I had the problem with the cam chain going slack per my previous post - http://gstwins.com/gsboard/index.php?topic=57896.msg655853#msg655853
After putting in a new cam chain tensioner and doing the timing I now find there is no compression when I try to start the bike. My neighbour the car mechanic wonders if when the cam chain became so slack it might caused a problem with the valves or even the pistons.
Is there something I can look at or check that would confirm/deny these suspicions and help me figure out why I'm not getting any compression at this time?
Did you check the cam timing when you pulled the engine apart? Was there compression before hand?
If the timing was correct and you had compression (it was running?,) it's very unlikely that your old CCT caused this problem. Keep in mind that the CCT's job is to take up slack, on the trailing edge of the cam chain, in order to prevent the chain from slipping. Timing is set from the leading side of the chain. If the timing was still good when you inspected (no teeth jumped between crank and cam), it's very unlikely that the CCT would have permitted enough variance in timing to put a valve into a piston.
Quote from: burning1 on October 09, 2011, 12:16:21 PM
Did you check the cam timing when you pulled the engine apart? Was there compression before hand?
Yes, we did the timing check when the engine was apart. My neighbour said that when he was rotating the crank it didn't feel like there was any compression. After everything is back together, I took a spark plug out, rotated the crank, and didn't find any noticeable compression.
QuoteIf the timing was correct and you had compression (it was running?,)
This is the first time I've tried to start it after the timing was checked.
Quoteit's very unlikely that your old CCT caused this problem. Keep in mind that the CCT's job is to take up slack, on the trailing edge of the cam chain, in order to prevent the chain from slipping. Timing is set from the leading side of the chain. If the timing was still good when you inspected (no teeth jumped between crank and cam), it's very unlikely that the CCT would have permitted enough variance in timing to put a valve into a piston.
I'm not totally sure of terminologies here, and I don't want to bother my neighbour again on his weekend :) , but after replacing the cct, the timing was noticeably off. We put the RT on the single pickup (I read that on a thread here for the single pickup versions) and both sprockets were off as far as the 2 and 3 positions. It took a fair bit of effort to put them back in the correct positions.
I hope I'm explaining things properly as this cam chain/timing stuff is all new to me.
Check the valve clearances with the cam lobes facing away from the shims/buckets, a much larger than previous clearance would indicate a bent valve. If you had the cams out and mixed up the shims you might have an open valve due to no clearance, also would be confirmed with valve clearance check. If the head was off you could just pour some water into the ports to see if it leaked past the valves, doubt you'd want to do that to an assembled engine.
Quote from: gsJack on October 09, 2011, 01:30:58 PM
Check the valve clearances with the cam lobes facing away from the shims/buckets, a much larger than previous clearance would indicate a bent valve.
I have never checked the valve clearances before so I have nothing to compare a current measurement with. Can that be done with the engine still in the frame?
QuoteIf you had the cams out and mixed up the shims you might have an open valve due to no clearance, also would be confirmed with valve clearance check.
The cams were not out during this process. My neighbour walked the chain around the sprockets - something he has done with car engines.
QuoteIf the head was off you could just pour some water into the ports to see if it leaked past the valves, doubt you'd want to do that to an assembled engine.
Do you mean the valve cover/cylinder head? Or part of the block? Sorry, some of the terminologies are new to me as I've never delved into this part of a bike before. Although I am reading up on how to take the engine out and feel pretty confident I could do that if I need to in order to check/replace things.
I really appreciate all the help and ideas you guys are providing.
While taking the cams off I noticed one of the cam journal caps was cracked in two. From everything I've read it can't be fixed and pretty much means this head is no good. I guess my choices now are looking for a used head to put on it or taking my sledge hammer and beating this piece of crap bike to scrap for all the grief it's given me.