Knocking bike....

[James Miller]

Hi all,

I did some mods to my bike(xr650) and i'm afraid i've screwed it up. I read an article on "uncorking" the xr650, and did what they said to do, take airbox restrictor out, remove baffle, rejet, all that. the thing I was worried about was the jetting, but it ran PERFECT when I rejetted, so I never thought twice about it. Anyway...been riding it for a few months now uncorked, and this morning when I went out to ride it was making a knocking noise. I tried to pinpoint the noise, and I think its in the cylinder. I rode in a good bit of mud last week, but I washed everything off really good and made sure not to get any water in the airbox or exhaust. Any ideas? I'm guessing i'm really screwed if it's a knocking piston....ain't gonna be cheap. I tried to listen, and it sounded like I might have heard a snapping sound after I had already heard the knocking as well, but it's hard to tell since I can't ride on pavement. Please help!

James

 

[nickyd]

got old crappy gas in it? that could be a cause.

 

[James Miller]

I don't think the gas should be old....it's only been in there about two weeks.

I just don't know what to think....I can hardly hear it unless i'm listening for it. Would it be normal? If it was, I don't know why I would have noticed it all of a sudden. The bike runs fine and everything....It's just a small ticking noise. I've never had this happen before, so it's new to me. I have no clue what to look for, so any advise would be great.

James

 

[nickyd]

James - are we talking a ticking like a TAP TAP TAP TAP (faster obviously) - or a KNOCK - which would be a clank - piston knock is unmistakable - start it up and let it run - while still cold snap the throttle a little bit - if you've got a worn piston (worn past its limit) it should knock under that load.....IF its simply tapping - it just might be time to adjust the valves. Could it be that it always sounded like that and since doing the mods now you take more of a notice? that happens to me a lot - I almost sh*T myself when I rebuilt a KDX...man it sounded like death - until I had some other owners confirm their make some weird clanking noises too. Hope that helps.

 

[James Miller]

Alright...Thanks, i'll go get the valves checked. You are right, its more of a tapping sound than a clank. It's hardly noticable, I just like to catch things before the detonate....Thanks for the help!

James