2000 RM250 engine noise

[cannonballgsu]

First off, i searched but couldn't find my answer, so maybe someone can shine some light on my situation. I'm new to 2-strokes so talk slow :laugh:

I recently bought the bike and spent a whole day riding it without any problems except it didn't want to idle but i attributed that to sitting up for a while. Well, the other day i decided to just run up the road, so i started the bike, let it warm then struck out up the road. I was in top gear (no i hadn't been fllat out for a long time, heard that was bad) and the bike sounded like it just bogged then shut off all within about 3 seconds. When i started to kick the motor over, the kickstarter was almost froze up. it would turn over, but took an enormous amount of force.

i pushed it home and once i got there (5 miles later :yell: ) it would kick over fine. when it would fire up it sounded like a can full of rocks being shook up. I pulled the clutch which was fine and pulled the top off and the piston and cylinder walls looked fine. I'm stumped and hoping someone can give a little help.

Thanks.

 

[Moose]

I don't know the severity of your situation. But our 2000 RM 250 rattles a bit. I'd say it's normal as there have been no problems with ours...

Does it sound like this? - http://s54.photobucket.com/albums/g99/sicchevelle/?action=view&current=ridingpictures343.flv

Maybe I'm going out on a limb (depends on the severity of the sound) but I'd say they're two different problems and the rattle is normal. I'm not totally sure, but I don't know your situation and this is the best bet I can give you as of now. If you post more it'll probably show that I'm wrong, and there is in fact a more severe problem.

 

[cannonballgsu]

it actually sounds like that, but worse and the engine sounds like it is binding. It also won't idle. the thing that makes me think something is wrong is the fact that it didn't make that noise until the incident the other day when it just shut off and somewhat siezed the kickstarter. Thanks a lot for the help.

 

[Moose]

I'm also new to dirtbikes completely, so I'm just trying to help you out with what I know. Have you pulled the kickstarter apart? Check that everythings in working order. That's all I can think of right now, hopefully someone else will chime in and help you.

Elliot.

 

[cannonballgsu]

i'm actually converting from roadracing sportbikes to dirtbikes so i'm learning. Thanks for all the help though, i'll keep tinkering

 

[kx125412]

It almost sounds like your mainjet is too lean and when you were wide open the piston expanded enough to seize it from heat and when it cooled down the piston shrunk down enough to run again. It seems weird that the piston and cylinder looked fine. There were no scrapes or scuffs at all?

 

[cannonballgsu]

the cylinder was immaculate, not a single scuff. I was told it may be the crank bearings, so i'm going to check that out next. hope the crank isn't trashed

 

[84cr125]

the cylinder was immaculate, not a single scuff. I was told it may be the crank bearings, so i'm going to check that out next. hope the crank isn't trashed

so you have taken the head off and checked it out, made sure there were no scores in the cylinder. Check through either the exhaust or intake port and make sure the rings are fine.

It sounds to me that you had a partial seizure, they usually occur when rding at WOT. the fact that you can still kick it over may be just beacuse the rings were actually not totaly melted to the cylinder.

 

[flattie]

pull the cylinder off.... u'll see the damage..... top end time, and while ur at it clean the carb

 

[cannonballgsu]

well, just an update, ended up pulling the bottom end and the crank bearings were gone. the crank was ok, but there was some metal in the bottom of the case. pretty much doing a complete rebuild, new piston and honing the cylinder

 

[Bunya]

Funny how this stuff goes. Your bike seizes up and shreads the main bearings - your crank and cylinder are fine. My bike was running great, no noise, 185 psi compression. I pulled it apart to do the top end just to be safe (I just bought it a month ago, top end supposedly done with only couple of hours. Not only is the piston, cylinder and power valve wiped, so was my crank - even though the main bearings are fine! :bang:

 

[Hawk45]

Just imagine that on a stroker!! YIKES!!! $$$$$

 

[cannonballgsu]

^yeah, i'd never recover from that one...

what sucks is that i bought the bike the week before this happened. was supposed to be fresh and not a problem. oh well, live and learn

with parts and labor its only going to cost me $330 to fix and i should have it finnished by this weekend. damn i'm ready for that!!!

 

[Bunya]

More than likely what happened was you first started to lose a crank bearing. This in turn caused the crank seal to fail. The seal failure allowed the engine to suck air into the crankcase causing it to suddenly run lean. The lean condition then caused the engine to run hot which led to the piston over heating and seizing in the bore.

Marc -

 

[cannonballgsu]

^that would make sense because it siezed but when it cooled i could turn the engine over again. apparently then it didn't have the main bearing however because there was play in the engine (like a clunk when turning it over)

Thanks for all the help!