'78 GS750/1000 swap resto-mod shenanigans

[HemoGoblin]

Hello! I got my first GS about 2 years ago that I sold because I learned what an "L" was. I couldn't have that. Anyway, I took on a $50 '78 GS750 that I wanted to restore. I don't want to do a factory-perfect restoration, but mods will mostly be limited to updating and improving where needed/desired.

This project was started a month ago in august so there's a lot to catch up on here... The main chapters include:

Acquiring a ROUGH '79 GS1000 because I decided to do a 1k swap as soon as I found out it was possible. I know the 16v 1100 is a more effective swap but I wanted to do an 8v 1000 for ease of swap. So far it has not been easy and I wish I had held out for an 1100 anyway, but more on that later.

Rebuilding the front brakes. New MC, SS lines, and rebuilt calipers.

Coil Relay mod

New plug Caps

750 Carb rebuild (in accordance with the PDF from BikeCliff, don't worry)

Fabricating new mounts for the 1k swap.

Today I pulled the forks on the 750 apart for a rebuild with Sonic Springs and new springs, but unfortunately, one tube is horribly chipped and corroded. This turned into tearing into the 1k forks to see how difficult the swap would be. Not looking optimistic as the bottom part of the neck is too narrow to accommodate the roller bearing that was used on the 1k.

I think that's the bulk of it. I'll upload pics with more descriptions of each individual project below.

Let's start with a picture of the bike. I'm new to posting in forums so be patient with my formatting and photo uploads.

I'll have to find a picture of the 1000 when I first got it because It was hilarious. Nasty King and Queen seat, huge highway pads, shift linkage, 4 sets of footpegs, a better jammer, cargo box on the back, and a bunch of other strange alterations. None of which were done particularly well IMO but thankfully the engine is healthy enough, turns over great, 120psi compression across the cylinders. All the carbs are present and accounted for, but I'm missing the rear half of the airbox which goes under the seat and holds the air filter (IF ANYONE IS SELLING, I'M BUYING).

This was a weird one. When I was first getting the 750 fired up, the pipes were super clogged with sh!t. seeds and weird stuff from mice and squirrels from sitting outside. The engine blew most of it out, but it was only firing on 3 cyl. I pulled the headers off and could the 3rd cylinder was CAKED up into the head with what looks like melted carpet foam. It was so hard I was carefully chipping it out of the head with a screwdriver! Never seen anything like it. The 750 engine also comp tested at 80 psi or less, so I'm glad I'm doing the engine swap in the long run. I know rebuilding the top end is fairly easy but I wanted to do the swap regardless.

Here's me when I first got the 1k engine out. I was very excited lol

Here is one of the rear motor mounts I made, after a couple of attempts, it finally came out clean, and lined up just like I wanted it to.

Finally, here is my busted fork tube. If anyone has any ideas of where to take the front suspension, I'm all ears. swapping the forks from the 1000 doesn't seem feasible (or at least worth it). Torn between buying replacement tubes for the 750 or looking into more modern swaps. I've seen the Bandit front-end swap done, but that's usually into a 1000 frame if I'm not mistaken.

Please excuse the Instagram captions on some of the photos lol

 

[Rich82GS750TZ]

Please follow the link in my signature for instructions on how to use Imgur to post more and better quality pics in a single post, by copying and pasting the BBCode. It’s a fun build your doing, but would be much easier to follow without having to click on each picture to view it.

 

[HemoGoblin]

Will do, thanks Rich. I've done it successfully before but couldn't get it to work this time. I'll check it out.

 

[Rich82GS750TZ]

That’s what I’m talking about. Much better.

 

[rphillips]

Yrs. ago I put a 4V 1100 eng. in a GS1000 and only needed to alter 1 eng. mount, all worked fine. Like what you're doing, will be following...Also saw you had 4 sets of pegs, Chuck is looking for one peg for his GS1000 in the wanted section. You may could help a fellow member out... Just a thought.

 

[HemoGoblin]

Hey rphillips, good to know, Ill send him a message! Im actually swapping the 1K into the 750 frame. Ive had to fabricate 5 out of 7 mounts so far lol. I wanted to build out the 1K into a Wes Cooley bike but unfortunately the title is gone. Last titled to an old man with dementia who cant find it I feel this is the best way of giving it life, but I dont think the 1K will be in their for very long. I want to swap in a 16v 1100 as soon as I can afford/find one. I really want to get into hot rodding these engines, cams valves etc. thanks for your interest!

 

[chuck hahn]

by all means contact me if you want to sell footpegs

 

[Rob S.]

First pic: That's a proper motorcycle! Can't say I approve of the highway pegs (or the crash bars). You could probably just use the crash bars themselves for a little stretch to avoid cramping on long rides. (I just use the engine itself.)

Second pic: Seat appears well worn. Buff it out, then get some Armor All on it ASAP.

Good luck, and welcome to the site!

 

[rphillips]

Wheew, glad you got the pictures sorted out, Waaay better. Hoping bike turns out the same...

 

[HemoGoblin]

Hello, quick update.

Since I last posted I have rebuilt the front end. I ordered new tapered bearings (25/48/12 upper, and 30/48/12 lower) so I could install the thou forks onto the 750. The thou forks were in much better condition, and they are 2mm bigger, so a win all around. I did have to add a spacer under the top nut (about 1cm) to accommodate the difference in tree lengths, but it turned out great.

I polished the fork tubes using 600grit, 1200, then buffing wheel. New seals and dust caps. Sonic Springs and Racetech emulators are next, when I can afford them. For now stock will have to do. 20w oil in the forks as recommended by my local old-school performance bike guy. (I'm a heavy boy)

Painted the frame with Rustoleum gloss enamel. Its not very durable, but it does withstand chemical well. The frame will be sent off for powder coating some day, but I have time and paint, not money, so I wanted to do something to spruce it up and neutralize the rust. frame was cleaned with degreaser, scrubbed thoroughly, then scuffed with scotchbrite, and used naval jelly on any rust spots. Degressed with alcohol and primed with same rustoleum primer, then paint.

Currently trying to get my wiring harness sorted out, as the old owner chopped it up good to add his Vetter. Shouldn't be too bad. Also trying to get the old Turn Signal Control Unit operational. Having auto-cancel blinkers on a 40 year old bike is neat to me.

Thou carbs have been soaked an rebuilt.

Painting the wheels is next, then putting the engine back into the frame + wiring. I need a good deal of bits and bobs to get the engine working properly like valve cover gasket, carb holder O-rings, ail filter etc. But money money money...