rm250 won't start

[chhamic]

kind of new to the motorcycle world and am in the midst of learning how it all works. bought an 87 suzuki rm250 about a month ago, started it, rode it a couple of times. i noticed that the previous owner did zero maintenance to it whatsoever. so i fixed the leaky exhaust and got a new air filter, and a few other small things, but nothing serious. and now that i've reassembled the bike, it won't start. it does spark, it is getting gas, but i can't seem to figure out where the problem lies. i ordered the manual, but it's not a readily available item, so it will take some time. i would appreciate any sort of help on this matter, thank you.

[bigE]

Did you try push starting it? I have an 86 RM250 and it will not be kickstarted when cold. I usually give it a shot of carb cleaner to get it running after its been sitting for awhile

[chhamic]

tried that about 6 times, it tried to come alive, but with no positive result. unsure if it's carb related, but prior to replacing small parts it ran just fine. i haven't yet touched anything mechanical, so i couldn't have messed up anything there. still clueless

[919Hooligan]

When you oiled the air filter, did you squeeze ALL the oil out of it that you could? You're supposed to wring it out to get the excess oil out. If you left a bunch in it, the airflow will be restricted and it won't run properly.

When you encounter a problem like this, the best way to fix it is to revisit everything you did, no matter how sure you are that you did it right the first time. Take it from someone who's owned over 50 bikes; if the bike ran fine until you worked on it, then you can almost bet the farm that the problem has to do with something you disturbed, directly or indirectly. Let us know what you find!

[the_privateer]

sounds like its time to rebuild the top end, may as well anyway on a bike that old. open it up and see what it looks like

[bigE]

try taking the air filter off and see if you can get her running. If it does run w/o the filter, the new one is not letting enough air flow to the motor. Could be over oiled like 919 said

[chhamic]

pulled air filter out, wrung out any available excess oil, tried starting, not much happened. tried leaving air filter out, same result. perhaps top end rebuild might be necessary. any other suggestions prior to the task?

[919Hooligan]

Before you spend the money and rebuild it do a compression check. You should be able to borrow a compression tester from autozone or advance auto. Wait till you get your manual, as it should have all the specs in it for your compression readings. You'll need it anyway if you rebuild it. If it comes out good then there is no sense in doing the top end.

Also, just for our information, why don't you list all the things you replaced or worked on when the bike was apart.

[bigE]

You could always squirt some carb cleaner in the cylinder and then give it a good kick (thats how i get my bike started after its been sitting for awhile)..... Also might check the timing

[zippo]

Did you try a new spark plug? Just because you can see a spark does't really mean you are getting a good spark.

[chhamic]

cleaned things up a bit, double checked everything. put in a new spark plug. now it will push start with ease, but kick starting is not so easy. even when warmed up, kick starting not always that easy. and does not hold an idle. what should i do now?

[919Hooligan]

Originally Posted by chhamic

cleaned things up a bit, double checked everything. put in a new spark plug. now it will push start with ease, but kick starting is not so easy. even when warmed up, kick starting not always that easy. and does not hold an idle. what should i do now?

Ok, now we are getting somewhere. That sounds EXACTLY like a bike that has almost no compression. Find yourself a compression tester and check it out. I have a feeling you are in need of a top end rebuild. Just the fact that you said "it will push start with ease" tells me that it has low compression. Are you doing it in first gear? Almost any bike with good compression will lock up the back tire if you try to push start it in first gear.

I think the privateer was on the right track with this one.

[83dr250]

I'f your push starting in first it must have low compression because the rear wheel should just stop and drag when you let off the clutch in first. I have a 1983 DR250 and the presure in the chamber should be about 150- 170psi. Did you change any of your carberator lines? are they hooked up right? only one line in and 2 out. My bike was having the same problem when I got 3 weeks ago and the guy didn't know what was wrong and the carb was hooked up incorrectly. When you turn your petcock "on" does gas almost immediately come out the air filter if so your carb is hooked up wrong. Another likely issue if it's not your comprssion is your CDI when you get your manual you can check it with multi-meter and see if it's good. How does it run once it gets going? does it pop or sputter in any of the RPM range?

[the_privateer]

Compression numbers vary so much between bikes and testing procedures (hot or cold testing, how many kicks, throttle open or closed, ect.) that the only way to really know if you have acceptable compression with a compression tester is to have a base line- which means testing it after everything (piston, rings, reeds, ect.) is fresh or at least definately within spec and testing it the same way every time

Not every bike runs the same carb, the rm and dr almost certainly don't, so the whole 1 line in 2 out most likely does not apply; for instance the mikuni tmx on my bike has 1 in (gas line) and 5 out (vent hoses). obviously the bike won't run without the fuel line; the vent hoses can get clogged making the bike breathe hard and flood ect. Refer to the manual when you get it for your specific hardware.

the inability to idle could either be the low compression or you just need to adjust the air screw and idle speed screw on the carb (again refer to the manual as the placement of these screws vary) how you do this (once you're sure of the compression) is to first screw the air screw all the way in, then turn it out 1.5 turns. adjust the idle speed so that you can get it to idle, then adjust the air screw to get the highest posible idle, then adjust the speed screw again to get the lowest possible idle. If you have to go more than 2.5 turns out on the air screw, you need a smaller pilot jet.

I don't recommend taking the top end apart before getting the manual, but you can get a peep show of your piston and rings by removing the pipe and looking up the exhaust port into the cylinder

good luck and try not to get discouraged, i know how much it sucks to have a bike that doesn't run taking up space in the garage, if you need anything i said cleared up don't hesitate to ask

[83dr250]

I was just trying to say your carb may not be hooked up correctly? manual is the solution to all problems

[chhamic]

Adjusted the idle and did a compression test, the numbers were extremely low. Decided that a top end rebuild would be helpful. Also decided to replace piston and rings, why not have a clean fresh start with this bike? Parts already ordered, should have everything running very well by next week, thanks for all the help.

[chhamic]

ok, so i pulled everything apart, piston was rubbing slightly on cylinder wall, but nothing that couldn't be easily resolved. replaced piston, cleaned everything very well. put everything back together accordingly. still will not kickstart. can push start it, but that was not my objective. a little pissed now, what next?

[bigE]

check the compression again. Did you have the cylinder bored and honed?? If not, you may have to get this done which means you will need a new bigger piston. Can yout kick start it after its warmed up now? I have an 86 RM250 and even with a new piston and rings, it still needs to primed to get it started when its cold

[919Hooligan]

bigE is right. When doing a top end rebuild (especially on a 2-stroke motocross bike) you almost always have to have the cylinder bored out to the next size and install a bigger piston and ring set. Did you have the cylinder checked out by the bike shop? Even if it looks ok to you, it may be out of round or tapered at the top. The only way to check it is with a micrometer.

[cing31fan]

Hey guys whats up cingular31fan here, I kind of have the same problem, but when I kick start it 2 or 3 times it will go puff and will see some smoke come out. It will pull start, however if I kill it I can't kick it half to pull it again? Just to add its a 1991 CR 125...