Valve shim adjustment

[Giblet]

OK, here's a question for someone. How much effect does valve shim adjustment have on fuel mileage? I'm thinking my GK should be getting a solid 40 mpg on the highway. I don't know when it was done last but I've put just over 10K miles on it in the 2 1/2 years I've had it & haven't done it. It sat up for several years before I got it and now has just over 30K miles on the clock. Runs like a scalded cat and has no excessive valve noise. It consistently gets 34-37 mpg on my daily 90 mile round trip commute. I typically have the trunk removed but saddle bags, fairing etc are in place.

[Jethro]

Valves that don't seal well for any reason will affect mileage quite a bit. You'd be loosing compression. The intake valves would suck in more fuel to do less work and the exhaust valves wouldn't keep all the gas in the combustion chamber. Power would be lower, but you'd compensate with more throttle, contributing to even worse mileage.

[Giblet]

Thanks Jethro. Makes sense as even the smallest things seem to upset bikes in general. Well, guess the beast may be off to see the "old" Suzuki mechanic. He's an older guy (Viet Nam vet) who used to have the Suzuki dealership here. Knows these bikes inside & out. Really picky. He has a beautiful GS1100E he has completely redone. Hate to do it but we're in an apartment temporarily & I have no place sufficent to work on it much past plugs & oil. I really miss my garage .

[Joe Nardy]

I agree that you should have them checked but don't be surprised if they are all within spec. These valve trains are rock solid once they get broken in.

Joe