Proper Timing chain alignment.

[IanDMacDonald]

Post #3 pretty much covers that.

Mmmmm . . . I don't think so. Post #3 says that he checked the timing plate, and it lines-up with the pointer. Makes no reference to the cam dots. I'm betting that the cam boss dots are misaligned.

[BA80]

I'm working on an 81 Special that belongs to my dad. Short story about what happened
My dad likes to start and run his bike through the winter instead of winterizing it for the cold weather. This past spring he went out and started his 81 special with no problems. He let it run for approximately 20 minutes and shut it down. Fast forward 2 weeks. He goes out but the bike only cranks but doesn't start. I tell him he NEEDS 12 VOLTS in the battery. Just because it cranks doesn't mean the battery is strong enough to make it fire. He charged the battery and tried again to start but only this time he get a couple really loud backfires through the exhaust. Short story even shorter... NOW there is NO Compression in ANY cylinder. Zip, zilch, nothing.
I cant see a valve in each cylinder getting bent. I can only assume that some how the timing chain has jumped a tooth or more. I need to know Where the Timing plate should be positioned when the cam dots are aligned with the arrows on the cap. Thanks

The pointer should line up with the 'T' mark which is TDC

In that case, Everything lines up perfect and I'm at a loss as to where to look next.

Maybe I read that wrong.

[IanDMacDonald]

No, I missed that Greg. You're right. But, if I'm reading that right, he's just asking, and has not actually opened the valve cover up yet?

[Chuckster]

Just for my own education, how would starting a bike with less than a stellar battery end up in bent valves? I was following this OK, until I got to that...

[BA80]

In post #1 Rob is saying he has no compression and possible timing chain slipped causing bent valves. However, he says all the timing marks are aligned.

I really can't see how valves could have gotten bent though.

[BA80]

Rob, is it possible the fuel valves were left on and the cylinder walls are gas washed? Check your oil level and see if the crankcase smells of gas.

[IanDMacDonald]

Just for my own education, how would starting a bike with less than a stellar battery end up in bent valves? I was following this OK, until I got to that...

It's really a couple of events happening, and it's just from what I read: many bikes have non-hardened crank ends, and when the bike is started with a less than full charged battery, the crank end shears off right before the gasket ending. Some have reported that this causes just enough imbalance to throw the timing off, and bend the valves. This was not a secluded event. It's reported forum-wide for many bikes.

[XJ Rob]

Rob, is it possible the fuel valves were left on and the cylinder walls are gas washed? Check your oil level and see if the crankcase smells of gas.

Yes.That could be the case. I have not checked the oil level or smelled for gas in the crankcase. Its a little awkward with one person and right now I'm on vacation. We thought about the rings washing out.But never expected it could happen. My thoughts were if the floats stuck open, wouldn't you have fuel on the floor from it running out the back of the carb?? I'll check that when I get back. Maybe we could drop a small amount of oil down the plug hole and see what happens.

[IanDMacDonald]

Yes.That could be the case. I have not checked the oil level or smelled for gas in the crankcase. Its a little awkward with one person and right now I'm on vacation. We thought about the rings washing out.But never expected it could happen. My thoughts were if the floats stuck open, wouldn't you have fuel on the floor from it running out the back of the carb?? I'll check that when I get back. Maybe we could drop a small amount of oil down the plug hole and see what happens.

Rob- I'll ask you directly, as there is confusion regarding of things have been checked. Have you pulled the valve cover and verified the cam boss dots are aligned?

[XJ Rob]

Rob- I'll ask you directly, as there is confusion regarding of things have been checked. Have you pulled the valve cover and verified the cam boss dots are aligned?

YES.
When the timing pointer is on the "T" BOTH the intake and exhaust cam dots are straight up on the arrows of the caps that hold the cams in place.

[skids]

YES.
When the timing pointer is on the "T" BOTH the intake and exhaust cam dots are straight up on the arrows of the caps that hold the cams in place.

That is theoretically correct. In real life, even with a new cam chain, you might find the best adjustment with the dots slightly outside of the arrows (by half a dot each). I have never had perfect luck at alignment!

[BA80]

If the cam gears are correctly installed and the pointer isn't fubar things usually will line up right. Sounds like his stuff does.

'nuff said.

[XJ Rob]

Update

Well I was finally able to check things out and it turns out that there are 3 bent exhaust valves. I'm not sure how but there is .026 and .030 clearance between the valve and cams. He will be looking for a good head. Probably wont see the road this year. Thanks for all the suggestions..

[BA80]

The question is, how did they get bent if the timing marks are lined up as you said?

[MPittma100]

Well I was finally able to check things out and it turns out that there are 3 bent exhaust valves. I'm not sure how but there is .026 and .030 clearance between the valve and cams. He will be looking for a good head. Probably wont see the road this year. Thanks for all the suggestions..

Three bent valves does not account for the 4th cylinder with no compression. You may want to consider having that head repaired at a machine shop. Before I started tearing it down, I would want to know exactly the cause of the problem.