metalic rattle

[SFerinTEXAS]

Developed a rattle at intermittent speeds last week. Found it Sunday. Turned out to be the front lower rivet in the RH exhaust, I believe to hold the baffle in place. Now to replace it...

Richard, remember when you were here and said the exhaust seemed really loud in my garage? That was just before I found the pipe separated. Been meaning to tell you...You were right.

[motoman]

Any of you ever considered that type of noise being the vacuum advance can?.........noisier at idle and becomes less with rpm. BTDT. Remove that left side ignition cover, start the bike and watch that vacuum can's shaft movement. That would be first suspect IMO.

[DAVINCI]

I did consider that, but I thought the 81 didn't have that can?

[crazy steve]

The '81 still has the vacuum, it was the XJ that eliminated it finally...

[motoman]

I did consider that, but I thought the 81 didn't have that can?

Dang Randy, your slippin'!..........figured you'd be the first to to throw that out there as problamatic.

[DAVINCI]

Stuck in 1979, what can I say?

[James England]

Finding the noise

A good trick someone showed me decades ago is to get a long screwdriver. Push the handle end onto your ear but make sure you block your ear with the cartilege bit at the front of the ear orifice. Then hold the handle end of the screwdriver onto it and hold the metal end onto various parts of the engine. It's amazing how easy it can be to hear mechanical engine noises and to locate problem sounds. Give it a try. I've used this trick for years and found the causes of loads of noises on different engines.....

[petejw]

its definately not the exhaust, and its not the vac advance
unfortunately, thatd be to easy

james, ive got a stethoscope and tried finding the rattle
using that with out any luck, looks like il be pulling the engine
sooner rather than later.

thanx for all ur opinions, much appreciated.

[petejw]

just to update what i found with the rattle,
as i mentioned earlier when i originally took the oil
pan off i found a broken piece of bakerlite in the bottom
of the pan, found that this sits at the front of the engine
directly under the primary chain to act as a guide,
other than the broken bakerlite the oil pan was clean,
after a cpl of weeks the rattle began, tonite i took the oil
pan off again and found shreds of bakerlite and aluminium
from the cases. heres a pic.

[trbig]

You think that non-stretching () hyvo chain has just stretched too much? Or do you just think it's just a faulty guide?

[petejw]

You think that non-stretching () hyvo chain has just stretched too much? Or do you just think it's just a faulty guide?

not sure tod, all the engines i have, have over 150,000k's on them,
ive got the pan off i can check the amout of movement in the chain
for u if u like, i dont know how much slack is in a new chain to compare,
i found the broken guide when i rebuilt the top end, it wasnt till a cpl
of months later that it began to rattle, when the rattle started i had
ridden it quite hard which didnt help but still no excuse for it to happen.

[natemoen]

Pete, is this the same engine with the vibration?

[petejw]

Pete, is this the same engine with the vibration?

unfortunately not, this is the one i pulled out,
the one with the vibration is the engine i just put in.

[trbig]

Yeah, the book doesn't give any kind of info on a measurement for the hyvo. I guess they thought it was supposed to last forever. Sounds like the problem though, but just a guess. If the chain was loose enough that with centrifigul force, every link in the chain would have been beating on that guide. I don't understand how ANY of those guides last as long as they do, especially the cam chain guides that basically change the direction of the chain.

[jjz28]

did anyone figure this out cause mine did this when i hook the vacuum advance to the 1st carb boot nipple. When i take off the advance it stops.