Topic: gnashing sound comming from left side of engine while under load.

[lostmykeys]

 I hope my spelling was correct on that word.
 I notice a rhythmic gnashing sound comming from the left side of the engine.If I pull in the clutch it goes away.
 I suspect the noise is comming from the front sprocket and chain but I just wanted to get some opinions before I buy a new chain and spockets

[LesterPiglet]

Is this while the bike is stationary in neutral?

[lostmykeys]

 Thanks for the response I should have said this happens when I'm riding the bike.The bike is a 78 f3

[cmonSTART]

You should be able to get a good look at the front sprocket fairly easily.  Do the teeth look/feel sharp and are they hooked at all? 

[lucky]

Immediately stop riding the motorcycle before it kills you!!!!

Not joking.

[BobbyR]

Do you notice any change in the sound when you are running a steady throttle, does it change hen you are going it throttle or when you are off the throttle and engine braking?. 

[lostmykeys]

 Lucky, what are you trying to say please explain i dont want to die.
 Bobby,I notice tthe sound most when i'm at steady throttle.If I pull in the clutch the sound goes away.
 If i'm riding down a mountain road and coasting with clutch engaged/engine braking the sound goes away.
 I only hear the sound when the bike is under load.

[LesterPiglet]

First thing, check your chain and sprockets.

[lostmykeys]

cmonstart,The spockets look good to me,the teeth are square not sharp or hooked.

[Duke McDukiedook]

Chain condition and age?

[phil71]

Lucky, that's pretty dramatic. You don't say if the sound is vicious and loud, or just a mild change in the sound of the engines. If it's high mileage or grossly out of sync, the primary chains could be slapping around some. They do that.

[lostmykeys]

 The sound is not that loud maybe I just need a new chain.

[LesterPiglet]

Put it on the centre stand and rotate the wheel and check for the noise.
Check the sprocket/s teeth to make sure thay are square at the top and not pointed.
Grab the chain at the 3 o clock position on the rear sprocket and pull it away from the sprocket. If it moves a lot you need a new chain. Chain and sprockets are best replaced at the same time.

[lostmykeys]

 I am still getting this sound.So far I have checked the chain as lester instructed by taking the tension out of the chain and pulling the chain at the 3 oclock on the rear sprocket and the chain stays put.
 I have taken the front sprocket cover off to see if the noise was from the chain rubbing against the cover.No change.The chain is well lubed and the sprockets look fine.The bike has a 630 chain with a 14 tooth front sprocket and a 41 tooth rear.

[lostmykeys]

 Just an idea,But could the starter clutch be making this sound?
 About one in every thirty starts,my starter wont engage and makes a grinding sound.I have a new starter that I havent put on the bike yet simply because the grinding sound is rare.I have had the bike three months and have put 1500 miles in it with an average 20 miles per ride.

[Really?]

a 14T front sprocket is on the small side me thinks.  Makes for a really tight turn.   At least it seams that way to me.  I may have a 17T and I know I went down only one tooth from stock.

[scottly]

Is the chain rubbing on the center-stand when the stand is up? I've seen this happen with non-stock exhaust systems; the stop for the stand was part of the stock exhaust.

[bytio]

Hi, I had a similar sound on my F2, the problem was an unevenly worn chain, so under load the tight to slack was giving the sound you describe, a new chain resolved the problem.
David