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Hi all, thanks for the forum
I just bought a very sorry looking 1985 vs750 that has not been run for at least 13 years.
Having done all the necessary checks I finally got it to fire and it starts and runs really nicely on both cylinders.
It warms up well, throttles up nicely when warm and settles to a steady idle.
It does however have a nasty knock. I thought it was a sticky valve but maybe its too loud and the bike seems to run too nicely to be losing compression with no backfires at all.
I listened to the block and the noise is firmly in the very top section, the knock continues even when I pull the plug on the faulty cylinder and I can't feel any movement in the piston when I press on it on the downward stroke.
Its been started and warmed as far as I dare 3 times now and I'm sure I heard the knock stop for a few cycles more than once, could I have bent a valve already, stopping it shutting properly or could it just still be very stuck (if its a valve at all)
This is my first Intruder so your expertise in this matter is greatly appreciated.

Thanks in advance fellas. I have included a link to a video I took for reference.
 

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First of all on a bike this old it is not a good idea to spend too much money trying to get it road worthy or mechanically sound. It will be all to easy to spend well over what the bike is worth.

Looking at the video I would not be running that engine untill I had found out what is causing the noise. It sounds like a bearing is on its way out....probably a big end or main ...esp since it keeps time with the engine speed. Sadly a full engine strip in on the cards....a noise that loud isnt going to be simple....I do hope I am way wrong but I dont think I am.

Do let us know what you find ....good luck
 

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First of all its a nice bike and pretty much deserves a bit extra love. I've done the same thing with a Yamaha XV500 a year ago. At the same time, I have to agree with Aussie Steve, this never going to be a financial success. The next one I'd rather strip the engine to find out what is the real source of the knocking noise, as it could be too many thing and we can guessing for weeks and could open new topics about it without moving forward. In this case you could keep your loss very minimal. Worst/best case scenario, nothing wrong with the engine (I doubt about it) and you replaced all the seals and gaskets on the way to re-assemble it. Wouldn't hurt anyway if it was sitting for more than a decade. Perhaps, you found so many problems (crankshaft, pistons etc.) and you still can pull the plug without spending any more on it. Or you just leave it as it is and use it than bugged the engine because of a $2 seal failed... It's a tough one. I wish you luck anyway...
 
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