CB750K Builds

[TOOLS1]

I would borrow a lift if I were you. Working on a bike that does not have a center stand is a total PITA. Even if you can fit a jack under the bike somewhere you will still need a way to hold it up straight. If I am working on a bike that has to have the wheel jacked up off the ground, the first thing I do is up my service rate. Then I strap it to the lift to keep it upright. Then I use a scissor jack to lift the wheel up. I try not to remove both wheels at the same time though.
TOOLS

[StealthCB]

I actually might be able to modify the 1980 center stand a bit to use. And, still, do you Remove the exhaust, as where you'd lift the bike the exhaust is in the way.

[TOOLS1]

I often put a board across the exhaust and jack on it. Sometimes you just have to "go after it".
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[StealthCB]

Haha!! That's right, Tools!

Hey, so I am finally closing in on properly trying to fire my bike up for the first time! I have a new petcock on order, new genuine Honda air box boots, ngk plug caps, and a few other bits. Checked the coils, set the timing, and I need to recheck the tappet clearances.

So, I have open headers currently, 120 main jets and 40 slow, and I'll be starting it up with no air box, most likely.  Anything I should be aware of and expecting with this setup? Will running with open headers require even bigger jets? Also, what should my mixtures screws be set at for this setup, do you think? I believe I fully seated the four then turned them out 1 1/4 turn. Thanks guys!

[TOOLS1]

You should not need to change jetting for exhaust changes. The exhaust does not make much effect on jetting. I would go 1 7/8-2 turns on the pilot. It does not hurt to be on the rich side.
Hey, have you seen Shiny lately? Last I heard from him he was heading into the woods with a bunch of strangers.
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[StealthCB]

Ok, thank you! Hey, you wouldn't happen to have a k2-k6 seat you could sell me, would you?

See, I'm not sure if you're being serious or not. Haha! However, I did text him not but a few days ok.

[TOOLS1]

I was serious. I warned him about Banjos in the woods though before he left.
Sorry, I do not have any seats.
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[StealthCB]

Haha!! Good call! I think as long as he stays in Virginia and doesn't go to West Virginia, he'll be just fine.

[StealthCB]

Ps, I was just kidding about West Virginia. Haha!!

So ready to fire my bike up for the first time! All I need to find is a seat or plan to make one.

[TOOLS1]

What you meant was "South Carolina". 
Make a seat out of fiberglass. It is easy to work with and inexpensive.
TOOLS

[StealthCB]

I've thought about that, but that's something else to take more time before I can ride. Also, I'd like to not cut that rear metal piece on the frame, but I know it would make fitting any flat seat much easier! However, wouldnt I have to limit the up travel a good bit so it doesn't slam into the seat?

Tech question. I have heard that the stock tappet clearances are actually not the best, and that there is a better known clearance to set them too. Is this wrong? And, what about setting the timing to fire just a bit after the "F" mark comes around to gain a bit more compression and power?

[TOOLS1]

You do have to have tire clearance unless you are going hardtail. That is why Cafe Racers have a bump on the rear of the seat. Valve clearances should be set to the factory specs! There is nothing to be gained by diverting from the. I like to keep them on the wide side of the range though. The longer the valve stays closed the more heat it transfers to the seat. This is what cools the valve.
For timing, you would want to advance the timing, meaning it would fire before the "F" mark. However, you are not really going to gain anything here either.
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[StealthCB]

Well, factory is .002 inlet and .003 exhaust, so what exactly do you mean?

[TOOLS1]

Mean about what?
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[StealthCB]

Sorry, when you said "I like to keep them on the wide side of the range".

[TOOLS1]

I was not sure what engine you were working on. On DOHC engines they have a range of allowable tolerance. I should have explained better.
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[StealthCB]

Well guys, my bike is ALIVE!!!! Finally got it to fire up and run pretty good, all things considered! I'll try and post a video tomorrow.

So, I need a kill switch and a start button. I already bought a sleek, black throttle assembly and I want to keep it clean looking. I found that I like the look of the CBR1000 (used on other bikes too) kill switch assembly, and I found plenty of decent used ones on eBay. I believe the stock assembly is "normally closed" and so is the CBR assembly. Do you see a problem with me using that assembly on my 1973 CB750? I could just go the simple route and buy a repro assembly, but I'd like to be a little more creative if I can.

[TOOLS1]

If I am thinking of the right assembly it has a plastic housing. The plastic housing is not made to clamp tightly to the handlebar, so it has a little nub on it that goes into a hole in the handlebar to keep it from rotating when you twist the throttle. Most of these used ones will have that nub broken off, so be careful what you buy.
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[StealthCB]

Good point. Thank you. I found an Emgo reproduction 1973 CB750 switch for only $30 and that is very tempting! However, I already bought a slim throttle assembly and I'd love to have the slim kill switch and starter.





The first image is the diagram 4 the switch from the CBR. The second is from my bike. I love another pair of eyes on this. Doable, right?

[StealthCB]

Well, I went ahead and bought a used CBR1000 switch for just $10 on eBay, so we'll see if I can get it to function properly. Should be a nice modern look on the bar. I am so insanely excited to start piecing this bike together and making it road worthy! Thank you guys for all of the support and advice so far!