Yamaha RD500 Balancer Shaft Mod

[@philipvick9513]

The reason that seems to be given for moving the balancer flywheel is to reduce footrest vibration. It was noted by Yamaha that the bike suffered from bad vibration. They rectified this problem somewhat in the 85 model by moving the balancer flywheel to the rear crankshaft. The balance shaft has two sets of counterweights that are 90 degrees to the counterweights of the front crankshaft in the original 84 assembly. The balance shaft spins the opposite direction of the crankshafts. The TSI mod locates the balance shaft counterweights 90 degrees to the rear crank counterweights and drives with the rear crank still in the opposite direction of the crankshafts. All I know.

[@LanceGamma]

Excellent job. Great tip on how to mark the flywheel by superimposing it onto the other gear. Thanks for taking the time to post. This is a very worthy mod.

[@squirrelman6719]

Helpful info for the other twenty-eight RD500 owners out there......somewhere.

[@Peter57808]

I had the first model here in Australia and it did not vibrate excessively, it would foul plugs constantly and seize the power valves every 1000k's. and yes I should have kept it but I was young and stupid at the time.

[@robbierockin939]

Hi excellent vid , but how would it cut down on vibration if basically moving the flywheel to the lower crank ? and esp if the balancer shaft still the same ? ,,cheers

[@weofnjieofing]

Great Vid! Anything to reduce vibration is a good thing. Is the RD 500 a "Big bang" engine? i.e. two cylinders fire at once? I'm thinking because 1 and 3 are at TDC that the Rd is a big bang. Also, is the Suzuki RG 500 a screamer? I'm looking at getting one or the other but would prefer a screamer over big bang.

[@philipvick9513]

in my mind a big bang engine would be one that all fires at the same time, so that being said all pistons would be at tdc at the same time and all hit the ignition together. The Rd500 being a V4 fires 2 cylinders at the same time so I would say it's not a big bang. A 2 stroke having only 1 revolution of the crank to produce it's power cycle means that the piston will either be at the bottom of the intake stroke or the top of the compression stroke. This is the same as the RG500. 4 strokes can have the pistons at the same position on 2 cylinders but be on different strokes. TDC on a 4 stroke can be either end of compression stroke or end of exhaust stroke. so in conclusion I would say the RD500 & RG500 are both the same. I think a big bang V4 would run like a bag of spanners lol. I think if both either front 2 and rear 2 ran together it would be classed as big bang but they don't 1&4 and 2&3 run together.

[@no1LCRACER]

there not a v 4 are they they are a parallel twin not a v 4 they not in a v shape they call them a v 4 ?

[@ajkaz-ub9de]

How did the mod work? Less vibrations?

[@fw1421]

If only they had sold these in the US.

[@Mr75044]

Its not actually a v4 Then.no common crank. Two 250 engines Geared together.

[@paulgilbert2819]

My bike has no balancer shaft fitted it has been tuned

[@Thoraldson]

That is what I want to do. Do you have any bad vibrations? What is your experience? Thanks from Germany