Nutty idea or what?


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RE5Guy
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Nutty idea or what?

Post by RE5Guy »

Hi all,

My '79 has always been rattling since I got it going again after 20 years of sitting but it has got to the stage where I am getting really suspicious of the primary chain. To get it going It needed a recond head and 2nd oversize pistons due to a little corrosion in 1 bore. I have dome maybe 500 miles on it since I got it going again. The bike has only dome 14,000 miles total. The engine feels very strong and uses no oil.

Recently I have attacked it and I have replaced the cam chain (shut it up a little), then the tensioner (shut it up a little more). But it still rattles.

It does have the clutch rattle, but it is a totally different sound to the annoying rattle I want rid of.

After some research I have just had the alternator off (snapped one of the &*&*%%#$#& mounting bolts) to check the little alloy button (it is there and clear) and the alternator it self for any notchiness etc and it seems fine.

Yesterday I checked the "looseness" of the primary chain using a timing light as described on another post. It definately "floats" off load. I have another '79 that I did the same exercise on and is as quiet as a mouse and its timing mark didn't move at all.

The carbs have had a rebuild kit in them and balanced by me twice, last time 2 weeks ago.

Anyone got any words of wisdom before I take the engine out?

Assuming I do have to take it out I have been reading up on what to do (as you do). The workshop manual talks about taking the head and barrels etc off and working your way down to the bottom end, but then turning the engine over and taking the bottom case off the top. Do I actually need to do this? If I disconnect the cam chain from the cams can't I then turn the engine over and take the bottom case off to get at the primary chain that way (end new seals etc etc as well). I realise I need to get the crank out to replace the primary chain but can't I get the pistons back into their pots from underneath? Obviously this way I don't need to disturb the top end at all which I know is fine.

So nutty or what gents? If not nutty, all and any suggestions welcomed.

cheers

Tony

daves79x
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Location: Knox, PA
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Re: Nutty idea or what?

Post by daves79x »

Tony:
I've actually wondered the same thing. I never tried it, but it is worth a try, I suppose. I don't mind taking the top end off except for the expense of the head gasket!

I's say off-hand that your rattle was all clutch, but apparently it is not. I'd also carefully check the oil tensioner for the primary chain. I think the chain can get pretty stretched before the tensioner, working properly, can no longer tension it. Let us know what you end up doing and what you find.

Dave

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