1978 CB750K K8 First Cafe Build

TommyT

New Member
OK new to this forum and have been checking out this site for some time and wanting to build a cafe for the last 3-4 years. Finally got myself an old CB750K off craigslist about a month ago for $550.00 it's running great and drives perfect. So naturally I'll cut it up and make it my own.

Here's a little background into my past and current projects. I've been building and racing offroad prerunner race trucks for the last 5 years. Having my own 1450 sq ft fabrication shop building and prepping a few vehicles at a time. here's a couple pics of my truck and ongoing project.

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Back to the motorcylce.

Here it is the day I brought it home.

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First to go was the king/queen seat and the rear fender section. l. I pulled the motor since the previous owner had heli coiled one of the spark plugs back in the head and was kind of suspicious of the job he had done. Overall it was done very nice and professionally like he said. Motor will stay sealed up, just with new paint and polish up the side covers and such.
I then turned to the look of the bike. Didn't want that cruiser feel but more cafe racer styling.
Decided to build my own rear fender and modify the rear frame to match the shape of the new fender as well.

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With that roughed in moved onto the giant tank. It looks straight as can be but stripped off old paint and found bondo and dents all over. So I figured why not practice making some knee dents on this tank. Worse case I'll get a new tank anyways. I think it turned out decent and definitely improved comfort when sitting on the seat.

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Still not sure what to do with the front of the tank since I want to run a drag bar or something lower profile but I'm sure they will hit the wide K8 tank.

Other minor upgrades I've done or are doing is replacing rear shocks, front progressive springs, new headlight bucket, new bars, relocate ign switch, switch to a 530 chain/sprocket, and paint.

I'll try and keep this updated as I make progress. Any comments or anything would be great. Love feedback from others.
 
Got the frame all finished up and painted. Also tore into motor, it's spotless inside so I'll just clean it, seal it back up with new gaskets and re paint it.

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Getting closer. Still have little things to finish up like linkage for rear sets, exhaust brackets and modifying pipe a bit to clear rearsets and such more. Finish air cleaner I am building and paint tank and seat. Also going to ditch the gauges once I get it going for a single speedo/tach unit to clean up bars a bit and bob/paint the front fender as well. Turning out just like I had hoped.

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looking nice so far but the seat hump looks a little small for my liking but it flows nicely!! looking forward to seeing the finished product
 
looking good but might I suggest getting a headlight bucket that has the gauges or a gauge integrated into it. I think that would really clean up the front of the bike. The gauges stick up to high and look kinda goofy. The rest of the bike is Brilliant.
 
Totally agree, I am acutally ordering a Vapor digital speedo/tach and going to french it into the back of the headlight bucket for a nice clean look. OR mount it between the bars and tank if there is room, it's a fairly small unit.
 
Does anyone have any good pics of how you moved the Kickstand. Totally messed up by not checking that clearance before assembly. :mad:

It hits the rearsets shifter right now. Might try to just bend it or shorten it a bit and see if that helps.
 
Getting closer. Tried to fire it up today but as soon as the fuel was turned on the carb started piss gas out the bowl gasket. Gotta order up some new ones and hope it fires.

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WEll it runs and sounds great. Gotta finish up tightening a few bolts, adjust chain, and bleed front brake then it's ready to ride.

Can't wait.
 
First thing you need to do is get rid of that tank....and sell it to me. Looks great man. The color on the frame is sharp! Very clean build.
 
Finally threw some paint and clear on the tank and fender. Just got to upholster the seat and it will be pretty much wrapped up and ready for it's first ride.

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Rode it around my shop complex a couple laps last night. feels great to finally get it riding. Still not running great, hope new points fixes that. The 1-3 points gap was almost .020 and the 2-4 gap was less than .006 my thinnest gauge. Adjusted those to .012 and it runs a lot better, but I believe timing is off as it's harder to start now. Not gonna mess with it until I get the new points in and adjusted. Also the #4 cylinder exhaust is warm but not nearly as hot as the others, has spark and fuel, any ideas there?

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Classic stripes, the 'crackle' seat stitch is interesting... Not for me, but still interesting....How about those RFY shocks? I'm debating picking some up for my cb750. What's the psi reading?
 
Yeah seat will change but it works for now.

PSi reading?? What PSI reading. haha. I tore them apart set floating piston in reservoir correctly, filled back with with 7 wt shock oil and charged to 80psi for now. Seem to work a lot better now. But then again don't really have any miles on it at all. Springs seem a bit stiff but we shall see. For the price not bad and a great start. Simple to disassemble, was thinking of getting another set for a magna I picked up.
 
TommyT said:
PSi reading?? What PSI reading. haha. I tore them apart set floating piston in reservoir correctly, filled back with with 7 wt shock oil and charged to 80psi for now. Seem to work a lot better now. But then again don't really have any miles on it at all. Springs seem a bit stiff but we shall see. For the price not bad and a great start. Simple to disassemble, was thinking of getting another set for a magna I picked up.

Any chance you took process photos of this shock rebuild??? It would be helpful.
 
I actually did not. I may be able to get some pics next time I tear them down if I buy another set. They are fairly simple to take apart, just some snap rings and simple stuff. Way less complicated than my race shocks I am used to.
 
I bought a set of RFY shocks but the bottom clevis hole was too small by .060 thousandths.
Did you have that same problem?

How did you solve it? New clevis or drill the hole?

BTW I am building a 1978 CB750 cafe with gold frame and black tank and seat also!!
 
donald branscom said:
I bought a set of RFY shocks but the bottom clevis hole was too small by .060 thousandths.
Did you have that same problem?

How did you solve it? New clevis or drill the hole?

BTW I am building a 1978 CB750 cafe with gold frame and black tank and seat also!!

Same issue w/ my 750. I drilled out the holes slightly. Bigger on one side and tapped threads into the other. This way I could use the stock bolt and not have to worry about a nut on the other side. The aluminum on RFY's are pretty soft :/ but it's easy to machine.
 
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