Topic: CB750 K3F - AKA The Red

[MoMo]

Just saw this thread Prokop, very interesting-like your Yankee/Czech ingenuity. 

On the bushings,  there were two styles-one with a collar and the other recessed, not sure which style mated to which model.  My 75 Red Rider called for the collar type but I installed the other style, worked well.


Nice work, will be following...Larry

[70CB750]

Thank you, Larry 

[Don R]

I don't recall ever seeing anyone doing a meld of F and K bikes here before; should be interesting.

Been done several times, it's called an F'nK

[70CB750]

I don't recall ever seeing anyone doing a meld of F and K bikes here before; should be interesting.

Been done several times, it's called an F'nK

I prefer K3Fka - kefka means toothbrush in Slovak

[70CB750]

I am halfway through cutting and laping valve seats - 3 and 4 are finished and mechanic's blue shows nice imprint.

[MoMo]

I don't recall ever seeing anyone doing a meld of F and K bikes here before; should be interesting.

Been done several times, it's called an F'nK

I prefer K3Fka - kefka means toothbrush in Slovak

Why not A Kafka?  ...Larry

[70CB750]

I don't recall ever seeing anyone doing a meld of F and K bikes here before; should be interesting.

Been done several times, it's called an F'nK

I prefer K3Fka - kefka means toothbrush in Slovak

Why not A Kafka?  ...Larry

Oh, that's a good one, Larry.    

[70CB750]

And Kafka or kavka means Western Jackdaw - http://en.wikipedia.org/wiki/Western_Jackdaw, LOL.

[MoMo]

And Kafka or kavka means Western Jackdaw - http://en.wikipedia.org/wiki/Western_Jackdaw, LOL.

Actually, I was referring to Franz Kafka Prokop.   Larry

[70CB750]

And Kafka or kavka means Western Jackdaw - http://en.wikipedia.org/wiki/Western_Jackdaw, LOL.

Actually, I was referring to Franz Kafka Prokop.   Larry

Yes, I know, just can't imagine styling a motorcycle like The Trial

[70CB750]

Cutting seats.

[edwardmorris]

The 60s? Or all three? Looks cleeeeen

[70CB750]

I did all three.

[edwardmorris]

Very nice! I'm sure you're happy with the oil stay tests now. Are you going to be doing any porting? Would love to see someone experienced do it first before I attempt it After cleaning out some of that carbon gunk, my ports look horrid, palgued with casting pimples and irregularities. I've been keeping an eye on the porting tests thread in the performance forum, but I only wish to clean mine to keep the carbon from gunking it up again. Any gains will be just a nice bonus

[70CB750]

I found out that the 45 deg sealing surface has to be limited from the top and the bottom.  Had to spent hundred more on tools, but it is worth it IMO.

Porting - good question, I am still thinking about that one.  Most likely I will compare the head with Hondaman book pictures and decide what can be done.

I did some head smoothing and cleaning on 4.2 jeep engine back in the day, but I don't think it made much of a difference.

[SOHC4 Cafe Racer Fan]

I found out that the 45 deg sealing surface has to be limited from the top and the bottom.  Had to spent hundred more on tools, but it is worth it IMO.

Porting - good question, I am still thinking about that one.  Most likely I will compare the head with Hondaman book pictures and decide what can be done.

I did some head smoothing and cleaning on 4.2 jeep engine back in the day, but I don't think it made much of a difference.

Hondaman is a big fan of porting the 750 head, to remove many of the obstructions resulting from sloppy casting.

[70CB750]

Machinist's blue imprint after lapping.

[bjbuchanan]

Morris
You don't have to go wild with the porting, just clean up the real rough bumps and lumps. There are threads out there on it, homebrew porting, DIY, they have some really good pics

70
The flange style should replace everything but the plastic end cap if the bike has the end cap. If it has it I believe it is utilized. It is hard to nail specifics, kinda like how everybody has done a different steering head bearing stack

[70CB750]

I am afraid I don't follow, what flange and cap?

[70CB750]

Installed one inner spring to measure spring installed height. I need a compass, none of my methods is reliable enough.

[rtbmrgl]

New fuse box rewired to the old plug.

That's a good idea, my fuse box is corroded, I was going to clean it up but this is a better fix.

[70CB750]

New fuse box rewired to the old plug.

That's a good idea, my fuse box is corroded, I was going to clean it up but this is a better fix.

Offered also by Hondaman:

http://sohc4shop.com/catalog/product_info.php?manufacturers_id=12&products_id=48&osCsid=5510e6252a4b462022769ece21b177ee

The fuse box itself I had to buy on e_bay, impossible to buy locally.

[rtbmrgl]

New fuse box rewired to the old plug.

That's a good idea, my fuse box is corroded, I was going to clean it up but this is a better fix.

Offered also by Hondaman:



http://sohc4shop.com/catalog/product_info.php?manufacturers_id=12&products_id=48&osCsid=5510e6252a4b462022769ece21b177ee

The fuse box itself I had to buy on e_bay, impossible to buy locally.

thanks for the info!

[70CB750]

Installed all inner springs to check installed height.

[rtbmrgl]

Installed all inner springs to check installed height.

70CB750, Whats the outcome of the spring height after cutting the seats, is it close to stock or do you need to add shims?