No Compression After Valve Adjustment 300cc By rapidjim (Read 791 times)

[rapidjim]

I got an interesting phone conversation last week concerning a customer doing his own valve adjust. After he adjusted his valves, he told me his 300 trike would turn over really fast but would not start. He said he went back and checked it again, with the same results and wanted to know what I thought. He told me how he adjusted the valves and it was the correct proceedure and gap. I asked him if he could do a compression check and he said he didn't have the correct adapter for his gauges and wondered if I would take a look. About an hour later, he showed up with his Magnum on a trailer. We unloaded it and bought it in the shop. When I attempted it start it I could tell by the way it was turning over that there was zero compression. So I did a leak down test and had air coming out of the carb, hmmm did he clip the intake valve? As I was removing the intake valve cover, to inspect the rocker, I heard a snap noise. Didn't really pay to much attention to it at that moment. Checked the lash and it was correct. Rotated the motor to watch the rocker movement and at this time we had compression. I removed the leak down tester and verified compression. Now I am puzzled. Look into the intake valve side with a flash light and didn't see any junk inside. As I picked up the valve cover, it slipped out of my hand, when I picked it up this is what I saw



It appears that the oil deflection flashing was holding the intake valve slightly open. Unlike the exhaust valve cover which has 3 bolt holes and can only go on one way, the intake valve cover has 2 bolt holes and will fit either way. I have not had this happen before, and never looked at the valve cover, must have been lucky each time or maybe this is only this way on the newer motors.

Whatever the case, I thought it would be worthwhile to make a post so it don't happen to others. Or if it does they know what to do.

[alleyoop]

WOW!! Great Find man that is weird and who would of thought of anything like that causing loss of compression.
Alleyoop

[rapidjim]

Nov 9, 2014 13:10:31 GMT -6 alleyoop said:

WOW!! Great Find man that is weird and who would of thought of anything like that causing loss of compression.
Alleyoop

Yeah I thought it was weird too that is why I made the post. Just enough flashing to hold the valve open if put on upside down.

[ellpee]

Interesting. My Magnum is giving me hard start grief too, and I've done nothing with the valves. It has started and run well at times, but as of six weeks or so ago it was in the crank-well-but-no-start mode. It's in hibernation for the winter now, so won't be messing with it again until next May or thereabouts, but I'll keep this in mind. I've tweaked around on it a bunch with minimal success, so I'm thinking I'll have to rent a trailer and take it down to one of the two local shops.

[rapidjim]

Valve adjustment is part of routine maintenance and should be performed at 800 miles.

[ellpee]

Is that EVERY 800 miles, Jim? If so, seems excessive.