03' RM250 not running right, help!

[tonyromero]

So as it things weren't bad enough as it is, I take the RM out again today and the bike just wouldn't rev. The more I accelerated it just choked and sputtered. It ran fine just yesterday and I have done nothing since then. So I suspected a fouled plug and replaced it with no success. However, the plug I used ( which the parts counter guy sold me after he looked up the part) was a BR9EVX
rather than the one that came on the bike which was a BR8EG.
Also , I used a 30:1 fuel mix yesterday and noticed quite a bit of smoke and spooge ( using the mobil 1 which supposedlyburns clean) so I tried 40:1 today. Is the fix as simple as using the stocker plug? If the plug was fouled (th original) which it appeared to be since it was black an oily, why would it have run well yesterday afternoon and poorly today? Anyway, any ideas will be appreciated.

 

[tonyromero]

oh, also I might point out that today I ended up going through a couple of deep puddles ( about as deep as the hub on the rim) . I checked the airbox and it looked good. Could the splash up have wet something that should stay dry?

 

[Studboy]

Hmmmm....let me give you a couple of answers here. You should be running an 8 range plug instead of a 9. Changing the Fuel/Oil ratio from 30:1 to 40:1 (with the same jetting)is only going to make your bike RICHER, foul more plugs, spooge more, and have less power because you have in effect RICHENED your fuel/air ratio (this is a common misconception.) Bottom Line, I promise you if you learn how to properly jet your bike for yourself (most stock bikes including yours come poorly jetted), it will not only run a lot better, it will yield you with less problems and more fun! Also, stay with the Mobil 1 premix, it is good oil and is not what is causing your problems.

 

[marcusgunby]

As studboy said you need a 8 plug and some even use a 7 in cold weather, goto www.ericgorr.com and he has a good jetting guide.

 

[tiller]

When you went from an 8 to a 9 plug you actually went to a colder plug. Since you are not reving the bike out and running a colder plug I am not surprised it ran poorly. At the very least try a #7 plug and go down a size or 2 on the pilot jet. The Mobile1 is not the problem.

 

[tonyromero]

Ok so I will go back to the 8 plug. Again though, my original plug was working fine yesterday up until the moment I shut the engine off. It certainly did not deteriorate during the night so at the very least it should have run well at least for a bit today even in its current state. The only thing that changed from yesterday to today (before I changed plugs) was the fuel ratio and I question whether that alone would cause the bike to go from running perfectly to running horribly. I know the RM comes rich for most people from the factory but I am at sea level and according to the mags and sites I"ve seen the jetting is spot on for my particular situation. I may lean out the needle one clip or so but the main is fine.

 

[mole1]

if the only thing you changed besides the plug was the fuel , i would suspect maybe some bad fuel or possibly some debris stuck in one of the jets or vent hoses . a colder plug would foul a little quicker but unless your jetting is way off i don't think it would be the immediate cause of your problem . changing plugs is inexpensive so i would replace the fuel and go with the stock plug and see if that works and if not then open the carb and have a look . don't you find the rm a lot more fun than a drz ?

 

[smarttoys]

How long were you riding the bike? Two strokes do load up during warm up. Sometimes it takes a while to clear it out. Especially if you run it with the choke(enrichener) on too long during warm up.

Now if you were out riding around for quite awhile, then that's a different story. ;)

 

[Studboy]

I would run the 8 plug unless you are trail riding. Get your jetting right first, and then mess with the plug. Run a BR8ES.

 

[tonyromero]

hmmm. I AM trail riding so what plug should I use if not the 8? I let the bike warm up at idle about 4 minutes and then putted around for another 2 or3 before I tried to get into the higher rpms. I guess I'll dump the fuel and go back to a stock plug but truthfully I think I am just going to sell it. although the DRZ was heavy it was more fun. I could go to the gas station and put gas right in the tank, it had the same plug in it 18 months after I bought it and ran great, and never gave me one problem. I took for granted simply pressing a button and zooming off. Kick starting is a pain in the a--!!.I am only a weekend rider. Although I'm sure the solutions proposed would work, I just want to ride with a minimum of hassle. I don't jump so a heavier bike
doesn't bother me. Anyone want to buy an 03' RM with service manual and spare top end kit? Only 1 hr on it? cheap! ( $4400)

 

[Studboy]

It's your choice... but I think you're mistaken in your choice to sell it so quick. Get it jetted right and geared right for your application and I promise you that you'll enjoy it MUCH more. Once jetted right you won't foul spark plugs and it will have much better low end response.

 

[Jawsrm134]

I think you loaded it up, Dont let the bike sit and idle for 4 minutes, Start it up take the choke off and ride it slow for about a minute then clear it out. If you let it warm up that long without reving it your going to foul plugs. Also dont rev it while its sitting there without a load on the engine when you come off the throttle the carb is still putting alot of gass in the engine and that will cause it to foul also. Try to start it with a new plug and ride it dont let it sit there and idle for long. Just dont blast right away. Mine is the same way. I just start it and ride it slow form a minute and then clear it out. The bike does not like to sit and idle, its the stock jetting its to rich. But all 2 smokes are finiky like that. once its cleared out youll have no problems.

Mark

 

[Rcannon]

Is is sounding more and more like the wrong bike. If your not jumping or riding hard, the suspension is not needed.

If you hate kickstarting, it is going to be tough without the electric start unless you have a lot of downhills only.

Personally, I have never found the kickstart to be a big deal. That is, unless your trying to start the bike in sandals, wet, and your foot slips off.

 

[MX-727]

Tony, most folks warm their bike up for about a minute, lightly blipping the throttle. A good rule of thumb, is that when you can touch the cylinder and feel it starting to heat up, you can take off and ride gently for another minute. After that, let it rip and go ahead and wind it out to "blow it out." If your jetting is slightly rich and you are doing a prolonged warm-up, you can foul the plug in a manner that the bike will continue to run, until you shut it off and it cools down. When you go to restart, you will find that it is very tough, if not impossible, to start. So, you then check the plug and find it's fouled, and you are confused because it was just running.

Read the jetting guide on Eric's site:
http://ericgorr.com/techarticles/carbtuning.html

Also check out Canadian Davis guide: http://justkdx.dirtrider.net/carbtuning.html

Just do it, you'll learn a bunch and it will help you understand what all of these people are talking about.

My general belief is that most bikes are jetted rich out of the factory, so one leaner on the pilot and raising the clip one position is my starting point. I wholeheartedly recommend that you talk to people in your area that have the same bike and talk to your shop to get an idea of what jetting has been found to work for your bike. Then, make those changes, put in a fresh plug and ride your bike in an open area. Get your bike jetted and running well before you tackle the woods. Then you can figure out if you need to change the gearing. If you spend a weekend getting it set up and learning how the bike responds to changes, you will end up with a bike that will be, with normal care and maintenance, trouble free for years to come.