Rear Wheel conversion

It’s while ago now that I spotted this gsxr750 wheel on ebay and the biding time was almost up, I knew gsxr wheel up to end1989 were 4.5 and  the cushion's drive/hub had five nuts'  The 1990 wheel change to an 5.5 and cushion's drive/hub had six nuts. I was after 4.5 wheel. Anyway' Times was run out and seam a good buy and nobody else was biding so put a bid in and took the dog for her evening walks. While out' I suddenly realized I counted the wrong-side I had in fact counted the brake disc side which also has five nuts on both wheels' years. And yes you guess it' I won the bid. At lest I got for good price.

Few days later when the wheel arrived I began to wonder what the b4 would look like with 5.5 wheel, why not try it up against the bike "hey" this may work. The more I thought about it! Wow' wouldn’t it look aces. The wheel fitted into the swingarm which I had acquired much early in my search for parts. I was to learn later that the swingarm wouldn't fit the frame of the b4' so back to the drawing board.



For a while it looks like things won't going to work and perhaps I should go back to the 4.5 wheel idea, I thought of cut/mod/weld the swingarm as I and a mate can Aluminium weld. My MIG isn’t setup for Aluminium, were my mates MIG can be.  But I decide not too...Too much work to spend on little four!.


Then a guy from the USA! "Cross the pond" started to post about fitting 5.5 to this b4. I believe he used an RF900 swingarm and an offset sprocket from RM250 which he had machine as the b4 doesn't use a nut to hold the sprocket on. I started searching for RF900 swingarm and learnt RF900 wasn't as liked here in the UK as else were' so finding a RF swingarm isn't gone to be easy and at first no joy. Then while on the net looking for another item' Up pop one and here it is, I haven't decided on how I will finish RF swinger yet will wait till see how parts fit, just because someone else has done the conversion before! Isn to say you can't improve on it' adding your own touches' makes it "Unique" and on the other hand we all can all get it wrong at some point! .

  

    



I believe the measurement across the pivot point on the original b4 swingarm is 220mm the same as the RF, the first swinger I tried fitting didn't fit because it measured 228mm across the pivot point on the swinger and that's without the end caps on, the RF900 measures 220mm and this does include the pivot-spacer-end-caps. This is why as far as I know most' if not all single-sided arm won't fit as they seem to be all between 228-284mm across the pivot and most! single-sided have different-type of pivot mounts point then the b4. 

 

                                                                                                                                                                                                                                                                                                                                                                           The photos which shows the two ends of the two diff swinger, the gsxr in the top of the photo and rf900 in the bottom shows the end-cups in place    

The guy from Cross the pond, Had his b4 back on the road for a while when he started to have trouble with the chain rubbing against tyre and frame, he did various things to the b4 to overcome the problems?. For the same reason' is why I haven't painted the rear wheel yet because I wish to keep the180/55 tyre on so I can carry out a dry-fit-run to see how the chain and things line-up. For checking alignment I will use Laser Chain Alignment tool rather then measure by hand as this is not alway 100% certain.                                
                                                                                                                                                                                                             The bottom right hand photo is of the end-cup for RF900 shown in-place in the above photo.
 

I have measurement of the original b4 swinger  somewhere just can't remember where I put them at this moment. If I was fitting the RF900 swinger into a RF bike frame of the same year, it would be Straight fit. Because I'm not' I need to make sure that both the b4 and RF are the same or very similar layouts to each other "ie" the rear wheel must follow in alignment/path of the front wheel and Swingarm needs to fit well into the frame' I need some end-float to allow free movement of the swinger when pivot bolt and nut is tighten-up but not to the point where the swingarm is moving from side-to-side between the bike frame which inturn will allow the chain to move in and out of alignment as I flick the b4 in and out of corners! . 

The single-sided arm link above' I came across after posted this post when I was looking for something else, I have no ideas what they did to fit the arm. do you know more? .
                                                                                         
Present-2nd build