good luck with yours.
steve.

 

[erwin844]

I would check the crank seals.

 

[SpectraSVT]

Steve...the powervalve, what way shouldI turn it to set it to zero so I can turn it to 1.5 turns? Is it similar to air screw? Turn it in to set base then go out from there?

 

[sick 96 250]

If I'm correct, with the powervalve, to set it properly what you do is take out the two bolts that hold it in place and pull out the tensioner itself. Just a pair of pliers and it should slide out. Then with it out the spring for the tensioner will set back to its orignal spot, put the tensioner piece back in and turn it 1.5 clockwise I think but look into that.

 

[SpectraSVT]

It looks like it would require me to remove the cylinder to get the pwervalve cover off? Its pointing straight at the frame up against the radiators or is this not what your talking about?

 

[steve.emma]

what that other bloke said was correct about timing the power valve preload spring but to do that you dont have to remove the power valve cover (which is blocked by the rads etc..). the preload spring cover is on the cylinder barrel on the LEFT hand side and is small,round,with a couple of bolts holding it (from memory) you should be able to get to it real easy.
BUT i would recomend you do what it takes to remove the powervalve cover (the one facing foward that you mentioned) because this will gain you access to the powervalve mechanism so you can see if its seized or broken etc.. removing the pipe will help as you can look up the exhaust port as well to see the valve working.

steve.

 

[sick 96 250]

Yeah i was talkin about the tensioner on the left side that was easy to get to. if its out of adjustment just a little it can make the bike run like crap. And what the heck is a Bloke??

 

[steve.emma]

lol... sorry about that, i guess bloke is not a word Americans use a lot. it just means "person" etc.. i think its a kiwi/aussie thing...