Finally Coming Together

With the petcock finished and the engine side covers polished, there isn't much left to do but ride this thing. I gave it a quick once-over, checked the air pressure and hit the road.

I visited a friend from the GS Resources to synchronize the carburetors. Thanks Ed! ON the road the new regulator works great - 13.8v at idle with the lights on, and a fully charged battery after 200 miles and sitting around all weekend.

With the carbs synced, the bike runs really well although I do notice the odd backfire and stumble. I may pull the carbs again soon to check them over, but only after I put some more miles on the bike to make sure it's not just "clearing it's throat". I'll also adjust the idle mixture screws a little too.

Other than that it's running perfectly. Being the perfectionist that I am, I might still play with a couple of small details. I don't have to, but I'd like to tweak the front suspension to perfection. I'm getting 65mm of front sag, which is about 30mm too many. And I'd like to maybe remove the passenger grab handle and plug the holes, but I haven't decided yet. In addition, the clutch cover seems to be oozing oil, but it's hard to tell because of the small amount.

Petcock the Third

Well, my second attempt at petcock repair failed because of a poorly-designed aftermarket diaphragm. The O-ring was too small. I should have learned my lesson by now but it almost never pays to mess around with stuff like this - just buy a new one and forget it.

So I did. I bought a NOS petcock on ebay for $36, which seemed like a good deal to me. Bolted it to the tank and no more gas oozing out.

Anyone need a slightly used petcock rebuild kit?

Petcock Reprise, Tach Seal

Well, I've put about 60 miles on the bike since getting it running, and it's a sweet runner. The carbs required only a little tweaking to get it down to a sweet, smooth idle, and it fires off on the first button push every morning. The brakes are hard as bricks and a delight to use, and the refreshed suspension gives the bike good behavior over bumpy surfaces with no head shake up to the speed I chickened out at - 115 according to the speedo. It got there mighty quick - this thing has tons of power. It's also enough to cruise in comfort at 80 mph on our LA freeways. The transmission shifts nicely after I adjusted the shift lever down one spline on the shaft to match my boot better.

So what's the catch? Well, there are a couple of small issues that I will have to deal with:

- A slight oil leak at the tach drive, and another at the valve cover gasket. Both dripped oil on the exhaust leaving me with a nice oil cloud at long stop lights.
- A gas smell emanating from the bike. Seemed to be coming from the carbs, which were damp on the bottom. This only appeared after parking.
- A couple of cosmetic issues that I want to deal with, including the caps at the end of the cams, the engine side covers and the chrome starter cover.
- The charging system or battery might be a little weak - at stoplights the lights dim slightly until the revs get back above 2000-3000.
- The clutch rattles (another common GS problem) but that might be solved with a carb balance.

Curiosity got the better of me, and a few days ago I decided to deal with the carb issue. A wet drain tube from one of the center carbs pointed to a leaky petcock. I was a little irritated by this because I had just replaced all the seals. One bolt sets the tank free, and with it on the bench I watched the outlet for a few seconds to verify that it was dripping slowly. I tipped the tank over and disassembled the valve portion of the petcock. Everything appeared to be fine, but there was a tiny bit of corrosion on the back of the valve lever. I sanded it on a piece of glass with 800 grit sandpaper until all traces of pitting were gone.

Back together it still leaked, which meant the problem was with the diaphragm. I pulled the back apart and sure enough, the o-ring on the diaphragm valve was cracked. Damn - Suzuki doesn't see fit to sell it separately, and I was starting to regret not just buying a new petcock. I grudgingly placed an order with Z1 enterprises for a new diaphragm. I always regret buying aftermarket parts, and this time was no exception. The diaphragm that arrived had an o-ring that was too small for the recess in the petcock. Why do I bother? I'll live with the seepage for now, but I will be buying a new petcock soon.

While I had the tank off I decided to reseal the tach drive and valve cover too, and do a valve adjustment. I removed the bolt and cable and started to gently pry the drive housing out of the head. Before I knew what happened, the housing broke off flush with the head surface.

Shit.

For better or worse I was tearing into this thing. I pulled the valve cover and tried to pry the stub of remaining tach drive out of the head. It wouldn't budge, obviously stuck in place with 30 years worth of aluminum corrosion. Damn, damn damn.

The next step would be to pull the cam but I was able to avoid it with a pair of vice grips, pick, punch and hammer. The carnage took out the gear, too, so it looked like I'd be buying more parts than I anticipated. With the valve cover off while I wait for parts, I figure it's as good a time as any to take care of all the engine issues that I still had.

Tank Cleaning and Petcock

The tank was rusty inside when I got the bike, a pretty common problem when a motorcycle's been sitting around for as long as this one had been. It wasn't rusted through or anything, which is good, and the pits didn't look too deep.

The fuel gauge appeared to work when I first turned it on, but the petcock leaked badly. With the tank on the bench and drained of old nasty fuel, I removed the petcock for cleaning. Then I pulled the fuel gauge to make cleaning the inside of the tank easier.

The biggest problem with a rusty tank is the little rust particles that get knocked loose and get into the carburetor. There's a couple of ways to deal with the problem, including some involving expensive liner kits that tend to be finicky and sometimes cause more problems than they solve. The tank has a dent, which is another problem for a liner kit - removing a dent will usually chip the brittle liner and cause it to flake off. Since I'm not planning on having it painted right away I decided to just clean out the rust as best I could and add a fuel filter after the petcock.

First I rinsed the tank with solvent, in order to get rid of any old fuel deposits inside. This loosened quite a bit of rusty flakes, but there were plenty more inside. To remove them and clean the rusty surface of the tank, I filled it with a gallon of phosphoric acid. You can get it at Home Depot, and while it is nasty stuff it's not as bad as it sounds. Really - it's used as a preservative in cola, among other things.

I taped up the petcock and fuel gauge holes with duct tape and rotated the tank slowly, over about 24 hours. Phosphoric acid eats rust but attacks the good metal only slowly. At the end of the 24 hours, I drained off the phosphoric acid and returned it to the container. It should be good for a few more uses, at least. I then rinsed the tank with the hose outside.

To get rid of the water and prevent flash rusting, I threw in a quart of denatured alcohol. Alcohol is hygroscopic (will mix with any remaining water) if I remember my high school chemistry lessons well enough. After swishing the alcohol around for a bit, I drained it off too.

Finally, I mixed a couple of teaspooonfuls of motor oil with a couple of ounces of solvent. I dumped this mixture into the tank and swished it around to give the inside of the tank an oily coating that would keep out moisture and prevent rusting until I can get some gas in it.

The petcock ("Fuel Cock" in Suzuki speak) leaked when I first tried to start the bike, so I pulled it apart for inspection. The main inside seal was rotted and the outer lip seal was no better. The molded o-ring between the petcock and tank was intact but hard as a rock. The metal parts of the petcock were fine, so I ordered new rubber to rebuild it. Like all the other OEM parts I've bought, they were fairly inexpensive - under $10 for all three.

With the petcock and fuel gauge sender back in the tank, it was ready to go back on the bike with some new fuel line and a fuel filter. I reinstalled the seat, too. Suddenly the GS is starting to look like a bike again, but without the forks, of course...