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You think your 750 would be better with...

  • Thread starter Thread starter makenzie71
  • Start date Start date
M

makenzie71

Guest
...a superior charging system? Less weight? 30 more horsepower? A Pre-Kat 750 motor might be for you!

I just dumped a pre-kat 750 motor in my 1981 GS750. I asked around before and no one ever really went that route. The motor is strong and reliable, but it's not so desirable a motor consider what is out there. You can get it for a song, though...I bought the whole bike for $500 in riding condition so, after I part the rest, I'll come out way ahead.

For anyone who wants to do it you'll need lots of washers. About 100 of them...or you'll need to be able to machine proper spacers. I used the rear engine lower mount because the kat motor fit in it and it was against the frame as opposed to a bolt on bracket. The rear upper mounting brackets fit the kat motor. I had to fabricate brackets for the front. All required lots of shims and spacers, but it's solid.

I hope to fire it up in a couple days.
 
Hi,

I will congratulate you on your ingenuity but...

useless_no_pics.gif



I'd love to see what you've done with the old girl. ;)


Thank you for your indulgence,

BassCliff
 
That sounds exactly what the '85 new 700E needs, yeah, we're gonna need some pictures of this.
 
justin7501.JPG


justin7502.JPG


justin7503.JPG


justin7504.JPG


The front mount hangers were the stock 750E hangers plus the stock lower center hangers put together. I positioned the motor where it needed to be then bolted the two hangers together so that the frame and the engine all had proper bolt alignment. Then I took the hanger off the frame and motor, leaving the two pieces still bolted together, and welded it solid. Later I'll cut some new hangers from 3/8" mild.

The biggest hurdle is the shear size. The Katana motor is not just a little smaller. It's several inches shorter in height and length...and like six or seven inches narrower. I lucked out in this bike/motor combo for the rear mounts just working out, but it left it a couple inches shy of the front mount. The bottom center mount is pretty much unusable. I'll have to play with that one later.

Stock exhausts won't work. The GS750E has a bigger exhaust than the Katana 750 otherwise those headers might have worked. The Katana headers hug too close to the motor and won't clear the frame. Not quite sure yet what I'm going to do there...I'm probably going to make an adapter to put the GS headers on the kat.

I don't know what I'm going to do about the oil cooler. Depends on the headers, I guess.

I had concerns about the carbs but, using the rear mounts, the carburetors and K&N pods BARELY fit. There's going to be a lot of room up top for the exlectronics and such.

That's as far as I've got so far. Anyone who wants to try to do this...don't do it alone! These motors weigh nearly 300lbs. I tweaked my back a little getting the GS750 motor out. I had to lay the kat motor on its side then lay the frame over it then chain it all together and lift the bike up that way. It wasn't easy. One more set of hands would have been faster, easier, and SAFER.
 
Hi,

Thank you for the pictures. You make it look easy! You're going to have quite a sleeper there. ;)

Please keep us informed!


Thank you for your indulgence,

BassCliff
 
Difficulty is in the eye of...or hands of...the beholder. It wasn't particularly easy, though...not doing it by myself, anyway. It was fun. I'll have the wiring up tonight and try to figure the exhaust out.
 
Nice job! Can you weld or have access to someone that can weld for you?
just a thought but maybe you can just extend or lengthen the header down pipes to clear the bottom of the frame. If the welds look ugly throw some exhaust wrap on there.
 
I can weld...that's how I got front brackets.

The headers clear the bottom of the frame...it's the down tubes. They actually need to be spaced further out. What I'm going to do is cut the primaries off the vance setup and find some other way to collect them. Or run open quads.
 
Sweet. Subscribing to watch the coolness.

Keep the updates and pictures coming!
 
How much to pick an engine up and how much for all the hardware to make it work?
 
makenzie71 said:
I can weld...that's how I got front brackets.

The headers clear the bottom of the frame...it's the down tubes. They actually need to be spaced further out. What I'm going to do is cut the primaries off the vance setup and find some other way to collect them. Or run open quads.
Click to expand...

Open quads? Now that would be interesting to hear. :cool:

Can't wait to see the finished project. Good luck.
 
Ranger said:
How much to pick an engine up and how much for all the hardware to make it work?
Click to expand...

Like I said I bought the 1993 Kat 750 for $500. My goal is to make the whole thing work without having to buy additional "things". You need to have the engine, carburetors, all the wiring....basically everything to run the bike. So you really don't need that much of a financial investment. But you will need some fabrication skills and a welder/drill and a proper saw.
 
makenzie71 said:
Like I said I bought the 1993 Kat 750 for $500. My goal is to make the whole thing work without having to buy additional "things". You need to have the engine, carburetors, all the wiring....basically everything to run the bike. So you really don't need that much of a financial investment. But you will need some fabrication skills and a welder/drill and a proper saw.
Click to expand...

I like the idea but too time consuming unfortunatly.
 
I'm compiling all the parts to install an '89 750 motor in my '83. About 9/10ths there. I have not decided on what size pistons are going in it yet...
 
The 89 is the same as what I've got. The swap ought to be about as straight forward as what I've done.
 
I've read that a 1052 (early 1100, later are 1127) crank and cylinder block will fit on the crankcase on these motors... 1127's with some machining.
 
I can say it's definite now...the Kat head and the 16v 750 frame do not work well together. Anyone else who does this swap with HAVE to use the lower rear mount the way I did. Moving the engine any further forward will not allow you to exhaust properly.

Also definite....you can forget making any off the shelf system work. I even tried cutting the manifolds off the Kat exhaust to get the clearance distance I needed to make my old Kerker header work. No amount of grafting will fit it. You will have to make your own exhaust from the manifolds back. It's actually not too hard for anyone with any welding experience.

I'm going to have to go to Lowes or Home Depot in the morning and get some aluminized conduit bends. Same thickness as standard exhaust tubing...if they have EMT that'll be even better (lighter)...and it's mandrel bent. The primaries on the Vance system that was on the bike were 1.5" and that's about the only way you'll get 1.5" tubing.

I'll have to think of something for mufflers, though. I wanted to use my same Kerker can, but I don't know now unless I make the system 4-2-1. Originally it was 4-1 and I suck at welding quad merges. For a little while I'll be running 4 open turndowns. I can't wait.
 
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