GS450 Pison replacements

[supertorro]

Hello everyone. I have just acquired a 1981 GS450 as a project bike. Unfortunately it has been maintained by badly trained monkeys, so it is in very very poor condition.

Now that I've managed to get the engine out and the cylinders pulled off, the cylinders need reboring.
Unfortunately, as seems to be the case for many, finding replacement pistons appears to be much the same as searching for unicorns.

I'm hoping to replace just the pistons with some oversize options, but this is the point where I have not the knowledge or skill.

Caveat: I know nothing about the detail around how engines work and have never pulled an engine apart. So if I ask some stupid questions, just be gentle before you rip me a new one.

Does anyone know of suitable alternatives to the oem pistons?
Clearly, a straight drop-in option would be most favourable.
Otherwise, another piston that can deal with minor modification to be fitted?

I found some threads on using the GS500 cylinders and pistons with the stock bottom end and head. If that's the only option then I'll try to find that, but I'll keep that for a last resort.

Silly question time
Why would any piston of correct size not be useable?
I understand there are quite a few measures in play here (width, height, valve recess count and location, etc).
Perhaps someone can enlighten me on how this all works.

Thanks

[2BRacing]

Hi Supertorro, Welcome to the GSR!

You have certainly found the site with the best information and resources on the GS Suzuki bikes. Unfortunately I have no experience of the smaller capacity engines, but new parts are available from Suzuki South in Wynberg, however they can be pricy. Second-hand parts may be available from Ryan's Motorcycle Parts in Voortrekker Rd, Parow (next to Craig's), but be warned, he is a "strange" guy to deal with and you need to be a bit thick-skinned and not take his comments to heart!

Regarding your situation with pistons etc, I suggest you speak to Allan Roberts on 083 233 8681. He is at 10 Watsonia Street, Goodwood. Tell him that I referred you. He will be able to suggest solutions and possible alternatives, and recommend where to have any machining work done. The "baseline" will be to have your existing pistons and cylinders measured up and compared to Suzuki specifications, so that you can determine which oversize parts may be required, and then search around for those sizes.

Good luck!

[supertorro]

Hi 2BRacing and thank for the info

I tried Suzuki South and was told they don't do parts anymore for the 450.

I'm going to try Allan Roberts and see what he says.

As a matter of broader general discussion I found somewhere (might be on this forum) the suggestion that the GS1000 pistons will fit.
Can anyone confirm or deny this?
I checked the parts fiche for 450 and 1000 and they are different numbers.

Searching continues

[sam000lee]

If you can find a good set of GS500 cylinders/pistons, there's no difference in the work you'll have to do to swap them in versus replace the original 450 pistons with another set. Here's my walkthrough of my GS500 cylinder swap that also might give you an idea of what you'll be getting into (500 or 450cc):

https://www.thegsresources.com/_forum/showthread.php?252902-My-GS450-gt-GS500-Cylinder-and-Piston-Swap

[fastbysuzuki]

Cruzinimage do a conversion (which requires a reboring) failing all else

https://www.cruzinimage.net/2018/06/28/80-88-suzuki-gs450-480cc-bigbore-pistons-kit-73-50mm-piston/

[supertorro]

Cruzinimage do a conversion (which requires a reboring) failing all else

https://www.cruzinimage.net/2018/06/...3-50mm-piston/

Thanks for the tip. It's what I have ended up doing. Now I am just waiting for arrival.