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1979 xr500 noise in top end

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I just got a 79 xr today it starts and runs fine but there is a loud noise in the top end at an idle and high rpm. Im figure all the timming is correct becasue it runs good and starts easy maby timing chain or valve?

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Suppose you'll need to go in to investigate,,What's the noise like,,loud knocking when you give it some revs would mean big end or small ends gone,,New Conrod needed,,Not saying that's your problem just what my 82 (same engine more or less) was doing when I first got it..,Knocking,,got progressively worse until it just gave up the ghost on the motorway,,Rod etc had it,,.Yours could be Camchain,,you won't know until you really start replacing things what the cause is.,Money will probably need spending,.Loosen and reset the Camchain tensioner as per the manuals instructions and see if it improves,,if not,,surgery,.

Edited by Horri

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Well I hope its the cam chain that one will be easy if not sounds like i will have a winter project on the hands. What do you think about buying a parts motor on ebay? think that might be more cost effective if i have to tear the motor down. Thanks for the help

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Don't know,,I know I pumped a few thousand at least into my 82 after the big end went,,Sent it to an engine rebuilders and they went nuts on replacing stuff,,(they don't know when to stop so just keep replacing anything slightly out of spec),,Never again will I allow a shop to have a free reign on replacing things., You need to find a joker who knows the motors,,he knows what you can get away with and what you can't in the parts replacement department..,Spares are good to have is basically all I can offer as advice,,The way you go about fixing yours is up to you.,Do the tappet gaps and try resetting the Camchain tensioner,,if that doesn't stop the noise you may have to go further,,ie Camchain replacement and maybe Camchain guides,,Very hard to say what would need doing until you try the Camchain reset at the least.,

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My problem I have at this point is it starts fine and runs great until it gets into mid range rpm and starts to spit and miss what do you think

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What do I think::Good question and my answer would be way too much most of the time.,always getting me in trouble my opinions.

Have you fixed the knocking noise??,,did you reset the Camchain tensioner.??

Spit and miss::,Could be anything,,Sparkplug==> get a new one and gap it correctly..,Coil another possibility==>test with another one,,Carb==> more likely==>thoroughly clean it.,,Airfilter==>clean and reoil.,,Resistor in sparkplug cap if it has one==>Remove and replace it with a hunk of copper or gold if you're incredibly rich.,There's a start,,Leave you to it.,

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