Friday, December 28, 2007

Front Forks

Lots of work happening on the beast while I've got some time off of work for the holidays.

The latest job to be finished was the forks. The chrome tubes were pitted with rust when I got the bike, and the rubber in the seals was old and hard, both consequences of the coastal location of it's slumber. A re-seal was definitely in the cards.

The old forks came apart pretty quick. Despite their pitted tubes and cracked dust seals, they actually held some air pressure from 27 years ago. Amazing. The oil was nasty with condensation and metal particles though.

I tried polishing the rusty fork tubes with 800 grit wet sandpaper, fine steel wool and chrome polish, but the left tube was too far gone. The right tube would work in a pinch - it had only one tiny pit that I filled with a drop of epoxy and sanded flat. I debated using epoxy to fill the numerous pits on the right tube, but I rejected the idea as too half-assed for me. I really like to do things the right way. So, despite the hit it would make to my budget, I sourced a replacement used tube on eBay. I ended up buying an entire fork set that had one good tube.

I bought some OEM fork seals and dust shields too. Not too expensive - less than $40 for the lot. And, since I can't resist improving things when I rebuild them, I also found a set of new Progressive fork springs to match the uprated rear shocks I've installed. I used 15w fork oil to replace the nasty stock stuff (in place of the recommended 10w20 engine oil) and give a little better damping.

The eBay forks come with an aftermarket fork brace (1980s Pro Circuit - I thought they only made dirt stuff?) which should do even more for the front end. The forks also had an air tube crossover kit, which needs a new fitting to work.

While the forks were off I disassembled the steerer tube and steering bearings. The tapered bearings on this bike are definitely over built, and 12,000 miles is nothing for them. New Bel-ray waterproof grease went back in, and I carefully adjusted them to eliminate any slop or unnecessary friction.

After thoroughly cleaning all the internal parts, I assembled the suspension on the bike and added fork oil to the stock level - 140mm from the top. I pumped it a few times and all was good. I then installed the front wheel and brake calipers and bled the brakes. A nice, hard lever was the result.

With it's improved suspension, new sticky tires, braided brake lines and modern brake pad compounds the GS1000 should handle and stop about as well as possible for a 30 year old beast of a bike. I might not be able to hang on the tail of the guys with modern 600s, but I'll sure be able to keep them guessing.

All that's left is cosmetics, and of course starting the engine for the first time in 27 years. I can't wait to get it back on the road!

Saturday, December 22, 2007

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...

Thursday, December 20, 2007

Front Brakes

The front brake system of the bike was not bad at all. It was full of old, nasty fluid, but no leakage and the pads had some life left. However, the rubber seals are nearly 30 years old, so for the sake of safety I wanted to replace them. The rubber hoses were cracked, and since the bike is fitted with shorter bars, were too long as well.

The master cylinder had a little grime inside, but no pitting. I bought a genuine Suzuki kit for it, and the quality and completeness of the parts was not lacking. A bit of scotchbrite and everything was as good as new. The master cylinder paint is suffering a bit, but not enough to warrant repainting. Possibly later...

The calipers were in good condition too. The pistons were a little tough to remove, but I did the channelock trick again (shhhhh!) and they came out with only a little drama. Each caliper took about 15 minutes to rebuild with all new seals and some new EBC brake pads. They're a nice, lightweight design for a '70s bike. Worlds better than the junk calipers found on some Hondas from the period.

Like with the rear brakes, I went to Earl's for new braided hoses. The stock system has three lines - the first one runs from the master cylinder to a tee on the lower triple clamp. Two more lines run from the tee down to the calipers on each side of the front fork. For simplicity's sake, I replaced them with two lines directly from the master cylinder to each caliper. The smaller braided lines fit easily within the stock hose brackets and work well. The little rubber boot doesn't fit over the long banjo bolt at the master, but it's not a necessary part anyway.

I installed the master cylinder and hoses, but not the calipers since the forks are not ready. I finally found some nice fork tubes on ebay - when they get here I can rebuild the forks and install the calipers and wheel.
In the meantime I'll keep working on the fuel system, cosmetics and a few other parts

Monday, December 17, 2007

Ignition system

As I mentioned in the engine evaluation post, the ignition produced a pretty weak spark. I set out to diagnose, and hopefully cure, the problem.

I pulled off the points cover from the end of the crank and took a look at the points. They were a little dirty and pitted, but not bad at all. The condensers didn't have any leaking electrolyte, so they probably were fine.

I checked the power supply to each of the ignition coils - both were around 12.5 volts, which suggests that the wiring and ignition switch is OK. I sprayed some contact cleaner in the bullet connectors and gave them a scrub with a scotchbrite pad for insurance before reconnecting them.

I disconnected the points from each coil and checked the potential voltage at the ground side - this would give a good comparison of coil resistance and the condition of the connections on that side of the coil. They were fairly equal at around 12 volts, so the coils were apparently in solid condition.

I cleaned all the connectors in the system and figured the next step would be cleaning and setting the points. Hopefully that would let it produce a nice hot spark.

I disconnected each set of points and gave them a quick brush with some 320-grit sandpaper. Then I checked the gap (.040, within spec) and gave them a blast of brake cleaner to get rid of any residual oil and dirt.

The result? A good hot spark. Maybe not as good as a modern bike or car, but certainly good enough to get this beast running again.

While I had the system apart, I also bought some new B8ES plugs from my local bike shop, and gave the ignition cover a good polish on the bench. I'll have to do something about the other engine covers eventually, but at least this one looks good!

With the new plugs in and the ignition system squared away, I sprayed some carb cleaner down the throats of my newly-rebuilt carbs and cranked it over. I was rewarded with a few second of (loud) idle through the naked exhaust ports. This thing is just about ready to run.

Monday, December 10, 2007

Carburetor Rebuilding

I couldn't reach an agreeable deal with the original owner of the bike for his set of VM29 smoothbores, so I decided to rebuild the stockers.

First I pulled off the float bowls to get an idea of the condition. Actually pretty good, so this should be easy.

I stripped the carbs down, removing the factory paint that sealed off the idle and mixture screws. I noted the number of turns for each one so that it would be easy to install them in the same place.

The carbs and rack came apart rather easy - no nasty gummed up fuel or overly bad corrosion was obvious.

I rebuilt each carb in turn - first I soaked the body, cap and float bowl in carb cleaner for 20 minutes, then gave them a quick wash with water. Finally I cleaned the hardware with solvent and gave all the parts a good looking over.

To reassemble, I added new orings to the drain, needle jet, idle screw, mixture screw and choke plunger. I had to get new gaskets for the float bowl and slide cover, since the originals tore when I disassembled them. The float valves were in good shape and didn't need to be replaced. Same for the needle and jet - all four sets were in great, lightly used condition. This bike would have been a perfect runner before it's 25-year slumber.

The stock carbs have a funny molded fuel feed tee, which has a tendency to leak. I used my favorite gasket sealer - Hylomar from the UK - to seal them. Hylomar is allegedly resistant to fuel, but I only used a tiny smear just in case.

The carbs went back in after a struggle - now I've still got to clean out the tank and rebuild the petcock, but the fuel system is getting closer to completion by the minute.

Monday, December 3, 2007

Rear wheel; shocks

The rear shocks on my GS were rusty and ugly, and they probably weren't very good even when they were new. So instead of wasting my time cleaning up 30-year-old springs, I figured I'd just buy some inexpensive performance shocks.

The MDI units found on ebay are well-known as decent shocks, especially for the money. They tend to be sprung a little hard but that shouldn't be a problem for this 500-pound beast of a bike.

On the GS Resources I found some second-hand but unused shocks for $55 shipped, about $20 off the usual shipped price on ebay. The shiny chrome springs will definitely spruce up the rear of the bike.

The rear end of the bike is now finished - the swingarm pivot bearings and rear wheel bearings were tight as a drum and didn't require any service. The rear wheel is squeaky clean and polished (after a good day's work with steel wool and alloy wheel cleaner) and is sporting a brand new Bridgestone Spitfire tire in the stock size. The swingarm itself is straight and now clean and the chain looks as if it has minimal wear (it's definitely been replaced at some point). the brakes are rebuilt and I installed some new shocks.