Am I going to whack out the handling? Cbr600 front end on cb550f

[StreetSpirit]

Hello fellow tinkerers,

I happen have a beautiful cbr600 F1 front end with dual discs and a mechanical speedo drive that, if I'm not mistaken, should bolt right up to the frame of my cb550f with some new steering head bearings. The current fork and front wheel are not in great shape, so I'm going to have to do something about them one way or the other. My question I guess is whether I'm going to completely destroy the handling of the bike if I do this swap. I like the retrofighter thing, but I want it to ride well in the twisties. The forks are approximately the same length, and the stock 18 inch rear wheel will probably be running a 130-140 to the 110 x 17 on the front.

I'm also likely going to replace the rear shocks, so I'll be able to adjust the geometry a bit. I guess the alternative would be to try and fit a taller narrower spoked front wheel on the bike, but this seems like a lot of work to be honest.

Any thoughts or experience to share? Is it going to be too twitchy for actual street riding?

Thanks.

 

[sxecafe]

Not sure you would destroy your handling, although I'm not an expert. People do swaps here all the time (myself included) with what appears to be good results. I would think/assume you would improve your handleing with better mechanics... are you mainly rerfering to geometry ?

 

[crazypj]

Check the weight of CBR600 compared to CB550 (stock 550 F1 is 420lbs 'dry')
Check overall length of forks.
Compare overall diameter of 110x17" compared to ~3.25 x 19"
You'll need a wider rear rim for a 130/140 tyre (at least WM4)
BTW, you need a wider rim for a 120/80 rear tyre
If they are 'early CBR600 the axle is smaller diameter, fitting different bearings into stock wheels may work?

 

[bbqb4racin]

My question I guess is whether I'm going to completely destroy the handling of the bike if I do this swap.

I didn't know a CB550f was such a great handling machine to begin with? Lol! JK!

IMO, you'll be fine with that swap. Not an extreme change. I'd consider it an upgrade. What are your plans for the rear?

 

[Swapmeet Louie]

Just the ergonomics of clip-ons and Rear sets is going to put more weight/stress over the frontend alone (if your going that route). I'd say it's a wise upgrade.

 

[StreetSpirit]

Check the weight of CBR600 compared to CB550 (stock 550 F1 is 420lbs 'dry')
Check overall length of forks.
Compare overall diameter of 110x17" compared to ~3.25 x 19"
You'll need a wider rear rim for a 130/140 tyre (at least WM4)
BTW, you need a wider rim for a 120/80 rear tyre
If they are 'early CBR600 the axle is smaller diameter, fitting different bearings into stock wheels may work?

Axle is 20mm and I sort of doubt I can go that big on the ID for the original wheel without machining a bigger pocket.

Currently the bike is sitting on a 130 rear (which might be why the back tire is completely squared off). So I probably should relace with a wider 17 or 18 rim if I can find one cheap. I'm just blown away by some of the prices I'm seeing to build a wheel up. Do I have any cheaper options other than buchanan/warp 9? There's always ebay I suppose.

 

[crazypj]

Try and find a supermoto rim.
May be difficult as Honda use 40 hole hubs and most SM use 36 hole ($200+ at Buchanans is putting me off doing rear rim )
You could always sleeve the fork legs and use stock diameter axle
You need to weld a brace under the seat/top tube junction, (same as I did on my 360)
All the Honda frames flex at that point, 550 is worse than 360.
If you check last page or so of build you'll see what I did on 360
Probably need some work around steering head as well as it does flex
Swing arm needs bracing or replacement, but that puts more stress into top of frame

 

[dp9]

axle is 20mm, which i assume is larger than the stock one? if thats the case you should be able to find bearings to fit it without a problem from McMaster-Carr. Even if you do need the seats enlarged, thats not "arm and a leg" expensive for a machine shop to do. When I did my swap (on the 360 in my sig) I found the right ID and OD bearings but the width was off, so I ordered an axle spacer for the bike the front end came from and had the machine shop cut it down to the exact difference btwn the new and old bearings. In retrospect I couldve used a tubing cutter, but I wanted it to be precise as it was inside my front drum.

as far as steering geometry goes, when I did all my research and asked everyone what they thought, the end-all-be-all I got from it was that "it depends." So I went with the racing approach: try it, see how it feels, if you dont like it, change it. my front forks are slightly shorter than stock, and pushed an inch or so up through the trees, and my rear shocks are about an inch longer than stock. all signs point to twitchy, so I put a gsxr steering damper on it to prevent the wobbles before they ever start. rode it all season without the hint of a problem so I'm either used to it, or its not that twitchy. my friends who've ridden my bike say it is "extremely flickable," which they all like. very happy I did the swap.