Thanks for your response
The bike has 28.000 original miles. Can I replace the piston rings myself with basis tools? What are the near term effects of not doing so?

Thanks!

I agree on balancing the carbs. There are many ways to make a balancer (or 'manometer') most of which range from half a dollar to five bucks.

Among the basic 'first things first' checklist I always do upon ackquiring a new bike, is a carburettor teardown and thorough cleaning. Chemtool or brakleen is not a substitute, you gotta get in there with your hands and eyeballs to make sure everything is up to par. You have no idea what kind of shiz might be in those bowls, ready to get sucked into the engine, and it's foolhardy to attempt to chemically 'flush' them through, sending who knows what onto your piston crown and into your valve seats. Not to mention, I'd say at least half of the running problems I've ever encountered on bikes can be traced back to a dirty carb, simple as that.

Take them apart, check each part carefully to make sure it's clean, make sure all your rubber plugs and gaskets are crack-free and supple. I've seen some carbs that had an extra jet (why?) in the mid-range circuit that was plugged off with a rubber plug, and if one plug is cracked or shrunken you could have high idle due to an excessively rich cylinder. Generally speaking though, fouled up carbs lead to a *lack* of power at different settings, not a surplus. The situation I just named is the only exception that I know of where internal carb damage led to excess power. Other than that, it's going to be an air leak in the manifold, or an imbalance between the two carbs, or a simple misadjustment of the idle screw.

The manometer will tell you if your'e balanced, and then you can adjust the idle screws after that point. A manifold airleak can be hunted down by spraying very small spurts of starter fluid onto the intake manifolds... if it's a sealed system, there should be no change in idle speed. If you have a leaky or cracked manifold, you'll get quick spike in idle speed as the engine sucks in some starter fluid through the crack. Make sure to keep the starter fluid away from the main intake or airbox, as this will obviously send back a false positive on the leak check.

Oh... and also know that some bikes require the occasional tweaking of the idle screws, that's just the way they are. I've had bikes that required almost constant tweaking at various stops as the engine temperature went up and down with the demands of the ride. I guess that's why idle screws are generally easy to access, and textured on the outside for easy manual manipulation.

Ahhh, good point on that... There is a good article on all of this on www.airheads.org

www.airheads.org/content/view/216/98/