Honda CB750K Cafe Racer project about to start with a monoshock??

rohalloran · Jun 8, 2018

Hi All,

Long time browser of the forum but this is my first post. I have to say to all, some of the bikes showcased on this forum are amazing. Great inspiration.

I picked up this bike earlier in the week. The engine is seized due to sitting up but as you can see someone had started to do some decent mods before it got pushed aside. The front and rear end are off a Kawasaki GPZ 900 I'm told and the tank is from a CB900 (or is it standard does anyone know)? The engine will be getting a complete rip down and rebuilt and I suspect I will go for the Cognito Moto GSXR front end conversion but I have to say I do like the monoshock conversion that was done (bar the wheel used). Love to hear what people think and their thoughts on the Monoshock / swingarm used. Hope to keep the thread updated with the progress as I go.

Thanks for looking.

rohalloran · Jun 10, 2018

Managed to get the engine out yesterday. Now its time for an engine stripdown and rebuild.

irk miller · Jun 10, 2018

Holy crap, that motor looks toast. Is the aluminum broken down as bad as it looks?

rohalloran · Jun 10, 2018

Hey irkmiller. It's only some corrosion on the casing. Looks worse than it is (so far... ;D)

cardinal · Jun 10, 2018

lemme guess... you live on a beach somewhere?

rohalloran · Jun 10, 2018

cardinal said:
lemme guess... you live on a beach somewhere?

Yes

It was left outside too which didn't help. Picked it up cheap so hopefully the internals are not too bad.

trek97 · Jun 10, 2018

irk miller said:
Holy crap, that motor looks toast. Is the aluminum broken down as bad as it looks?

Haha, I thought it was foaming engine degreaser.

The Limey · Jun 10, 2018

Spoked wheels from a Zephyr?

rohalloran · Jun 10, 2018

The Limey said:
Spoked wheels from a Zephyr?

Now there is an idea.. I like the simplicity of the GSXR conversion Cognito moto offer but have mixed thoughts on the rear end. Leave as is or switch back to the twin shock :

brad black · Jun 11, 2018

fix the old style forks and keep the 16" wheel for some wacky retro cool.

The Limey · Jun 11, 2018

I was thinking the Zephyr wheels would, hopefully, mate up well with the Kwak rear end.

teazer · Jun 11, 2018

I'd be tempted to leave the chassis alone. Just rebuild the motor and fit a decent looking tank and seat - Maybe an F2 shape. Dump the K tank.

Wheels are old Kawasaki and actually look good in that set up. Forget the redesign. Just get it running and ride it.

doc_rot · Jun 11, 2018

+1 for keeping the ninja wheels. Different and unique. How many CB750s are running USD cognito setups? Plus the ninja 900 wheels would be perfect for a vintage race vibe.

irk miller · Jun 11, 2018

I'll also add that the Ninja wheels give off a Euro Comstar vibe, which is an excellent look and appropriate.

rohalloran · Jun 12, 2018

Thanks all for your input. It will be a while before I make a call on the wheels and suspension but some food for thought there. Need to get the engine completely ripped down first and start that rebuild. I have since found out that the carbs that came with it are also off a GPZ.. 8)

teazer · Jun 12, 2018

I noticed they were CV flatslides and assumed they were off a GSXR slingshot. If they are jetted well, they should be a significant improvement on the street compared to stock carbs. Will be interesting to see what's inside that motor in terms of cam and pistons.

canyoncarver · Jun 12, 2018

The mono conversion looks good ( so many are shite ), so does that front end. I dig the Kawi wheels and forks. Build that motor into an 836 and go hoonin'.

rohalloran · Jun 13, 2018

Thanks all. I must admit, there was a good job done on the monoshock conversion so part of me woudl like to keep it. I know the fabrication shop that did the work also so I know it was done right. I think what's putting me off currently is the colour of the wheels against the frame and swingarm.

Taking off the head this weekend to see what lies beneath! Pictures to follow.

clem · Jun 13, 2018

Can you verify that the linkage and mounting points were installed in the exact location that they were in on the donor bike? If not, then no way to tell how good it is until it's ridden. Leverage ratios are important on those setups.
It looks like they added the top mounting point directly from the donor right?

Sent from my SAMSUNG-SM-G930A using DO THE TON mobile app

teazer · Jun 13, 2018

If the motor is stock, I agree that a set of bigger pistons and a mild cam would wake it up. I just looked at teh intake manifolds and someone spent a lot of time on the conversion.

What have you been able to find out about its history?

Leave the frame color if it's not too chipped or pitted and get the wheels powder coated in Silver or white. You could maybe get away with bright yellow wheels if the tank and seat picked up the yellow in some way. Subtle? Maybe not so much, but could look bold.