Author Topic: 750 oil hose - rebuild  (Read 2492 times)

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Offline HondaMan

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750 oil hose - rebuild
« on: June 20, 2021, 08:34:25 AM »
OK, now that I am not employed...
...about 10 years ago I bought the crimper, crimp rings, and some [metric] hydraulic hose to make oil hoses for my 750. But then things got so busy I never had time to tinker with it to make them correctly, etc.

Does anyone have some old and leaky oil hoses (or even cracked-open ones) with the end pieces on them that you would like to try having rebuilt? I have 2 or 3 sets to experiment with, then will probably offer it as a service to help support this forum, like the other gizmos I make.

I have to figure out some sort of pressure-tester jig so they can be tested after being crimped back together.

Most of the time it is the inner (return) oil hose that weeps, and I have most often seen this at the engine's end.
See SOHC4shop.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
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Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

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Offline Don R

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Re: 750 oil hose - rebuild
« Reply #1 on: June 20, 2021, 09:05:01 AM »
 I have a set that got pressure washed a little too good, I'd go for a rebuild. I'll check my spares too. 

  Edit, I found a nice set so I can swap them to my bike that needs attention now and another pretty yucky set that are loose already so I'll get the one set swapped out asap.   Long story short, plan on two sets for me.   
« Last Edit: June 22, 2021, 08:31:25 PM by Don R »
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Offline seanbarney41

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Re: 750 oil hose - rebuild
« Reply #2 on: June 20, 2021, 04:02:45 PM »
yeah, I got some crusters that I could send.  Several years ago there was a member in the Chicago area having these done and I always meant to have some done.  But then I never got around to sending them and he is long gone.  I have forgotten his name, which is terrible, since I met the fine fellow in person more than once.  He was using braided stainless hose as a sort of upgrade.  How original looking is the hose you intend to use?
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Offline BenelliSEI

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Re: 750 oil hose - rebuild
« Reply #3 on: June 20, 2021, 04:09:29 PM »
I have 3 or four sets. Let me know if you want me to send them in! John D.

Offline MauiK3

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Re: 750 oil hose - rebuild
« Reply #4 on: June 20, 2021, 06:39:08 PM »
I’ll look in my stuff to see, glad to help.
1973 CB 750 K3
10/72 build Z1 Kawasaki

Offline HondaMan

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Re: 750 oil hose - rebuild
« Reply #5 on: June 20, 2021, 07:00:19 PM »
I'll take a shot of the hose and crimp rings I have to post here.
See SOHC4shop.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

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
Link to My CB500/CB550 Book: https://www.lulu.com/search?sortBy=RELEVANCE&page=1&q=my+cb550+book&pageSize=10&adult_audience_rating=00
Link to website: https://sohc4shop.com/  (Note: no longer at www.SOHC4shop.com, moved off WWW. in 2024).

Offline stocky

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Re: 750 oil hose - rebuild
« Reply #6 on: June 20, 2021, 11:10:08 PM »

Most of the time it is the inner (return) oil hose that weeps, and I have most often seen this at the engine's end.

This is exactly where mine was leaking, was driving me nuts so finally decided to drain all the oil and replace the hose just this past week. Looked around locally for someone to rebuild but wasn't really successful and the ones I saw online were fairly pricey, so decided to try DIY.

Here's a pic of the stock crimped one next to the one I made.



Haven't gotten it back on the bike yet, so I can't be sure it won't leak just yet but a simple low pressure test in the water gave me enough confidence that it should hold up just fine.

Offline HondaMan

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Re: 750 oil hose - rebuild
« Reply #7 on: June 21, 2021, 01:11:21 PM »
Picture?
See SOHC4shop.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

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
Link to My CB500/CB550 Book: https://www.lulu.com/search?sortBy=RELEVANCE&page=1&q=my+cb550+book&pageSize=10&adult_audience_rating=00
Link to website: https://sohc4shop.com/  (Note: no longer at www.SOHC4shop.com, moved off WWW. in 2024).

Offline stocky

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Re: 750 oil hose - rebuild
« Reply #8 on: June 21, 2021, 08:53:39 PM »
Picture?

ill try attaching instead of inserting img.

Offline Squiddog1

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Re: 750 oil hose - rebuild
« Reply #9 on: June 22, 2021, 06:30:21 PM »
I have a set I can send.

Offline Stev-o

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Re: 750 oil hose - rebuild
« Reply #10 on: June 22, 2021, 06:45:01 PM »
Hey HM... there was a member here a couple years back that was rebuilding them, and they looked great. I called him Mo, cant recall his forum name.

He would refinish the fittings and use SS hoses, he did a couple sets for me, he had an exchange program.

I have an old set that I would like rebuilt if you could do them like this...


'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline MauiK3

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Re: 750 oil hose - rebuild
« Reply #11 on: June 22, 2021, 08:10:51 PM »
My K3 hoses are from him, I can't remember his name. Very nice stuff.
1973 CB 750 K3
10/72 build Z1 Kawasaki

Offline PeWe

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Re: 750 oil hose - rebuild
« Reply #12 on: June 22, 2021, 10:23:41 PM »
Black braided hoses looks nice.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Don R

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Re: 750 oil hose - rebuild
« Reply #13 on: June 24, 2021, 06:43:15 PM »
 I swapped a nice set to my Gold K0 so I have two loose pair now.   Gave me an excuse to get busy, I re-used the o rings since they were still pliable and thicker than what was in my metric kit.
No matter how many times you paint over a shadow, it's still there.
 CEO at the no kill motorcycle shop.
 You don't need a weatherman to know which way the wind blows.

Offline 72 yellow

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Re: 750 oil hose - rebuild
« Reply #14 on: June 25, 2021, 08:32:55 AM »
Why did Honda use the molded hose on one ??

Offline Don R

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Re: 750 oil hose - rebuild
« Reply #15 on: June 25, 2021, 09:40:48 AM »
  I haven't  noticed molded hose on any of mine. It might be a pressure/suction difference. Maybe an old repair?
  I'm going to clean mine up today so they will be ready to send.
No matter how many times you paint over a shadow, it's still there.
 CEO at the no kill motorcycle shop.
 You don't need a weatherman to know which way the wind blows.

Offline 72 yellow

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Re: 750 oil hose - rebuild
« Reply #16 on: June 26, 2021, 12:38:00 PM »
  I haven't  noticed molded hose on any of mine. It might be a pressure/suction difference. Maybe an old repair?
  I'm going to clean mine up today so they will be ready to send.
Interesting.  Both the ones on my 72 CB750 and a set I bought off e-bay had the molded hoses.  Both look like factory crimps.  No idea if they are original.  The parts book shows straight for both.  Another mystery.

Offline seanbarney41

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Re: 750 oil hose - rebuild
« Reply #17 on: June 26, 2021, 12:49:24 PM »
I always assumed they started out straight/unmolded.  Then endless heat cycling and their cramped routing ended up causing them to take a permanent shape.
If it works good, it looks good...

Offline 72 yellow

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Re: 750 oil hose - rebuild
« Reply #18 on: June 27, 2021, 11:39:08 AM »
I always assumed they started out straight/unmolded.  Then endless heat cycling and their cramped routing ended up causing them to take a permanent shape.
Would the cramped routing cause the hose to crimp and restrict flow ??  Still curious.

Offline bryanj

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Re: 750 oil hose - rebuild
« Reply #19 on: June 27, 2021, 12:21:54 PM »
Back in the 70's there was a bad batch of hoses that caused oil starvation and cost Honda, at least in UK, quite a few engine rebuilds with cranks, shells and rods. Where we all learned to read crank markigs
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline PeWe

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Re: 750 oil hose - rebuild
« Reply #20 on: June 27, 2021, 12:37:13 PM »
Too long hose that got a knick when mounted?
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline bryanj

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Re: 750 oil hose - rebuild
« Reply #21 on: June 27, 2021, 03:05:56 PM »
Brand new out of the crate bikes, i believe the hose itself was faulty
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline Hoosier Honda

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Re: 750 oil hose - rebuild
« Reply #22 on: June 27, 2021, 05:01:27 PM »
I have a set for rebuild also once you are up and running with it and have a price.

Offline HondaMan

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Re: 750 oil hose - rebuild
« Reply #23 on: June 28, 2021, 08:27:42 PM »
I'm currently looking for some springs to insert inside the hoses. Since these are simple hydraulic hose they could possibly kink (like the OEM ones did in the early Brit bikes, noted by BryanJ - I remember hearing of that, never saw it myself) which would be bad...racers I knew were installing springs inside the suction-side hoses because of one experience with a LeMans start race when the pit crew had used straight 40W oil, thinking it was better than hot 20w50 on race day. The rider got partway thru the first lap with a pretty cold 750 (it had not been run in qualifying laps) and the oil light came on for a few seconds at redline speeds: at the end of that race the bike still ran, but noisily. Later that year in teardown they found one or more 'spun' bearings. But hey, the bike ran the rest of the season with 20w50 oil!

I have also seen several 'collapsed' oil lines (suction side to the pump). One was (is, it's still in my box-o-lines here, awaiting rebuild) obviously folded near the lower connector, probably because the engine was put into the frame (during rebuild) with the lines attached and the lines were wrestled past the frame afterward. This broke the inner liner. Another (suction) one has the inner liner letting go of the body of the hose, forming a 'flap' that would close the hose partially when the oil was hot, making the liner more flexy. The symptom was that after warmup the oil light would come on above 4500 RPM pretty reliably, and when a gauge was added to the main journal the pressure could be seen to drop as the RPM raised, perfectly backward! That one puzzled me for quite a while, so I kept the hose to remind me: now it will be one of the first new ones!

Back in their day, these hoses came pre-formed from Honda. This will make me puzzle over their length a bit. Also, the feed hose for the post-1975 "F" and K7/8 bikes are different from the early ones, have to find one of those sets, too. The end fittings changed on it and the length was slightly longer, IIRC.
See SOHC4shop.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

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
Link to My CB500/CB550 Book: https://www.lulu.com/search?sortBy=RELEVANCE&page=1&q=my+cb550+book&pageSize=10&adult_audience_rating=00
Link to website: https://sohc4shop.com/  (Note: no longer at www.SOHC4shop.com, moved off WWW. in 2024).

Offline Don R

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Re: 750 oil hose - rebuild
« Reply #24 on: June 29, 2021, 10:05:13 AM »
 I'll check to see if my F0 oil tank has the hoses attached and their condition. My plan was to combine an A frame with a wrecked F to make a drag bike frame.
No matter how many times you paint over a shadow, it's still there.
 CEO at the no kill motorcycle shop.
 You don't need a weatherman to know which way the wind blows.