Rattling Sound

I recently bought a 1982 Yamaha XJ650 Maxim. I managed to get it running the day after I bought it, and today I was able to get it on the road. However, this whole time there is a sound like a chain rattling coming from the engine. I have to take the carbs off and rebuild them, but I figured if the rattling noise coming from the engine is an issue that needs addressed, I will take care of it while I have the carbs off.

Can anyone tell me what it could potentially be? Keep in mind, this bike has not been run in about 5 years other than small amounts of time for tests until I owned it.

 

Welcome to the forum. Have you checked the exhaust system, the headers can make a noise if the nuts are loose? On the engine the cam chain can rattle if the tensioner has not been adjusted, I think some were manual tensioners. Do you have a Haynes manual for the bike?

 

Thanks for welcoming me. I do not have a Haynes manual for the bike yet, but I have found where I can get one. I have not yet checked the exhaust system, but the last guy to own the bike before me did some exhaust work, but he mostly cut the previous exhaust ends off and welded new ones to it. He did not do anything else with the bike, so maybe the cam chain is loose? It sounds like a chain rattling so I thought it might be the cam chain, I was just hoping to avoid having to pull the engine.

 

The valve clearance maybe off as well .

 

Can the valves close too hard to make a noise ? And if so why ? Ive noticed on a hot day and after my motor gets hot i start hearing a noise. When the motor is cool, up to normal temp on a cool day no noise.

 

Interesting question regarding valve noise.

 

take the cam cover off see if the chain is hitting the top of the cover.
go through the steps measuring the shims which is the first thing you want to do with a bike you just purchased
then turn the motor clock wise and see how much play is in the chain. how far you turn the crank shaft before the cams start moving.

some 650's have an auto cam chain tensioner which can be removed cleaned and reset
I like the manual tensioners you can put one in if the auto one is not working or replace it with an auto tensioner
check the chain see how far up you can lift it.
the chain can be replaced with taking the motor apart

the time to do the tensioner is when the carbs are off for easy access.

the shims should make a ticking sound if properly adjusted should sound like a sewing machine.

center stand the bike and make sure the oil level is correct look in the sight on the clutch cover you should have an air bubble in the top of the sight about the size of an m&m.

if the exhaust has any shields left on it they may be rettling. it could also be the header clamps are loose
does it rattle when on the side stand or on the center stand if the springs on those are incorrect or the bumper is missing on the centerstand those could be the rattle when up.

you can use a mechanics stethascope or screwdriver to locate the sound if it is in the motor

you have 3 chains cam chain oil pump chain and primary chain.
primary chain has an oil tensioner

there is also something called cam endcap play

 

82 Maxim has an automatic cam chain tensioner.

I would add one possible problem - the "sewing machine" sound of the valvetrain can turn into more of a "can full of marbles" if there is a problem with oil pressure/oil flow.

In addition to the oil fill level, verify that the filter assembly is correct. Incorrect Reference: https://www.xjbikes.com/forums/threads/oil-filter-assembly-install-detail.130464/

 

Gotcha, thank you for the helpful tips on all of that. I got my carbs cleaned and rebuilt then reinstalled only to find that now my starter clutch is out and I'm just going to split the cases to replace it, so I might as well check my valves and cam tensioner while I'm in there. As for the oil, I have read that the full synthetic oil can cause issues (of course I put full synthetic in thinking nothing of it) so I'm going to replace it with conventional oil and see if that helps me out. I did also find that the previous owner did not replace the gaskets on the float bowls and boots for the carbs and I ended up with a vacuum leak and unable to sync my carbs as a result so I ordered some new gaskets and I'm hoping I can get the carbs synced.

 

I have done two engines see my post the dreaded starter clutch , what you will have the springs loose their tension and on one of the engines one roller was called. I bought a starter repair kit from England has stiffer springs and the plungers are drilled on end for better oiling . After pulling the engine from the bike took me about an hour using a floor jack and a milk crate . I used a good wood palate to put engine on and split the case , this took a little over a hour to tear down , get several ziplock bags, sharpie marker, and take pictures as you go . I recommend buying a set of torx sockets , as set of Allen metric sockets . You will need red and blue locktite, a tube of Yamabond...I feel it is better stuff than RTV . A rubber mallet is another item avoid using a hammer, when you get all the bolts out tap case to split with the mallet. As long as your chain guide is in good shape you wont have to pull the head. What ever you do NOT rotate the crank with the cam chain tensioner out ( don't ask how I know about this your cam timing will be off) .