1978 GS750, Saving a strange project..

[DirtDiver]

I don't have the tools to do a real test of the compression or tuning, so when I get to that part I'll need to take it to a shop. I got busy with work stuff over the last few days and time in the wind tunnel for some of my jump school stuff, so I haven't gotten to yank out the carbs yet. That happens today though since I've got the day off.

Plan of the Day:
Carb Removal- Strip, Dip
Gas Removal- Maybe soak it in vinegar as another member suggested. I want to make sure its clean as can be
Oil Drain - There doesn't appear to be anything in the reservoir, but Id still like to drain it so when I get to the engine, that portion is taken care of.
Battery Removal - Thing is going to get junked


Question though..

I don't have a bike lift, but is there a guide or suggestion of how to support the frame, and remove the engine without total destruction and chaos ensuing? I've seen some guys use those quad stand jacks and some sort of ratchet straps, but is that a good way to go about it?

[DirtDiver]

BEHOLD!!! More photos to share of this wonderous strange thing.. And in the great awe inspiring words of former NY Governor candidate, Jimmy McMillan (If you don't know this awesome guy, look him up, legendary facial hair), the use of Electrical Tape, Zip Ties, and Tom ****ery is too damn high!

So I took off my carbs, no idea if I'm dealing with CV or VM yet though - Soon to come I guess. In some respects they look clean, though it may not show up in the pics well. In other respects, they are grimey, and in need of a soaking. Also it looks like there is some gapage with the (floats I think, still learning names, brass colored cylinders), not sure if they are supposed to sit all the way down or not. But gaps appear on all 4 carbs. I think someone ran some seafoam at some point as slight green colored liquid came out from sections when I drained them. Some oil or black liquid came out, and then obvious clear fuel. It was a wonderous swirling fountain when I tipped them to drain.

I also drained out the tank via the fuel line attached to petcock. The good news, the fuel was normal coloring, no chunks or visable grit came out, and in the gas can nothing seemed to have built up like a slurry. The bad news, some decent rust on the under belly. Shouldn't be anything to crazy to clean up.

Trashed the little cute pouch hipster bob put on the bike, along with the chunked up rear fender plastic thing, and the head lamp with what I think was pipe wrap to help secure his tension brackets. Removed the battery for now, was going to toss it, but considering I may need it between now and acquiring a new one, I decided to stow it away. Some decent corrosion on the mounting brackets and battery box thing, but the battery it self seemed fine.

After getting a solid view at the wiring, I have solidified my choice to just redo the entire electrical work since its looking nightmarish. How do you like that dead man switch? Pretty high speed huh? I mean, last owner has pretty much proved he loves eating lead paint chips and licking windows.

All in all though, despite being a disaster zone, its pretty damn fun to go tinkering around with this thing.

[DirtDiver]

[DirtDiver]

Oh, and I definitely have no damn clue as to what that lil square thingy is that shows .8 on it. There is no power at all coursing through the wires since the battery is removed. What I do know is there is some sort of bubbly yellow crusty stuff all over the wiring cluster near it. So, I can only assume its bad joo joo and must be destroyed with fire.

[1978GS750E]

I think you may be talking about the gear indicator. It's about 3/4" wide X 1" tall indicator that was originally in the instrument cluster. Finding one that works is a rarity! It should change numbers as you go thru the gears and will be connected to a sensor that is mounted near the front sprocket.

[sam000lee]

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.

[gwyon]

http://www.thegsresources.com/_forum/showthread.php?193730-Colored-wiring-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.

[gwyon]

Here it is, from Chuck Hahn:

http://www.thegsresources.com/_forum/showthread.php?229045-77-gs750-jet-size

[DirtDiver]

Here it is, from Chuck Hahn:

http://www.thegsresources.com/_forum...gs750-jet-size

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.

[DirtDiver]

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..