Timing gear noise

Jackson · Post by **Jackson** » Sun May 15, 2005 11:32 pm

I have recently checked the adjustment of the valve clearances on my G80S. With the engine at TDC when I spin the inlet push rod backwards and forwards I can clearly hear a tapping noise coming from the timing chest area. This does not happen with the exhaust pushrod.
I cannot reproduce it with any load on the push rod, only at TDC.
Is this backlash between the cam gear and crank pinion?

I fitted a new (new) crank pinion 3 years ago while the engine was installed in the bike. When I recently had the bottom end out, the flywheels would not spin free at one point with this pinion against the exhaust cam gear - even with my original worn cam gears!
I then purchased another new pinion and the flywheels span completey free so the engine was rebuilt.

Now I have this noise on the inlet.
Is my diagnosis correct? Should I worry about it?
If there is such variability in new crank pinions where could I get new/low wear parts that will perform ok?

Don Madden · Post by **Don Madden** » Mon May 16, 2005 3:54 am

On the pushrod noise, check for excess side play in rocker shaft or the p/r end touching the rockerbox near the oil dischrge hole. One the pinion, if it binds at the timing punch mark check to see if the pinion has split at the keyway.
Cheers, Don Madden.

itma · Post by **itma** » Mon May 16, 2005 9:31 pm

sounds as if you have no shims on the inlet cam spindle, the test was, run bike with cover off, exert pressure on end of shaft with hammer handle or similar, if noise stops, QED
absense of slack on decompressor cable is also cause of unexplained noises from this area

SPRIDDLER · Post by **SPRIDDLER** » Tue May 17, 2005 1:53 pm

No shims on my camshaft,
And I keep rattling along...
These AMC's,
Don't bother me,
When I'm wearing, my sheepskin thong...
(Sorry, it just came over me).

itma · Post by **itma** » Tue May 17, 2005 6:44 pm

don`t you find a sheepskin one rather ticklish Neville?[:0]

SPRIDDLER · Post by **SPRIDDLER** » Wed May 18, 2005 3:49 pm

Not really Ken, I pick the ticks off first.
It's all I wear in the summer, baa in the shepherds' beer tent at livestock fairs.

itma · Post by **itma** » Wed May 18, 2005 9:12 pm

[:D]now that I gotta see!!!![:D][:D]

are you in fact of the Barclay Wills/ Copper fraternity down there in Sussex?

SPRIDDLER · Post by **SPRIDDLER** » Thu May 19, 2005 1:56 pm

Yes Ken, I'm not far from Rottingdean where generations of Coppers live(d) and entertained the public with with their traditional thongs. I've a couple of Bob Copper's books.
I was anoraking with Bacon last night (as I didn't have any wet paint) - he mentions that tappet/cam noise can be caused by excessive end float on the cam spindle. He suggests relocating the spindle bush correctly in the timing cover. I have never seen inside an AMC timing cover so I may be talking through my thong. "A little knowledge is worth two in the bush", as we say here in Sussex.

Chazzyb · Post by **Chazzyb** » Thu May 19, 2005 5:44 pm

quote:Originally posted by Ken Bryant

sounds as if you have no shims on the inlet cam spindle, the test was, run bike with cover off, exert pressure on end of shaft with hammer handle or similar, if noise stops, QED
absense of slack on decompressor cable is also cause of unexplained noises from this area

Surely this is difficult on a magneto-in-front or coil ignition engine?

itma · Post by **itma** » Thu May 19, 2005 7:27 pm

absolutley correct, but then I`m so far back un time I still regard mag in front engines as not quite Matchless, give me a break, it was late!!!!

basic remedy re shims still holds