Author Topic: 1972 CB750 Four K2 -- Rebuilt to NEW OLD STOCK -- PIX ON PAGE 50  (Read 247413 times)

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Offline Tews19

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #450 on: April 07, 2014, 01:13:50 PM »
I may have your battery box. If interested PM me buddy.
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #451 on: April 07, 2014, 01:24:31 PM »
I may have your battery box. If interested PM me buddy.
Thanks Nick, I already found a cheap one.

Offline timbo750

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #452 on: April 07, 2014, 10:29:34 PM »
I would like to know more about the strainer and the associated boat part as I have not heard this before. Mine too had crud stuck in it and it is now slightly damaged after removing.

Project 1 CB750 - http://forums.sohc4.net/index.php?topic=126864
This is where I read it, I suppose we need to page Hondaman on this one as I've had no luck finding it on any boat parts site. Maybe the part number changed?

http://forums.sohc4.net/index.php?topic=101408.msg1241884#msg1241884
I just ordered a new screen from Yamiya assuming they actually have it in stock. But usually when its not in stock they won't let you order it.

Project 1 CB750 - http://forums.sohc4.net/index.php?topic=126864


Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #453 on: April 08, 2014, 10:33:19 PM »
Cool. I tracked one down at a dealership in WI, but they won't ship via regular mail. I'm trying to find someone who can pick it up and mail it to me.

After two hours of frustration, I stopped trying before I destroyed the oil pump. I tried Jerry's method but the seal is so crappy it disintegrated completely after only a few taps and all that is left now is the metal outer ring, fully infused into the case. There's one approach, which is to drill behind the seal using carb bits, but I'd rather not do that unless it becomes necessary. Would a machine shop be able to mill/grind/cut it out of the cavity? My local machinist has been great with helping out on my project (yes, the same guy who screamed death when I said the words "motorcycle parts") and may not charge me my left kidney.

Offline Kickstart

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #454 on: April 12, 2014, 02:49:14 PM »
Are you talking about the shaft seal in the oil pump (the one that you have to order as a Gl1000 part)?  If so, I was able to get mine out by very carefully using a small blind bearing puller from my cheap HF blind bearing puller kit.  I tightened up the puller just enough to not slip out when hammering.  It took a lot of careful attempts.

Machine shop would probably be your safest bet though.
- Chris
75' CB750F Orange flake (rider)
75' CB750F Blue (Project)
75' CB750F Painted black (Project)
No Reserve Racing #171 AHRMA

Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #455 on: April 12, 2014, 03:53:53 PM »
Are you talking about the shaft seal in the oil pump (the one that you have to order as a Gl1000 part)?  If so, I was able to get mine out by very carefully using a small blind bearing puller from my cheap HF blind bearing puller kit.  I tightened up the puller just enough to not slip out when hammering.  It took a lot of careful attempts.

Machine shop would probably be your safest bet though.
Yup, that's the one. Eventually worked out though.

The shop out in Lowell IN, Midwest Accurate Grinding has the Blanchard Grinding Machine that Bill Benton pointed to earlier during the brake rotor discussion. I took the rotor there and fired in the dark, by asking if they had a way to get the seal out. They took a look and said they have a small milling machine that they don't advertise and offered to take care of it. Will be picking up both next  Friday (only time I have free), will post pix when  I have them here.

Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #456 on: April 12, 2014, 07:40:28 PM »
This just in from Marc AKA Powderman. I'm actually going to say I can't wait for Monday so that this can be on its way home  8)  The before pix are somewhere on top of this page, many thanks Nick for hooking me up with the correct MC and thank you Marc for doing your magic ;)



Here it is stripped and blasted and ready to coat:



And completed:




« Last Edit: April 12, 2014, 07:42:27 PM by edwardmorris »

Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #457 on: April 14, 2014, 04:41:06 PM »
No luck with finding anyone in the WI area to pick up the oil screen, so I kept searching, eventually tracked down a Honda dealership all the way out in UT that still had three of the oil screens left. I bought them all just in case someone needs them around here. Came out to $28 each with the shipping, but still much better than $42 shipped that Yamiya and eBay were asking. One thing that pissed me off though, is the way the packaged them  >:( I was hoping to see some nice red labels.

Another dealership in WV had some unobtanium left, NOS OILhoses! I don't know if I should put these on my bike or sell them on eBay to add to the project fund. What do you guys think? Yamiya has an aftermarket set for almost $450 shipped  :o If the originals are worth more, I could use the money on the project...but these would look sooo nice on my bike too  :-\

Edit: OIL hoses, not brake hoses  ::)
« Last Edit: April 14, 2014, 09:18:50 PM by edwardmorris »

Offline Powderman

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #458 on: April 14, 2014, 04:56:20 PM »
Your M/C went out today.

Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #459 on: April 14, 2014, 06:27:23 PM »
Your M/C went out today.
Sweet! Thanks a bunch!

Offline Kickstart

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #460 on: April 14, 2014, 08:54:56 PM »
IMHO, I wouldn't use the NOS brake lines unless they have a relatively recent manufacture date.

When it comes to braking you don't want to take any chances and I'd be concerned those brake lines may have deteriorated due to age.

- Chris
75' CB750F Orange flake (rider)
75' CB750F Blue (Project)
75' CB750F Painted black (Project)
No Reserve Racing #171 AHRMA

Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #461 on: April 14, 2014, 09:20:25 PM »
IMHO, I wouldn't use the NOS brake lines unless they have a relatively recent manufacture date.

When it comes to braking you don't want to take any chances and I'd be concerned those brake lines may have deteriorated due to age.
Sorry Chris, that was a mistake on my part, those are NOS OIL hoses, not brake lines. The packaging  has aged to $hit but the hoses look near perfect. I haven't torn them out just yet, not sure if what to do with them...

Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #462 on: April 17, 2014, 06:18:27 PM »
Some goodies returned today, the oil pump seal is out and the rotor looks amazing. Thank you Bill Benton for the Blanchard Grinding tip, less than 1/2 mm was taken off so its well withing spec. Made some time to clean up the hardware after stripping paint and a three day soak in evaporust.
« Last Edit: April 17, 2014, 06:22:04 PM by edwardmorris »

Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #463 on: April 17, 2014, 06:56:03 PM »
OK, so here are the stamped/scribed letters on the crank and the case.

Crankcase:      B B C C C
Crankshaft: J L A A B A A  P L 3 3 4 4

so did I read this chart right? My main bearings are (from left to right)

C (Green) C (Green) B(Brown) B(Brown) B(Brown)


Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #464 on: April 18, 2014, 08:53:04 PM »
And the rods. They all read 1.

Con. Rods:                             1 1 1 1
Crankshaft: J L A A B A A  P L 3 3 4 4

So if I'm reading this right, I've got all four D(yellow) ?


Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #465 on: April 20, 2014, 09:38:40 PM »
Wow, no input on the journals?

Oil pump is cleaned up, need to do some feeler gauge checks, but this is the worst of the wear spots. How does it look?

Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #466 on: April 20, 2014, 09:40:48 PM »
More

Offline HondaMan

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #467 on: April 22, 2014, 06:24:22 PM »
Those look pretty typical for these engines: the pumps make about 25% more flow than is even needed when new (hence the bypass valve at the pump). Even with 40% of the rotors torn out by events like a shattered piston (racing), they still put out enough oil flow to run well into the 9k RPM range all day. Back when we could get new pumps, I think I bought maybe 1? Today, I just replace the seals and, thanks to Elan, the oil stopper and spring, and make sure the tunnel where the stopper plunger sits is round and smooth so it won't stick open.

Honda made these pumps one-off, by hand, until the F0 bikes. Each one was hand-lapped to fit the rotors. Thus, the rotors themselves can seldom be "fixed" as we don't have their jigs. But, if a pump starts flowing low, the body can be disassembled and the lips of the covers milled back a few thousandths to decrease the internal losses, which then boosts the flow again. The scoring on the covers is where most of the losses come from, unless whole chunks are missing in the rotors. In that case, another pump is the best approach.

But those look fully adequate!
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

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Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

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Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #468 on: April 24, 2014, 04:57:29 PM »
Thanks Mark, for the insightful help. I'll leave these be until reassembly.

Turns out my carbs are a complete disaster. Details here

 http://forums.sohc4.net/index.php?topic=136518.0

waiting on a correct set to arrive from Mr. Benton (this guy is amazing!). I suppose I'll try and fix up the bad set and sell it eventually, but for now its back to the loooong to do list of things. Hopefully some progress and an update this Sunday.

Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #469 on: April 24, 2014, 11:01:04 PM »
Separated carbs. Short version on the franken carb story is that my #2 is not the right one, but the other three are correct. Will clean out the internals this Sunday to see if the jetting is right.

Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #470 on: April 24, 2014, 11:04:27 PM »
I've listed some goodies for sale to help the budget, PM if you want any of it.

Like New condition webcam 41-a
Battery box + electrical panel ready for paint/PC
NOS OEM Oil pump screens

Offline Garage_guy_chris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #471 on: April 25, 2014, 10:16:39 PM »
Ive never seen that info and part numbers for rebuilding the oil pumps?  Im glad i stumbled across it because i would like to refresh my pump.  Where did the part numbers come from as any parts diagram i have seen show the pump as a unit and no break down on internal parts.
1971 Cb450 Cafe  (on the road)
1974 Cb750 Restomod (on the road)

Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #472 on: April 25, 2014, 10:26:35 PM »
Ive never seen that info and part numbers for rebuilding the oil pumps?  Im glad i stumbled across it because i would like to refresh my pump.  Where did the part numbers come from as any parts diagram i have seen show the pump as a unit and no break down on internal parts.
#8 here

http://www.motogrid.com/pages/OemParts?aribrand=HOM#/Honda/CB750K2_A__MOTORCYCLE%2c_JPN%2c_VIN%23_CB750-2000001/OIL_PUMP/CB750K2-JPN-A/2Y143410E14341015B

Its still not a complete breakdown, the rotors aren't listed anywhere because they were one offs made by Honda.

Both my spares are sold though.

Offline Garage_guy_chris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #473 on: April 25, 2014, 11:20:16 PM »
Ive never seen that info and part numbers for rebuilding the oil pumps?  Im glad i stumbled across it because i would like to refresh my pump.  Where did the part numbers come from as any parts diagram i have seen show the pump as a unit and no break down on internal parts.

Sorry i should have been more specific. I meant Ive never seen a parts diagram that show the shaft seal in the middle and the two outer o rings.

2) outer o-rings   91305-426-003
1) shaft seal        91208-MN1-771
4) o-rings             91302-377-000


For the shaft seal is it a direct fit part,  a week or two ago i read Hondaman saying the shaft seals were a no-go and the closest part requires machining of the seal bore in the housing ?
1971 Cb450 Cafe  (on the road)
1974 Cb750 Restomod (on the road)

Offline edwardmorris

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Re: 1972 CB750 Four K2 -- Project "Ice Cream"-- ENGINE TEARDOWN
« Reply #474 on: April 25, 2014, 11:32:29 PM »
Ive never seen that info and part numbers for rebuilding the oil pumps?  Im glad i stumbled across it because i would like to refresh my pump.  Where did the part numbers come from as any parts diagram i have seen show the pump as a unit and no break down on internal parts.

Sorry i should have been more specific. I meant Ive never seen a parts diagram that show the shaft seal in the middle and the two outer o rings.

2) outer o-rings   91305-426-003
1) shaft seal        91208-MN1-771
4) o-rings             91302-377-000


For the shaft seal is it a direct fit part,  a week or two ago i read Hondaman saying the shaft seals were a no-go and the closest part requires machining of the seal bore in the housing ?
Oh that, I just bought the super kit from Elan. Had everything but the screen and the gasket for the pump body.