Missed my flight...BUT got my bike started!!! :)

[bexabarr]

Talk about priorities! :twisted:

Thanks for all the help with the carburetors... I was supposed to leave today for my trip, but I ended up missing the flight. I will be leaving tomorrow morning. Anyhow I took advantage of the day and put my carburetors together and got them on the bike. After a few years of sitting I actually got it running! BUT only after putting a wet rag with gasoline in the air intakes. The bike starts, but I can only keep it going with off and on pressure on the throttle and the choke all the way open. I'm guessing that the floats are set incorrectly (25 mm), and it is not getting enough fuel. But as of now I'm just happy that it started... oh and it has an occasional backfire (could this also be a problem with the timing?). Thanks again for everything in advance, since I probably won't have time to reply till next week.

[FTGRET]

It sounds like you have the filter box off It won't run without it.

[Anonymous]

Rags soaked with gasoline are a bad thing most any time and place, and you have backfires...

[bexabarr]

First of all thanks for the replies....

After trying to start it up for 10 min... I decided to take out the filter (under the seat) and stick a "moist" rag... it wasn't soaking... just to get some fumes in the engine. It fired up smoothly, on the first try. I only did it once, the rest of the times after that it started by itself... but it would either die of within seconds or I could only get it going with the throttle and choke on full. I don't think that it backfires because of the gas rag, since it did it a couple after I stopped using it (and not during).

Any ideas? Thanks again.

[nabrams]

If the bike has been sitting for some time you're going to have many tasks to perform before the bike runs properly.
Here's some advice I gave to somemone:
I've "restored" two GS450 bikes that had been sitting for long periods (mine and a friend's) so I've encountered almost all the typical issues.
You will almost certainly need to do a thorough carb cleaning. The fact that it started up is deceptive. It will not produce smooth, full power till you get those carbs spotless. Your air filter element, air box and all boots that connect to the carbs will have to be checked (any air leaks and all bets are off - see my other posts about this). Your regulator/rectifier and stator should be checked (as described in the garage section of this site). It is also likely that you'll have some loose and/or dirty electrical connections.
Some of the cables may need lubrication and adjustment. Of course, you will need a new battery.
If you've never done any of the above stuff then it will take you a while to learn it all and to acquire the right tools - anywhere between 25 and 60 hours of work - I'm trying to be realistic here based on my own experience. The second time I did a "restore" (on my friend's GS450) it went much, much faster. A Clymer's manual is a must.
If you're in no rush and you enjoy wrenching an hour or two a night then I'd say go for it. If not, you could take it to shop and pay an arm-and-a-leg for them to do half-baked job that you'll have to "finish up" - once again, I'm speaking from personal experience I had with a Honda many years ago.

Here's some more:
You had a running bike before the carb rebuild, so I'd guess your main problem is with the carbs. However, it is possible that other factors are just borderline enough that a slightly worse carb situation would expose those issues as well.
Before tearing the carbs down again, verify all the easy stuff first:
1. Put in brand new plugs - I can't tell you how much time I've wasted just to finally realize that my plugs were so wet and fouled that the bike had no chance of starting. This is especially common after doing carb related stuff.
2. Verify your air filter element and box and boots are all set up properly and that there are NO air leaks.
3. Using those new plugs, check that each one is sparking. If the bike is properly carbureted, even a faily weak spark should ignite the fuel/air mixture.
4. Verify that your petcock is letting fuel through to all carbs.
If all of the above checks out OK and you still can't get her started, then it's time to tear into those carbs again. Make sure your floats aren't leaking (there should be no liquid sloshing around inside of them) - I once overlooked that very important test and spent many hours fiddling with other things till I remebered to check if my floats were leaking. Sure enough, one of them was leaking like a sieve.

Also:
Your starter motor may be really dirty inside, preventing full electrical contact: been-there, done-that.

I would NOT replace any gaskets if the leaks are relatively minor. If they are minor just seal them up with high-temp silicone - worked like a charm on my friend's GS450.

The 1980 GS450 is CDI ignition so there's no timing adjustment necessary.

Of course the gas tank must be drained.
Soaking the carbs in gas is useless, you must disassemble the carbs and clean them meticulously (especially if they've been sitting for two years).