The weight of the counterbalance and the weight of the piston are completely different.  The piston works back and forth on a stroke of 94mm, and the crankshaft has counterweights built in to help reduce the vibrations.  The counterbalance shaft and weight works at twice the crank speed and spins around on a much smaller radius.  The piston does not care what the counterbalance shaft is doing.....and because the counterbalance is not part of the crank the counterbalance does not really affect the stresses in the crankshaft/piston/rod.  The counterbalance works through the crankcase to reduce the amount of vibration getting to the frame.....and if the balance is not exactly right you will just get a bit more vibration in the frame......not a deal killer for the weight changes in this scenario of going from 94mm to 100 mm - especially when Lancer says the weights are very similar.

When I had my bike apart I wondered about the weight of the flywheel?  It seemed really heavy, and one of the things that people do when they want to accelerate faster is take some of the mass off the flywheel.  The big weight helps to keep the speed of the big single steady - so cutting down the mass would allow more speed variation and make it easier to stall at low rpms when letting out the clutch to get the bike moving.

ZAR wrote on 10/11/12 at 19:48:02:


The modern USA version is the Chevy Spark, I have one and it is a pretty nice car.

The concern with the liner being that thin is heat and distortion, this would be better as a liquid cooled engine where you can control the heat better. An interesting mod. for as long as it works, but I doubt it will go 50,000 miles, or even 25,000 before the sleeve starts to shift in the aluminum. This is a problem with boring out the Buells and why most of the aftermarket jugs have thicker sleeves with the base machined to fit in the case. I don't think 1.5mm will be too thin, that's around what I have with the 1050 kit on my Buell, the rings never really touch that part so there should be no force in that area.

In the quest for bigger displacement, what cylinders will fit if the case is bored? What are the options for a stroker crank/conn rod?

Is that thing really gonna be able to breathe through the stock valves?  Guzzi small blocks all had the same heads...350 to I think the 650's, maybe even the 700's, same cases too.  But they were all Heron heads so flow was their big issue.  I was gonna pull the trigger on your 97mm kit...maybe I'll wait a bit.  Anyone know the weight of the flywheel?  Seems like 1or 2 lbs shaved off wouldn't be too bad.  I've heard of some Enfields going minus 5.  Anyway this thread is in my fav's...wanna see what happens

Charon wrote on 10/12/12 at 11:18:26:



I own a good many of these ... 1 of which even ran ... it was a GR in a GR frame and - well original GR. All the rest are GR motors going into GS500 frames.
Anyway that disengaging flywheel may have been the real reason the GR650 was a 1-2 year only bike. It is jekyll and hyde. I know of someone who bypassed it in his 851 build of that bike, (as in it is staying light, he's removed all the parts that come apart) in a GS frame ... and I am thinking of fitting it with the disengaement locked shut, as in, its heavy all the time.

Cool.
Srinath.

Another Suzuki Tempter, not sure of the year but it is the early version of the LS650 or 400 engine
Look at the R side engine case, cyl and head and header
drum brakes front and rear





'83 GR650 Tempter....totally different look from the our 650 engine