Author Topic: 1972 CB750 Four K2 -- Rebuilt to NEW OLD STOCK -- PIX ON PAGE 50 (Read 278290 times)

HondaMan · « **Reply #875 on:** April 20, 2015, 10:39:40 PM »

Quote from: edwardmorris on April 20, 2015, 06:25:53 PM

New o-ring and screws for the retainer/cover/thingy.

Does anyone know if there's an oil plug/puck missing right below where the o-ring is? I can't find anything in the parts fiche but that looks too large a hole for a dowel pin. Also, it looks like its the oil galley behind it anyway, am I missing a part here? Don't recall finding anything there on either bikes.

Yep, there's (originally) a rubber plug in that hole. Without it, the covers often develop a leak after while at that site, because it is oil under some mild pressure (about 10 PSI) for the tranny there. Honda never sold the part, though.

Some time back I made a post when I built a K6 that had one so loose it just fell out. The hole is just deep enough to make a threaded hole of it and I cut off a very short slice of a bolt (about 3 threads long, with a Dremel grinder wheel) and cut a slot across it to make it a "screw plug", then Loctited it in place with red Loctite for a permanent fit. Because of the shape of the oil passage inside the hole, it cannot screw itself in further, and because of the side cover it can't unscrew, either.

I've done 2 engines like this, both are running fine, still! The 2nd one was a K2, I think?

I don't know how to find that post here, but it's around? I just looked across my hard drive, don't have the pix of it here. I'll look tomorrow at work and see if they might be on my computer there, as I worked on that engine there back when my employer used to let me do it in their shop.

edwardmorris · « **Reply #876 on:** April 24, 2015, 05:53:49 PM »

Thanks for that detailed explanation Mark! Saved for future.

Right now, in the interest of time and my general lack of skills, I took the easy option of calling every Honda stealership in the tri-state area. Finally secured two more drops of unobtainum in this form (might as well be the last of them left NOS)

Kickstart · « **Reply #877 on:** April 25, 2015, 06:29:39 PM »

I know it's a little belated, but congratulations on getting the case back together!
And amazing work tracking down that rubber plug!

Regarding the cases, I noticed you put the Hondabond on the lower case... was that just your preference or was that a tip you got from someone? It seems to me that's the better way to do it, and I'm thinking that might have saved myself a lot of hassle had I done it that way... but I thought most people put it on the upper case (while it's upside down) so I assumed there was a good reason to do it that way.

Quote from: edwardmorris on April 17, 2015, 08:05:01 PM

Crank got a new seal, bearing groove retainers etc. all in place and just about ready. Near new shifter forks from Bill Benton (super young engine) and a really good later year shifter drum that I got from Stev-o in trade for a Kawi Z1 master. Used a ketchup bottle to generously lube up stuff, then Hondabond time!

Edit: Fixed pic 2

edwardmorris · « **Reply #878 on:** April 25, 2015, 08:54:40 PM »

Thank you!

Crankcases:
Just my pref. Also it seemed like the upper has spots that just float and don't have a lower case counterpart to mate with. Its also a PITA to get around the crank and rods etc. I did however do a couple spots on the upper, around that giant dowel and o-ring. Only thing to watch for is not touching the HB when lifting the lower. I managed by grabbing on to the oil pan area galleys and the large oil filter hole up front.

edwardmorris · « **Reply #879 on:** April 29, 2015, 08:38:21 PM »

Problem? Throw a NOS part at it

NOS neut switch fit flawlessly. Also forgot to take a pic earlier with the oil pan and its shiny new drain bolt.

What a day. Took off because it was supposed to be warm enough to get things done. Started with getting the cylinders ready, installed gasket kit o-rings after cleaning, then thread chased everything on the top end.

edwardmorris · « **Reply #880 on:** April 29, 2015, 08:40:06 PM »

Yamiya first overs, shiny new. Installed the rings, what a PITA the 3 piece oiler is

Lubed up the pins with plenty oil.

edwardmorris · « **Reply #881 on:** April 29, 2015, 08:41:33 PM »

Everything I could find NOS on the top end is here, all installed.

edwardmorris · « **Reply #882 on:** April 29, 2015, 08:44:10 PM »

All new dowels of proper height all around. Light copper spray on the base gasket and some hondabond near the cam chain tunnel and oil returns.

Then the pinnacle of stupidity.

DO NOT USE THE RING COMPRESSORS THIS WAY

edwardmorris · « **Reply #883 on:** April 29, 2015, 08:46:50 PM »

Quick phone call to Bill and all was back in order. All new dowel pins and o-rings up top followed by MLS head gasket (forgot pic) then torquing time!

edwardmorris · « **Reply #884 on:** April 29, 2015, 08:48:16 PM »

Advancer got new springs, shaft and o-ring. Lubed up and installed.

edwardmorris · « **Reply #885 on:** April 29, 2015, 08:50:25 PM »

High temp thread sealer to install cam tower studs. All done, then realized I installed the studs backwards

Removed, threadchased, acetone cleaned (some run off ruined engine paint, need to touch it up) then reinstalled the right way. All new dowels and o-rings.

edwardmorris · « **Reply #886 on:** April 29, 2015, 08:51:49 PM »

All new pucks, sealed and installed. Readied the NOS Cam and NOS sprocket.

edwardmorris · « **Reply #887 on:** April 29, 2015, 08:55:55 PM »

Lined up things as they need to be, then torqued down the towers to 80 in-lbs, and the sprocket bolts to 90 in-lbs. Looked at the time and realized its been 12 hours straight at this starting here

http://forums.sohc4.net/index.php/topic,126735.msg1677361.html#msg1677361

So covered it all up and came back inside. Totally forgot to take a pic of how it looks now

SOHC4 Cafe Racer Fan · « **Reply #888 on:** April 29, 2015, 09:16:45 PM »

NOS cam?! Where did you find that?

edwardmorris · « **Reply #889 on:** April 29, 2015, 09:22:03 PM »

Quote from: CB750 Cafe Racer Fan on April 29, 2015, 09:16:45 PM

NOS cam?! Where did you find that?

Frank/754 sold me his. Despite my sincerest efforts, I couldn't get him to sell me a NOS oil pump

(He has plans on using it with his 1000cc build). But thank goodness to Elan's super kits and some near new goodies from members here, the engine is ALMOST a NOSSER

SOHC4 Cafe Racer Fan · « **Reply #890 on:** April 29, 2015, 09:41:48 PM »

NOS oil pump is truly unobtainium.

evanphi · « **Reply #891 on:** April 30, 2015, 03:06:24 AM »

WOW some fancy stuff going on...

Your engine, if it could talk:

Restoration Fan · « **Reply #892 on:** April 30, 2015, 05:23:48 AM »

Wow. Just wow.
VERY impressive and the way you're documenting it is going to be invaluable to many people doing this after you. Thank you for taking the time to do that.

MCRider · « **Reply #893 on:** April 30, 2015, 11:57:51 AM »

Quote from: CB750 Cafe Racer Fan on April 29, 2015, 09:41:48 PM

NOS oil pump is truly unobtainium.

I have the nearest thing to a NOS pump in one I bot from Ebay with 7500 miles on it. Just popped the sides on it to do a Elan rebuild, and the rotors are nice and pristine. Why the rebuild you ask? Even with the low mileage it would wet sump the oil out of the tank into the crankcases in a matter of days. So even Frank's may need to be opened up and the rubber bits refreshed.

I think I'd install it first and see though.

Only New is truly New. Like the Cycle X one.

SOHC4 Cafe Racer Fan · « **Reply #894 on:** April 30, 2015, 12:10:22 PM »

Yeah, but that Cycle X one is PRICEY!!! Granted, if you are running a competition motor and you have huge sums of money wrapped up in your engine, you don't want your oil pump to fail and cause a catastrophic failure.

edwardmorris · « **Reply #895 on:** April 30, 2015, 01:19:59 PM »

Quote from: MCRider on April 30, 2015, 11:57:51 AM

Quote from: CB750 Cafe Racer Fan on April 29, 2015, 09:41:48 PM
NOS oil pump is truly unobtainium.
I have the nearest thing to a NOS pump in one I bot from Ebay with 7500 miles on it. Just popped the sides on it to do a Elan rebuild, and the rotors are nice and pristine. Why the rebuild you ask? Even with the low mileage it would wet sump the oil out of the tank into the crankcases in a matter of days. So even Frank's may need to be opened up and the rubber bits refreshed.

I think I'd install it first and see though.

Only New is truly New. Like the Cycle X one.

I was planning to rebuild it anyway had I managed to acquire it. Mostly wanted the untouched impellers and end caps. Came pretty close to it, found a set of impellers and end caps from member Godffrey here with super low miles and almost no wear on them. Have a pump with even fewer miles and better impellers saved for the K3, thanks to Bill Benton

MCRider · « **Reply #896 on:** April 30, 2015, 01:48:35 PM »

Nice scores. I do think we are all suffering from some misplaced paranoia. Other than the rubber bits, the rotors can get scratchy, but doesn't affect performance. And I've never heard of one failing. Under any circumstance. (Hmm I wonder what RC used?)
OCICBW

Nevertheless, fresh and pristine will always feel better.

SOHC4 Cafe Racer Fan · « **Reply #897 on:** April 30, 2015, 01:52:07 PM »

Not sure what RC Engineering ran on their bikes. It probably did not cost $750!

MCRider · « **Reply #898 on:** April 30, 2015, 04:23:13 PM »

Quote from: CB750 Cafe Racer Fan on April 30, 2015, 01:52:07 PM

Not sure what RC Engineering ran on their bikes. It probably did not cost $750!

My money's on stock. Maybe RC Jr can tell us someday.

edwardmorris · « **Reply #899 on:** May 01, 2015, 06:11:08 PM »

Question:

I forgot two things when putting the cases back together. The carb overflow tube guide and the electrical wire routing guide under the counter sprocket cover. Is there any danger in undoing and re-torquing just those two bolts? One's a 6 and the other's an 8 mm.

News:

Author Topic: 1972 CB750 Four K2 -- Rebuilt to NEW OLD STOCK -- PIX ON PAGE 50 (Read 278290 times)