45 inch engine sounds

[old man emu]

I don't have anyone close by who has the experience with 45 inch engines to give me an answer to this.

I'm wondering about the noise I hear when I'm running at 40 - 50 mph. It's hard to describe the noise, and I can't make a recording to post, but the noise sounds like something being flung around in a tube. The noise seems to be coming from the front of the engine. At idle, or low speed, the noise isn't there.

My guesses at the noise are:
1. Primary drive chain a bit loose - although I've just adjusted it after fitting a 33 tooth engine sporket.
2. Something in the generator.
3. Front fender vibrating - although it is secured by its braces and via the horn mount bracket to the front forks.

The engine has just been rebuilt, and pulls like Paul Bunyan's blue ox, Babe. Everything else that is bolted to the bike is bolted on tight.

I hope someone can help.

[liberator]

Does it disappear when you slightly retard ignition? > she's pinging...check for ignitiontiming or airleaks

[john HD]

Check your rivets on your front fender, i had one loose one that would buzz and rattle. Peened it over no more noise.

Worth a try anyway.

john

[old man emu]

My fender rivets went West long before I got the bike. I've got machine screws and nuts, but since every other nut on the bike has shaken loose, it will definitely be worth checking the fender (mudguard) bracket screws.

I'll try the spark control next time I'm out riding it.

[Mark44]

You mentioned that you have recently adjusted your primary chain after installing a larger sprocket. If the primary chain or drive train is too tight, that can be the cause of some terrible noises. You want about 1/2" of up-down play in each chain. Recently my primary chain was a bit too tight, and the noise the machine was making made me think the generator bearings were failing. After readjusting both chains, the noise went away.

[old man emu]

Ahhhh! that seems to be the best suggestion. I think my primary chain is too tight.

[old man emu]

Wrong! My chain was flapping like Samantha Markle's jaw at a news conference.

After having the tension adjusted on both chains, the bike is singing like a sewing machine again.

OME