CB750 early K with K7 combination...

[CR21]

Hi forum members! I am after a bit of advice. I have a lot of spare parts, and my friend wishes to build a cafe racer.

I have a K7 frame, K3 engine and swinging arm and wheels that he can use.

I have heard that the K7s chain alignment is slightly different to the earlier models, will this effect the above combination as he would be putting an early engine into a late frame?

Any help would be appreciated, I would rather he builds a cafe racer from bits rather than stripping a whole bike 

Cheers
CR21

[hairygit]

The chain alignment is down to the heavier (630) chain on K7 models, since the K7 motor is basically an F1 engine fitted with PD carbs as long as you use the K3 swingarm and wheel and sprockets there should be no problems.

Sent from my X6pro using Tapatalk

[CR21]

The chain alignment is down to the heavier (630) chain on K7 models, since the K7 motor is basically an F1 engine fitted with PD carbs as long as you use the K3 swingarm and wheel and sprockets there should be no problems.

Sent from my X6pro using Tapatalk

Thanks for the reply 

[neilg]

Just to add on from this, will a F1 motor go straight into a K7 frame without any issues to chain alignment. I see the final drive shaft is a different part number so would this need swapping. Anyone know?

[K2-K6]

Honda pair the K7 with the F2 and as far as I know they both use the 630 o-ring types chain as original equipment.

All the 750 engines, again as far as I'm aware, fit all of the frames with no mounting exceptions regarding alignment.

The sprocket output shaft is different for the F2/K7 as that bottom end uses a larger higher load bearing to take the expected increase in forces of a much bigger heavier final drive chain.

I don't think chain alignment is any different at all, just that they had to accommodate the extra chain width in the direction of going away from the rear tyre, if that makes sense. So fitting a 630 chain and sprockets gives the correct alignment for that kit.

[neilg]

Think I'm with you. My plan was to use a F1 motor in a K7 frame. With the thought of the extra forces and the "weaker" F1 bearing perhaps using the chain/sprockets from the F1 would sort this. Again anyone any thoughts??

[steff750]

  yes it will work fine you just need to go with whatever chain and sprocket combination you choose
i have a F2 motor in a K0 frame it also has a sidecar fitted so the gearbox gets a lot of stick , i would like to think that the heavier chain will never snap lol.
as its already been said earlier you might be restricted to tyre width,i have a  155x15 car tyre fitted and i dont think i can go much wider than a 165 x 15 also the swinging arm is a limiting factor anyway

[neilg]

Fascinating stuff when you mix n'match. Have to say I was very surprised when I started out on this project at just how much difference there was in the K7 frame when compared to earlier models, particularly rear of the swing arm pivot.
Many thanks for all your thoughts

Neil G