GS750/850 8v 894cc or 920cc pistons - group purchase interest? 475cc-489cc GS400/425

[Chuck78]

I wanted to check in with everyone here and see how much interest there was in going one-up over Wiseco's GS750 844cc 10.25:1 piston kit and getting a small batch of 72mm 920cc pistons made up to fit GS850 cylinders (can be easily made to fit 750 crankcase), or possibly +2mm overbore on GS850 cylinders with 71mm 894cc pistons. If anyone is interested in this, please chime in now.


This will require GS750 cases to be clearance slightly to accept GS850 cylinders. There are no big bore GS850 options available off thevshelf, so this may be of interest to GS850 owners as much or more than 750 owners.


I am looking at some one-off JE Pistons 920cc slugs (I can only get 6 pistons for myself at a high cost, no more available, but VERY NICE!),
or possibly having Wiseco make a batch of 12 or 14 pistons (6 or 10 for me, 1 or 2 sets more from interested GSR Members to meet their 12 piston minimum) for around $425-$440/set of 4,
or have MTC Engineering re-make a run of minimum 20 pistons of their no longer manufactured 72mm 10.5:1 920cc pistons that I am currently running - $540/set from MTC (they make REALLY NICE stuff)


So if anyone is interested in a set of 920cc gs750 Pistons, or resleeving a GS 400 or 425 to 489cc, let me know and that may dictate which supplier I use. The JE are going to be the nicest but I can only get enough for myself and they will be PRICEY...


I will be having GasketsToGo.com make the GS425-489cc gaskets that I need in MLS, but for the 894 or 920cc, OEM Suzuki MLS GS1100G head gaskets work perfectly.

[Chuck78]

I'm running a set of NOS MTC Engineering pistons now for many thousands of miles the past few years. With the GS750 OEM cams advanced to 104/106 degrees, the thing breaks loose a 150/70-18 Avon RoadRider quite well, and when it heats the rubber up momentarily from spinning it, it very powerfully lifts the front end of this heavyweight engine'd bike well into the air and quite frankly terrifies me! I need a more predictable sticky tire or more self control!

I'll likely be getting at least 2 of the 72mm JE Pistons because 71mm 475cc on the GS425 may not be enough for the little racer twin to get all out performance out of the small twin cylinder 325lbs GS that I'm trying to squeeze out if it. 489cc and 850 or 1000 sleeves and GS1000 valves is likely where I'll be going with the GS425. This bike may turn into a vintage racer project instead of a racer themed street bike.

My Rickman race frame was a Z1 powered '76/'77 Rickman CR900, so switching to GS power, & with my love of 8v GS750 kickers, I figured I had to go around 900cc on it as well. I'm all for the +3mm overbore on 850 cylinders, but the +2mm 894cc may run a bit cooler and last longer. Which really potentially/hypothetically means you could jet the 894cc slightly leaner for more power than what may be safe on the 920cc. But then high octane fuel negates that.

Let me know if anyone else is on board.

Thanks,

Chuck in Ohio