GS550 Bored 740cc Officially Done!

[brveagle]

Welp, It's done. It's running. It sounds amazing. I got the jetting somewhat close as it idles and pulls through the rpms strong. I haven't riden it, just idled it in neutral, but the rain is stopping me from riding it around as of yet.

But it does run.

I'd like to thank everyone on this board for their help, especially RacingJake, Nerobro, and Terry. RacingJake helped me think through this whole thing and was good about answering PM's.

Anyways, here's the specs.

1980 gs550e
650 top end increasing the cc's to 673.
Bored out 650 top end, 3mm to 740cc's.
Adapted High dome pistons from gs750 to make the 740cc.
Base spacer from Cometic
Vance and Hances 650 4-1 header.
Lockhart Oil cooler.
Custom Cam Chain tensioner
Along with some other performance goodies, sums up all the fun.

Can't wait to get it on the street, it's been a long winter for it.
Let the break-in process begin.

[AOD]

[first timer]

congrads, this thing should rock. can't wait to hear about the first ride.

[Mike_H]

Vance and Hances 650 4-1 header.

V & H make a 650 header? More info please!!!

[brveagle]

Here's all the pics i can find, i think i posted some of them here awhile ago.



(all together now}


(piston's i ended up using.)


(vance and hines )

The pipe sounds awesome and fits great. It has a nice rummble, but is not too loud. I spent forever looking for one to fit the 650 top end for my bike, but it looks and sounds great. The picture doesn't do it justice after i shined it up.

[Nerobro]

Guess what's hiding in my basement...................

[RacingJake]

I'd like to thank everyone on this board for their help, especially RacingJake, Nerobro, and Terry. RacingJake helped me think through this whole thing and was good about answering PM's.

Hey buddy I didn't do much......you did all the work \\/

[brveagle]

Guess what's hiding in my basement...................

The curiousity is killing me

[Nerobro]

A set of 4, NOS GS750 pistons. *grins* along with a bike that should only end up being 380lbs...

[78550Detroit]

How much was the cost on the build?

I have a 79 GS550E for a parts bike that I got from a friend a while back. I found a 78 GS550 that I bought that was already together and running. Since I have the spare motor from the 79 GS550E I was thinking of doing a rebuild/build up on that motor just was wondering what the approximate total cost would be to do this?

[Nerobro]

you'll need to ask Brveagle on the cost of the overbore. But you can expect to pay $100-300 for a GS650 top end. The gaskets will run you about $100. The GS750 pistons... OEM price is like $200 something. And the spacer is about $100.

I got my GS650 top end for $100, and it had usable gaskets. My pistons cost me $30. I still need to buy rings.

If you don't mind just 673cc... go with just the 650 top end.

[brveagle]

I'd recommend jumping to 673cc's first... It'll give you a good jumping off point, plus you'll really learn how your engine works and exactly what it takes to expand on your performance.

[78550Detroit]

Thanks for the info

doesn't sound like it would be as exspensive as I thought. Brveagle what did you spend on the overbore? Where do you guys find the parts for these old engines can you get them from local motorcycle shops or do you have to order from online companies?

[brveagle]

doesn't sound like it would be as exspensive as I thought. Brveagle what did you spend on the overbore? Where do you guys find the parts for these old engines can you get them from local motorcycle shops or do you have to order from online companies?

300 for bore and hone... i took it to a good shop though, hence the little higher price..

ebay for engine's

[78550Detroit]

Thanks again for the info

Heres a pic of the bike I am fixing up got it on craigslist for $400.00 . I already swapped a lot of stuff over from the parts bike like the seat, grips, etc. and I had to fix some dents in the tank and then I painted the tank and other body parts last summer. Starting to shape up pretty good. Still need new front tire and fork service, but I can't believe how well it runs for what I paid for it. Starts up on usually first or second kick.