Topic: modern font end

[shugsi]

hi all...im looking for info on fitting a 1992 CBR600 front end onto a 1979 CB650Z...can any one tell me what size the steerer tubes and headrace bearings are on both bikes?

Rewar wheel: is fitting the rear wheel a straight forward job as well? oh and has anyone fitted a more modern swing arm as well?

Some guys have fitted the CBR 600 front end and realise that the brake/clutch lever clamps have no mirror mounts..well over here in the uk we have the Honda CB600 Hornet which uses the same front end as the CBR 600 but is a naked street fighter type bike, so im gonna fit the lever clamps amd also the yop yoke (as that is the same diameter as the 91-95 CBR 600 but has clamps for standard handle bars)..

Shugsi

[Mark M]

I do hope you will be looking at some serious frame braceing to counter the
major frame flex you are going to suffer. The frames are bendy enough with the old
tyre sizes and modern rubber, would hate to think what some modern fat radials
will do to the handling....hinge in the middle is an expression that springs to mind.

[shugsi]

think in the past it was all down to weedy forks amd useless rear shocks but modern stuff will make a big difference..dont think i will need extra brazing as not uping the horse power, well not unless i can show horn a cb900 into it with a big bore kit ha ha... ..the modern stuff is also lighter and the wheels will have less rolling mass, only thing is it will sit lower so will ditch the centre stand and fit a 4-1 Harris exhaust..

[squirley]

I am not totally sure about the bearing sizes, but I believe that the cbr is both 30mm top and bottom.  As for your cb, I don't know.

I think Mark's suggestion to brace the frame is a good idea, its not only just horsepower that can torque a frame, more traction from wider lower profile tires can transmitt more forces into the frame.  Might just be something to think about.

[Geeto67]

I did an FZR 400/600 conversion on a stock 1974 kawasaki - trust me you need frame bracing. You will start cracking factory welds if you ride the bike hard.

Also pay attention to your rim and tire size as I believe the cbr stuff is 17".

All if ti is custom work there is no bolt on stuff when it comes to these bikes. I belive the cbr600 rear axle shares a diameter with the SOHC and DOHC bikes but that is about as bolt on as you are going to get - you will need custom spacers and a welded brake stay to make it work with your stock swingarm.

For the front end...well you are pretty much on your own on that one. I know the DOHC cb750 guys have figured out how to make the cbr f2 wheels and brakes work with their stock forks but I don't know if those forks are the same as the cb650. Do a search at cb1100f.net and see what comes up - lots of info there and will give you some ideas.

[squirley]

FunJimmy did a very similar fork swap, and I am sure he could share some good info.
I swapped over a gsxr inverted fork, and it was quite easy. If I had wanted to keep the newer rims and tires it would have been pretty straight forward, however I wanted to run spoked rims which turned out to be a little troublesome.  The bottom bearing ID was 30mm along with the upper.  I used a standard roller bearing for a honda 550 for the bottom and the top on was from what I believe was a yamaha.  The top bearing OD was a little smaller (.5mm) from the 550 steering head, but nothing a little shim didn't fix.
Find out what your stock bearing sizes are and head to the local bearing supplier.  If you look long and hard enough, the sizes you need most likely exist.

[shugsi]

thanks lads...over here in the uk a lot of guys build "stret fighters" and some build them around old bikes and most dont go down the extra brazing on the frame route, the bikes handle ok...actually they handle a lot better...but as some have said watch the tyre width, dont go too wide..i beleive the std cb659 steerer is narrower than the cbr so will have to press the cb item into the cbr yokes (i beleive the term is "trees" over in the US? )...the bike wont be ridden hard as its gonna be a posing bike ha ha..well no point in doing all that work and flying past at 100mph plus lol...will be building a Gpz 550 for that...oops swear word there ha ha...