It RUNS!

[Dave_A]

Well, I got my bike ('82 GS450TZ from a Salvation Army auction) put back together and running....

It took a good amount of starter-spray, and the fuel valve in 'prime' to start it, but it does run (and backfire occasionally, and the exhaust is grey smoke... Of course, I only ran it for about a minute or two after getting it to run w/o the spray, but...) now.

I was doing this with the air-filter off (so I could get the spray into the carbs), and I don't know how this will affect the backfiring. I didn't run it long enough to see if the smoke would go away, and I couldn't tell if it was oil smoke or not (too dark outside). I also don't know if it will start cold w/o spray - I'll find that out tomorrow...

Thanks for the info (in my previous posts)...

[SqDancerLynn1]

By there nature our bikes will not run properly without air box installed

[Anonymous]

I was really worried the first day I took my new old bike for a ride. There was white or grey smoke coming from both pipes. It didn't go away until I had ridden about 15 minutes. I've since realized that it was just water vapor boiling out of the pipes, and perhaps the crankcase. It didn't repeat until I had occasion months later to start the bike and let it idle for just two or three minutes before shutting down: Then, when I started the next day it spit amazing amounts of water from the header/muffler connection and the whi/gry "smoke" was back (temporarily). Make sure your oil level is correct before you take it on the road, then don't sweat a light colored smoke for the first 30 minutes of your first ride. If you don't see heavy, smelly, dark-colored smoke (or oil spitting out from some other orifice) you can't be losing large amounts of oil, and you'll be safe to continue a shakedown/diagnostic cruise.

[Dave_A]

Update

The smoke fixed itself, and it no longer backfires while running (there's an occasional soft 'pop' in the exhaust, but not what I had before (the backfires last night sounded like .22 rimfire shots)). I had the airbox in the whole time (just no filter in it), and re-installing the filter changed nothing.

However, it still idles around 5K RPMs, and it backfires once quite loudly when shut off ('gunshot-loud', and simultaniously fires a jet of flame out the back of the right-side muffler) which I think is due to the last fuel-air charge not being ignited in the cylinder (because the switch is off), but going off in the pipe instead...

I think the idle issue may be due to improperly re-assembling the throttle (so that it's allways part-open), but I have no idea what's causing the 'final-stroke backfire'...

[Jay B]

The idle may also be the idle screw if you have one. Look under the carbs on the right side (as you would be sitting). You should (again if you have one) a knob under there. Use it to adjust the idle. I think but wont swear to it that most of the Suzuki's should idle between 900 to 1100 rpms. Can someone give him the right numbers?

[Dave_A]

Now it runs RIGHT!

Ok, I just checked the throttle cable. I had it in backwards, so the throttle wasn't closing all the way. Thus, when I started it last night, it went from off to partial-throttle (5,000RPMs), and due to being shut off at this speed, backfired when I turned it off.

Now, it idles between 1,000 and 2,000 RPMs, does not backfire when shut off, and appears to be in perfect running order. The exhaust no longer has smoke in it, either.

[Anonymous]

Chances are that there's a lot of carbon inside the cylinders and/or the exhaust. It starts to glow, when the engine is really heated up, which causes the unburned air/fuel mixture to ignite. That could be the reason for the pop when shutting the engine off.
Take it for a nice long ride to clean the engine up, and see if the problem goes away.

[Jay B]

Idleing between 1000 and 2000 is still too high. Might want to lower it. Glad you found the problem.