Topic: My 1977 CB750F2 restoration - UPDATE July 24, 2019 - Oil leak fixed?

[kap384@telus.net]

Made a 50 mile round trip after work today to grab some shots.  Here are some of the better ones:

[DanielB]

Great job, very nice.

[kap384@telus.net]

Great job, very nice.

Thank you

[kap384@telus.net]

Heading off to parents farm in a few hours so I'm closer the the hand-off point for GZ tomorrow.  Almost 500 miles planned today.

[lucky]

Looks very good!
Good workmanship too.

[Mayor08]

Very Nice!

[vozzy]

Your old man should be proud. . . Looks sweet!

[kap384@telus.net]

Thanks everyone!!

[kap384@telus.net]

So, noted a little oil consumption last year, and after a warm-up run this spring, a small stain started on the floor.  As leaking oil is not a Honda hallmark, I ventured to find the source.  Drip was coming off the bottom of one of the header pipes, but tracing it back, the drip was originating from the bottom of the lower dry sump oil line on the engine.  The fitting was dry, so that's not the source, but my homemade oil line is wet


I notice the top of the line is damp up at the oil tank.  Not nearly as wet as at the bottom, but that could just be gravity wicking all the leak to that point.  Peering in behind the oil tank, I see lots of oil wetting.  So off with the rear tire, back fender and inner fender:



Source not obvious to me yet, will do further digging tomorrow.  Looks like top side of condensation chamber perhaps.  Maybe I plumbed incorrectly or simply a leaking hose or fitting.

[kap384@telus.net]

Well, I'm hoping its the return line at the tank.  I won't be able to tell for sure until I pull the feed line so I can get a wrench on the return line to tighten.


The valve cover line to the condensation chamber was really brittle and not sealing as well.  I'll tighten it up too, but I'm pretty sure it's not the majority source or I think it would mean my rings are shot with that amount of blow-by!

[kap384@telus.net]

Was able to get maybe 1/4 turn (maybe less) out of the return line.  Hopefully that's the fix.  Finish buttoning it up tomorrow.  Will take it for a rip as soon as the skies quit opening up here.

[piute]

 Tryed to read all from the start ,Great job ! I'm real happy with the chouice of the F2 and not going Cafe as lots of "K" model owners do,The more I see your bike the more I like mine there the same and you kept it stk.My F2 was nice stk. but decided to make it my own and bagg's with Fairing, maybe your Dad would appreciate that ? The p.o. Dead dropped it on right side so dents and bent .Left side was great (pic.)till I made the changges of a few different paint Ideas.Keeping the last (pic.)have a charging prob now.
 Getting bags on and have few different fairs to try .
   Your build has made mine look A lil dirty,Being a painter It's all in the details,And going Blk. Powder coat will help most come winter(most just ceramic paint now)

[kap384@telus.net]

Will be good to see photos once you have bags and fairing on

[piute]

       Have baggs mounted ,(faring bracket needs modified a bit.
      working on wiring(cust.plug)and patch N paint.(just old stuff
          Also should have this by end of week,To pull dog trailer

[kap384@telus.net]

Good looking' shepard.  Those Bates bags?

[tweakin]

Hope it all works out Kap...  Keep us posted.

[piute]

  SORRY,
don't mean to run blocker on your build,Just not used to see these F2 around anywheres but here. I don't know what kind of Ole baggs theses are,just new what i wonted and Shinyribs on Nabbles750 turned me onto them.Got damn lucky.Was excactly what I wonted.
  Back to your build So whats your next step ?

[kap384@telus.net]

Assuming I have the oil leak fixed (Test run in an hour or so), the only real nagging items I have are getting my nice Frankenstuff replacement side covers painted to perfectly match the original tank and tail complete with new emblems, and pop off and refinish the tank emblems.  Then I'm saying I need to focus on the next project.

[kap384@telus.net]

Put 70 miles on last night and whatever was leaking is worse than before    Whole right side of the bike is wet!!!  Gonna sleep on it and investigate tomorrow.

[tweakin]

Put 70 miles on last night and whatever was leaking is worse than before    Whole right side of the bike is wet!!!  Gonna sleep on it and investigate tomorrow.

That sucks Kap.  You mentioned you tightened your oil lines, make sure there is not a crack where the bung is welded into the oil bag.  I overtightened one once and the oil bag started leaking.  Good luck.

[kap384@telus.net]

Yep, certainly thinking the same thing is possible as it's one of the only 2 things I materially changed (tightening the lines and siliconing the valve cover vent onto the condensation chamber as it was loose and has some vapor leakage)

[kap384@telus.net]

Replacing all of the dead Photobucket links.  Piss me off.  Highway robbery.

[kap384@telus.net]

So, being the 50th anniversary of the CB750, and having a local vintage motorcycle gathering in Ponoka, Alberta celebrating it, I thought I'd get my act together and address the oil leak on my 'F' and hopefully ride it on the 350 mile round trip to the show.  It's been 7 years of breaking a leg, changing jobs, building a house, collecting more projects and racking up the miles on my Africa Twin (5 States and 2 provinces including Alaska this year already).


If you followed forever ago or if you are new, long story short, I restored my parent's 1977 CB750F2, completed a leg of the Godzilla run, but then developed an oil leak that I couldn't easily pinpoint.  Problem was, I'd fabricated my own oil lines as no new ones were unavailable and the originals were seeping oil right through the rubber.  Seemed like a good fix initially.  New o-rings on the engine connections when I installed them.  40 years ago my Dad had brazed the bottom of the oil tank, which I then powder coated. A potential source if that had cracked. Long story short, even pulling the rear wheel and the inner fender, it was hard to find the actual leak source as the oil was just collecting on the hoses at the low point by the engine.


I had intended to replace my oil lines with ones from Cycle X, but they were out of stock last month.  Then I discovered that CMSNL has re-manufactured oil lines for my bike.  So I ordered those, new o-rings, a new oil tank drain bolt and new washers for the drain bolt and tank ends of the hoses.  Wait!  Aluminium washers in the tank ends of the oil lines!  Whoops, I was missing those! Also, the drain bolt was worn and beat with an integral sealing surface that didn't look great.  Thinking any or all of these were my source.  Regardless, my plan was to replace every oil wet sealing or oil carrying component on the bike.  Good news, Dad's brazing was fine and the tank is good.


New hoses look great a VERY close to original.















My old lines went to the garbage





My old oil line, tank end, and no sealing washer as shown in the parts fiche.





Aired up, leaky carb addressed, fresh oil and fuel, bled rear brake and adjusted chain.  Vintage plate and test ride today to hopefully prove road worthy for Saturday.

[kap384@telus.net]

Had a slight weep from 1 line.  Discovered that I hadn't actually tightened as much as I wouldn've liked, but rather my wrench was bottoming on the frame.  Went in with a different crescent and got another ⅔-¾ rotation.  Fingers crossed that did it.  Find out tomorrow!

[majorzozo]

Hey Kap,

I know this is an old post but just wanted to say beautiful job.  I am restoring a 78 750F and can only hope it turns out half as nice.  Yours looks brand new.  Hope you are enjoying it...