GSXR/Katana 750 engine in a GS550?

scott s

Over 1,000 Posts
DTT BOTM WINNER
I've found just enough information on this to make me want to know more.
Seems like it's been done more "across the pond", and more with some of the larger c.c. bikes.
Add to that the fact I'm new to the Suzuki's and all the nicknames for parts and models and such and I'm a little lost.

What I do know is that there are short stroke and long stroke 750's and I was told to go for the long stroke version.
I was also told that some engine mounts match and some will require brackets to be fabbed.

Does anyone have any experience with this swap? Any pics, links or websites?
 
88-89 are the engines to avoid. 90-91 are the long stroke. All the Kats are short stroke, up to 98.

Not sure on your question. Seems many have the long stroke engine in the short stroke frames. I haven't seen anything about mounts not being the same.
 
I'm talking about putting one of the new air/oil cooled engines in a 1980 GS550E frame. The '80 GS550 is a completely different bike with old school UJM styling.
 
scott s said:
So '90-91 GSXR and any '98-up Katana for the long stroke engine?
Correct.

The 90-91 are putting out 102 ponies to the rear wheel. How's that going to play in the old frame?
 
IIRC 86-87 are also long stroke. Do some frame bracing, get a stiffer swing-arm, and make some beefy motor mounts with oversized bolts and you'll probably be fine unless you are racing it.
 
It's my understanding that the GS of that era had pretty beefy frames. Of that era...
 
What about air cooling versus oil cooling? Aren't some of them strictly air cooled and some air/oil with an oil cooler?
 
doc_rot said:
IIRC 86-87 are also long stroke. Do some frame bracing, get a stiffer swing-arm, and make some beefy motor mounts with oversized bolts and you'll probably be fine unless you are racing it.
I believe you are correct, the Slabsides were long. Also oil cooled.
 
Did they ALL have an oil cooler of some sort?
And we're some 5 speed and some 6 speed.
 
scott s said:
Did they ALL have an oil cooler of some sort?
And we're some 5 speed and some 6 speed.
I believe so, on the oil.

Not sure on the tranny. I know my 91 is a 6.
 
You want to stick an oilhead Gixxer motor in a frame from a GS550?

People have been locked in asylums for less than that! A greased pogo stick would be better able to manage the power!
 
You might consider installing a GS650 cylinder and head on your GS550 cases.
It is a relatively straightforward conversion, but needs the upper engine case to be bored out for the larger diameter cylinder sleeves and the stock GS550 cams have to be used. The GS650 cylinder head has a much better combustion chamber design than the 550, probably the best 2 valve cylinder head in the Suzuki line.
The dorky little 550 carbs are 22mm, but can be bored out to 24mm and you can keep the stock intake manifolds and airbox. Also, check those intake manifolds; on my '77 GS550, I found a pretty large rearward-facing step, which I trimmed out with a knife and smoothed with a Dremel. If you get the carbs bored out, have the manifolds matched at the same time. If you are running the stock airbox and filter, remove the top of the airbox for more flow. Do a plug check; you will probably have to go up a couple of sizes on the mainjet and noodle with the needle position.
I believe the conversion is posted on the web someplace.
If you need still more "grunt" from the 550, the GS550 cylinder can be hogged out to take GS750 sleeves (the upper case needs boring, too) and gives you a 740 cc GS550. The caveat here is, the crank has to be in tiptop shape or mechanical mayhem will probably ensue at high rpm. You have to check the squish band on the head and get it machined for the 750 piston diameter; getting a head gasket for the lashup might be difficult and I was never able to find out what head gasket the guy who did the conversions here in Canada, used.
I don't know how well the GS750 pistons would work in the GS650, due to the different cylinder head combustion chamber and piston crown shapes.
Others have used GS750 or GS1000 carbs, but the intake manifolds have to be changed out and you're on your own as far as the air filter.
The above mods let you keep the stock GS550 wiring, alternator, etc., stuff you would probably have to change out with a Gixxer conversion.
Pat
 
Is it possible, or advisable, to use a smaller oil cooler from a different model? The GSX750-F was fully faired and, I suspect, the oil cooler is the size and shape for packaging.
It has 13 rows. I see smaller ones on eBay, etc,. Some 9 row coolers, some from a Bandit 600, etc.

The Katana was "de-tuned" from the GSX-R for more mid range punch. If I need, or could use, a smaller oil cooler for space requirements on the '80 GS550 frame, think it would be a huge issue? It would be right out front in the open air.

 
Take a look at one from an 01-02 GSXR 1000. Mine is pretty small. GSXR750 of the same years may work too.
 
1fasgsxr said:
Take a look at one from an 01-02 GSXR 1000. Mine is pretty small. GSXR750 of the same years may work too.
Those are water cooled bikes, their oil coolers will not handle the load the oil cooled engines need.
Scott, there are other coolers such as used in cars that offer very generous cooling in a more compact but a bit thicker package.

Here is a GSXR1100 in an '83 GS550 frame. Pic is from many years back. Granted this is not apples to apples from the early frame but you can fit these later engines in.
GS11engineRS.JPG
 
Oldmanonasuzi said:
Those are water cooled bikes, their oil coolers will not handle the load the oil cooled engines need.
Scott, there are other coolers such as used in cars that offer very generous cooling in a more compact but a bit thicker package.

Here is a GSXR1100 in an '83 GS550 frame. Pic is from many years back. Granted this is not apples to apples from the early frame but you can fit these later engines in.
GS11engineRS.JPG

Looking at pics online, the early and late style 550 frame cradles were very, very close. I see that they used the rear mount. I'm told there are two ways to do it; front mount or rear mount. Rear mount eases chain alignment issues but can cause exhaust interference. Front mount is the opposite. Luckily, there is a guy making collars to adapt the exhaust. My plan is to go with the rear mount option.
 
That picture is my bike, image taken in 2009 at a time I got injured and all projects went on hold. I just brought this bike back in the shop.
The engine is set in place with 3 of the mounts finalized. None of the 550 mounts were spot on for this engine but they are all quite close.
The 750 and 1100 engine lower mounts vary a slight amount such that the 750 might be closer to retrofitting but either way you will need to make new mount tabs.
One thing that does not show in pictures is the chainline is wider than the early bikes. I spread the frame to suit. I do not recall how much wider but it needed to be done. That allowed a later swingarm, I think I have a bandit arm in this with a Yamaha R1 rear wheel.
 
What do you mean "spread the frame"?

And I don't want to open up a box 'o' snakes, but talk to me about pods on the Katana 750 engine. I hear that the cams and carbs on the Kat 750 make it horrible to tune, but GSX-R cams and/or earlier carbs are easier to fit pods.
 
Back
Top Bottom