2000 RM250 smoking help!

(New to the forums)I just got a 2000 rm250 for $1000.as my first dirt bike I have experience with quads but not dirtbikes. I'm only 15 and don't Know much about two strokes. Ok so lately it's been smoking white. And everytime I rev it blows white smoke. It also spits oil out of the silencer. The guy I bought of said he ran castor 40:1. The other day I went to a bike shop a guy told me that I should run it 32:1 but he also said I was gonna foul plugs but he said it's better to run the bike at that to keep the engine from wearing out. So I bought some Honda 2stroke oil and got myself a ratio rite cup and mixed it at 32:1. After that I went to go ride out in the dessert(Barstow,CA). I turn on the bike and it smokes quite a bit. I also noticed it didn't have that nice rev 2 strokes should have. I also at times it would turn of on me and I would have to kick it like 10 times to turn it on. Is it Fouling the plug? Flooding? The plug is a black color. It would kinda poped a little when I would twist the throttle threw gears. Sounded like it was revving to high and didn't sound smooth.

Then today I started it and it started idling really low and it would pop when I would let go of the throttle.

Also I think my clutch side cover is cracking core me if I'm wrong. The bike has quite some oil on the head pipe and under the engine. I have no idea where the oil comes from. I had already degreased and washed the bike.

Also does any body know which is the coolant drain bolt?

Tell me if you guys see anything usual. All I have done to the bike is change gear oil, clean filter, clean silencer, change coolant(had to drain through the hoses couldn't find the bolt), fresh fuel.

Also when I changed the gear oil it was like chocolate brown and smelled burned. Is that good or bad?

Also if you see the photo with the clutch cover it looks like it's cracking I'm not to sure. ImageUploadedByThumper Talk1439272705.428909.jpg

Thanks for any help!

Thank you for any help.

ImageUploadedByThumper Talk1439272348.399721.jpgImageUploadedByThumper Talk1439272372.323952.jpgImageUploadedByThumper Talk1439272413.441786.jpgImageUploadedByThumper Talk1439272428.278445.jpgImageUploadedByThumper Talk1439272447.126286.jpgImageUploadedByThumper Talk1439272470.071711.jpgImageUploadedByThumper Talk1439272493.114213.jpgImageUploadedByThumper Talk1439272516.654957.jpgImageUploadedByThumper Talk1439272541.412873.jpgImageUploadedByThumper Talk1439272563.554893.jpgImageUploadedByThumper Talk1439272602.182441.jpg

Not to sound like a jerk, but why would you buy bike with obvious oil leaks if you know nothing about fixing motorcycles  ?


If you are in love with it, get a service manual and follow the recommend service work.


If you are not, clean it up and sell it.......


The bike was run without a skid plate, so it probably has rock damage to the cente cases (oil leak).


The motor is 15 years old, so it will need a carb rebuild (meaning the wear components and the gaskets) , new crank seals (the right one is gone, and thats why you have so much oil and smoke) , and of course a top end.

Thanks for the reply. Well like I said it is my first dirtbike. Our first bike isn't always the best.

So you think it's not worth fixing? Is it hard to find parts? I got because it was cheap and thought it would be good bike to learn on.

there probably isn't a crack the oil is sludge coming from your exhaust port and leaking down to the bottom, you're  leaking fluid into the crank either from clutch side seal or water pump seal 

My first bike was an 86 yz 250 with a cracked case. Any bike can be fixed if you're willing to spend the money. I knew when I bought my bike it needed work and I wanted to learn how to do it. Now for your problem. It needs to be rejetted for sure if you keep the mix at 32 to 1. I run mine at 50 to 1 but I only trail ride so it's never screaming for any length of time. Read the jetting thread at the top of the two stroke forum and search everything you can to get more info. The more you learn the easier things will be to fix. Also looks like the seal for the primary drive shaft is leaking. Try to get a manual. It is worth every penny.

That's exactly what I want to do with the bike. I wanna learn how to work on it. Finally somebody gets me lol.

Would the stock jetting be ok it only had a procircuit pipe and a pro filter.

Would the problem be a leaking crankshaft seal? I pulled the plug and it is black and oily. I have a feeling it's burning transmission oil. I could be wrong.

How hard is it to change the crankshaft seals and the primary shaft seal do I have to split cases?

I'm going to try clean the carb and see what jets it has on and see if it makes a difference. Here's a pic of the plug

Thanks for the help.

ImageUploadedByThumper Talk1439783382.985910.jpg

Would the problem be a leaking crankshaft seal? I pulled the plug and it is black and oily. I have a feeling it's burning transmission oil. I could be wrong.



What type of transmission fluid are you using ? if its blowing white smoke then it could be burning transmission fluid how is it idling ? does it have a high idle or does it take a while for it drop to idle after you rev it ? try unbolting the exhaust pipe and lifting up the bike forward exhaust port down and see if sludge pours out


That's exactly what I want to do with the bike. I wanna learn how to work on it. Finally somebody gets me lol.

Would the stock jetting be ok it only had a procircuit pipe and a pro filter.



depends on how restrictive they are



How hard is it to change the crankshaft seals and the primary shaft seal do I have to split cases?



if the suspected leak is from the clutch side then you only need replace the primary drive crank seal, it doesn't take the splitting of the cases you just need to remove the primary drive and then underneath the primary drive is the crank seal 


I'm going to try clean the carb and see what jets it has on and see if it makes a difference. Here's a pic of the plug

Thanks for the help.

attachicon.gifImageUploadedByThumper Talk1439783382.985910.jpg


That plug just indicates what already has been suspected the bike is running really rich 

I've changed the gear oil already and washed the filer. I used Honda 2 stroke gear oil 85w I put in 850ml. I don't know if that was too much oil. But the previous owner didn't look like he took much care for the bike. The filter was really dirty and the gear oil was chocolate brown. It's smelled burnt too. I drained a quart of oil from the bike.

So when I start the bike it idles fine and it only idles high if I put the choke on.

When I let it sit and idle its fine. But sometime It starts to idle really low and will die if I don't rev it. When it idles low it sounds really quite almost as if wasn't even turned on.

The bike could be idling fine and sometime if I let idle for too long it will start to idle really low and dies. And it takes like 10 kicks to turn on again. (Starts first kick when cold.)

When I rev it blows white smoke out which is really noticeable.

I cleaned the plug and it stopped smoking for like 30 sec and it came back.

And if I ride for like 10 min it starts to drip oil from the silencer.

I could be riding it sometimes and if I stall it on accident (still getting used to it) it's takes like 10 kicks to start it. It's like if it was flooded.

The bike doesn't rev cleanly it kinda spits when I really step on it.

I took the pipe of and it has lots of carbon on the walls. The piston looks fine no scratches from when I looked through the exhaust port.

Through the spark plug hole I can see that the top of the piston looks brown I don't know if that's any good.

So the right crankcase seal is behind the clutch right?

Is there a way to post a video of it running. It would be a lot easier.

Sorry for all the writing.

Thanks for the help. ImageUploadedByThumper Talk1439792658.322129.jpgImageUploadedByThumper Talk1439792684.509095.jpgImageUploadedByThumper Talk1439792752.686391.jpgImageUploadedByThumper Talk1439792787.910313.jpg

That's just all the stuff I've done to it.

And one more thing is that when I ride it sounds like if it was hitting the rev limiter on the low gears as I shift. It doesn't have nice clean revving sound like a two stroke should have.

I have a video of it but I don't know how you would upload it.

Thanks for any help.

you mean its boggy through the rev range ? you sure you have the choke on or off 


anyways part number 14 is the clutch side crankseal and 16 is the primary drive gear i would only replace them if i knew 100 percent that there was a leak and you need to do a leak down vacuum test to confirm a leak from there



Edited by 78SuzyQ

That's exactly what I mean it's kinda boggy. It runs and everything but it lacks a little power and it kinda boggy . The choke is on when you pull the black knob rite and down position is no choke? Right?

just play with the choke and air idle screw with the air filter off for beginners then see how the bike runs 

Read the faq at the top of the forum and the jetting thread. It's invaluable. Also consider a complete engine rebuild top and bottom. It will be worth it in the long run. No engine damage from blowing up because you don't know when it was done last. Do it right the first time and it will be worth the investment. Some may not believe me but my 2002 rm250 was rebuilt when I got it and I put an hour meter on it. It's due now because it has developed a small knock but it has 440 hours on it. Like I said I don't race, but good parts and maintenance is worth it's weight in gold. I know it may be hard at 15 to wait to rebuild because you want to ride, but it would be worth the wait. Start cutting everybodys grass and walk their dogs for extra cash!

Thanks for the help. I already took that in consideration.

Things I want to do on my bike :

Top end rebuild

Carb clean

Compression check

Leak down test.

My main goal is to get me a manual. That's the first thing I'm gonna buy!

I know I'm only 15 but I think I can learn how to do some repairs on my bike.

But money is my worst enemy. I will try saving that cash for the top end for sure.

Does a top end run about $100-150?

With gaskets, rings and pins?

And my dad isn't very much of a mechanic. He was barely nice enough to get me my first dirtbike. So the only help I got is the forums and a manual.

Thanks for the help.

Edited by UlyssesGuz24

Look in your service manual and check what stock jetting is. Mostly all two strokes come with too rich stock jetting. You would want to change that if your going to run racing oil in a 32:1. Usually you can find the recommendations online for your 250. I had to do that on my bike and after was a total difference. Hope this helps :)

And before you do your jetting. To get the right readings, you want to really look in to cleaning the air filter, top end, checking power valves, and muffler packing.

Thanks. One thing I think wanna do is clean the power valve.

I run Honda racing 2 stroke oil.

Ima play with the jetting and see if the smoking stops. Thanks or the help.

Dont worry these are all  inor issues.Running a bike without a skidplate isnt an issue.First thing you want to do is get the manual for your bike specific model.You need to check and eliminate one thing at a time,I would start with new plug,new filter,change fluids,etc.Before any of that give that bike a good wash and degreasing,repack the silencer.You can find alot of answerrs on Youtubwe and Google.Also feel free to message me about anything.ats a great bike and with a little work and carte it will be running fine.

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