G12 CSR engine noises

[ajsm18]

Fordingbridge - only just in Hampshire!

[bunners]

Fordingbridge that's not far, 20-30 minuets from me,I can come and have a listen if you like, bring my stethoscope with me, its better than a screwdriver, I live near Hursley

[ajsm18]

Hi Bunners
That's very kind of you. If you could pop over some time I'd be very grateful. If you let me know a time that is convenient for you I'll get the bike out. Saturday is out for me this week I'm afraid.
Thanks again
Mark

[ajsm18]

Me again. Back with more stupid questions!

If you run the engine with the rocker covers off you'll quickly cover your knees with a fine spray of oil if the feed is OK. Are you getting a decent return to the oil tank? A more specific definition of the "rattly noises" would be helpful in trying to diagnose the problem!

Should there be that much oil when running the bike with the rocker covers off?

I thought I had found the source of the rattle when I discovered that the engine sprocket nut was loose. Having fixed that, I started it up again with the rocker covers off and, although oil did seep out around the rocker spindles (one took much longer to get wet), it certainly wasn't a "fine spray" and I didn't get covered in oil at all! Is this likely to be source of noise and does it mean I have some sort of blockage somewhere?

I have also noticed that I can hear the "clanking" noise as I turn the engine over on the kickstart, not just with the engine running.

Having started the bike again, the noise does appear to come from the top end of the engine and is, to me, a fairly obvious noise. It does start easily, though, and there is no undue smoke. It smokes a bit on starting but that soon goes.

Would poor lubrication of the valve gear cause a lot of noise?

Sorry to ask so many questions. You'd think I'd only just started riding old bikes, instead of the nearly 40 years I've had them! I guess the difference is that I'm trying to get things working well now instead of the 'bodgery' I practiced in my youth!

One other thing. I've read that primary chain slack should be about 3/8th of an inch. How much effort should be applied to the chain to check it? It moves that far easily but I'm always worried about over-tensioning chains

Many thanks, in advance

Mark

[1608]

I think clanking noises when simply kicking the bike over is a sign that there is some serious wear. Why not let somebody with knowledge ( preferably AMC twin experience ) have a listen. I'm afraid you'll have to bite the bullet and strip the top half at least to get a better idea of whats wrong.

[ajsm18]

I'm afraid you'll have to bite the bullet and strip the top half at least to get a better idea of whats wrong.

Sadly, I suspect you're correct. Alternatively, I may give up on it and sell it

[1608]

Thats a shame, but why give up?

[ajsm18]

Thats a shame, but why give up?

Too difficult for my skills and too expensive to pay someone. Plus, although I'm really attached to my 1947 Model 18, the G12 has never really impressed me! I think that, perhaps, an early 60s 650 twin wasn't the best option to choose when I wanted a "classic" on which I could travel further and faster than a rigid 500 single!

We'll see. I'm not completely incompetent but very slow! I may tear the top down when I've got a bit more time.

All the best

Mark

[Andyozz]

Hi Mark
Having read all the previous valid comments. One more thing to check when you pull the top end and barrels off. Check the end float of the cam follower slippers.
Easily done with a small piece of wooden dowel or push rod placed down on the top of the slippers and moved side to side.
I had a similar problem recently that manifested itself as a rattle which seemed to be in the top end which was in fact the slippers being pushed side to side affecting the valve clearances and timing when the engine was running. When I set the valve clearances the followers must have been to one side, but when the engine was running these moved to a more central position causing the clearances to close up.
When i stripped the engine I found the cam follower had started to wear into the aluminium crank cases!!!! possibly due to a bodged engine rebuild at some to in it's life.
anyway this was easily remedied with a small amount of engineering and putting a hardened washer / shim either side. Also check the four oiling jets that squirt high pressure oil onto the cam followers. these are located and fed from the small high pressure oil gallery found at the top of the crankcases below the barrels when you split the crankcases.

Another thing to check is the oil feed to the camshaft left hand side of engine (behind the 2 blanking plugs) and the clearance of the camshaft bushes. By applying oil pressure to this side the camshaft end float is always put onto the right hand side camshaft bush by hydraulic pressure. worn bushes prevent any build up of hydraulic pressure and hence camshaft endfloat slap / rattle

Don't give up though. I have spent many hours in the shed cursing, swearing and getting generally despondent with these old machines, but once you ride it after a successful rebuild the Cheshire cat smile imprinted on your face is priceless

[ajsm18]

Hi Andy,

Thanks for the ideas on things to check and for the encouragement! I'm sure I'll get it sorted in the end, it is just very frustrating!

Regards

Mark