2003 rm 250 cylinder problem

[ShawnR]

Bought the bike last night knowing there was problems, the compression was really low. So I checked it this morning and the gauge literally say 0 compression. Then after cleaning up the bike I noticed there is a very small hole in the left side of the cylinder by the power valves. A screw driver head couldn't fit in it. My question is I'm going to rebuild the top end but do I need a whole new cylinder? Or can I patch this somehow and still use it?

[Doug Fugly]

That hole is not your problem, it's simply the tapped and threaded bolt hole for the powervalves cover.

Remove the head and cylinder to have a further look.

Edited April 20, 2014 by 2-Strokes 4-ever

[ShawnR]

What exactly is the problem with the bolt?

[Doug Fugly]

What exactly is the problem with the bolt?

None.  The hole is just the end of the drilled and threaded hole FOR the bolt.  My 03 is exactly the same.  You need to take a look at the piston and cylinder.  Are you sure you checked the compression correctly?  Is there resistance and the kickstarter?  A hole in the piston, a very badly scored cylinder, or a bad main seal about the only reasons for NO compression at all. 

[ShawnR]

No like that's a light hole in the cylinder man! No threads or anything

[mgtkr1]

that hole doesn't look right to me. its as though someone has used too long a bolt at some stage and its gone through. this wouldn't cause zero compression though as its below were the exhaust port (were the piston makes its power stroke/compression) if the compression was compromised im sure you would still get some sort of reading. are you sure the head is sealed/isn't figure tight? are the rings in tact? with such a non existent reading im sure all will be revealed once the head/barrel are removed

[ShawnR]

So I realized I was doing the compression test wrong, I have all plastics off and the carb. I completely cleaned the carb, checked the pilot and jets and everything. A lot of dirt was in the carb. Cleaned that up. Cylinder is still on the carb so I hooked the test back up. Checked the cylinder head bolts. Everything is tight. I don't have gas tank on or the two exhaust springs that clip to the cylinder. (Weren't on when purchased) kicked over 4 times with throttle wide open and still 0 compression. The kick starter isn't extremely easy to push down, but it's not hard either. With three fingers you gotta push decent to get it moving. I had the right power valve cover off and the inside is spotless, the cylinder looks almost new. I'm going to see if I can pop start it or get I too turn over. If anyone has any ideas let me know please. Here's another picture of the hole in cylinder

[Afrothunderkat]

It;s like you don't listen. That hole goes no where. I can see the threads from here. FORGET ABOUT THE HOLE


Open the bike up and look inside before you REALLY make some holes.

[Doug Fugly]

Dirt in the carb is a BAD sign. Dirt ruins motors. Tear it down or continue to know better...

[ShawnR]

It;s like you don't listen. That hole goes no where. I can see the threads from here. FORGET ABOUT THE HOLE

Open the bike up and look inside before you REALLY make some holes.

I pulled top end. Cylinder is actually in good shape. Doesn't have any grooves or anything. Bad part is that the crank rod is loose (up and down loose) and there were a bunch of brownish aluminum pieces all on the sides of the crank shaft. I'm assuming aluminum because a magnet wouldn't pick the pieces up.

[ShawnR]

Dirt in the carb is a BAD sign. Dirt ruins motors. Tear it down or continue to know better...

I'm the process now. Loose crank arm ( up and down movement) and something shattered in the bottom up. Brownish metal pieces laying on side of crankshaft. Magnet wouldn't pic them up so I'm assuming aluminum. Maybe the bearing. Idk.