loud ticking/slapping (1979 cb650)

[rappz7]

Ive got a pretty substantial tick/slapping noise going on in what sounds like the top/mid engine. Gets louder with acceleration and was there before the engine tear down. I adjusted the valves when rebuilding the top end and installed new exhaust header gaskets as well (maybe ruling out exhaust leaks, as i heard this may create a ticking sound). Although I didn't use stock exhaust studs but instead I used bolts as I had lost/damaged a few during the tear down. Could these maybe not be tightening those headers down tight enough? I tried adjusting the cam chain with the adjuster nut to no avail. I don't know if maybe the adjusters stuck, or perhaps my cam chain is stretched out, It seemed tight when i reinstalled it. Im lost here Ive been trying to figure this out for a while. Anybody with a little insight out there? All input is welcomed and appreciated. Also I noticed header pipes 1 and 3 were cool enough to touch while 2 and 4 were extremely hot.

 

[crazypj]

Check plug caps ain't cracked, could be hearing HT spark to head instead of inside it?

 

[esmoojee]

Did you do a compression check after rebuild? My first thought was a loose cam chain. Torque the cam cap bolts to spec? I'd double check timing also.

 

[rappz7]

Did you do a compression check after rebuild? My first thought was a loose cam chain. Torque the cam cap bolts to spec? I'd double check timing also.

Did not check compression. Im also thinking cam chain. I meticulously torqued and checked each bolt during the rebuild so Im almost certain that isn't the case. I was messing with the timing which in doing so I managed to keep it running sort of without the choke full open but did nothing for the ticking noise.

 

[crazypj]

The 650 just has a lock nut on adjuster underneath carbs bout dead center of block., 550 had a screw slot so you could check adjuster was moving. Best way to adjust cam chain on 650 is with top cover off so you can feel down inside and check slider is moving.(at least you have re-usable rubber gaskets to ake life a little easier) Adjuster has a domed head lock-nut so you can't tell if special lock bolt moves when re-tightening nut. Many times when servicing 650's (when they were a current model) I had to use a flat screwdriver and push the slider down and often hold it down while re-tightening lock-nut. The Hyvo cam chain rides up the sprocket (gear?) so is quieter than a roller chain until things get really bad. 650 isn't too bad but CB900's (with a substantially longer chain) often 'sawed' a slot through front of cylinder.

 

[rappz7]

The 650 just has a lock nut on adjuster underneath carbs bout dead center of block., 550 had a screw slot so you could check adjuster was moving. Best way to adjust cam chain on 650 is with top cover off so you can feel down inside and check slider is moving.(at least you have re-usable rubber gaskets to ake life a little easier) Adjuster has a domed head lock-nut so you can't tell if special lock bolt moves when re-tightening nut. Many times when servicing 650's (when they were a current model) I had to use a flat screwdriver and push the slider down and often hold it down while re-tightening lock-nut. The Hyvo cam chain rides up the sprocket (gear?) so is quieter than a roller chain until things get really bad. 650 isn't too bad but CB900's (with a substantially longer chain) often 'sawed' a slot through front of cylinder.

Thanks for the info. Funny you mention "saw through". I had to get new cylinder jugs because something very similar seemed to happen to me. I was leaking oil from the front of the engine when I first got the bike. I thought it was a crappy gasket or warping or something, just kept an eye on the oil and parked it in the grass. When I took the engine apart I saw a very worn down, for lack of a better word cam chain housing as well as a crack in between the fins on the jugs. The guy before me just slapped a bunch of silicone on it and left it. I should have seen the warning signs than but didn't think anything of it. Thats why I feel it may be the cam chain is worn and making a racket. I will take off the top cover and check it out tomorrow to see if my hunch is correct. I guess Ill take it from there.

 

[crazypj]

Thanks for the info. Funny you mention "saw through". I had to get new cylinder jugs because something very similar seemed to happen to me. I was leaking oil from the front of the engine when I first got the bike. I thought it was a crappy gasket or warping or something, just kept an eye on the oil and parked it in the grass. When I took the engine apart I saw a very worn down, for lack of a better word cam chain housing as well as a crack in between the fins on the jugs. The guy before me just slapped a bunch of silicone on it and left it. I should have seen the warning signs than but didn't think anything of it. Thats why I feel it may be the cam chain is worn and making a racket. I will take off the top cover and check it out tomorrow to see if my hunch is correct. I guess Ill take it from there.

Bike has to run for thousands of miles without service to have that happen.
Can't remember ever seeing a 650 worn through but I did so many in mid 80's I forget what I've done.
Spent about 3 yrs doing mainly CB750/900 motors as they had two chains, one much longer than the other plus a 'hidden' adjuster for the 'long' chain :