Rapping noise that cycles?

Getting ready to get my shims replaced because of small intake and exhaust measurements. Changed the headgasket as it was leaking(fixed problem) and after driving the bike for the first time afterwards a intermittent rapping noise started. It sounds like rap rap rap rap rap rap times 25-30 times, then silence almost like it's cycling. Somtimes I can give it throttle and the noise goes away. Also I notice it more when it's idling. Not sure if that's because the engine is quieter then or what? I have thought maybe stuck vales?( not sure of the fix there) or cam chain? (reset it when doing the head gasket) I have listened to the head at various spots trying to nail it down and can't hear it above the sound of the chain turning. Any ideas?

 

I've tried a dowel all over the motor and can't hear it at all anywhere? Weird...Also only happens after it warms up a bit.. reminds me of chappering teeth after gettin gout of the pool.. (im skinny)

 

My 81 seca 750 makes similar noises .... i always just attributed it to valvetrain noise ... I know these bikes tend to be kinda noisy (especially when compared to modern ones with similar engines) but it's always been a bit unsettling for me as well. I'm sure someone with more experience in that department will chime in before too long.

 

I would agree except the noise started recently...?

 

Check out this post I had up a little while back:

Knock Knock... What's there

I finally figured out what the noise was. It was the valves smacking closed. I think it was sticky valve seals but I still am not shure. I have no idea why it cycled but when I pulled the head off and spun the motor over... it was perfectly silent.

I will know more I suppose when I get everything back together but other than knowing it's coming from the head I got nothin else.

Best of luck

 

I have no idea why it cycled ....? yours cycled too? I wonder if it's valve noise in mine...my largest measurement was .003 when i measured

 

Well I pulled the valve cover of and a few things. I can pull the chain with very little effort so that there is 2 centimeters of slack..and it just sags then..also i see marks on the underside of my valve cover from the chain....What now?? It has the automatic chain adjuster so do i try to re-set it by un screwing the chain bolt out or what?? Anyone?

 

Simple.
Pull the Plugs.
Pull the Ignition Crankcase Cover.
Wrench the Engine over two full revolutions in its normal rotation.
Come to a smooth and gradual stop.

Reverse the direction and jack-over the engine backward in a sudden movement.
This will present the slack in front of the tensioner and it will automatically take up the slack.

Repeat several times.
Have an assistant tap on the Tensioner with the butt of a hammer handle while you are reversing the direction on the engine.

The tensioner should take-up the slack and life in Iowa will be better and less noisy.

 

LOL...Life in Iowa is not very noisy anyway!!! unless you're married to the wrong gal! Which thankfully I'm not. It might help that I have hearing loss in my right ear from all those years of shooting......I'm off to find the hammer! Thanks again Rick!

 

Unless you don't have an automatic cam chain tensioner, depends on what XJ you have and no where in your post or signature do I see anything that tells us what bike it is. The procedure is a bit different with the tensioner that requires user intervention...

 

It's an 82 xj750j with an automatic chain tentensioner. Rick already knew the bike. But I should have posted the year, make, model anyway. As for the procedure.....I performed it last night about 5 times. Put the cover back on and ran the bike for about 15 minutes. I still get alot of chain noise.......How can someone know if it's a cam chain Death Rattle?

 

The Cam Chains are rated for close to 60,000 Miles.

I'd suspect that Tensioner. It should have taken-up that slack.
I know that Auto Tensioner has a Dual, Spring within Spring design.
Hard for it NOT to take-up slack when it can.