1977/80/82 GS550 Project - cafe tracker thing

[nerdsports]

So my father in law wanted a motorcycle and came to me to put it together for him. I had a 1980 GS550 whole but no title and the engine/tranny were shot. I had been contacted by a guy a few hours north of me that had an engine but also had a frame with a title. We made a deal and I picked up the engine and frame.


The bad news was the frame had a hackjob of a hardtail welded on.

It was going to take a lot to get the swingarm pivot area cleaned up...

So I ended up cutting both frames in half in the engine cradle area.

Not having a lathe, I am fortunate to have a friend that's a machinist by trade. Got slugs made for the frame rails.

Tacked together.

I am also working on my brother's 1977 GS550 and have changed damn near everything on it so I'm reusing a lot of stuff off his bike. Here I have mounted the 77 GS550 tank (they have different mounting points) and cut off some of the rear frame.

Cut back the shock/frame gusset to weld on a seat hoop.

Tacked on the seat hoop.

Kicked up the seat hoop and threw on the 77 GS550 front end. Don't mind the rear end, it's from the 80 GS550.

My father in law asked for bars that were comfortable (ie he didnt want to be throw over the tank with clipons or clubmans).

 

[nerdsports]

Mounted the tail light & license plate bracket.

How it sits at the moment.

Made the seat pan and added mounts. I should be foaming it this afternoon.

Used silicone bronze to weld up the tank badge mounts. Throwing bondo over the area will only lift it and bubble the paint at some point.

Used the ol' yoga mat seat padding & shaped it.

Started working on blending in the frame/shock mount gusset.

Laid out the template for the electronics tray.

Mocked it up and arranged the components. It's roomy because there will be a good amount of wiring passing through. I didn't want to clutter it up too much.

Here's a side shot. I'm using circuit breakers instead of a fusebox.

 

[nerdsports]

Welding up the electronics tray. Using 1-2-3 blocks to make sure the joints are straight.

Finally cut out and bent the electronics tray.

It's been mounted to the frame and I made attachment points for the starter solenoid and CDI. And made a short frame around the battery just need to make a strap to hold it down. (will get pics)

Blended in the shock/frame gusset.

Made a little mount for rear turn signals.

Tray bolted on.

The 4-1 that was on the original donor bike was shot. The collector was boogered up with JB weld and other crap... in fact I was able to snap it apart by pulling on some of the header tubes. So I used a 1977 4-2 system. It wasn't fitting originally because the kickstand is in a different position but I bit the bullet and cut the kickstand off.

Still waiting on the new mufflers but I added tabs for hangers on the frame, then took it all apart.

Finalized all the detabbing, welding, grinding, etc and started tripping the paint off the frame.

Progress has been uninteresting. I'm degreasing, cleaning, polishing, painting, etc.


Had to share this. Found this under the dust boot on the forks. Forks came off my brothers GS550 that he purchased from a vintage dealer in West Palm Beach. Theyre being rebuilt.

Got the tank back from Magic City Kustoms. Found the right color vinyl for the seat. Should have it back this week.

 

[nerdsports]

Frame with one coat of paint and the painted tank.

I am normally against painting an engine "aluminum" because it never looks as good as actual aluminum. In this case, I'd have to put A LOT of time into cleaning them enough to be presentable so I went with a 'cast aluminum' engine paint.

* The side covers will be polished and bolts replaced with stainless allen bolts. I also have a gasket kit when it comes time to reassemble after paint. *


So... total mistake in not testing the engine when I first got it. It had sat for 5+ years. My friend suggested a compression test (cold). Very disappointing results but after reading some stuff online I figured I'd hook up the coils and carbs and test it on the table. Looks beastly with the cut header tubes pointing up.

And here are the compression numbers before and after.

Some frame shots. I started getting impatient so I bolted some stuff on before I threw the engine in.

I need to drill out 3 exhaust bolts that were torched off by the previous owner but that's all I need to do before I throw the engine back into the frame.

Finally put the engine in the frame.

Then made it a roller.

 

[nerdsports]

Got the seat back from upholstery.

Threw the header tubes on and fitted the mufflers to make sure they were angled correctly.

The right muffler has to go another .25 to .5" to the right.

Finally rode the bike last night. Well, I rode it a few days ago but it wouldn't rev passed 3.5K. I went through the carbs a handful of times, through the coils, replaced the coil pickup & advancer. It ended up being the main jets were way too small. Rode well but still has some pops and breakups after a hard shift into the next gear.

Made these to mount the turn signals to the headlight mounting bolts. Drill (as straight as possible) and tap.

 

[Guest]

That's looking pretty tidy, good job!!! The only thing I have to mention is the lack of any sort of fork brace, you may find that front end a little wobbly without one. The standard guard has a brace built in so you could cut one done, alternatively if you don't want any guard at all just fit a fork brace.

 

[Fjbj40]

What did you do to ensure frame alignment before welding?

check valve clearances, it may improve the compression number.

Very nice work overall!

 

[nerdsports]

That's looking pretty tidy, good job!!! The only thing I have to mention is the lack of any sort of fork brace, you may find that front end a little wobbly without one. The standard guard has a brace built in so you could cut one done, alternatively if you don't want any guard at all just fit a fork brace.

Thank you. I will most likely be adding a front fender.

What did you do to ensure frame alignment before welding?

check valve clearances, it may improve the compression number.

Very nice work overall!​

​

I took measurements from certain points before and after. I made sure it was squared up and the slugs were tight so they did a really good job getting the frame halves straight. I had to shave some of the ends one time so they fit together tighter.

I haven't looked into valve clearances but definitely will. Thanks!

 

[steve murdoch]

Show-off!
Great work, nerdsports.
Gotta love previous-owners-syndrome-discoveries....i don't need no stinkin' fork seals.

 

[LunArBasalt]

beautiful build!!

 

[nerdsports]

Show-off!
Great work, nerdsports.
Gotta love previous-owners-syndrome-discoveries....i don't need no stinkin' fork seals.

Thanks, Steve. I couldn't believe the rag shoved in there. Some people!

beautiful build!!

Thanks!


I haven't ridden it much (even though I should be riding it nonstop) but the bike shut off on me last week. The positive battery bolt came off. lol So now I'm wondering if the sputtering it had was because the coil had bad power due to the loose connection. In any case, I still need to get the idle sorted. I have to check for vacuum leaks and do some plug chops.