Topic: 1976 CB750K Stock/Cafe Hybrid

[greasy j]

lookin good!

glad you like the tank. I really love that color. thanks to that decal it has a super thick coat of paint, so it should last.

I'm doing another one in green right now.

what are you doing with the seat? using the cowl?

nice work!

[heyjones]

Thanks for the kind words. I think for now I'm going to pass on the seat cowl, I'm going to bobb the rear fender, hopefully that will tighten up the back a bit.

So today I finally took the plunge and got the cylinders on. I've been dreading doing this, for some reason it seemed like a very mysterious process to me. In most build threads you see them lowering the cylinder, and in the next photo they're on. But it wasn't as difficult as I was expecting. The 2 and 3 pistons are easy because the wood holds them still, but the 1 and 4 are pretty tricky since they are allowed to "wobble" a bit. Also, there are a lot of sharp edges in there... I started seeing red all over the pistons and realized I had sliced my finger somehow. Here are a couple of things I learned along the way;

1) clean the mating surfaces before you paint, unless you like ruining your paint job and cursing loudly

2) the end of the cam chain guide with the removable pin seats into the bottom case

3) ring compressors aren't necessary

4) if you use a foam brush to coat the pistons with oil, you don't have to worry about rogue bristles

Here are some photos...









The last things I'm waiting on are getting the valve cover polished and the rocker towers drilled. Should be ready to put this thing in the frame next weekend!

[rickmoore24]

cant wait to see her fired up!

[heyjones]

#$%*.



I thought I was going to have the rocker tower back on tonight, but then I snapped this bolt off. What are the odds that I'll be able to get at this with a screw extractor so I don't have to take the whole top end apart again? Also, will any similar bolt work to replace this one or should I order one?

[MCRider]

Twere me, I'd move on and fix it later, years later.

OCICBW, but to me that bolt, all four of them, are unecessary and are used to draw the head down gently. Before going at the real head nuts.

Don't take my word for it, let someone else speak. I can accept being wrong.

How'd you ever break it in the first place?

[heyjones]

I broke it by thinking that they had to be torqued the same as the bolts...

[rickmoore24]

Falcon ASS!!  That does suck, but it's not what keeps the head on or sealed, but I'd still try to get it out and replace it (otherwise you'll think about it constantly). If you go for it take your time, I've had good luck taking broken off bolts by going easy and starting with a proper punch to line the bit up and get it started, soak the #$%* out of it first though and some heat too. Goood luck!

Rick

[MCRider]

I broke it by thinking that they had to be torqued the same as the bolts...

That would do it.   

The head should come off easily at this stage. You could mask off the top of the cylinder and drill it out. Might need a heli coil. I've never had good luck with ez outs, they always break.  I've heard about reverse drill bits working, never tried them myself.

[greasy j]

bummer, man. I'm anti-ez out at this point. they always seem to break. the reverse drill bit might work...

[heyjones]

Yeah, I'm going to have to drill it out. I used the wrong bolts, too! The ones I put in don't have the phillips head on them, so I'm not really sure what the hell is even in there now...

[MCRider]

Yeah, I'm going to have to drill it out. I used the wrong bolts, too! The ones I put in don't have the phillips head on them, so I'm not really sure what the hell is even in there now...

It may have been too long and hit the bottom of the hole? I've often used non-stock screws there as the stockers get lost. But the length is important I think. Maybe not.

In any event, for future reference here's my position on these things: Upon assembly, use them to draw the head into the locating dowels, Orings, and to flatten the gasket. about like a spark plug, runnem to resistance then 1/4 turn. Always in sequence and staggered, insides forst, then the outsides, like rolling out dough.

Then the head nuts get full torque, sequential and staggered. Then you'll need to snug up the 4 screws agains as they will have loosened from drawing the head down with the nuts. But just snug with a hand tool. Assuming that Honda meant for the Phillips head in the screw top to mean something, they couldn't be intended to take much torque.

(I know this is not your problem, I'm just saying) Upon disassembly, the 4 screws come out first. A rap with an impact driver should do it. Or you can use the hexes as the screws will have become tightened with age. A thin 10mm wrench goes in the fins for the 2 outsiders. The 2 insiders can be had with a deep well thin walled socket or T handle. If you wait until after the headnuts come off, the head will have relaxed and expended into the scres to the point where it would be sheer luck to get them out. There is a thread running right now about someone who has ruined the head on oneof those screws. Not fun.

With the head nuts in place those screws should usually come out easily.

[thelowmax]

I am very impressed with not only the work that you have done on the bike (wow), but the efficiency with which you have, basically cataloged not only each and every step, but the thought process behind them. Very, very cool.

The only bit of information that I can add, other than "Go on the internet and read everything you can (and then guess)", is a great engine cleaner... Simple Green Heavy Duty BBQ Cleaner. It's an eco-friendly cleaner, non-caustic that goes on like Scrubbing Bubbles, in a thick expanding foam. Cuts that baked on engine oil and has most of it dripping off. A little scrub with a brush and rinse with water. Works great, easy to use, safe for paint, rubber, electrical wires, etc..

[tweakin]

Great looking paint.  Your bike is coming along nicely.

[heyjones]

Thanks for all the input and encouragement, guys. I managed to get the cam/rockers all put on this afternoon. I misread the torque values again (#$%*), but luckily I noticed before it was too late. Now I'm trying to wrap my head around setting the valve lashes. I've read plenty of posts regarding it but it's still not making a whole lot of sense.

[KB02]

For what it's worth, maybe this will help:
   With the piston in the firing position (It highest point of travel with both the valves closed) measure the distance the rocket arm is from the valve stem. Adjust to desired distance.

Not sure if that was the part you were struggling with or not, but there you go.

[heyjones]

So I made a little bit of progress on this thing finally. Got the top end back together, set the valve clearances, got the engine in the frame by laying it on it's side and lowering the frame onto the engine (for a minute I thought that I had gotten it stuck in the frame and freaked out), then this morning I got the wheels back on. To do that I just left the bike on its side, then assembled the rear wheel and slipped it onto the swing arm, popped the front wheel on and lifted the whole thing up.





I'm going to black out the rims later, but for right now I just want this thing running. I can always pop the wheels off later. I ordred a set of stainless steel carb boot clams from Carpy:

http://www.cb750cafe.com/parts.php?id=55

So once those get in I can get the carbs back on, then I plan to hook the oil tank and lines back up, then start in on the electrical stuff. I bought a replacement wiring harness from PartsNMore:

https://www.partsnmore.com/cat_index.php?model=cb750_sohc&category=electrical

It looks like I'll have to make some modifications to it but it beats starting from scratch! Oh, one issue that I'm having is with the new fork ears I installed. I think they're too thick and are going to hit the tank, so I'm considering going back to the stock ears but painting them black. But we'll see how that works out.

[MCRider]

YIKES! I see you don't have the spacer washer in that top fork clamp. DO NOT tighten that till you get the spacer in there or you'll be looking for a new triple tree. Just ask around.

As to the fork ear clearance, many run into that with cafe bars and such. You can limit the fork lock to lock travel by drilling and tappingthe fork stop tabs and inserting a small screw. Or wrapping them with small hose clamps.

[haggeo]

love it...

[rickmoore24]

Here she comes! Good job on everything, the bike is coming together nicely.

[Flying J]

YIKES! I see you don't have the spacer washer in that top fork clamp. DO NOT tighten that till you get the spacer in there or you'll be looking for a new triple tree. Just ask around.

what can you use to replace that spacer? Can i just grind down a washer flat on one side?

[MCRider]

YIKES! I see you don't have the spacer washer in that top fork clamp. DO NOT tighten that till you get the spacer in there or you'll be looking for a new triple tree. Just ask around.

what can you use to replace that spacer? Can i just grind down a washer flat on one side?

We've had a thread on this just recently. What I discovered was the washer under the cylinder head nut is the proper thickness, but the OD is larger leaving it to stick out a tad. And yes, grind the flat into it. I thinned it to perfect thickness rubbing it on a file. Much better to have the larger OD than break the clamp.

If you need exact details search on clamp washers or clamp spacers or such, we posted all the measurements. Do you not have the stockers?


We could not find a stock hardware item that was thick enough and the clamp will still break. This is serious, as the clamps are expensive if you can find one, and hard to impossible to repair.

I have tons of cylinder head washers. I don't think the OEM part is available, except Yamiya has them in a set of hardware for real $$.

[heyjones]

I should still have them in a box around here somewhere...

[heyjones]

More progress today. I went with my friend down to San Diego to pick up a '72 CB350 Twin, which put a fire under my ass to get this thing back on the road. The guy he got it from is the brother of the original owner, and had a permanent registration in Virginia! Apparently they like to encourage people to keep old cars and bikes on the road, unlike California who makes it borderline impossible.



So today I got the wiring harness in, the airbox with new boots (people aren't lying when they tell how flexible new ones are), the oil lines on, and I started trying some different positions for the rear fender. In fact, the carb boots are almost too flexible, I'm having a really hard time getting the top of them to go flush with the carb bodies. I forgot to take a photo but I'll take one tomorrow and post it, see if anybody has any recommendations.





I also started polishing the fins using these foam sanding blocks I got in the painting section at Lowe's, they work really well and it helps to lighten up the cylinders. Should look killer in the sun!



Oh, and I saw this bike out in Balboa earlier this week, it's got this pretty cool fighter jet theme to it.

[heyjones]

Okay, so here's the problem that I'm having with my carb boots...



I'm having a really hard time getting them to go any further up than that. Any suggestions? I also took a better photo of the fins after the first pass of polishing, and I'm really happy with how they turned out. I also gave the seat a once over with some Arm & Hammer wipes, though I'm sure there's gotta be something better than that.

[rickmoore24]

Yeah, those MF'ers were tough to put on. Mine are old as sin and I got them on by hitting them with a torch for a few seconds to get softened up. It may also help to take off the bottom of the airbox to get some leverage on the velocity stacks with your hand up inside; its a tight fit. Good luck getting those on.