78 xs 1100 engine noise

[spec1974]

ok well i'm kinda new to the whole yamaha scene,i have had a few old cb's but never a yamaha, any way i just picked up a 78 xs1100 , the thing runs fine, plenty of power, but when you get on the throttle you hear a noise that kinda sounds like piston slap, i've put a few hundred miles on the beast and she's still going strong and the engine sound hasn't gotten worse, the motor has 40000 miles on it, but i swear i've seen these bikes go amost 100000.Does anyone have any idea or know if these being a common problem, also if i have to rip the motor down i might as well rebuild it so any suggestions of where to start looking for those parts would be greatly apprieciated.
Thanks

Rob

[dntemp_ca]

Take the left side cover off..the one covering the ignition advance mechanism. Go for a ride and carefully glance down to see what's happening with advance. If it's chattering back & forth wildly, it will make a very un nerving noise. The mechanical advance could be gummed up and need cleaning/lube; or you could have a vacuum hose leak; or the vacuum hose could be hooked up to the wrong nipple (it goes on the nipple on the #2 carb body, not the nipple on the carb boot.) My 78E had a similar noise...drove me nuts. Found out it was the advance chattering like crazy that caused this. Cleaned that up and although it still wobbles slightly a certain rpms; it's much better now.

[Ken Talbot]

A loose cam chain can also cause a fair bit of noise. The adjustment procedure is fairly easy, but you want to be sure to do it absolutely correctly. Get it wrong and the adjuster could come loose, the chain could get loose enough to jump a tooth or two, and the top end will be trashed.

[spec1974]

it only makes the sound when the bike is moving and in gear, when you put load on the engine, also the compression of the bike averages about 125 no cylinders are more then 10 pounds apart

[TopCatGr58]

Hey there Spec,

Try a higher grade of octane gas, regular is pretty low now, compared to where it was back in the late 70's, could be as simple as that!?
T.C.

[skids]

Re: 78 xs 1100 engine noise

It might be the HyVo chain slapping against the top of the casing. It is not a pinging sound if it is doing this, it is more of a "whack" noise, and propably only occurs when you transition between deceleration/acceleration. There is no adjustment for this, to my knowledge. If it is just occasional, I would say, don't worry about it. If it is constant while throttling hard, I do not think the HyVo slap is the problem.

Originally posted by spec1974
but when you get on the throttle you hear a noise that kinda sounds like piston slap,
Rob

[shawn]

Might be applicable here.

On my Goldwing Wing I had the same sound. Everything I could find said piston slap. Never got louder or worse but only happened under power.

A friend of mine suggested that it may be the carbs. that sounded odd to me but I figured I would give em a good clean anyway.

Cleaned em up put em back on and it has never made that sound since.

Might want to start there before you rip into your engine.

[scalded dog]

Sounds like the cam chain. Later 'Dog

[spec1974]

how do you adjust

how do you adjust the cam chain to the right specs?

[scalded dog]

Take your spark plugs out. to make it easier to turn your engine,remove the screws from the left side cover, take a wrench , I think its 17 mm, turn the motor clockwise several times, stop turning when the c mark is stationary on the timing pointer, on the front of the engine, there is a little round thing called the cam chain tensioner, loosen the lock nut on the side of the cam chain tensioner, loosen the bolt, the cam chain will automatically adjust, tighten the bolt to 4.3 ft lbs, tighten the locknut to 6.5 ft lbs. replace cover and spark plugs. you are ready. Later 'Dog

[TopCatGr58]

Re: how do you adjust

Originally posted by spec1974
how do you adjust the cam chain to the right specs?

Hey there Spec,

Dog described it pretty good, just BIG WARNING, if you pass the "C" mark DO NOT TURN IT BACKWARDS, just go around again, SLOWLY until it lines up!!

But seeing you having to ask kinda hints at that you haven't taken much time to peruse the site, check out the tech tips, there is a ton of information here that will greatly aide you in your quest to keep this wonderful machine running in tip/top shape!! So, please take an hour or so and read thru the tech tips sections! We're not trying to discourage anybody from asking any questions, just that many have already been answered there!

Also, before posting any new questions, do a search on the topic you intend to ask about, there are hundreds of threads, and again, it might have already been asked and answered!?

Welcome, and enjoy!!!!