CR250R Problem

[BradyB]

Hello everybody, I'm pretty new to this website and have a quick question. I recently bought a 1983 CR250R retired racing bike just to ride around in local pits and trails and what not. The bike is in pretty decent condition for it's age, and I've got it looking pretty nice for an older bike. I replaced the kick-start assembly, painted it, put grips and levers on it, new brakes, all new fluids, and other little stuff. I brought the bike out, put her on her stand, and went to kick the hell out of it, and upon kicking the bike over, I realized it has absolutely no compression, as in I can push the kick all the down with my index finger. I checked the plug just for the hell of it, and it has a nice strong blue spark, and all of the gaskets are in fine condition. It has brand new 2 stroke gas in it, clean carburetor, and all new oil and anti-freeze. The owner (one and only owner, that is) said the bike has been sitting for one year without being run. Does anybody have any idea why it has no compression? I'm assuming the rings may be stuck and getting it to fire a couple of times might unstick them?? Thanks

[Kroynon]

If it has zero compression you're going to have to pull the jug. Piston is probably cracked, holed or worse. Either way, trying to get it to fire won't fix the problem. If you have a leak down tester you could find the compression loss area before you tear it down but I would suggest popping the cylinder off so at least you can get a good assessment of the engines overall condition.

[Excitable]

pull the exhaust off and have a look inside.

[Fenmore]

pull the cylinder....at the very least your gonna need new rings. 

[Tweak-venetica]

Bump for the poor fellow . 

 

Mate did ye get the lady up and running ? whats the update ? 

 

I'm new here aswell , but more than happy to pass off my 2 cents . 

 

Have you checked the exhaust as recommended ? OR whats up bro ? 

[BradyB]

The bike still doesn't have any compression but runs fine with an unbelievable amount of power. I've only ever ridden 4 strokes so riding a CR250R for my first 2 stroke was pretty much life changing  . Does anybody have any idea why the bike runs fine but doesn't have any compression? Thanks!

Edited January 6, 2015 by BradyB

[KcDavis]

Perhaps you just have incredible strength. Have you actually tested the compression to see what it is?

[babears]

Im guessing if it runs good you have compression but if you can easily push the kick start with a finger it is a kick start problem

[BradyB]

I'm getting a compression tester tomorrow. I don't understand why I would have a kick start problem because I just replaced the entire kick start assembly. Does anybody know if it is possible to lower an 83 CR250? I'm only 5' 3" with a 29" inseam and I put brand new tires on the bike which brings her to a... "pleasant" 39 1/2" seat height  . Thanks everybody!

Edited January 7, 2015 by BradyB

[skagganetti]

If you have zero compression it won't run, or if it does it'll be like a 400lb man on a pw50. May be a bad gasket or something. Drain the oil and see what it looks like.sounds like new top end time.

[BradyB]

I know it's been a while. Sorry for the late reply everybody. I brought the ol' girl back out of the garage last week. The bike had stopped running completely at the end of last season so i just crammed it in the back of the garage. I grabbed the kick start lever and (same as always) no compression. So, I did what any dedicated rider would do and skipped school and worked on a dirt bike. I took the top end apart, and to my astonishment, the piston looks brand new, the jug is perfect, and all the gaskets look fine. The connecting rod felt fine and the rings were mint. I removed all of the gaskets and cleaned the surfaces on the top of the case, bottom and top of the jug, and bottom of the cylinder head and put it all back together and refilled all the fluids. Brought it out into the driveway, got my trusty 5-gallon pale (which I need to use just to reach the d*amn kick lever) and found that I still have no compression, and now the bike does't run. Any ideas anybody? And again, any possible way at all to lower the monster? I will attach a picture of it too incase anybody is curious. Thanks a lot! -B 

[seer]

I've seen a ton of pictures posted here that claimed a perfect bore when it was completely ruined.

Post pics of the piston and cylinder.

You need to measure to know if you're ring are good.