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Tech question, but not Buell - 1982 XL500 thumper
https://ukbeg.com/forum/viewtopic.php?f=8&t=3291		 Page 1 of 1
Author:  Bonzo [ 31 Oct 2009 17:01 ]
Post subject:  Tech question, but not Buell - 1982 XL500 thumper
Hi folks, it's not Buell, but there a probably more knowledgeable folk on here than on the dedicated XL forums I've looked on.

When I start the bike there is a metallic knocking noise coming from the engine, I can even feel it through the handlebars. Once the engine is fully warmed up it disappears, and the engine sounds like a sewing machine, although it will reappear every now and then for a few seconds.

My first thought was a stuck decompression lever, but it isn't that. I'm now thinking it's sticky cam chain tensioner, that takes a while to start doing it's job properly, in combination with a worn out camchain. Or it may be the cam holder is worn (IIRC the cam runs straight in the head with no bearing or bushing).

Does anyone have any suggestions of what the most likely culprit is :?: Also, can you remove the camchain without dismantling the bottom end :?:

I've ordered a manual off e-bay, so I'll soon be able to help myself a bit. I don't want to buy any unneccesary parts, as they'll cost me more than the bike is worth (no documents, strictly off road), but I'll buy whatever is need to get it running 100% :P
Author:  Mitch [ 31 Oct 2009 17:41 ]
Post subject:  Re: Tech question, but not Buell - 1982 XL500 thumper
how noisy is it? does it disappear when you rev the engine up to about 2 - 3000 rpm?

piston slap perhaps. my bmw f800 does that , or slack cam chain
Author:  Bonzo [ 31 Oct 2009 17:45 ]
Post subject:  Re: Tech question, but not Buell - 1982 XL500 thumper
Mitch wrote:
how noisy is it? does it disappear when you rev the engine up to about 2 - 3000 rpm?

piston slap perhaps. my bmw f800 does that , or slack cam chain



Difficult to say, it may disappear at those revs, but it's hard to tell. I think it's too noisy for piston slap, I think it would self destruct before it got warmed up if that was the problem. Cam chain and/or tensioner is my main suspect.
Author:  Mitch [ 31 Oct 2009 17:58 ]
Post subject:  Re: Tech question, but not Buell - 1982 XL500 thumper
4th post might be a bit helpful :?

http://www.thumpertalk.com/forum/archiv ... 39415.html
Author:  tubbs [ 31 Oct 2009 18:05 ]
Post subject:  Re: Tech question, but not Buell - 1982 XL500 thumper
used to sell them new.................sounds like cam chain tensioner or the cam may have float and be picking up in the head the other end the cam chain is.
and from memory you would need a split chain if you do not want to strip motor as crank is just a tad to long to get over and up the chain tunnel.
:old:
Author:  Adam [ 31 Oct 2009 18:41 ]
Post subject:  Re: Tech question, but not Buell - 1982 XL500 thumper
I'm certain Tubbs is correct about the tensioner. Is it a manual retension or automatic? In any case pull it out and free it off. The workshop manual will tell you how to retract it for refitting. You may find some marks on the motor to tell you the postion for a reset, but on some early Hon*as, you let them tick over and slacken a bolt that allows the tensioner rod to move. You can get replacement chains with a soft link for re riveting.
Author:  Bonzo [ 01 Nov 2009 03:57 ]
Post subject:  Re: Tech question, but not Buell - 1982 XL500 thumper
Thanks for the tips folks, I'll wait until my manual arrives, then I'll boldly go where no Bonzo has gone before :yup:
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