Topic: 750 oil hose - rebuild

[72 yellow]

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.

So the 2 hoses I have (one on the 72 CB750) and the spare one that are pre-formed would be original from the factory ?  The crimps are both the same as on the picture above.

[Kickstart]

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...

My K3 hoses are from him, I can't remember his name. Very nice stuff.

It was edwardmorris  - He did a couple sets for me (one for the F0 and one for my K2 race bike)... and maybe a spare on top of that... can't remember.    

Looks like he hasn't been online since Dec 2019. 

[Don R]

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.

I do have good F0 and F2 hoses for a pattern if needed.   

[MauiK3]

I thought I had old hoses but I don’t.