'81 GS550 Cafe Build

[D-Mac]

Now for the BAD news. Since the starter now turns over, I used my compression tester and got the following readings (#1-4): 50, 60, 60, 40. Throttle wide open too. When I added some oil to two of the cylinders the compression did NOT change, which would suggest it's not the rings.

The compression tester. My only hope is that Harbor Freight made a faulty one (not impossible, but unlikely).

Even though the compression sucks, I'm gonna try and fire up the bike tomorrow. If the gauge is right, it shouldn't start. At that point, I'll need to beg/borrow/purchase/make a leak down tester and go from there. I reaaaalllly don't want to have to rebuild the top end, but we'll see what happens.

I also drained the gas tank today.


Ever see gas this color?!


Petcock doesn't work (I assume on "prime" it's supposed to drain). Does ANYTHING on this bike actually work?!

The offending part. I'll probably replace it rather than rebuild it. Not a high priority for now.


The inside of the tank looks pretty good. Probably Kreem coated I think. I might end up re-doing it anyway with Caswell. We'll see. It doesn't seem to leak at present.

On removing the petcock, it appears that there might have been a leak of some sort. Or maybe just an old dent repair. Bondo? JBWeld? Other? I'll be stripping the tank, so we'll find out later I guess.


A minor ding.


Other than the silly decals and minor surface rust, the tank is otherwise in good shape.

[GateKeeper]

Take the petcock apart and see if anything is wrong with it, there are not many parts to it, and it could just be dirty, a good cleaning is all it might need and maybe a new seal

[TheBigRed]

I'm sure someone with more experience will be along shortly to correct this if it is wrong, but I'm pretty sure your compression readings are not valid as they were done on a cold engine. I'm pretty sure specs in manuals are for when taken on warm engines.

[D-Mac]

I'm sure someone with more experience will be along shortly to correct this if it is wrong, but I'm pretty sure your compression readings are not valid as they were done on a cold engine. I'm pretty sure specs in manuals are for when taken on warm engines.

You are correct - they are supposed to be done warm. I'm not convinced they'll be that much higher when (if) I get her started, but I will hope and see what happens.

[Flyboy]

Nice to see the progress, I like the clubmans.
Don't sweat about the compresion readings to early, you will get wrinkles before your time.
Fire it up and run it a bit, you will see the compression readings come up dramaticaly, the more yu run her, the better the readings will get, until they are right up there. Motors that have stood idle for a while do that, everything needs to heat up, work itself loose and seat in properly again.
Lastly you may just have a bunch of tight valve clearances, do the shims and you know you are good.
Keep up the good work.

[D-Mac]

Two fuses, a bunch of false starts, a small fuel spill, a bunch of missed meetings at work (I work a block away so I sneak home often), and one mental lapse, but IT RUNS!!!!

Now I can re-do the compression test on a warm engine and find out what's wrong with the charging system too (previous owner says it won't charge - I didn't even have time to check the battery level while it was running).

More info soon. Gotta fix a dishwasher and ferry my kids around first....

[Flyboy]

IT RUNS!!!!

Yeeeeehaaa, the sweetest sound, good job.
Now you can tear into it with gusto.....expecting updates.

[D-Mac]

Lots of updates - some good, many not so good. The electrical problem has been isolated (bad R/R, although I'll probably replace the stator as well).

I've entered the "tear down/assessment" phase now.

I'll post lots of pics later today.

[D-Mac]

Edit (I think I'm messing up the Display Mode - I'm reposting this in an attempt to fix it).

Update time!

Since the petcock is completely blocked (even on prime I can’t get any fuel to come out, and the PO disconnected all the vacuum lines long ago) I rigged up an old fuel cell to the bike to try and start it.

Below is a video of the bike running. Note the backfiring through the carbs and out the pod filters. Nice. With holes in the exhaust and loose aftermarket filters it’s obviously very lean. Carbs are probably pretty clogged as well and compression readings are still in the basement too. No matter – I will eventually run a leak-down test and likely rebuild the top end anyway. Carbs will get a full cleaning, rebuild, and complete rejetting on a dyno (I have some access to one and I’ll be doing a complete tune once it’s back in running order…..which will be a loooong time).


Click on the video to watch it…..

Now that I’ve determined that the R/R and possibly the stator are gone, it’s time to start pulling stuff off the bike. The next task was removing the exhaust pipes. Recall those rusted bolts on the headers? I soaked them in PB blaster+WD-40 for three days with cycles of heating and cooling. All were nice and loose when I started to remove them. Result? Less than ideal….

Only THREE exhaust bolts came out cleanly. It turns out that another three were ALREADY broken off in the collar (!) and held on by some sort of glue/JBWeld/wire!? Lovely. I guess the previous owner decided that it would be ok to just glue the old bolt heads back on and forget about it!? The two that I broke snapped off with very little torque. Crap.

I broke out into a bit of a cold sweat when the first one snapped off, but all but one stud is protruding a little, so there’s still some hope. I will continue to PB-Blast them. Worse-case scenario I’ll deal with it when I remove the cylinder (a little EDM can always save the day if I decide not to drill it out).
Behold the OEM exhaust. Really heavy! It will likely be replaced with a 4-1.

Up next was removing the rear wheel. It went well, but I rushed a bit and everything got hung up on the rear axle. A little maneuvering and it was out (needs grease, and I probably should check the run-out too).

I removed the carbs next. Boots were stiff, but it’s very easy on this bike compared with some of the twins I’ve worked on. Note how they’re “bleeding” fuel on my work bench……right near a charging. I really gotta get a fire extinguisher for the garage.

Then I removed the intake rubber pieces…..

….and I saw LOTS of this inside the engine!

It looks like the PO was in love with gasket sealer. It flaked off in huge pieces in my hands. I wonder how much of this stuff the engine has digested?
More in the next post….

[D-Mac]

Still more updates....

Next up I removed the counter-sprocket cover……the screws were already pre-stripped. Here it is removed.

My little impact driver was having no effect, so I ran off to Sears and bought a much larger one. Heh heh. It made short work of three screws. The other three were too far gone, so I dremeled slots into two of them and got them off! This is my first time struggling this much with fasteners (small impact driver and heat has always worked for me before). I also have a set of Japanese screwdrivers, which usually helps, but these were just too far gone.

The big problem was the one remaining screw at the back of the sprocket cover. It’s recessed, so all attempts to dremel a slot in it resulted in me carving a slot into the cover! Doh! I ended up drilling it off, and the release in clamping force allowed me to spin the shank off with my fingers. Unfortunately, since I couldn’t get the drill centered, I accidentally machined a little out of the cover. Argh.

It’s a minimally important screw since it’s not fastening anything that holds in oil. I’ll probably stick an o-ring in there and see if that works. Replacement on Ebay is only $14 if that fails. It’s a bummer that I got so close to getting it off flawlessly. I’ll need to be more careful with the cases.
Check out what was behind the sprocket cover. This is AFTER I removed about 2lbs of soil, pine needles, and pine cones from back there!

Upon removing the sprocket cover, I discovered that the counter-sprocket was COMPLETELY LOOSE (not even hand tight). The only thing holding it on was a single bend in the locking piece! The sprocket is badly worn and looks to be an original (it has the right number of teeth anyway and it looks like a sprocket with 20,000 miles on it).

Then it was off to the store for a 21mm socket to remove the oil drain plug. There was definitely some gas mixed in with the oil - likely from the stuck float bowls combined with the lack of a vacuum operated petcock shut-off. I was careful to check the oil level before I started the bike (made sure it wasn’t too full or thin), but I’m glad I didn’t run it too long like this! (The smaller dish to the right contains old brake fluid).

My last project for the weekend was to remove and disassemble the calipers – also a first for me.
I got them off the bike easily enough (although I forgot to loosen the rear ones on the bike so I marred the cover getting them apart in my undersized bench vice. Here’s the rear, which looks worse than the front.

Would you trust your life to this?

Inside, the seals and boots looked worn, but intact. The pads will be replaced along with all of the seals, etc. (no sense taking a chance on brakes!) Getting the caliper pistons out was a BEAR – especially one of the rear ones, which was rusted in place. After applying high pressure air, I got the worst one to turn enough to grab it and pull it out. I marred it in the process, but it is definitely getting replaced anyway.
Ugh.

I’m now boxing up everything I’ve removed so far. I’m off to buy a small parts washer (and fire extinguisher) tomorrow and then I’ll be looking over the calipers, removing and looking at the master cylinders, and pulling off more bits in preparation for removing the engine.
I will have lots of time to work on the bike over the next couple of weeks.

I’m a little ahead of myself, but any suggestions for a color scheme? I really like red/black/silver, but I’m clueless about what colors to put where. I’ve looked over all sorts of café bike pics but I have trouble making up my mind, so I’m very open to options. Everything is getting repainted except the engine if I can help it (although I might paint the cylinders to set them off from the bike a little).

[Motocrossx23]

Good luck with this! You definitely have your work cut out for you, but believe when I say that once you get past the dirt and the grime, the broken bolts and headaches, it's going to be so nice when you see progress in the direction of something "clean and new"

[D-Mac]

I picked up a small parts washer today, a lot of Simple Green concentrate, and a bunch of brushes. Rather than trying to set this up at home (where I have almost no space in my poorly-ventilated basement and it’s freezing and condensing rain in my unheated garage), I made the decision to temporarily re-locate to my office. It’s only a block from my house and I have thousands of square feet of lab space to use (complete with chemical-resistant tables/floors, air supply, vacuum lines, gas lines, de-ionized water, fume hoods, heavy-duty ventilation, comfy chairs, music, enormous sinks, and bad coffee). Best of all, we already use Simple Green to clean everything in the labs, so the smell of my parts washer will be familiar to everyone who works there.

Here is my parts washer station.

Note the fume hood.

My first attempt was to scrub 30-years worth of grime from behind the sprocket cover. This is easily the dirtiest piece on the bike.

10 minutes of scrubbing and nearly all of the crud was off. Not perfect, but good. This is the piece I drilled into, and I also discovered a crack along the bottom that goes all the way through. The washer pump was so clogged that the pump was dying, so I had to empty it out when I was done.


I like working in the lab so much that I’ve made the decision to move the ENGINE there as well. I’m close to removing it (should happen later today).
More pics soon. Once I get the engine out, I’ll split my time between it and the other major components (tank/forks/wheels/seat/wiring…..ugh). After Christmas I’ll take it down to the bare frame for modifications and painting.

Off the top of my head color ideas…..

Option 1: SILVER+BLACK - Black frame, black/silver wheels (returned to the way they came from Suzuki), a little more silver on the triple trees (strip paint and polish), black headlight (?), and maybe a silver tank (painted since it’s steel) with a little black accent of some sort on it. Silver engine with black accents (perhaps the ends of the valve covers and the cylinder could be done in black). Sear cowling painted silver to match the tank with a black cushion. The more I think about it, the more it sounds like the colors on my RT!

Option 2: RED HELL – Bright red frame (ok, maybe silver), wheels mostly silver/black, with a little red accent (calipers + inside of the wheels perhaps), red tank and seat cowling with a white racing stripe down the middle.

Option 3: ????

[D-Mac]

Latest discovery: The stud on one of the three cap screws that hold on the oil filter cover is stripped. The filter cover was "glued" on with a ton of sealant (looks like the same stuff used on the engine intakes).

Needless to say, I'm going to replace the stud and use a proper o-ring to seal the cover. Can these studs be removed with the standard "double nut" technique? I've never done it, but I think that makes sense....

[tkent02]

Needless to say, I'm going to replace the stud and use a proper o-ring to seal the cover. Can these studs be removed with the standard "double nut" technique? I've never done it, but I think that makes sense....

Yep, they usually come right out.

[Motocrossx23]

Why bother if it's stripped? Just get a pair of vice grips on it and twist. You're replacing it anyways right?