Was running fine and now no compression / no start
Posted July 24, 2002 - 05:52 AM
Posted July 24, 2002 - 05:46 PM
One thing I did notice was that his decompression lever wasn't working. After we push started the bike it ran ok. Also the decompression lever started to operate properly. You may want to check your decompression lever out. Maybe it is stuck.
If you have a manual you may also want to check your valve clearance.
Posted July 24, 2002 - 11:33 PM
If not that, several people have lost compression mysteriously and have had it reappear after starting. By lost, I mean push it through easily by hand. In every case, I have seen, it was lost while sitting and came back after starting. To start it, give it 1/16th throttle, kick it, then 2/16ths, kick it, and so on. Eventually, you open it up enough to get enough air in there for it to fire up. You can shut it down immediately and the compression will be back. I have had this twice on my bike and seen it twice on two different bikes and the same each time. The second time it happened on my bike, I pulled the head (and wrote it up on TT) cleaned the valves (coral like deposit on back of exhaust valves) and put it together thinking I had fixed it. Still no compression, but it had compression after starting once.
Recently I lost compression after riding while washing my bike at the track. I used the 'add throttle til it starts' trick and then cut it off. I still didn't have compression. I started it several times and ran it for maybe 10 minutes total at the track w/o compression. I got home, still no compression, started a few times, still none. Tore it down, saw no problems other than intakes a little tight (not enough for this). While in there, put in new piston, rings, wrist pin, clips, lapped valves, reshimmed and had perfect compression when I put it back together. Oh yeah, I did the solvent leak test before I pulled the valves with contact cleaner and it held fine. I cleaned up the head and pushed the valves a few times and then tried it again and a couple leaked. I assume I got trash in the face while cleaning.
I have no idea why it lost compression, why it wouldn't come back, or what I did that convinced it. It wasn't the rings or shims because they don't just go out all of a sudden like that. I think.
Start it using the 'increasing throttle' method, unless binding, clacking, etc., and it will almost surely have compression after that.
Posted July 25, 2002 - 04:29 AM
Posted July 25, 2002 - 11:14 AM