GS 425 Pistons Ruined....Options

[SqDancerLynn1]

He was talking about a 71mm bore at one point, that's why i mentioned cooling

[Nessism]

The 400 and 750 used the same pistons.

[BrianH]

Oh crap I'll have to cancel that order then.

[droyce]

I have a gs400 and from what I'm getting out of this is, I can bore my 65mm out to a 69mm and slap some gs850 pistons(69mm) in it? and bingo I go from 398cc to 448cc?

What about pins/clips?

[Mekanix]

This may be of some assistance, there is allot to read but there is lots of information as well.

http://www.thegsresources.com/_forum/showthread.php?t=170287

and this

http://www.thegsresources.com/_forum...d.php?t=172422http://www.thegsresources.com/_forum...d.php?t=172422

[droyce]

That's definitely an interesting building you have there Mekanix. In one of those threads it says you can slap any GS4xx-5xx cylinder/head on to a GS4xx base? Wouldn't the difference in stoke cause a problem with this?

And I never saw an answer to my GS850 piston question, did I miss it?

[Mekanix]

Depends on the year. Anything after 1980 400 to 500 have a 56.6mm stroke. (that I've been able to find) In the 1970's they had a 60mm stroke and also had a roller bearing crankshaft. After 80 they had plain bearings.

What year is yours?

Is it the 2 or 4 valve per cylinder model?

[droyce]

1977 GS400, 2valves per cylinder 65mm bore, 60mm stroke

[Mekanix]

Ok if you find a piston with a bore that you can comfortably bore to. Like a 67mm or 69mm and still have enough liner left then its just a matter of using a few gaskets to move your cylinder and head higher. Cometic can make you a base gasket in what ever thickness you want.

you need to know what the wrist pin diameter is for yours.

Hopefully its 18mm, there are several engines using the 18mm pin and a few using a 20mm pin.

after that you need to find out what the deck height is and compare it to another piston your interested in.

[Big Jay]

We have our 69mm GS400 heads gaskets done, and will now be offering a 69mm kit for these motors.

Jay

[SqDancerLynn1]

I meant if he tried to go to 71mm bore

[Suzuki mad]

If your still looking at standard pistons try this guy.

http://www.suzukisimon.pwp.blueyonder.co.uk/gs400.htm

[droyce]

We have our 69mm GS400 heads gaskets done, and will now be offering a 69mm kit for these motors.

Jay

Jay, by kit do you mean pistons/pins/headgasket to make the GS400 into a 69mm bore? If so, how do I get ahold of one of these kits?

[davidduarte]

I seem to recall in the owner's manual for my 425 mentioning something about Suzuki not making a performance upgrade for it, but that you could take half of an 850 kit and use that in your 425 for more power.