Arrgh - more trouble

[Guest]

Thought I'd get a couple of months trouble-free after my carb rebuild, but oh well.

Something sounds wrong. I have a slight loss of power in the lower RPMs, and the bike got louder and has a high overtone - like an old air-cooled Volkswagon. I also get some popping/backfiring when I rev it up to 4-5000rpm.

I think it happened yesterday, but to be honest, it could have been gradual over the last week and I just noticed it when it got worse.

What would you guys check first?

[maro]

the usual suspects,

all cylinders firing?
Any pipes cold?
How are the plugs looking?
are you synched?


I was having low RPM issues on #4, turned out pilot jet was clogged from pieces of that rubber cap... this was not long after a rebuild.

good luck.

[bwringer]

Check exhaust sealing as well -- both the seals at the cylinder head (usually heard as a ticking noise) and the asbestos/fiber seals underneath where the pieces of the exhaust system join together.

[Roostabunny]

the usual suspects,

all cylinders firing?
Any pipes cold?
How are the plugs looking?
are you synched?


I was having low RPM issues on #4, turned out pilot jet was clogged from pieces of that rubber cap... this was not long after a rebuild.

good luck.

Problem found while checking the plugs. Not a usual suspect, but a simple problem.

A #3 header flange bolt had vibrated loose, and the second bolt was on its way.

Go figure - all I ever read about those things was warnings about how not to break them off in the head (soak with PB blaster for two weeks, etc) and how to get broken ones out of the head. Looks like the PO replaced the ones on #3 with stainless. I'm not sure why probably extracted a broken bolt and didn't want the headache again.

[Roostabunny]

Check exhaust sealing as well -- both the seals at the cylinder head (usually heard as a ticking noise) and the asbestos/fiber seals underneath where the pieces of the exhaust system join together.

And Brian gets the prize!

Bonus points (like they'll do you any good) for knowing the bolt spec so I don't have to take it off when I go to Ace.

Thanks fellas!