The best way I found (without expensive analyzers and stuff) is to read your spark plugs. If your engine isn’t running right at a certain rpm range (Hi, Mid, Low) ride the bike at that range until it starts acting up then cut the engine without letting off the throttle. Pull the spark plug and compare it to the chart at this web site http://www.dansmc.com/spark_plugs/spark_plugs_catalog.html. Make adjustments accordingly (increase or decrease the size of the appropriate jet)

I'll see if I can save the chart as a pic and post it.

 

I'm no graphics expert but here they are

 

Hey good stuff! I hadn't seen a chart like that or thought about it in a long time.

Joel

 

I did a Hypercharger upgrade on my Volusia and didn't want to loose the gas milage that re-jetting would have caused so I started making restrictor plates from the bottom of coffee cans and reading plugs. When I got to the right size opening I made an adaptor plate out of 1/4" aluminium.

 

Good point nimadd, good thing about 4 strokes is they handle a lean condition much better than a 2 stroke engine would. More than likely why most all 4 strokes come from the factory jetted lean, and most 2 strokes come jetted a bit rich.

 

A picture says a thousand words. This was my 86 Mercury 150hp V6 outboard after running it with dirty carbs.

I should have taken the 3 hours to clean the carbs.

 

Wow! Looks like a beat up old hockey puck of carbon on that piston.

 

That's not carbon. You can see the rings at the right side cylinder wall.

 

YIKES!!! I guess I shoulda expanded that picture first.

Joel

 

Pinging at its finest!! (or worst)