Topic: '78 CB750F - Orange-ish Black

[Davidov]

PAMCO ignition installation and wiring. It looks like good quality. My only wish is that it came "plug and play" with bullet connectors, but that would make it cost more.

List of shame:
Washers used to make a longer bolt work on breather cover
Missing valve cover cross-point bolts under the breather cover
Of the 4 oil line bolts, 1 was an oddball philips head.
1 different intake valve
Half of the valve springs were installed narrow end UP
List of excessive wear:
Rocker shaft hold-down bolts loose on intake 1-2 towers
2 loose cylinder studs
And of the exhast valve guides were all WAY out of spec

So yes, this rebuild was money well spent!

[Davidov]

I did all the concluding work, the hardest part of the whole rebuild! Friday night (Saturday morning) about 1:55am, I fired it up.

I have heard of oil starvation to the head after a rebuild, so I took every precaution. Oil pump screen was cleaned, new o-rings on the pump dowels, and a new gasket. New oil pan gasket as well, added thread sealant to the oil pan bolts. Pump was primed after that work during the rebuild.

I kicked it over manually(by foot?) several times. I cranked it with the starter at intervals. The oil light never went out, but I was sure there was oil flow. I decided to go for it, and cranked it with spark, and behold it started right up. Oil dummy light went off immediately.

The Pamco ignition and fresh compression make it feel soooo much better while starting. About 3/4 stroke of the kick lever and its running.

Still need to synch the carbs, and give it a few break in runs on my neighborhood "test track". 

I'll post a video soon.

[70CB750]

Nice! 

[Davidov]

Wrapped the exhaust during reassembly. Besides the scavenging advantages and more power  ....I think an aircooled engine can benefit from this. The whole front face of the engine is usually shielded by the exhaust pipes.

[seanbarney41]

PAMCO ignition installation and wiring. It looks like good quality. My only wish is that it came "plug and play" with bullet connectors, but that would make it cost more.

List of shame:
Washers used to make a longer bolt work on breather cover
Missing valve cover cross-point bolts under the breather cover
Of the 4 oil line bolts, 1 was an oddball philips head.
1 different intake valve
Half of the valve springs were installed narrow end UP
List of excessive wear:
Rocker shaft hold-down bolts loose on intake 1-2 towers
2 loose cylinder studs
And of the exhast valve guides were all WAY out of spec

So yes, this rebuild was money well spent!

actually the oil lines each have one oddball bolt stock.  The hardest ones to get at have both hex head and crosshead stock.

[Davidov]

actually the oil lines each have one oddball bolt stock.  The hardest ones to get at have both hex head and crosshead stock.

Huh, I figured that was the case since there were different part numbers. Still, I only had 1. So I made them all match.

[Davidov]

All Balls tapered roller bearing kit installed for steering stem. I installed this kit before on a 69 CL350, and the results were very pleasing.

My 750F had some low speed steering wobble that disappeared after the tapered bearing install!

[Davidov]

The heavy, ugly 630 chain had to go as well. It came new in the package when I bought the bike, so I had no reason to convert it back then.

New DID 530 non-o ring chain with new sprockets installed now.

[SOHC4 Cafe Racer Fan]

That rusty one was a problem waiting to go bad.

[Davidov]

First ride to work in a few months. Didn't miss a beat!
I've logged a little over 200 miles on the rebuild now (slowly but surely).

I did the first oil change at 40 miles. I'll do another one now (over 200), and then wait until 500 to do it again.
After that I think I'll started doing 1000-1500 mile regular intervals.

[MRieck]

That 530 chain conversion is a must. You probably pick up 2 HP right there.

[Davidov]

That 530 chain conversion is a must. You probably pick up 2 HP right there.

And no more "That chain is huge! It looks like it belongs on heavy equipment!" comments. 

[seanbarney41]

That 530 chain conversion is a must. You probably pick up 2 HP right there.

And no more "That chain is huge! It looks like it belongs on heavy equipment!" comments. 

I disagree that the conversion is a must.  Sure you pick up a couple pony's...but they are lost as soon as the 530 wears, gets sloppy, and stiff after 8000 miles or so.  My original 630 is hangin' in there after 26,000 miles!

[MCRider]

That 530 chain conversion is a must. You probably pick up 2 HP right there.

And no more "That chain is huge! It looks like it belongs on heavy equipment!" comments. 

I disagree that the conversion is a must.  Sure you pick up a couple pony's...but they are lost as soon as the 530 wears, gets sloppy, and stiff after 8000 miles or so.  My original 630 is hangin' in there after 26,000 miles!

I suspect modern 530s are as strong or stronger than old OEM 630s. So the xtra hp stays around.

What modern hyper bike has a 630 on it?

[Retro Rocket]

That 530 chain conversion is a must. You probably pick up 2 HP right there.

And no more "That chain is huge! It looks like it belongs on heavy equipment!" comments. 

I disagree that the conversion is a must.  Sure you pick up a couple pony's...but they are lost as soon as the 530 wears, gets sloppy, and stiff after 8000 miles or so.  My original 630 is hangin' in there after 26,000 miles!

I suspect modern 530s are as strong or stronger than old OEM 630s. So the xtra hp stays around.

What modern hyper bike has a 630 on it?

You are correct Ron, all modern hyper bikes have 520 , 525 or 530 chains and they are far lighter and stronger than the old 630, 630's will become obsolete, I'm not exactly sure why they haven't already. If a modern 200+ HP bike can get around with a 520-525-530 and not have the stretch problems, most modern chains are pre stretched anyway, then our bikes won't have any problems at all....

[seanbarney41]

That 530 chain conversion is a must. You probably pick up 2 HP right there.

And no more "That chain is huge! It looks like it belongs on heavy equipment!" comments. 

I disagree that the conversion is a must.  Sure you pick up a couple pony's...but they are lost as soon as the 530 wears, gets sloppy, and stiff after 8000 miles or so.  My original 630 is hangin' in there after 26,000 miles!

I suspect modern 530s are as strong or stronger than old OEM 630s. So the xtra hp stays around.

What modern hyper bike has a 630 on it?

all this I theoretically agree to, but I still have not had a 530 chain last anywhere near as long...and just going by feel alone, I think a chewed up sticky sloppy 530 eats more hp than a smooth running 630

You are correct Ron, all modern hyper bikes have 520 , 525 or 530 chains and they are far lighter and stronger than the old 630, 630's will become obsolete, I'm not exactly sure why they haven't already. If a modern 200+ HP bike can get around with a 520-525-530 and not have the stretch problems, most modern chains are pre stretched anyway, then our bikes won't have any problems at all....

[Retro Rocket]

You need to look at the tensile strength of the chains Sean, thats what is important, not just the size, there are good and bad in all chains...

[Davidov]

The 630 was just a "bigger is better" production change.
530 chains are easier to find. Like many said before, the technology of modern 530 chains has come a long way.

So I agree with it being a worthwhile conversion.

[Davidov]

Ongoing project update:
Taking a trip from DFW to Austin to watch Moto GP on the 750F, so I've been going over everything with a fine tooth comb.

I had a new tire mounted and balanced. So I took the opportunity to replace the rear wheel bearings. Left and Right bearings and the sprocket carrier bearing came in the All Balls kit. I really like their products, I've used the steering bearing kits on 2 bikes now. (including the 750)

The bearings were definitely original type, single sealed.

Shortly after the rebuild I noticed some slight "sweating"/"seeping" from the edge of the valve cover. No big deal, but then the right side by Cyl 4 started trailing along the cyl head while riding. 

I think I'll try the sneak in a http://www.cyclexchange.net/Engine%20Parts%20(Non-Cafe-Gaskets).htm Cycle X "leak proof" gasket without removing the engine. No frame kit either....I'm stubborn, I know.

[Davidov]

The other pictures didn't really show up.

HondaMan found that some valve cover gaskets were thinner than original parts and may cause a leak.
It looks like this Vesrah gasket may be one of the too thin types.

This is after a few minutes of warming it up after an oil change.

Going to have to change it out   

[seanbarney41]

Davidov, my F3 valve cover refuses to seal in exactly the same place, but on both sides.  I have changed the gasket twice, and stuffed Threebond into the gap with the cover loose and then torqued the crap out of it.  This worked for a few thousand miles but the leaks just come back.  I think my cover or cylinder head has warped.

[Davidov]

How bad does your F3 leak, Sean?
Have you looked into the Cycle-X leak free gaskets I posted above?

I prepped the surfaces very well, the cyl head was soda blasted during the machine shop work.
The first few hundred miles it would barely sweat on both sides by cyl 1 and 4.

I'm using a OEM type gasket, if that doesn't work I'll go with the Cycle X gasket.

[seanbarney41]

It's not too bad...just makes a mess is all.  I will be riding other bikes this season.  Time to pull that motor and freshen some stuff anyway.  I will check the flatness of the head, use a different valve cover and look into that CycleX gasket, although I have always had the best luck with Honda OEM gaskets.

[SOHC4 Cafe Racer Fan]

I had the same issue with my Cycle X valve cover. It was warped.

[Davidov]

It only made sense to replace the front wheel bearings as well.
Did it with a All Balls kit for the front. Awesome price, great product.
I found the original single-sided seal bearings, so the modern bearings are a welcomed upgrade.


Update on oil leaks, I unbolted the valve cover with the engine mounted in the frame to replace the gasket. Let's say, it's not easy, but it can be done.
When I reassembled the engine I used 3-Bond on the upper side of the gasket. I did have it installed correctly, judging by the asymetrical cutout for the cam chain/sprocket. Most of the gasket came off no problem (thank to the 3-bond), but some of it stuck to the valve cover, so cleaning it was a bear.

I used a DK brand gasket from 4into1, with Permatex non-hardening "form a gasket 2" brown stuff on the cyl head side of the gasket.

I noticed some of the valve cover bolts (I changed them to allen/socket head black oxide bolts) were easier to break loose than some of the others. Maybe the bolt material strectched a little after a few warm up cycles? But that shouldn't matter, they are 10.9 grade bolts. (Yes, of course I torqued them the first time)

The only visible problem was pictured below. The right side, where the leak was, looks like the bolt holes became oblong. Either the Hondabond became too tacky during install, and caused the gasket to stick and slide. Or the heat cycles made the gasket slide since the cyl head gets hotter than the valve cover, and the top side was glued to the cover.