You think your 750 would be better with...

[kingofvenus]

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...

[makenzie71]

The 89 is the same as what I've got. The swap ought to be about as straight forward as what I've done.

[kingofvenus]

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.

[makenzie71]

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.

[Ranger]

For a little while I'll be running 4 open turndowns. I can't wait.

I really wanna see a video of that.

[makenzie71]

Where we are now...crappy pics...bite me...

[posplayr]

More power to your, you sure are not afraid to have at it. One thing I was wondering if you checked how the exhaust would hang. Seems the motor may be a bit forward so the a$$ end of the pipe will come a bit high.

[makenzie71]

The exhaust is going to have to basically be a full custom. Just to get the point clear:

If you do this same swap, you WILL HAVE TO BUILD THE EXHAUST FROM SCRATCH!

I'm using two headers I had on hand...a vance and hines for the Kat and the old school Kerker for the GS...two of the primaries on both for collapsed from previous owners running then into **** (I will never understand how they manage to do this) so I'm not worried about cutting the one system that was pricey and the one that you just can't find any more.

I'll run the primaries back to the collector for the Kerker exhaust and use that same old school megaphone or I'm going to take a couple of original GS "megaphone" looking mufflers, core them out, and do a dual setup.

[makenzie71]

Got a bit done today. I made some 12" primaries and ran them to 2" secondaries...so it's basically a 4-2 system. The exhaust dumps under the frame just behind the brake lever through dual 2" tips. I still have a lot of welding to do to get it all right...it turned into quite a fiasco to get it all together.

Later I'm going to make some new manifolds that'll bolt to the head and hold the exhaust up via springs or clamps so I don't have to keep rethreading bolts into my aluminum head. When I do this I'll make a prettier system.

That's all I've really managed to do today...more welding tomorrow, and I'll get pictures up tomorrow as well.

[posplayr]

The exhaust is going to have to basically be a full custom. Just to get the point clear:

If you do this same swap, you WILL HAVE TO BUILD THE EXHAUST FROM SCRATCH!

I'm using two headers I had on hand...a vance and hines for the Kat and the old school Kerker for the GS...two of the primaries on both for collapsed from previous owners running then into **** (I will never understand how they manage to do this) so I'm not worried about cutting the one system that was pricey and the one that you just can't find any more.

I'll run the primaries back to the collector for the Kerker exhaust and use that same old school megaphone or I'm going to take a couple of original GS "megaphone" looking mufflers, core them out, and do a dual setup.

what if you space up the front mounts to adjust for the exhaust angle?

[makenzie71]

what if you space up the front mounts to adjust for the exhaust angle?

The Kat headers would still hit the frame. I looked at everything I could think of:

Tilting the engine back = Kat headers hit the frame, GS headers with modified manifolds hit the frame and hang too low.

Movig the whole engine forward = the bolt heads for the forward mounts sit directly in the exhaust path.

Raising the engine up about 3" would make the GS header, with modified manifolds, work but the front sprocket would be too high.

[makenzie71]

Got the exhaust together! 1.5” primaries to 2” dual...umm....pipes. I’ll still add some tips to turn the ends down and that may help with the noise a little, too. They’re just ugly. This winter I’ll buy some better bends from JC Whitney or something and do it again a little neater.


It’s actually not extremely loud...but it’s still pretty noisy. I love that kind of thing but I’m going to whip up some baffles for the sake of the neighbors. However, I honestly didn’t run it long...actually I only ran it long enough for the oil line to blow off the cooler. I forgot it didn’t have clamps. I got covered in oil. Yay me.


I thought the exhaust was going to be a challenge but the real challenge is going to be shifting. The shift linkage does not clear the frame. I can’t notch the frame because of the kickstand. I was trying t avoid rearsets but it looks like I’m going to have to move the pegs back and use a straight shifter instead of the linked one.


My only other real concern will be gearing but I can cure that easily enough later. The Kat 750 came stock with 17/47 gearing. I’ll be running 16/38. It’s a 16% higher gear ratio but it’s all I have in stock.


This weekend, I’m dedicated...I will ride it.


And now for some bad pictures!

[Smokinapankake]

Very interesting project! There sure is a lot of room to fit that engine in, isn't there?
Is that a stock swingarm that has been braced, or what exactly is that?

[makenzie71]

Yeah the Katana 750 engine is quite a bit more compact than the GS750 lump.

This is the thread about the swingarm:

http://www.thegsresources.com/_forum/showthread.php?t=163579&highlight=widened+swingarm

[makenzie71]

And today we have....









Just for a quick once-around. Still a lot of tidying up to do but that's the gist of it.



My fancy new shifter. Rearsets and this GS just don't go together and not shifter/peg combo cleared the frame...so I made this. Also, clearly, I need to change the output shaft seal.





My new instrument combo...the Vapor tach sucks...or at least it did on my fritzy stock electrical system. So I'll be using the stock KAt tach and my Vapor for speed and oil temp.

Ran the bike earlier...rode for about a mile and only had to push about 1/4 mile. Ran out of gas I think...or that's how she was acting. I'm going to fill the tank up later and we'll see. I heated up my boot soles pretty good, too.

Bike sounds pretty mean until she runs out of gas.

Next on the agenda...setup my pegs and brake lever, get the headlight mounted with the instruments, and cut/weld some turn downs on. Also need to flush the brakes, forks, and engine. Today's was her first mile three years.