Author Topic: Thoughts on this one?  (Read 334 times)

Offline Wenman

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Thoughts on this one?
« on: October 23, 2018, 10:33:56 PM »
I love my little Cb550f to death it’s vintage cafe brat looks melt me every time! However I’ve managed to acquire something a little bigger as a next project a CB750 1981dohc!
I’ve always had an attraction to these bikes and wanted something with a little more grunt that I could add a sporty feel too! This one came with a CBR1000 Fireblade front end and has only done 14k on the clock!

The rear however has a swingarm from a CB400 sf (I think)including brakes and wheel!

The question is how easy would this be to fit properly?
Obviously I’m considering whether the sprockets are going to match or even line up, what mods are require to the pivot bolt and what spacers etc are required?

Should I be thinking of going back to stock or can it be done?

I know it’s quite a complicated question and without measurements and magical science won’t get step by step ‘how to’ guide just wondering if it’s feasable?
Be good to have a rear wheel that’s more in keeping with that front end!
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I’ll try and attach a photo!
« Last Edit: October 23, 2018, 10:37:37 PM by Wenman »
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Offline Bryanj

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Re: Thoughts on this one?
« Reply #1 on: October 24, 2018, 07:56:29 AM »
Everything CAN be done if you have a gas axe, welder and lathe

Offline K2-K6

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Re: Thoughts on this one?
« Reply #2 on: October 24, 2018, 10:25:59 AM »
I've always liked those Honda's from that era and had a 900 in the eighties.

Doesn't look bad from the photo.  First thing youd need to look at is getting a chain on the sprockets to see what you have in the way of alignment. They used pretty skinny tires originally, and the gearbox sprocket could be too far in to clear the wider rear tire and rim. If you clear that then you at least have an easier path with less fundamental stuff.

What style bias are you considering?

Offline SumpMagnet

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Re: Thoughts on this one?
« Reply #3 on: October 24, 2018, 04:13:38 PM »
The first challenge is to get the rear wheel perfectly centred. If it's not dead in line, you will have all sorts of issues!

Then you can drop a chain on and see how the alignment will work. Or not

It is possible to machine the sprocket carrier down some to bring it in, and you may be able to buy or have made a front sprocket with more offset to get it to line up. Tyre clearance will limit you, as will the frame clearance and front sprocket cover.

When you have all that done, getting spacers turned to fit us the easy bit!

I have seen some fairly chunky back wheels fitted to these, so Google a few 'Spencer Replicas' for 750/900 fitted with alternative running gear and see what size rear tyres/rims they have. I reckon you should be ok with this rear end but it will take a bit of fiddling
« Last Edit: October 24, 2018, 06:13:26 PM by SumpMagnet »
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline Wenman

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Re: Thoughts on this one?
« Reply #4 on: October 24, 2018, 07:43:57 PM »
I've always liked those Honda's from that era and had a 900 in the eighties.

Doesn't look bad from the photo.  First thing youd need to look at is getting a chain on the sprockets to see what you have in the way of alignment. They used pretty skinny tires originally, and the gearbox sprocket could be too far in to clear the wider rear tire and rim. If you clear that then you at least have an easier path with less fundamental stuff.

What style bias are you considering?

Thanks for that.. by bias I take it you don’t mean tyre? 😂
If at first you don't succeed.. hit it with something!

Offline Wenman

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Re: Thoughts on this one?
« Reply #5 on: October 24, 2018, 07:45:10 PM »
The first challenge is to get the rear wheel perfectly centred. If it's not dead in line, you will have all sorts of issues!

Then you can drop a chain on and see how the alignment will work. Or not

It is possible to machine the sprocket carrier down some to bring it in, and you may be able to buy or have made a front sprocket with more offset to get it to line up. Tyre clearance will limit you, as will the frame clearance and front sprocket cover.

When you have all that done, getting spacers turned to fit us the easy bit!

That all sounds promising! Thanks for the update!

Al

I have seen some fairly chunky back wheels fitted to these, so Google a few 'Spencer Replicas' for 750/900 fitted with alternative running gear and see what size rear tyres/rims they have. I reckon you should be ok with this rear end but it will take a bit of fiddling
If at first you don't succeed.. hit it with something!

Offline Wenman

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Re: Thoughts on this one?
« Reply #6 on: November 09, 2018, 10:15:10 AM »
Any more thoughts?
If at first you don't succeed.. hit it with something!

Offline haynes66

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Re: Thoughts on this one?
« Reply #7 on: November 09, 2018, 04:02:56 PM »
chain alignment is obviously critical so the first thing i would do is scour ebay for a cheap original swingarm and rear wheel with sprocket. establish exactly where the rear sprocket is, then sell the bits you dont need. i did something similar with my 500 lash up project and bolted some guide bits to the frame. you can do pretty much what you want after that. 750/900 parts are pretty cheap at the mo
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