Suzuki GS 6/550 Yes, 672 block and pistons on a 550 cases..

[Nerobro]

SO GS1100E, what did you think of the GS6/550?

[80gs1000e]

Well I got to ride the mutant and yes, its not a 550 anymore by any means. Pulls very....very hard and gets light up front right off the line easily. I can attest (as I am also a 550 owner) that this "550" is a totally new beast. Same weight, extra ?? horsepower and torque. Adding the second disk up front was also a nice bonus. Pretty darn cool...

....now if we can just get these guys to change some fork seals to go along with the numerous deep engine swaps and other heavy duty wrenching sessions... :twisted: 8)

[skreemer]

Both Nerobro and I need a carb synch desperately. I'm probably going to place an order tonight for some parts that need to be replaced. This weekend for me will be a full wrenching weekend. There's space in the drive way if anyone wants to join us... Maybe bug Joe for some space? There was also a discussion on shimming valves... I know mine are lock nuts not shimmed so mine are pretty easy. Pick a site and drop em off on thursday and then cage it over on saturday?

[80gs1000e]

I neeeeeeeed to do my shims, and a resynch would be nice also. I have to figure out this weekend, school and studies and lotsa stuff going on. Lemme do some research....

[kevan]

This is a very interesting project. Is the stroke of the 550 the same as the 650?
Thanks for sharing.

Kevan
GS750
182,000kms

[Nerobro]

Yes it is. That's what made me thing the project was going to be easy. :-) It wasn't as easy as I thoguht. But it wasn't all that bad either.

[Nerobro]

It's been done.

Skreemer and I have made the GS650 head, block, and pistons fit on a GS550 crank and block.

There's a lot more involved than originally thought.

First, the block wouldn't fit down into the crankcase. The cylinder liners don't actually touch down in thecrankcase so it was a matter of trial and error to find out where the interferece was.



As you can see... some of the interference was pretty severe.



Look carefully and you can see where we ground casting flash off of the inside of bore 2, and Skreemer is working on bore 3

[Nerobro]

Super Scary... Skreemer with a dremmel. He's not quite the artist as I, but he's competant :-) And look... I let him inside my engine with that thing.

It involved a LOT of grinding. none of it was all that deep, just a lot of it. If I did it again, I'd split the cases, pull the headstuds, and have a machine shop bore the crankcase. But that was well beyond my budget ;-)

[Nerobro]

Testfitting. This was probally our 4th or 5th fitting of the block.



This is one of our last goes at making clearance. An artist at work... you can't see the work. ;-)

Seccond, much to our chagrin, the headgasket is different on the 650 and 550. so I had to reuse the 650 headgasket. I will be buying 650 headgaskets from here on out. Here's the reason why... The 550 uses an o-ring to seal the chaincase. The 650 just uses the soft fiber gasket. the 650 headgasket also has integrated oil gallery seals. The 550 uses seperate seals.



Finally, the timing chain was a pain in the butt. I did not realize that the 650 crank has more teeth on the crank sprocket, so that the camshafts use larger sprockets as well. Well, thats' not the whole story really. Lets just say that the discovery process led to me almost bending a valve. And that's an "I hope" I didn't bend a valve.

[Nerobro]

We swapped the sprockets from the 550 onto the 650's camshafts. And after following the directions in the book, managed to sucessfully time the 6/550 motor.



As it stands, the engine is now in my 1980 GS550E, and will crank over. And makes spark. Attaching the carbs is anotehr story. The carbs I'm tyring to put on are the carbs that came WITH THE ENGINE, but appear to be almost 1/2" to narrow. We're chalking that up to time hardening the carb boots. And the boots appear not to match up well with the ports in the head. We're going to put my 550 boots on it and see if that corrects the problem. My 550 boots are also much softer and more supple.



We found out that the boots that came on that head. are NOT gs650 or 550 boots. We aren't sure WHAT they they really are. They're damned simmilar though.

[Nerobro]

If you can identify these, we'd like to sell them. They're in good shape if a little stiff. No cracks at all.

so.. yeah. You CAN fit a 673cc top end onto a 550 bottom end.



549cc piston versus 673cc piston



Aw.. .look It's all dressed up.



working furiously last night before we discoverd the carb boot issue.

[Ironriot]

Is it just me or did you fix all the pictures????? And as for those little rubber boots my 550 came with them also. They seem to be some sort of mystery becuase no really knew what I was talking about. You can't see them individually in the fiches but they come with the little intake flanges when you order them new

[Nerobro]

Yup, I did. As well as I could. I couldn't re-edit the original post because I can't have more than 4 images in a post. :-)

[nisom512]

So what kinda power do you think your pushin now. i know it's been a year almost, but hows it running?

[brveagle]

So what kinda power do you think your pushin now. i know it's been a year almost, but hows it running?

It's completely worth it. A little known fact is that by swapping to a gs550, you are increasing displacement from 549cc to 673cc's. A 124cc gain.