Temperamental starting

[Tlamar]

First off you guy’s are awesome, I have been lurching around here ever since I got the bike (81 GS550T) in May and have learned more from you guy’s, than the folks at Clymer ever thought about printing. This is my first bike and I have really enjoyed working on it. Although I’m looking more forward, to taking my MSF class in August, and being able to ride it instead of always just working on it.

I finally got the old girl looking good and running like a bat out of hell (sort of!). But I still have a small issue. When I first got the bike and got it running I noticed that I could ride it as long as I wanted (with the petcock on prime) but as soon as I turned the bike off even for just a second it did not want to start back up until it cooled down. I still had good spark but it was like the bike was starving for fuel once it had been turned off. I chalked it up to a bad petcock, bad o-rings, or airbox rubbers and went along with the rebuild, but unfortunately I’m still having the same problem, and I have noticed that when it does start back up it’s almost like it only starts when I let off the starter button and quickly give it gas, and it still doesn't like to run except on prime, even witht the new petcock. Here is a list of what I have done to the bike:

1. New Intake O-rings
2. New Airbox Rubbers
3. New Petcock, I have tested this by sucking on the vacuum line and fuel flows, but I'm not sure if the flow is adequate
4. Kreamed the tank
5. Cleaned and bench synchronized the Carburetors (twice)
6. Cleaned the Gas cap (Thought maybe a vacuum issue)

Here are some before and after pictures to hopefully make up for the long post.
I hope this works!!

[Dogma]

Wow, that cleaned up nicely. Well done.

About your problem, I don't really have an answer, but more questions.
Are the valve clearances correct?
Do you choke it when it's warm?
How good is your battery?

The big question is why it needs to be on prime to run.
Do you have an in-line fuel filter?
Is the vacuum line between the petcock and #2 carb in good shape, clear, and unkinked?
Has the Kream stayed bonded to the tank or is it fouling the fuel system (I hear that happens often with Kream)?

[Headphase]

Have you changed the fuel lines, maybe they are dodgy?
Also, is the vacuum pipe connected?

[Tlamar]

The valve clearances are within spec, and the vacuum line, fuel line and battery are brand new. The tank liner is solid; in fact I had a pretty good time of getting the bolts that hold the petcock on, to go back in.

I don't have an inline fuel filter, and the vacuum line is as short as I think is possible with still being able to get it on the tank. I don't have the vent lines hooked up coming off of the carburetor or the crank case vent line hooked up to the airbox (wasn't sure if it was necessary for it to run properly). when the bike is warm having the choke in or out doesn't seem to make any difference.

Do you think it would be better if I put an inline fuel filter? I will also try to find a clear fuel line so that maybe I can see a change in fuel flow.

[Tlamar]

Just thinking out loud (Scary Huh) but do you guys think that it is possible that the heat coming off the engine could create a vapor lock within the petcock valve?

[seuadr]

when the bike is warm having the choke in or out doesn't seem to make any difference.

it should make a noticable difference just about any time.. might check to see if the choke is staying engaged? check the plugs, are they tan or black and wet?

[Tlamar]

The plugs are a light tan color and are dry as a bone. Which is why I think it is a fuel problem. But at this point I'm lost.

[chef1366]

Check the spark when it won't start.

[Matchless]

it’s almost like it only starts when I let off the starter button and quickly give it gas,

This indicates that your battery voltage is too low at the coils while the starter is turning, as soon as you let the starter go, the voltage is enough to generate a better spark. Check battery and voltage at coil, especially when hot.
Most likely it will start if you bump start it when hot and not use the starter?

[Tlamar]

Thanks to you guys, I think I have got it figured out. I tested the voltage at the coils and was getting around 11V on both coils with the engine cold. I then checked the drain from the coils and found that one coil was draining a lot more power than the other one, so I replaced it with a coil from my parts bike. It fired rite up and ran great, turned the bike off after it got warm, and it fired rite back up just like its supposed to. I did this several times then decided to call it a night and bask in the joy that, I now had a fully functional bike.

The next day it fired rite up, but after getting warm I had the same problem again. (Doooooh!!!). I then went through the ignition system and charging system with a fine tooth comb and found that although my Stator is outputting 75VAC, the regulator is toast!! (I get continuity in both directions). So I ordered a new regulator from Electrosport which should be in tomorrow hopefully.

Do you guys think I should go ahead and see about replacing the stator, or at least have one on standby even though the other one checks out okay?

[twistedwankel]

Do you guys think I should go ahead and see about replacing the stator, or at least have one on standby even though the other one checks out okay?

Never hurts to have a spare of a known good electrical part. That said: If your stator which has no moving parts (itself) tests good why change it? Had I caught the poor bullet connector issue earlier I'd still be using my factory issued one from '81 and do still have the original RR and everything else except the bullet connectors.

http://stores.ebay.com/Tim-Parrott-Enterprizes_W0QQcolZ4QQdirZ1QQfsubZQ2d999QQftidZ2QQtZkm

This person for flat rate of $80? will rebuild your stator or send you one all ready rebuilt and you ship back your core to avoid additional $20 charge. Cheaper than buying one new and should be okay as warranteed and factory core. Will match your connectors too. Quick turnaround as he usually has Suzuki ones in stock.

Pick up a junk one and get it rewound if your's is still good?

[robertbarr]

I'd still take a look at the mechanical linkage to the choke (aka starter) plungers. Each plunger should have a good centimeter or so of travel. If they're not moving all the way back in, you'll have trouble with warm starts.