Topic: CB750 K3F - AKA The Red

[70CB750]

I need to get tool to meassure it correctly. Seems like I will need to shim springs, but I have to verify it.

[70CB750]

Assembled head, took me only a year to deal with the late F valve issue.

[70CB750]

Hondabond to keep water out  of the stud cavity.

[70CB750]

MLS head gasket.

Nuts in place and tightened.





I had problems with some of the M6 bolts that go in - had to grind 10mm socket to get them tightened.

[rtbmrgl]

Hondabond to keep water out  of the stud cavity.

Good idea, I wish had known before I put my motor together, ......next project.

[edwardmorris]

Is that Hondabond or o-rings or both?

[70CB750]

Thank you, Mark.

Ed, it is Hondabond and that rubber cylinder used on late engines.  With jugs off I coated those 4 exposed studs with vacuum grease, shrunk tubing over it as the first line of defense.

To make sure there is not too much Hondabond I filled the holes, installed rubber sleeves and tightened the head down without gasket. That squezed HB out and I cleaned it off the head and jugs surface and also cleaned rubber sleeves.

Only time will tell to what effect this exercise was.

[rtbmrgl]

Thank you, Mark.

Ed, it is Hondabond and that rubber cylinder used on late engines.  With jugs off I coated those 4 exposed studs with vacuum grease, shrunk tubing over it as the first line of defense.

To make sure there is not too much Hondabond I filled the holes, installed rubber sleeves and tightened the head down without gasket. That squezed HB out and I cleaned it off the head and jugs surface and also cleaned rubber sleeves.

Only time will tell to what effect this exercise was.

Years from now if someone else rebuilds the motor they will sure appreciate what you did.

[andrewk]

Did you end up shimming the springs?  Worth the year of effort I hope, you'll have a solid good running engine!  My projects all seem to be on the same time table, too.

[Stev-o]

Looks good 70CB...

[70CB750]

Thank you.

No, I did not shim springs.  First, it is hard to measure correctly.  The span for installed height is 0.8mm and to get repeatable results is impossible.

It measures differently on each side of the spring but from what I could tell, the spring height was right on the upper limit and I decided it is better to leave it than bring extra stress in springs.

[70CB750]

The torque wrench setting is confusing, at least for me and even reading the manual did not help.  I figured it out, but last night I had doubts, so I rigged this primitive torque verifier.  The fishing scale showed 30 pounds force on 6" lever - that makes it 15 foot pounds; right on the money.

[Stev-o]

Fish scale? That's a first....ha!

[bytio]

Which torque setting do you mean, is it for the main cylinder studs? As they can go up to 18ft/lbs, I used HD studs so went up to the 18ft/lbs

[70CB750]

I done it with Hondaman book in front of me, I believe the interval is 13.? to 15.7 footpounds  for original studs.

Even torquing is more important than reaching the highest number.

[bytio]

Ok thanks, just looking at the genuine Honda workshop manual it says torque to 14.5-18.1 ft/lbs, so yours on the lower end of that scale. Which valves have you used?

[70CB750]

I still want to check it against manual before I install towers.

Here is HM list:

Engine (CB750K0-K6)
Head nuts, rod nuts, and crankshaft (case) bolts: 14.5 ft-lbs.
6mm bolts on head and crankcases: 85-95 in-lbs.
6mm bolts on cam towers: 6-7 ft-lbs., add blue Loctite.
8mm bolts on back of crankcase: 14.5 ft-lbs.

Frame
Swingarm bolt: 40-45 ft-lbs., less if arm locks up or if bolt has been used many times.
Front axle caps: 14.5 ft-lbs., tighten flush side first, to rear.
Front axle bolt: 14.5 ft-lbs., make sure the bearings are neutral and not bound, else move their positions until axle spins freely.
Rear axle bolt: 20-30 ft-lbs: same rules about the baerings as the front axle.
Drive chain adjuster bolts: 10-14 ft-lbs.
Engine bolts 8mm: 14 ft-lbs. if used many times, 18-20 ft-lbs. if new.
Engine bolts 10mm: 20-25 ft-lbs.
Engine bolts 12mm: 25-30 ft-lbs.

http://forums.sohc4.net/index.php?topic=57279.0

Super flow valves from CycleX:

http://www.cyclexchange.net/Honda%20cb750%20%28%2077-78%20%29%20%20F%202%20Section%20Page.htm

[bytio]

Thanks, Hondaman is the Guru, here is a pic of the workshop manual

I hope you have better luck with the cyclex valves than I did (and HM), I found after 2000 miles the nitrate coating on stems came off, damaging the guides and seats with massive oil consumption, have stripped rebuilt with APe guides and valves, all great now

[70CB750]

I already had valves when I learned about the nitrate issue - there was not much to do but go with it.

Anyway, I cleaned the blacking from few of the stems and measured it with micrometer - there was literally no measurable difference, it was not coating it was more like chemical blacking of the valve.

I will take my chances and if the oil consumption jumps up, I will replace valve guides again.

[bytio]

Sounds sensible, maybe it just got a bad batch. I like the hondabond in the dead old drain hole, wish I had done that, it all looks great

[SOHC4 Cafe Racer Fan]

By Cycle X, do you men Kibblewhite?

[70CB750]

Cyclex is where I bought them, not sure who makes them.

[70CB750]

Which torque setting do you mean, is it for the main cylinder studs? As they can go up to 18ft/lbs, I used HD studs so went up to the 18ft/lbs

You were actually correct.  I looked it up in F manual supplement and F head torque spec is 18 foot pounds - so I tightened some more.

Thanks for pointing it out.

[Finnigan]

Strong work so far, i'll be looking at your thread for reference later

[70CB750]

You are a brave man:) I feel very lost at the moment.

Here is my camshaft timing setup, it works like this, but I have to interpret the readings.