GS550 Bored 740cc Officially Done!

[Ace07]

Thanks for all the information Chuck. I am really curious about the Wiseco big bore 650 pistons. I am wanting to rebuild this bike to the best of my ability, and it sounds like I would be able to get a little more power out of the big bore 650 pistons. I have never started a thread before, but I will try to get one going about the 650 big bore pistons.

[Ace07]

Ok guys I started a new thread in the performance/tuning/mods section of the website. Is called "Potential Group Purchase - Wiseco GS650 741cc pistons". If you are interested in a set please inform me on the thread.

Thanks,

Andy

[Chuck78]

Awesome, I'm really glad Adam aka Loud ET got that 1981 catalog and scanned the GS big bore kit page, and also very stoked that Ace took the initiative to call Wiseco!

[Kenny]

Anyone done this to their 550 yet and put it on a dyno? Also what clutch is used? Stock?

[Nerobro]

Anyone done this to their 550 yet and put it on a dyno? Also what clutch is used? Stock?

No dyno run personaly, I believe someone else has. The trouble there is they did it differently. Stock clutch is fine for the torque. Same clutch on the GS650.

For horsepower, you can do some back calculations. Top speed with 549cc, was 110mph. After, 140. IIRC... it's been a while. Mind I had a big foam airbox on mine, as opposed to the stock airbox, and an alphabet headers 4-1.

[Rob S.]

For horsepower, you can do some back calculations. Top speed with 549cc, was 110mph. After, 140.

That's quite a jump!

[Nerobro]

That's quite a jump!

Yes. Yes it is. I bet.. we can find if i'm lying by searching the forum. I can't be bothered at the moment. :-) Dealing with memory that's 15 years on is less reliable than posts I made 15 years ago.

.............. I'd do a much better job on the bike now, than I did then.

[Chuck78]

I believe you can use a 77 - 79 GS750 clutch basket because it has one extra disc & plate than the 550/650, but uses the same parts otherwise.
I have one of these engines built & sitting on my workbench, but have yet to swap it, too many bike projects, too little time!

[Rob S.]

Yes. Yes it is. I bet.. we can find if i'm lying by searching the forum. I can't be bothered at the moment. :-) Dealing with memory that's 15 years on is less reliable than posts I made 15 years ago.

Didn't mean to imply you were lying. Wait, what were we talking about?

[Nerobro]

Didn't mean to imply you were lying. Wait, what were we talking about?

hahaha, I'm implying my memory might be fuzzy. :-)