Okee Dokee Bob ... My 2¢ worth ... and yes, it's a long distance guess ... I've seen several instances where there has been significant carbon buildup ( especially in the front jug ) ... and in several instances it's been attributable to ( my estimation ) of the rerouting of the crankcase gases through the intake circuit ... Pull the plug ( you may see the problem exhibited on the plug ) and buy/borrow a borescope ( cheap ones are available through sites like Harbor Freight ) that will be able to give you a birds eye view of the top of the piston ... Another thought is that you say the noise goes away once it warms up? ... Piston to bore clearance may be excessive and you're hearing "piston slap" ... just a possibility ... If it is carbon run some of the "mechanic in a can" chemicals and see if that helps ... Old schoolers use to induce water into the intake while keeping the rev's high and "blasting" the carbon ... This does work but be careful

 

I might have mentioned something about being stuck in a mexican jail...

 

I was in El Paso, so close enough. Lol

 

I'm agreeing a whole bunch to what Larry said....

Bawb, correct me if I'm wrong, but you were fine with the bike till a bunch of people told you something was wrong with it? Engine making too much noise?

Stop listening to other people critique your bike, LOL...

I know you've spent a lifetime on 2 wheels, so have I. I have spent a quarter century on Harley Davidson motorcycles of one form or another, and they make noise. It drives newer riders who came up on water cooled engines crazy. I'm not the mechanic Lucifer is, but hearing a little bit of engine clatter doesn't mean your engine is no longer trustworthy, and is going to GRENADE, LMAO....

When you crank up an air cooled engine, (100 yr old design) you're probably gonna hear a little bit of pushrod and valve clatter. Just a little bit. I'm not talking about obvious knocking, but it doesn't sound like that's your problem. I haven't followed along, so maybe I missed where a mechanic has told you that you have a definite problem. Hopefully not.

All I'm saying is people have made businesses trying to quieten down brand new Harley Davidson engines, and thousands of people have paid them for their products. You could probably have ridden every one of those bikes that they freak out about the noise a 100,000 miles with no issues.

If I missed something and you do have an issue, hopefully it gets fixed. Let me know how it goes as I am curious....

 

Teaching a small class today on how to start a carbureted engine.

 

 

 

When I bought my bike used, I pulled the plugs and looked at the top of the pistons and found them carboned up pretty good. Started the bike, held the throttle open a bit and squirted water into the intake. Did the breather bypass and the pistons looked much better.

 

Not sure I follow ya there Russ ....... ?

 

Water, Stan.

Auto complete can be a booger.