hmm food for thought pistons

[minkathecat]

Yes its pistons again
ive been looking at fzr400 1wg pistons plus 50
so that makes the size 56.5 dia on piston
anyone know wrist pin dia and oall length of piston and also what the centre of wrist pin is to top of piston
i know we can mod 600 earlier pistons
but this would mean if they fitted with a bit of machining not needing to open gasket out much and would save on re sleeving to back fit your old pistons
any taker stripes you know out about this.

[SevenThreeSeven]

I was curious about the FZR400 (and late-model FZ400) because their specifications listed the exact same bore and stroke as the GSF400 and GSX-R400.

What I learned: the Yamaha piston is "shorter" than the Suzuki piston (and the Yamaha piston is a bit lighter than the Suzuki piston, but the connecting rods weigh exactly the same). The Yamaha piston skirt is shorter and the distance between the wrist pin (centered) to the top of the piston is shorter. As a result the connecting rod for the Yamaha is very slightly longer (center to center from big-end to wrist pin) than the Suzuki piston. Also, the wrist pin on the Yamaha is slightly smaller diameter than the pin on the Suzuki.

Altogether the situation ends up being just enough of a jumbled-up mismatch that I don't think you could arrange a "mix-n-match" of the Yamaha and Suzuki piston/wrist pin/connecting rod.

Perhaps you could completely substitute the Yamaha connecting rods + pistons on the Suzuki crankshaft. At this point I haven't done any measurement comparisons of the big-end of the connecting rods to see if there's any compatibility.

[Variablevalves suck]

Same as the early gsxr you usually find the older motors had a smaller bore and longer stroke, they used longer con rods with 15mm wrist pin.

As the motors developed most of the manufacturers went bigger pin and short stroke to ( I think) increase the rpm limit,
might be wrong, could have just been the way they went but they have generally gone wider bore hence early fzr 6 having 59mm piston then later going to 61, this again could be to increase valve area but everything went bigger.

You could take a look at zxr as they are 56mm.

[minkathecat]

thanks guys just thought they would be similar to the early 600 fzrs that can be fitted but thought this would just be a bore out on the liner and a bit of fetteling
ah well shit happens back to the 600 pistons we know we can mod.
regards john

oh by the way guys if you do a search on ebay for liners thir is pakistan will do you some to your drawing for about 70 quid shipped just in case anyone has some good pistons that are not to worne new rings aint a problem.

[Variablevalves suck]

So re reading 737's informative post you might just be able to use the yam piston because the earlier gsxr had 15mm wrist and longer lenght rod

BUT had the same big end journal size!

If you want more information you need to read Chris's big bore post that covers earlier parts.

[minkathecat]

hi chris looks to much trouble be better to go for the 600 pistons and get more ponnies
ps everything finished on the bike now well the first one and gess what the only bloody thing i didnt take to bits the thermostat housing is dripping now SODS LAW take it off lol