The 81 lives!

Thanks to the help from a few good friend, my 81 is now running again.

This was the one that started the nightmare I'm in the middle of now. It was running fine until we tried to fix the starter clutch and it never ran again. Then I got the 79 and most of you know how that was working out for me.

Compression was all over the map so the first thing we did was put it back together and set the timing. Then checked the compression which was low but at least it was even across the bike.... but it was still only 70 PSI. Used some cleaner, let it soak, put some oil down the holes and checked again. Up to 85 across the board. Hmmm still really low.

Wouldn't start. Backfiring at both ends. The timing was still off somehow. Used a timing light and checked under the inspection cover and it was on.... but Dave though it must be out of phase somehow. He thought that maybe the disc with the holes (I don't know the name of it) was somehow put on out of phase. The manual really doesn't explain this part. So we started swapping coil wires and it almost started. Swapped the coil wires to another combo and bam it started instantly. Ran like a top.

I think I'm going to pull the motor and sell it with the ignitor on Ebay to hopefully recover some of the money I've been losing on this little adventure. I'll post a video of the motor running as proof it starts and runs so we know its a good ignitor, the engine runs, and it doesn't smoke like a train. I'll keep the rest of the bike for parts for my 79 since most of the parts are a straight swap.

What did you do about the low compression, what was causing it and how did you resolve, swapping coil wires wouldn't resolve that. In the past when seeing those results it has been because your Cam and Crank timing are out. Would expect to hear you referring to approx. 140 PSI and not 85PSI

We measured is again after running it for a while and it still came up as 85 across the board. Dave is pretty sure his compression gauge must be off so we are going to pick up another one and retest it. He doesn't think it would start as easily as it does on 85 PSI. Once we got the coils sorted a tap on the starter and off it went, despite the low battery from all the mucking about. Since we verified the timing was correct he doubts that all of the rings would be stuck exactly the same way for all of them to read 85.

He is coming back out when the engine I bought off of ebay arrives and we'll recheck it then with a new gauge.

Stupid question (and may have been asked before)- are you doing the tests with the throttle all the way open?

Even with your throttle shut you should still be achieving far higher compression results if all is good, crank and cam timing and valves not being held open by incorrect shimming, rings nice and free. Prove your tester on a known good cylinder of another vehicle.
Something sounds not quite right to me, but hey sounds like your getting somewhere all the best look forward to hearing you have got a result and you have put that machine on it's back wheel

Just a thought regarding the "compression tester" I had a learning experience a long time ago. I used to use the hose from the compression tester to pressurize the cylinders when changing out valve seals on cars. In order to do that you need to remove the schrader valve in the end of the hose. When I replaced it (being and auto mechanic at the time) I grabbed a schrader valve off of my bench and put it in the end of the hose. That schrader valve core was from a tire valve. Looks the same but it's not. The schrader valve core for compression testers is a special valve core with a very light spring. If you use a valve core from a tire or tube, the spring pressure in that core is strong enough that it causes the compression tester to read low at or around the 50-80 psi range.

It could be at some point that your buddies compression tester was leaking down and not holding the reading and the cause of that is the leaking schrader valve core. Could be he or someone before him changed out that valve core and used the wrong one.

Maybe this will explain the low reading. Good luck.