Engine Brakes?

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Aug 22, 2007
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#1
Yesterday I went for a short ride on my 1984 honda 250 xr (maybe 10km's) when I got back to my driveway I was going 1/2 throttle in first down it when all of a sudden my bike locked up and backfired. I could not get the bike into neutral and the back tire was completely locked. So I put on the clutch and wheeled it down to my shop. After wheeling it down my driveway it went into neutral no problem. However now when I kick it when trying to start it the bike has no compression, the engine brake is permanently on, I can feel the air coming out of the pipe that the air usually comes out when the engine brakes are on. When I kick over the bike I can see the mechanism on the outside of the case moving and there is a disconnected spring however there is no way that I could even keep the mechanism from moving never-mind a little spring. Does anyone have any idea what the problem could be?
Thanks, Brett
 
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#2
The symptoms you describe sounds exactly like a typical engine sieze. You were riding along, the piston siezed and locked up the rear wheel. When it cooled down it broke loose but now the rings are toast and you have no compression.

Rod
 
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#3
I had considered this however the bike had tons of oil and it was a nice short ride so it was not that hot
 
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#4
First, I do not believe that your machine has a mechanism that is called an engine brake (although some diesel engines have them in various forms). Four strokes tend to use the engines compression to help slow the vehicle when you let off of the throttle while the bike is in gear and the clutch is out, this is often referred to as engine braking, but it does not use any "brake" mechanism.

Tons of oil is not necessarily a good thing, and can be as bad as not enough.

Since you say that you have no compression, I am inclined to believe that it's time for you to pull the top end and take a look. At a minimum, you should plan on replacing the rings. Rod is probably right, and your reluctance to believe that this is your problem does not prevent it from being your problem. If replacing the rings doesn't fix your problem, then you have far larger problems to fix, so you should hope that it's just your rings (it could be a shattered piston).
 

CaptainObvious

Formally known as RV6Junkie
Damn Yankees
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#5
It's not engine brake, your engine is broken.
 
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#7
ya, if thats what you mean by the little black lever underneath the clutch I was not to sure of the name