Author Topic: 76 CB750K engine rebuild thread - With Video! (Read 12430 times)

michrobi · « **Reply #25 on:** July 08, 2009, 08:32:53 PM »

Here they are after...

So what's the deal on these after being bead blasted? Do they have to be painted? They look so pretty it would be a shame to paint them if I didn't have to.

Colonel · « **Reply #26 on:** July 08, 2009, 08:55:48 PM »

That's incredible... Turned out fantastic.
Now I am depressed...

michrobi · « **Reply #27 on:** July 09, 2009, 01:42:58 AM »

Okay, fresh out of a hot soapy bath and blow dry...

I notice this breakage on the rear of the bottom case. Is this a dealbreaker? I can't think of what was there, and nothing large in the tub drain.

michrobi · « **Reply #28 on:** July 09, 2009, 03:11:24 PM »

I think that broken thread is for the front of the chain guard. Can anyone confirm that?

michrobi · « **Reply #29 on:** July 09, 2009, 06:45:41 PM »

Here's where I'm at...

Studs out

Here is how I did it. A 2 shot presoak in WD-40 from yesterday and another shot about an hour before I started. Only had to use the hair dryer on 2 studs.

Only 2 shots here to cover 2 hours of pressurized solvent blasting and air.

Going to let my garage air out and start on the bottom case... Lesson learned

This thing on?

michrobi · « **Reply #30 on:** July 09, 2009, 06:53:53 PM »

As of today I have everything I need.

michrobi · « **Reply #31 on:** July 09, 2009, 09:41:32 PM »

HD Studs installed and torqued. This job wasn't nearly the nightmare I was sure it was going to be.

I have the shift drum in the exact position it was in when I removed it, but that center fork sticking up above the gears doesn't seem right. What's wrong with this picture?

michrobi · « **Reply #32 on:** July 10, 2009, 12:51:45 AM »

I'll tell ya what the service manual does, it answers questions. I'm done with the lower case assembly except for the kick gear and spring. What's the trick to getting the spring around one rotation and clipping it while keeping the assembly lined up? Or is it just get a friend and have strong hands?

I have installed the upper case main bearings, crank, main drive shaft and new primary chains. My batteries died just as I started, so no photos. They're charged now and I'll get back to you shortly.

michrobi · « **Reply #33 on:** July 10, 2009, 04:02:06 AM »

This kick starter assembly isn't covered very well in the manual. Finally figured out what had to be done after banging my head on it for an hour.

The top half except the cam chain. This HD Tsubaki chain is coated in a cosmoline type of substance. Is it okay to give the chain a bath in solvent to clean that off, then oil/install?

Anyone know what is supposed to connect to this broken thread?

Gamma · « **Reply #34 on:** July 10, 2009, 07:13:02 AM »

Thats was one of the 2 bolt holes that hold the Drive sprocket cover in place.

michrobi · « **Reply #35 on:** July 10, 2009, 06:29:31 PM »

Getting those chains on solo was an interesting exercise.

I'm ready to rejoin the case halves. I would greatly appreciate any advise for this step. I plan to use Hondabond HT on the mating surface. Is the center fork going to need to be guided into place around the main shaft, or will it be gravity aligned when in neutral? I measured the distance from the case to the fork, and have the main shaft in position.

michrobi · « **Reply #36 on:** July 11, 2009, 01:15:09 AM »

Cases mated and torqued.

Oil pan primed and painted

michrobi · « **Reply #37 on:** July 11, 2009, 09:52:07 PM »

Shift linkage rebuilt

Pistons & rings installed.

michrobi · « **Reply #38 on:** July 12, 2009, 02:33:48 AM »

Oil pump/pan installed

Cylinders on

This head has had a simple overhaul including completely cleaned head and valves, lapped them in and installed new valve seals.

I didn't get shots of the new cam guide and roller, but they're in there. I feel like I've reached a significant milestone with the head on.

michrobi · « **Reply #39 on:** July 12, 2009, 10:18:10 PM »

Ignition reinstalled

michrobi · « **Reply #40 on:** July 12, 2009, 10:26:33 PM »

I'm having a hell of a time getting the cam chain on the sprocket. It almost seems like the cam chain is too short. It all gets wedged between the sidewall of the chain housing, the chain and the sprocket. Once I get the cam into position with the chain and the sprocket around it, there isn't enough room to move the cam, chain or sprocket, they're tight. In order to get the chain around the sprocket, I'll have to get the cam down into the bearing towers. But the only way there's room to move the chain is if the sprocket is all the way on against the bolt surface, and I can't get the chain around the sprocket if it's on the cam. Arggg!

Jerry Rxman Griffin aka MuthaF'er · « **Reply #41 on:** July 12, 2009, 10:45:30 PM »

It's been a while but I do believe you need to install the chain on the sprocket then fit the sprocket onto the cam. Looking at my shop manual: assemble the chain on the sprocket before mounting the sprocket. Place the cam on top of the holder and align the timing index line on the right end so that it is parallel to the top surface of the holder with the key groove toward the top. In this condition the base circle of the #4 cam is toward the top and the #1 cam is in the overlap position. At this point the sprocket can be mounted.

You should be installing the cam from the left side (#1). The manual could be better but my take is you put the chain on the sprocket then feed the cam through the sprocket from the left side (#1) by twisting/turning the cam for the lobes to clear.

michrobi · « **Reply #42 on:** July 13, 2009, 01:12:41 AM »

I got that mutha. Thanks Jerry.

Bill/BentON Racing · « **Reply #43 on:** July 13, 2009, 06:02:58 AM »

The work looks good,c/fork wasn't hard was it?I am going to install studs in Drew's engine tonite.I took off top end last nite and got a couple pics of cam chain guide and rollers after 30,000m.If you have any CB 750 apart always check and replace as needed.I will get Drew to post later today.If you are going to fix where rear c/shaft sprocket goes ,do it now,you can get to it.Bottom end when learned is easier than top end I think,so do not be afraid to take apart,with the help on this forum we can do anything!Bill Benton

michrobi · « **Reply #44 on:** July 13, 2009, 06:12:58 PM »

Rockers installed and gaped the valves

Getting pretty close, alternator and clutch, and I'm there. I think I'll work on cleaning up my covers a little bit.

Flying J · « **Reply #45 on:** July 13, 2009, 06:31:13 PM »

Are you going to degree in your cam? Id like to see your step by step on that. This is a great thread.

odin836 · « **Reply #46 on:** July 14, 2009, 01:48:42 AM »

Agreed! A great thread...
Shame we can not be there to hear it start up...

michrobi · « **Reply #47 on:** July 14, 2009, 04:58:33 PM »

Degree in the cam...

Step juan is to find true TDC for your crank.

I taped a degree wheel on to the center of my rotor zeroed out on the case's TDC mark

Then with the engine to TDC on #2-3 according to the case mark, I lightly clamped a thin punch on the head that poked down through the #1 spark plug hole about an inch. (Be careful here that you don't clamp your piston stopping device in the way of a valve, or you'll bend something.)

Then I rolled the crank counterclockwise (The direction the kick starter kicks the engine) until the piston stopped on the end of the punch, and took note of the degree wheel's setting of 43° off center. Then I rolled the crank clockwise (The opposite of the kick starter's kick direction) until the piston stopped at the punch again, and took note of that 53° reading.

If the two measurements aren't the same, then you are off center by exactly half the total variance. So in my case, I'm off by 10° on my measurements, so my case TDC mark is 5° off.

This shot shows my true TDC on the degree wheel

Now that I have TDC lined up, I secured a Dial Indicator on the little flat spot at the tip of the #1 intake rocker, and zeroed the gauge at no lift. (This can be anywhere in the rotation that the rocker is at complete rest with the intake valve fully closed.)

The unit I use is a Harbor Freight spesh that came all together with the clamp arm, vise grips and indicator in a nice wood box. (I don't see it on their site.)

Now turn the crank counterclockwise until you start up the lobe on the #1 intake rocker, and go slow because the reading you want comes up fast. Stop when the dial reads 0.050. (The first "50" on the dial in the initial rotation on 1" gauges.)

michrobi · « **Reply #48 on:** July 14, 2009, 06:57:26 PM »

Correction, 240° is the best I get. My degree wheel got off center the first run through. Anyone else been through this with a stock 750 and a 41 Webcam? Anyone know the stock cam specs by chance?

michrobi · « **Reply #49 on:** July 14, 2009, 07:34:05 PM »

Wait a second, that's not right. It's the "opens" and "closes" I'm supposed to be looking at on the 0.050 reading.

Do over...

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Author Topic: 76 CB750K engine rebuild thread - With Video! (Read 12430 times)