Swing Arm Swap Pro's- Help!

So I am doing a swing arm swap on my 81 KZ750. I am actually using a CBR F4i swing arm, which will require cutting, welding and machining but I think it can be done! I also used the front forks from the F4i.
I have spent time searching the threads and have not come up with exactly the info I'm after. Sorry if I overlooked some threads.

My questions are:
- What length shocks are you using for your swing arm swaps? Just the stock length?
- How are you aligning the front and rear sprocket and are there any suggestions for which front sprocket to get?

Thanks for all your help!

:woohoo:

A totally different bike but I shaved a few mm of the sprocket carrier to have the chainline clear the frame and tyre and I used an offset front sprocket to line things up nicely.
I used stock length shocks,though my wheel/tyre size changed. Im not sure about the angle of the shocks,I dont remember calculating anything,I think I just eyeballed it.
One thing to think about with wheel/tyre size is the line between the front sprocket,swingarm pivot bolt and rear sprocket. You dont want too much of a peak at the pivot bolt or you can have the chain scraping across the top of the swingarm (by the pivot bolt).
Another thing to watch out for with a rear end swap, is the chain hitting the inside of the shock.
Hope this helps.

Thanks a lot for the reply and the tips.

So the swing arm is officially on and bolted up for a test fit. I ended up having to cut the swingarm pivot on each side but that is ok, I'll make some plates and tig them in.

The main issue is the sprocket alignment. It seems that the front and rear sprockets are around 1" out of alignment. I was thinking of just getting an offset sprocket but that seems like a large difference.
Has anyone sorted through the sprocket issue before? if so, which one did you use?

It looks like I'll have to cut and notch the frame as well for chain clearance...

There are photos around of the AC Sanctuary boys notching frames for chain clearance. Im not skilled enough with a welder for that,so I went the other way.
I went through a few wheels before I settled on a Bandit 600,with a 160 tyre. Then with straightedges I measured the distance between the edge of the tyre and the inside of the frame downtube. This gave me my maximum space to play with. I then subtracted the thickness of the chain which gave me the measurement of clearance I would have either side of the chain. I think I had about 9mm in total. I then was able to shave the rear sprocket carrier down to center the chain line which gave me 4to5mm clearance either side. Turned out to be enough. Offset front sprocket and that was it.
Another thing I thought about ,which might affect you if youve trimmed the swingarm by the pivot, I fitted a GSXR600 swingarm on mine (had shock mounts made up and welded on). It was a very close fit and I only needed a couple of washers to get it snug but as it was such a bulky arm,especially by the pivot,the up and down movement was limited. The sides of the arm would jam in the frame when the arm moved up ( if the shocks were compressed on the road). I had to grind/sand some of the alu off the arm until it moved upwards freely.

nixon wrote: .

The main issue is the sprocket alignment. It seems that the front and rear sprockets are around 1" out of alignment. I was thinking of just getting an offset sprocket but that seems like a large difference.
Has anyone sorted through the sprocket issue before? if so, which one did you use?

It looks like I'll have to cut and notch the frame as well for chain clearance...

Every wheel /swingarm swap is different but once you have done one or two it's pretty much the same procedure and with a correctly centralised wheel rim up to 5.5" wide it's usually fit a 1/2 " - 3/8" or 5/8" ths offset front sprocket and then machine some material off the sprocket carrier face to bring the chain in line.
You can buy the sprockets from EBAY, APE, TALON, etc and most motorcycle drag race and performance shops like PITSTOP, SCHNITZ RACING etc etc and the spline pattern is pretty much the same small diameter "Z13" on all early kwaks and many Suzukis so it's worth looking at OEM sprockets first as these will be cheaper..
JT'S sprocket catalogue lists all OEM sprockets with diagrams and dimensions and is great for this purpose as there are many stock sprockets with various offsets and you may also find one in the F4i's 525 pitch which will save finding or making a rear in 530 that will fit the wheel.
With the z900/z1000 for example using the earlier ZX7/ZX9 5.5" rim it's a 5/8 th offset front and 8mm off the sprocket carrier and the chain just slips past the tyre and frame by a couple of mill
( Going to a 6" rim 190 tyre means notching the frame by 5mm and using a 7/8 ths offset front. )
The 650/750 frame is pretty much the same width as the 900/1000 at the pivot so you shouldn't have to notch the frame up to a 5.5" rim.
Last 650/750 frame i did used Suzuki RF600 (teapot) running gear with 160 tyre if i remember correctly and there was no frame clearance issues.

Thank you very much for the thorough reply. That was super helpful for me to begin figuring out the sprocket issue.
I will be checking around to try to find a 5/8" 525 sprocket. These don't seem all that easy to find so far!

nixon wrote: I will be checking around to try to find a 5/8" 525 sprocket. These don't seem all that easy to find so far!

Yes! most of the aftermarket offset sprockets are 530 or 630 to fit Kawasaki and Suzuki as these are the most popular choice of bikes for drag racing and modification.
Shops like Talon or JT etc will make one off sprockets in any size but it will be expensive for 1 item.
Personally i would go 530 pitch front as these are readily available and then find a 530 to fit the rear or buy a piloted blank and make my own.
Maybe an earlier honda model in 530 used the same stud pattern but having to have a one off rear made in 530 should be cheaper ( by 50% or more ) than having a 525 offset front because of the less maching operations involved.

I wanted to share a site that has been super helpful in finding a sprocket that will fit.

Check out www.motomike.eu

You can plug in all the sprocket info that you need and it will find one that will fit with a JT Sprockets part number.

For me, turns out that a 530 sprocket from a VTR or CBR1000RR will fit the F4i wheel.

This is the one that I am thinking of getting, likely in 42 Tooth :
VTR Sprocket

And this is the stock F4i rear sprocket:
F4i Sprocket

The dimensions seem to all be the same, minus the 525 or 530 pitch, so it looks like it should work to me!

Now to find a 530 5/8 offset front!

I am considering the PBI Sprocket or the D&G Sprocket .

Any experience with either of these, or know of any other options? The PBI is quite a bit cheaper, so that one is tempting obviously.

nixon wrote: I wanted to share a site that has been super helpful in finding a sprocket that will fit.
Check out www.motomike.eu
You can plug in all the sprocket info that you need and it will find one that will fit with a JT Sprockets part number.
Now to find a 530 5/8 offset front!
I am considering the PBI Sprocket or the D&G Sprocket .
Any experience with either of these, or know of any other options? The PBI is quite a bit cheaper, so that one is tempting obviously.

Same info on motomike as I have in my JT catalogue just not as much page flicking to do.
Those sprocket suppliers are well known so either will do.

No matter what, you need some fabrication work. PBI has great sprockets. Anyone who makes the flat plates, will do.
This is a 5/8" offset. Had to weld to the frame, (KZ900)
Wow 6 yrs ago. The Caged Heat AA/Gasser was still being built! (10 yrs.)
Common sense and money!!!
Good Luck!

You know far more than I do about Kz's....but is that not a bit over kill for a street bike? I could see going to that extend for a drag bike, but it seems as though a lot of people are using the 5/8's offset without too much additional work...?