CB250RS wheels on an XBR

[mthee]

Thanks to xbally, I now have the pair in full + the larger CB750 disc to go on the XBR.

At the rear, I measured the RS hub to be 4mm wider on both sides. This agrees with a gent who did the same wheel swap in 2012. His solution was to mill the 8mm off the sprocket carrier face in order to avoid using an offset front sprocket;

guest1540
Guest

Re: xbr500 cafe racer project - only 2 months to complete
« Reply #31 on: August 12, 2012, 09:10:43 PM »
Quote
Hi, steve mentioned that a cb350 rear sprocket might fit but the mount holes are 5mm out (105mm). I have sourced a cb400 (1979 - 1983) sprocket that has the correct 110mm between the mount holes, 70mm centre and 34T. When the wheel is centered in the swingarm, I have the same 8mm problem with chain alinement. Rather than have a one off sprocked made, (I'm not happy with the possible torc affect resulting from an offset drive sprocket). Also, for ease of future replacement I have had the sprocket flange milled back 8mm. This resulted in several mil off the cush drive carriers and a spacer under the retention circlip.  Problem is that I had to strip the wheel for the engineet to mount the hub for milling. If you choose to go down this route you would need to have this work done before the wheel is rebuilt!!!!. Because I now have to rebuild the wheel I am fitting a 2.5 rim also. I made a detailed drawing and took several photos before striping and I'm gona have a go at rebuilding the wheel my-self -can't be that difficult - right!!! End quote.

Given that some consider the RS cush drive to be a bit weak, I'd like to be able to ask him how it all performed.

Does anyone know Guest 1540?

Or has anyone done the mod with a 4mm offset drive sprocket and a 4mm dish towards the sprocket side?

[Moto63]

I stand to be corrected on this one and I will get my tape out next time I go in the old workshop as I have a set of both rims, but aren't the rs rims narrower than the xbr's??.

[mthee]

Ta for the heads-up, but I've got a matching ali rear rim in XBR size, 2.50 and timbo ran a 100/90 on his 1.85 front rim, so must be safe, especially as his was a fast XBR! I haven't come across a 2.15 front, but have eyes peeled.

http://www.thumperclub.com/smf/index.php?topic=7634.15

[Moto63]

Morning Matt, I've gone with a aprillia 125 city cross front rim on the "tracker ". Ally rim plus the same size , width and diameter, got it laced to a suzook GN250 hub same spoke pattern as rim. Cheers, Michael

[Moto63]

Oops sorry it was a DERBI city cross, NOT an aprillia 😉😉🤘

[mthee]

Good to hear about alternatives. How was the hub and disc for fit?

The 250RS hub needed an additional 5mm spacer on the right and will need a 3mm dish or caliper bracket skim for the disc to fit. It's all apart for cleaning and painting and I had this crazy idea that I might relace it myself! The way I see it, in place and spoked up loosely, with the front brake applied, the disc and hub will be held in the correct position. Tighten the spokes in the correct sequence (lots of experts on YouTube passing on this knowledge) and watch the wheel run true by observing the disc between the pads.

What do you think and what are you using for the rear wheel on the tracker?

[Moto63]

I'm going for ktm front forks so have also gone for the ktm disc and caliper. I've got to get some new yokes milled up to suit, that's what has been holding the build up a bit, trying to find someone who will do the one off yokes. I've gone for a Honda dominator rear wheel, smaller diameter but got the same rolling diameter by going with a taller side wall on the rear tyre, also gives that true tracker look t'boot 😁.... not sure which I'm more excited about, completing the tracker or picking up the new Norton. Hopefully 2019 will be a good year. Cheers, Michael

[mthee]

Nice. I read about your Norton intentions and something about a Guzzi?

[Moto63]

Yes I've decided to sell both the ktm390 and the guzzi v7 stone I bought off Martin (xbally) and go for a new Norton atlas nomad 650. Defo going to keep the tracker (once it's finished 🤣🤣) very excited about the Norton, hopefully be a good bike. I'll be keeping the guzzi until I get a definite date for picking up the Norton. (Probably August) The ktm will be going up for sale in march probably.
Cheers , Michael

[mthee]

Having removed the spokes to get the rust off and treat, some of the nipples could do with replacing. I'd go the stainless route, but the pot that I usually urinate in had to be sold the other day...

Can I confirm the spoke size for the CB250RS at 3.3mm? If so, are these nipples on eBay suitable? I've  messaged the seller for confirmation of length, but no reply.

https://www.ebay.co.uk/itm/SPOKE-NIPPLES-SET-36-for-3-3-mm-spokes-motorbike-motorcycle-Mz-etz-ts-es/253428799873?hash=item3b01889981:g:yfQAAOSwMl9ahwTG&redirect=mobile

Also, I haven't been able to source nipple washers, so if anyone can point some out for me, I'd be much obliged.

[themoudie]

Aye mthee,

Give Central Wheel Components a ring on 01675 462264, knowledgeable and very helpful.

Website: Central-Wheel_Co

Hope this helps. All the best with the circular jigsaw puzzle! 

My regards, Bill

[mthee]

Thanks, Bill, will do. Having removed the spokes from the hub, I will need that luck to reassemble with the appropriate dish. Although I'm giving it a go with plenty of time, I won't be rushing off down the bookies to place a bet on my success!

Update:The very nice chap at Central wheels says they only do full spoke sets in imperial sizes for the rolled threads. Matey on eBay might have 10 nipples for £7, so might be the route to go, as that would be the right number to cover the most corroded of the originals, if the size is right.