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Thread: 1978 GS750, Saving a strange project..

  1. #21
    Join Date
    Jun 2013
    Location
    MA
    Posts
    367

    Default

    If it were me I would wait on dipping the gas tank in vinegar until you're ready to put gas in it so that it doesn't re-rust. They become very susceptible to flash rust (within 30 mins) after removing the vinegar and then you're probably going to have the gas you fill it with sitting there for months until you have the bike ready at which point you would probably want to flush it again and use fresh gas when you're ready to start it up.

    PS you can get a gallon of apple cider vinegar from most grocery stores for around $1.50 so that's what I've used for doing.


    Your carbs are VM type, in other words mechanical slides instead of the vacuum controlled slides with rubber diaphragms. If I understood you correctly, the `brass cylinders' are the slides and the gaps you see underneath them is normal. The gap controls the idle. All four are adjusted together by the idle screw and there is also a screw underneath each carb that varies the height for each individual slide. Once your carbs are dipped with new o-rings, etc. you'll want to sync them by adjusting the individual screws so that the slides are opening the exact amount in unison.
    Last edited by sam000lee; 04-21-2017 at 08:50 AM.
    1980/1981 GS450 Beater
    1977 GS750 - Fixing up to tour on 2017
    1977 CB550F SuperSport

  2. #22
    Join Date
    Sep 2015
    Location
    Maine
    Posts
    26

    Default

    http://www.thegsresources.com/_forum...iring-diagrams

    If you're going to make a new wiring harness, this thread with colored wiring diagrams might help you. The author includes a diagram of a 78 750's stock wiring, plus a diagram with relay modifications. I did the coil, headlight, and horn mods. Your bike has spoke wheels and a single front disc, which usually means a 1977 model. I think the wiring is the same as a 78 though.

    Stock carburetors are VM26s. There is a good tutorial for rebuilding VM carbs on BikeCliff's site. And there is a great chart for GS carbs and their jets and settings somewhere on this site. I'll look for it.
    K.

    1978 GS750E
    1981 KZ440D

  3. #23
    Join Date
    Sep 2015
    Location
    Maine
    Posts
    26

    Default

    K.

    1978 GS750E
    1981 KZ440D

  4. #24
    Join Date
    Apr 2017
    Location
    Texas
    Posts
    16

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    Quote Originally Posted by gwyon View Post
    Thanks for that sir! I had been skimming through the Red Carpet welcome, but didn't dive too far into it as I wanted to get the carbs out first, to try and dip and clean them before I worried about rebuilding. Since the bike came with pods, and I prefer the look of, I am going to get some K&N ones and then jump to the tweaks other pod users have had to do here (in regards to needle and jets, ect). But all of that post cleaning and damage assessment.

  5. #25
    Join Date
    Apr 2017
    Location
    Texas
    Posts
    16

    Default

    Good to know about the flash rusting, I wasn't aware that it would happen so quick. Guess I will hold off on that, and focus mainly on the exterior first. The visible area should clean up, its the underside that Im a little worried about.

    As for that digital counter, it does seem to fit your dimensions, but the guy had it hidden under the tank and like I said, there is some sort of corrosion looking stuff all around the wiring of it. Itll get trashed when I finally get to the electronics road at some point..

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