Hi Guys,
New to forum so hello to all, I am building a 650 engine and putting it into a 500 frame. I am lightening the reciprocating parts and crank to suit. I have the 500cc engine and the 650, so I will carefully weigh all the parts before I go any further. I am hoping to get close to the 500#'s with the new and modified 650 parts. I have done this work on other bikes successfully in the past, just not with the added complication of the balance shafts.
My question is, if I take a proportional approach to this, can I re-balance the now lightened parts balance shafts to suit. I have nerve damage in my right hand and cannot handle the excess vibration, dead hand no brakes. Are these shafts optimised for a particular frequency to suit the frame or done to a formula to offset the secondary forces.
I would appreciate hearing from anyone who has rebalanced the assembly including the balance shafts before.
I will be statically balancing this to start with, followed by dynamic balancing, and reducing friction on shaft balancer journal surfaces. So I am hoping to account for extra momentum of the shafts, from other places.
regards Ian
Sorry, I can't really help with this. My plan was to remove the balancer shaft, and rebalance the engine to suit. Might be worth posting in the general and project sections as well.
Hi Burning1,
Thanks for the tip, took your advice, Thanks.
Regards Ian
I never tell anyone what to do with regards to engine modifications, only what my own experience has shown. Regarding that balance shaft, I built my first engine leaving this piece out, which means you have to epoxy the oil holes in the case that are designed to provide lubrication to the balance shaft journals. IMO, the only savings is the reduced overall weight of the bike. I spoke with Mike and Falicon regarding a balance of the remaining parts and asked about the balance shaft. He said he did not want that, and only required that I send the crankshaft, one piston assembly with rings and the pin. I can tell you, that the vibration was terrible, reminded me of the Brittish bikes I used to have. I picked up another doner bike and built it with the factory crankshaft, balance shaft and rods, in factory trim, no balancing, or modifications at all. I did replace the pistons, with a 1 mm oversize bore (75mm), blower pistons from Ross. Really nice machining, I installed them right out of the box. I could tell that they were considerably heavier than stock, and there is more vibration that normal, but this rotating assembly has held together through some severe dyno testing without failure. I may disassemble before the ECTA's first event in April and have Mike do his thing with the crankshaft. In my experience, I have never seen an increase is HP output as the direct result of balancing. I know that this is contradictory to what is reported just about everywhere, but I haven't seen it with any of the engines that I have built. FWIW, the GS500 engine now in my bike is a totally stock lower end, with the Ross pistons, stock camshafts, stock intake and exhaust valves, race springs, titanium retainers, and my own porting on the heads. Running 20PSI manifold pressure, four 1200 CC/minute RCE injectors, methanol fuel, and 10,500 RPM at 20% throttle opening, the bike made a very easy 140 HP. The subsequent run at 40% throttle nudged 200. These are RW corrected horsepower on the Dyna Jet Super Flow machine, the best out there. At 30 PSI, the motor will make 240-260 BHP. The head gasket is the stock .009 steel shim, and the cylinder block has been "O" ringed. No blow outs, no leaks, it is an amazing motor. I picked it for the 500 class (ABF-500) for Bonneville, because it was the only twin with four main bearings, and Suzuki used the GS750 clutch. The transmission gears have all been undercut, because it would jump out of every gear under load. Also have a Zipper, outboard support bearing. Look for this machine at the upcoming 2012 speed trials. Time to put to rest all those stories about the lowly GS 500.
I've been reading a up a little, and I've heard various stories about attempts to rebalance the GS engine without the balancer shaft. Bob Broussard, I believe it was, had bad luck with a Falcon re-balance, but much better luck with other dealers. Might want to search his posting history.
Interesting stuff here! Post more please. Good reading!