rm250 specific question

[overbore]

on the carb for the 01 rm250 has anyone disabled
or unhooked the power jet and closed down the air
bypass on the choke?and if so what effect would it
have on performance?having some weird carburation
problems that I am trying to figure out.
Thanks for any and all responses.
If you have a rm and know everything about these carbs
please give me some ideals.
overbore.

 

[marcusgunby]

you need to run a richer needle if you dissconnect the power jet(not sure which needle however) i did it once to a 1998 KX125 and noticed no difference if it was connected or not, i would unhook it for short (non flat out runs) tests.

 

[RM_guy]

What type of problems are you having? I know my bike spooges a lot but seems to run fine across the board with no sputtering. While I never disconnected the power jet I have played with the choke knob but was unsuccessful in cleaning up the spooge. I did file the slide for a larger cut away and that helped with throttle response but didn’t help the spooge.

I rarely wind my engine out so I attest most of the problem with that but I still want to fix it. The only thing I haven't tried is a half step needle. Changing the clip now is either too lean or it still spooges. In fact now that this has come up I'm going to order a needle today, Thanks :)

 

[ETS]

I cut the slide 1mm, dropped the needle and went to a 62? I think pilot jet and it cleared up the spooge big time on my 01'. It was a nasty mess after each ride the way it was. I run blue marble oil and golden spectro and they both made a mess until I cleaned up the low to mid.

 

[RM_guy]

I did the same thing but still have a problem. The 62 on the pilot doesn't sound right though. It might be a 42 (which I believe I changed mine to). I run Maxima Super M 32:1 in several bikes with absolutle no spooge so I don't suspect the oil or mixture.

 

[overbore]

Thanks for the replys

wow, I didnt figure I would get very many answers
on this specific question.Thanks.I am having a problem
that I believe to be carburetion since I just had the whole
motor gone thru and ported.The bike before doing the
motor would run on after climbing a hill and acted like a
air leak,which I know couldnt be now since the rebuild.
It now after getting hot after about a hour of riding just
runs on like it running out of gas and when you start
applying throttle it goes away untill you let off the throttle
again.Too much compression,not enough octane,ect,ect.
I dont know,but to far into this bike with redone suspension
and everything to give up on it.
Any ideals please help.
Thanks overbore.

 

[overbore]

anyone

 

[marcusgunby]

tricky one, i would try better fuel as it seems to be heat related (no im not saying race fuel runs cooler before people jump in;)-so maybe you are getting preignition?could try retarding the timing just to see if it helps?not really got many more ideas.

 

[RM_guy]

Maybe too lean on the low speed circuit? What is your current jetting?

 

[overbore]

48 pilot and 168 main with choke air bypass closed off
and air screw out one and a half.
I do think its something to do with pre ignition from
fuel or something but I know the guy that rebuilt my
motor and ported it to be one of the best,so it has to
be something like you guys say with timing or fuel.could
it be that the slow jet is to big and causing some fuel
still left to pre ignite when I shut down quick?
Thanks rmguy and marcus for any help here.
overbore.

 

[overbore]

what plug are you guys running I forgot to ask.currently running a br8eg.

 

[RM_guy]

I run a BR8ES. Same heat range but different electrode but should make a difference.

I don't remeber what jetting that I'm running. I'll check tonight and let you know.

What octane gas are you using? I'm using 93.

 

[overbore]

octane

have tried 93 octane from a couple of places
being shell and bp local.
mike

 

[RM_guy]

Well, my wife finally got me to clean up my shop and I can't find where I wrote down my current jetting so I determined it by checking what jets I have left.

158 main
stock needle w/clip at 2nd notch from top
42 pilot
air screw out 1.5 turns at about 70 degrees air temp
slide cut away .5 mm
Choke knob at stock (I think it's 12 clicks out)

Like I said earlier, I'm going to try a 1/2 step leaner needle soon to clean up some spooge.

 

[overbore]

Thanks for taking the time to check this stuff rmguy.It didnt hurt anything going
down from 168 stock to 158 and the pilot from 48 to 42?My sons rm250 also is
a 2001 with fmf gnarly and fmf shorty running tight woods.
overbore.

 

[RM_guy]

I had Eric Gorr port my engine for Mo Power so that may account for being able to lean it out more but it was even way too rich before the porting. I never got it properly jetted before porting it so I can't say what it should be. I wouldn't expect it to be a lot different between ported and stock anyway.

I just kept leaning it out until it started clearing up and that's the jetting I ended up with. I do go to a 160 on the main when the weather gets cold (below 40) because it leans out too much.

 

[marcusgunby]

too big a pilot does cause funny running but i dont think it will do that, maybe go one or 2 sizes up on std? i would try better fuel and timing as its easy to do.

 

[overbore]

Thanks again for both of your answers.I try something in
the next week and post again if I find anything for sure.
I always thought it would be nice to have a forum that just
had for sure fixes that everyone could look at to help people
instead of wondering if the problem ever got fixed.
Thanks again overbore.

 

[overbore]

Finally got out to test again on the bike and didnt
change anything except closing bypass air choke off,
and opening up the air screw up another turn and then
idleling the bike down after changing air screw.And also
made a effort to not ride the clutch as much to make
engine run cooler and it only hiccup a few times after
about a hour rideing.I also realize that its cooler outside,
but this is definetly heat related and giveing it more air
should have leaned out and run hotter.go figure.
well thought I would post anyway after finding what I did.
thanks overbore.