ok ladies and gents im fairly new to the dirt bike scene and very new to the motocross world I have a few questions I would like to ask...I have a 1990 (from minor research on vins I believe to be a 90) rm 250 I purchased about 2 weeks ago non running but was told it was last ran about and month ago prior to purchase (but who tells the whole truth on craigslist lol) so I have a no idea exactly what all it needs to run stock properly I do know that I tried poppin the clutch down a hill and got it to start 3 times but every time bogged out with in a few seconds or died when reved the throttle...so theres all the info I know about it currently as it sits...I have taken the time to break it all the way down to the frame and and forks with the front tire in the process of re painting...my questions would be are there any newer plastics I can throw on it? the back spring moves a lil side to side is that correct or does it need to be rebuilt (correct me if im wrong but from research ive heard that it is supposed to do that because of a spherical bearing design of that time?) I plan on just taking the motor to a shop to be rebuilt (don't know if it needs it yet but just gonna do it anyway) so feel free to tell me what upgrades and tuning I should do to the motor to get the maximum amount of power out of it...I was also wondering what class I could ride it in? would it be a decent bike to ride/race? is there anyway possible I could pu a slightly bigger back and front tire on it? any info/ suggetions is appreciated I will post pics of it as soon as possible..thank you can cant wait to hear from yall...happy, safe and thrilling riding to all!
RM250 90 rm 250 questions
- Thread starter Tsimpson23
- Start date
nice to hear from you Tyler
we are here to help. That bike is a tad old school to be racing IMO. The suspension is nowhere the new bikes technologies so it will make it hard to be compete. Like playing basketball in flip flops when everyone else has on J's. 
Let see some pics of this beast. There are a few of us RM owners on here. I would have tried cleaning the Carb and changing the spark plug, clean out the pipe and silencer, put some fresh premix in it and go from there. Good luck!!!
we are here to help. That bike is a tad old school to be racing IMO. The suspension is nowhere the new bikes technologies so it will make it hard to be compete. Like playing basketball in flip flops when everyone else has on J's. Let see some pics of this beast. There are a few of us RM owners on here. I would have tried cleaning the Carb and changing the spark plug, clean out the pipe and silencer, put some fresh premix in it and go from there. Good luck!!!ya ill up load some pics off of my phone here in a minute...im not really looking to try and get professional off of racing (when you say imo what do you mean by that?) or anything just looking for something to do with my free time lol but you think I could race it just for fun or would even be worth trying?...I do need to change the spark plug on it and clean the carbs I need to order a new cable that connects to my spark plug because the end I guess went bad and the previous owner tried to just rig the broken wire up... how would I go about cleaning the pipe and silencer?
James
Staff member
The first thing I would do is put fresh fuel with the correct pre mix in it. 32 to 1 is pretty standard. Then I would put a fresh spark plug in it. Then I would pull the carb and clean it thoroughly with carburetor cleaner. Before you pull the carburetor I would get a manual. Because while you have it apart it is a good idea to make sure that the floats are adjusted correctly. 15-16 mm should be pretty close. This job isnt hard to do. But the manual will give you pictures and better description than I can at this point. I would also clean and re oil your air cleaner. Or better yet replace it they dont cost much. Once youve reassembled the carb install it. You may need to make some adjustments on the carb. First will be the Idle screw. This will typically have a jam nut on it. Loosen the jam nut and run screw in till it bottoms out. Then back it out about 2 full 360 degree turn. The next adjustment will be the air screw. This should be on the same side as the idle screw. Run it in till it stops and then back it out 1 and a 1/2 turn. This should get you started. Ahhh but there is more. Once youve got it running she isnt ready to ride yet. You need to ensure its jetted correctly. You should have taken them out during the carb cleaning they will be found inside the carb bowl with the floats. I dont know what sizes they should be but with a little research at your local bike shop you should be able to find the right sizes. If none of this works, I would then go on to the reeds. Those are mounted on the back side of the cylinder and infront of were the carb goes into the intake boot. But since you dont know what condition they are in you may as well replace them while you have the carb out for cleaning. But worn reeds will make the bike very hard to start and if you can start it. Its gonna run like crap anyways. These are pretty easy to do and if you start the job say on a saturday morning. You could be riding in a couple of hours afterwards. These are all simple jobs.
Now if none of this works it could be time for a new stator, but only if your not getting spark. Or worse yet a new top end. Not hard to do but kind of expensive. At or about $200. Or even more worse a replate on your cylinder. But we wont go there just yet. Lets hope for the best and see what happens.
OK disregard most of what I just said. Because I went back and read you whole post. Especially if your going to have the motor rebuilt. The whole motor right? Not just the piston and rings. If you want a good running engine it will be worth your while since the shop is going to have it to have them do the bottom end also. Just for piece of mind. Have them go through the carb too. However..... you could do all of this yourself if you have all the right tools and only pay for parts. Not labor. That will be a huge savings on your wallet and its good to know how to work on your own bike. As for your plastics. Pretty much any of the online parts warehouses should have plastics for your bike. However you may have to look around a little due to the age of your machine. But they arent hard to find and should come in a variety of colors to choose from. But I would stick with yellow fenders white number plates and yellow radiator shrouds. Thats about as close to factory colors as you can get.
As for class of racing........... At the bottom typically novice or D class. But Im not a good source of info on that. Im a desert and trail rider. But have fun with it. I had a 92 RM 250 and it was a joy to ride.
Now if none of this works it could be time for a new stator, but only if your not getting spark. Or worse yet a new top end. Not hard to do but kind of expensive. At or about $200. Or even more worse a replate on your cylinder. But we wont go there just yet. Lets hope for the best and see what happens.
OK disregard most of what I just said. Because I went back and read you whole post. Especially if your going to have the motor rebuilt. The whole motor right? Not just the piston and rings. If you want a good running engine it will be worth your while since the shop is going to have it to have them do the bottom end also. Just for piece of mind. Have them go through the carb too. However..... you could do all of this yourself if you have all the right tools and only pay for parts. Not labor. That will be a huge savings on your wallet and its good to know how to work on your own bike. As for your plastics. Pretty much any of the online parts warehouses should have plastics for your bike. However you may have to look around a little due to the age of your machine. But they arent hard to find and should come in a variety of colors to choose from. But I would stick with yellow fenders white number plates and yellow radiator shrouds. Thats about as close to factory colors as you can get.
As for class of racing........... At the bottom typically novice or D class. But Im not a good source of info on that. Im a desert and trail rider. But have fun with it. I had a 92 RM 250 and it was a joy to ride.
Pull the pipe and silencer then make sure there is no excessive carbon build up in the head pipe. Run some gas or other cleaner through it as far as the silencer just pop the end cap off and get some new packing. That's about 15 bucks at any bike shop.
thank you joe,jax and james I really appreciate your posts...I have done some research and found a manual for it around 32 bucks I have read that if you have a manual it tells you exactly how to fix everything is that correct? im not the most super mechanically inclined when it comes to motors but I know a lil bit so your opinion on wether it would be smarter to take it to a shop or work on it myself would be appreciated I do agree that workin on my own bike would later be easier for me to pin point any problems a lil better down the road but I also don't wanna mess to much stuff up in case im not doing it right..i looked in the port hole form the exhaust at the piston and the top end where the piston slides up and down (cylinder sleeve if im correct?) and didn't see any major scratches or gouges but there seems to be a fair amount of oil that has leaked out onto the exhaust idk if that's correct (I will try and post pics tomorrow when I get around to messin with it) I do wanna put a new piston and rings in it anyway just for the heck of it...and would it be worth boring out to a bigger size or just keep it standard stock size? thank you all once again you have all been a lot of help
Oil in the exhaust is normal for two strokes, as there is oil in the fuel.
No need to bore it out, the stock piston will make enough power for you.
I would get your manual and do the top end yourself. It's pretty easy stuff, and the manual will show you how to measure the important specs. Good luck-BIG DAN
No need to bore it out, the stock piston will make enough power for you.
I would get your manual and do the top end yourself. It's pretty easy stuff, and the manual will show you how to measure the important specs. Good luck
-BIG DANIn regards to your mechanical abilities or the proclaimed lack there of. Depending on your manual, be it a Haynes, Chilton, or a Factory OEM manual (which I highly recommend even though it cost more). They are super easy to read. There isnt a whole lot of super technical words. That manual was written for the end user (You and Me) to read and understand how to maintain and repair our bikes. Im not the smartest guy in the world and I use my manual for almost everything I do to my bike. No matter how simple. Mostly for the torque values on the nuts and bolts.
However because this is your first bike in a long time and you may or may not know exactly what your looking for when inspecting stuff. Especially your cylinder. It might be best if you take it to get done. One thing that I have done in the passed was asked the mechanic if I could come watch. Especially if I was unsure or just didnt know what to look for. Im not saying your cylinder is bad. But to the untrained eye a cylinder could look just fine. But it really needs to be line honed or even replated. So be sure to ask if you can observe what they are doing just for your own general knowledge.
However because this is your first bike in a long time and you may or may not know exactly what your looking for when inspecting stuff. Especially your cylinder. It might be best if you take it to get done. One thing that I have done in the passed was asked the mechanic if I could come watch. Especially if I was unsure or just didnt know what to look for. Im not saying your cylinder is bad. But to the untrained eye a cylinder could look just fine. But it really needs to be line honed or even replated. So be sure to ask if you can observe what they are doing just for your own general knowledge.
Take it to get rebuilt?? And then when its time to get rebuilt again, It wouild be his first time again? So he mise well take it and get it rebuilt again?
Get a manual and read it over and over again. Watch youtube videos... If you can't find one for your specific bike, Look at other 2stroke bikes. They are all pretty well the same. If you get stumped, Post up some pictures on here and we will get you through it.
I rebuilt my first rebuild with my manual and some phone support from my best good friend Bubba Gump aka M33. So it can be done.
I suggested taking it to have it done of a few reasons. After he already said that was what he was going to do anyway. When I first got back in to riding 07 or 08. I only got to ride my bike for just a few months before it started having running issues. So I did the top end on it by myself $180 in parts. Which didnt cure the problem. Because what I didnt notice or think was abnormal (because I didnt know) was the exhaust bridge was damaged. After several weeks of research I learned that possibly the nikasil coating was worn out. Not just damaged but flat worn out. So I sent the cylinder off to get replated. $500 later including shipping both directions another top end and the cracks welded up in the cylinder and repair to the exhaust bridge none of which could be seen the first time I had it apart. Nor could I repair on my own. I had a screaming machine $680 dollars later. And none of that included the new head pipe and silencer or the RAD valve. Atleast this way if he has it done some at a shop he can start riding with a known good engine. And when it comes time to re do the top end again then do it himself. Not to mention the fact that he already admitted to not being mechanically inclined. Which leads me to believe that he may or may not have all the tools to do the job. Sometimes its just better to pay somebody who knows what they are doing first. That way he can ride get to know the bike, and do simple maintenance stuff to build confidence.
Tyler its your bike its your money. You do what you want to. Im only trying to save you some headache. Replacing the top end is easy and can be done with simple hand tools. I can even list them as I had an RM 250 and did what your needing for top a top end. Sockets 8mm, 10mm, 12,mm and 14 mm, spark plug socket and a 5-150 inch lb torque wrench.. I can do it in about 3 hours start to finish. Matter of fact you can damn near take the whole bike apart with just those tools short of the wheel axels. But as I mentioned about the headache. If you pay to have it done the right way the first time. You can start riding with the confidence know it was done correctly the first time. While your enjoying your bike you can save up some cash to buy the extra tools the you may not have to do more indepth stuff like splitting the case halves to rebuild the transmission or replace the clutch pack or what ever.
Tyler its your bike its your money. You do what you want to. Im only trying to save you some headache. Replacing the top end is easy and can be done with simple hand tools. I can even list them as I had an RM 250 and did what your needing for top a top end. Sockets 8mm, 10mm, 12,mm and 14 mm, spark plug socket and a 5-150 inch lb torque wrench.. I can do it in about 3 hours start to finish. Matter of fact you can damn near take the whole bike apart with just those tools short of the wheel axels. But as I mentioned about the headache. If you pay to have it done the right way the first time. You can start riding with the confidence know it was done correctly the first time. While your enjoying your bike you can save up some cash to buy the extra tools the you may not have to do more indepth stuff like splitting the case halves to rebuild the transmission or replace the clutch pack or what ever.
Is there any replacement forks I can put on them from another bike?
Yes. But depending on what you replaced them with you'd probably have to replace the tree also. But yes it can be done. Or...... You could just rebuild or have them rebuilt, resprung for your weight. Maybe even a revalving. And still be money ahead by comparison to replacing them.
I also took the silencer off and cleaned the little packing that was in there and was wonderinf if I could soak that thing in just some water and dawn and let it dry real good before I repacked and put it back on?