[benjamin]

I am new to this forum and to older bikes. I have a cbr f4 but its almost to fast for the crappy roads i live near so i plan on tracking it. For a more cruiser style bike I am really interested in buying a 70s cb 550 or 750, I like the idea of the 750 because i would eventually like to do a big bore kit up to 836cc. There is a 550 for sale down the street and I was wondering if a 750 engine would fit into a 550 frame. It doesnt matter if the mounts line up I just want to know if it will fit.

 

[joe c]

i dont know, but the 750 looks a lot bigger. my guess is it wont. thats just a guess.


jc

 

[benjamin]

i heard the 650 would fit with the same mounts so i figured there might be a chance

 

[Geeto67]

quote:
I am new to this forum and to older bikes. I have a cbr f4 but its almost to fast for the crappy roads i live near so i plan on tracking it. For a more cruiser style bike I am really interested in buying a 70s cb 550 or 750, I like the idea of the 750 because i would eventually like to do a big bore kit up to 836cc. There is a 550 for sale down the street and I was wondering if a 750 engine would fit into a 550 frame. It doesnt matter if the mounts line up I just want to know if it will fit.

The short answer - No.

The longer answer: The 550 case is way narrower than the 750 so it would take extensive frame modification, of the cradle to get the motor sqeezed in there.

That being said there are guys who have punched their 550s out to well over 600ccs. The 79-82 cb650cc motor is the evolution of the 550 and will fit in the 550 frame but you will have to use the 650 electrics to power it (the 650 internals are different). The 550 is a lighter bike than the 750 and a good handeling frame. If the 550 close to you is a good deal

do a search on www.sohc4.us and you will see all sorts of posts regarding hipo mods for the cb550.

If your F4i is too fast for your local roads, what with it's amazing brakes and suspension and blinding acceleration, what do you think a 70's cb will be? If the bike is too fast for the road, maybe your riding technique needs an adjustment. 70's bikes have crappy brakes and even worse suspensions. Sure they give a better feeling of speed at lower speeds but you really need to have your a-game to ride one spiritedly on public roads since the brakes and suspension will give you no room for error. In terms of ride quality - if your F4i feels like a new corvette, than a 70's cb by comparison will feel like a 1970 Chrysler Newport with manual brakes.

 

[benjamin]

My idea with the cb is that it will be riden slower, and not as agressivly, the cbr is obviosly better at braking and at cornering but cornering is pointless when theres gravel at most bends. I want to be able to push the cbr to its limits with out having to drag it out of a field and pull gravel from my arm.

as for the 650 swap i have a 81 cb 650 in my garage, it runs, but not that great. And it only has four gears, could i match up the 550 tranny with the 650 engine, or could i swap tranny internals.

 

[Geeto67]

quote:
My idea with the cb is that it will be riden slower, and not as agressivly, the cbr is obviosly better at braking and at cornering but cornering is pointless when theres gravel at most bends. I want to be able to push the cbr to its limits with out having to drag it out of a field and pull gravel from my arm.

as for the 650 swap i have a 81 cb 650 in my garage, it runs, but not that great. And it only has four gears, could i match up the 550 tranny with the 650 engine, or could i swap tranny internals.

No the internals are different. Your first sign that the trannys are not interchangible is the 550 is kick start (and electric) and the 650 is e-start only.

There are guys who have adapted the cb650 barrels and heads to the 550 bottom end but it took some machine work but not a lot and not complicated. I like this way better because it means that you can keep the 550 electrics (650 is CDI with a spark controller and a brain box, 550 is points which you can upgrade to a dyna S or dyna 2000).

Read this post:

http://www.sohc4.us/forums/index.php?topic=13519.0

should cover all your questions right now and creat a whole host of new ones.


Edited by - geeto67 on Nov 07 2006 12:49:13 PM