jetting help rm 250 01

[ZOOK250]

i have an 01 rm and still having jetting problems. i havent had enough time on the bike to figure it out. please help.

the problem is when i am at 3/4 to full throttle there is a noticable gurgle that is quite bad. i am running an sst combo, everything else is stock.

i have jetted down to a 158 but it was 50 derees out.no power to lean.since then have run a 162 main but gurgle is still apparent.

could this be a needle problem? or a power jet issue?
i have also been told to lean out the pilot jet circuit.but i thought that affected 1/8 to 1/4 throtle.

the arena cross series starts here in mid january, so the temp will be quite low. 35 to 50 degrees inside.

how does a power jet system actually work?

particulars elevation 750 ft above sea level
temp 35 to 50 deg.
mix 32:1 silkolene 92 oct.


thanks

 

[Durt Cycler]

Go leaner on the main ( 158 try ) and put the clip in the 2nd postion. Try that and see how it runs. NOTE: you also might wanna go 10 clicks on the idle from 18 stock. good luck :D

 

[Mike Fallon]

01 rm 250

on my 01rm250 i had the same trouble i went to c12 race fuel 155 main two down on the pilot and one up on the needle on pump gas 92 octane i whent one down on the pilot and one to two up on the main from the 155 but the race fuel makes it run the best if you jet it wright i also had the head done iam at800ft and at 40 to 50 deg now i have not done eney thing with the power jet:D

 

[MN KDXer]

Have you checked the pilot jet? The CA RM250's came jetted horribly rich, with a 52 pilot and 168 main.

With pump gas, I ran 158M w/ a 48P, #2 clip position on the stock needle @ 60 to 85 degrees. And, a 160M, 48P, #3 clip on the 1/2 step (next richer) needle. With pump gas, the bike needs to be jetted carefully or you will get nasty pinging. The 1/2 step needle seemed to help a bunch.

You may want to try race gas. With Arena Cross, you won't be using much fuel anyway. The guys who used race gas in their 01 RM250's reported significantly better performance. I rode a bud's 01 250 w/ R gas, and it was a totally different bike than mine; smooooooth powerband w/ more power everywhere.

Also, consider a different pipe than stock. I ran the Bills Pipe, and it added power everywhere and extended the powerband over-rev considerably.

Another cure, would be get your hands on a 02's powervalve and/or cylinder. The 02 RIPS! I'm not sure what parts you would need, or what will make a difference, but I'm working on finding out.

 

[Chief]

Zook250,


My bike ran pretty rough (sputtering) right out of the box. It was more mid and low throttle.

I'm at about 1000 to 1500 ft elevation. The only thing I tried with the powerjet was diconnecting it and I noticed no difference. I think it kicks on at 8500 rpm and shuts down under that.


I had the squishband widened (lower compression) and the slide cut 1mm (leaned to 1/4 throttle). These changes made a dramatic improvement in smoothness.

I have tried different exhaust valve settings and by far I like the zero tension setting the best.

The last mix I used is sunoco 94 w/amsoil 50:1. It is also the best running mix I have tried so far (no spooge) but I would like to go a little richer on the oil.

Jetting at 50 degrees 50 pilot, stock needle dropped down one from the center and 165 main. (I think I could go leaner on the main, but I have not yet). Bypass 4 clicks out, airscrew 1.5 turns out.


I like the way it runs right now but still have some pinging at times. I plan on trying different fuels. From what most have said, finding the right fuel and jetting for it is a big key.

One thing MNKDXer told me that helped a lot was that I could access pilot and main jets by rotating the carb and going through the drain plug. Just loosen the bands. Feed the throttle cable towards the carb near the steering head to make it easier to rotate.

I trail ride so we are probably not looking for the same type of performance, but I'd like to know what you try and how it works for you. Good Luck.

Joe Chief

 

[ZOOK250]

thanks for the suggestions. with the sst pipe fmf says to run a 158 but a noticed a considerable power loss at this jetting. my bike came with the 168/52 combo, i havent changed the pilot jet yet. does anyone know where to get a proper screwdriver to take apart the top of the carb to get to the needle?

 

[Chief]

ZOOK250,


There are 2 small allen screws on top. You can access them by rotating the carb. (opposite what you would for the drain plug).You will need one of the longer allen wrenches The first time I took the top off, I removed the seat and possibly the gas tank. It's the only way to get a decent look at what you are doing. Now I just rotate the carb, but it's a very tight spot to work in, considering you don't want to bend the throttle cable too much.

Joe Chief

 

[RM_guy]

Joe's right. You can get to the top of the carb but it is very tight. The first time I rotated my carb I knocked some of the vent hoses off so make sure they are in place when you're done.