Sticky float?

[jayz]

Is this a sticking float? 1981 GS550T has been running great. Rode it to work yesterday, started right up in the morning. Four hours later I try to start it and it won't fire. It did backfire very loudly once. After about ten minutes of cranking and cussing it suddenly started and ran like nothing was wrong. I drove it several other trips after that and it started right up every time.

This morning it started right up, but this evening when I went to leave work it wouldn't fire. It backfired a few times. At one point it did start for a few seconds but when I fiddled with the choke it died and wouldn't fire again. I eventually ran the battery down and had to leave it at work.

I tried the blowing through the breather hose trick but no luck. Also, yesterday I didn't notice gas spilling, but today I had tons of gas pouring onto the engine. Looked like it was coming from the air box. There was no puddle under the bike until I started messing with it, then it leaked like crazy.

Also, I just replaced the petcock last month with a OEM vacuum petcock from Bike Bandit, so the petcock should be ok. (It had a on/off petcock but I got tired of changing my oil every month after forgeting to turn it off.) My spark plugs look good, none were wet or black.

So, sticking float?

[SqDancerLynn1]

Time for a carb clean & oil change, If CV carbs replace the needle seat O rings

[jayz]

Thanks for the post. My son just bought a 1980 GS550E and we need to clean the carbs on it. I just ordered the O-ring kit from www.cycleorings.com, and I ordered one for my 1981 GS550T too. But my bike has been running prety good, so I was hoping to put off the carb clean for a while (I'd rather be riding it!) Oh well, I guess it's sooner than later.

So is the float sticking what made my bike not start? I took the battery home to charge it. Do you think if I tap on the float bowl I can knock it loose so I can get it started to get it home?

[fgh]

That sounds like a sticky float, except that if you have a "GOOD" vacuum actuated petcock on her you won't leak fuel at all when its off. Unless of course you left it on "Prime". Did you do that? Set the petcock on "On" or "Res" and pull the lines off the petcock. If anything comes out of either line the petcock is bad. If fuel comes out of the vacuum line then the petcock is likely your problem. If fuel does not come out of the vent line but does come out of the fuel line then the petcock is still bad and you have a sticky float or leaky needle valve.

And yes if you have a sticky float you can sometimes free it by tapping on the carb. If the float has gotten stuck twice in a short period of time its time to open the carb and have a look at it. LOL

[Steve]

if you have a "GOOD" vacuum actuated petcock on her ...

Hopefully it's a good one. 8-[

I just replaced the petcock last month with a OEM vacuum petcock from Bike Bandit, so the petcock should be ok.

.

[t3rmin]

If you blow into the breather tubes enough you could end up with leakage even with good sealing floats. Whether that applies depends on when you did that and how much, but just a thought.

[jayz]

I didn't notice any gas leaking until after I blew into the tubes. Then it POURED out. I blew into the breather tubes very hard several times.

I removed the vacuum hose from the petcock and it was dry. I removed the fuel line from the petcoack and a few drops of gas dripped out. I dried the nipple off and came back about tweny minutes later and the nipple was slightly wet with gas again. I dried it off again and it's stayed dry. I put a tissue under the nipple so I could see if any drops of gas fall out, and so far it's stayed dry. Do you think I could have got a bad petcock, or does this seem normal? My #2 plug is not fouled.

I had it in the "ON" position yesterday, I didn't leave it on "PRIME." (I know you had to ask! :-D)

[t3rmin]

Sounds like you might not have stuck floats. You could test that by leaving the petcock on PRIME for a few hours and see if you get drips out of the airbox overflow tube or gas in the oil.

Also it sounds like your petcock is functioning acceptably at the moment. But even if the petcock is leaking your float valves should prevent overflow. But like I said you can get gas pouring out of the bike after blowing hard enough and long enough on the vent tubes.

It's possible you *HAD* a stuck float, but it's cleared up...? It's possible for the petcock to be intermittent as well -- mine would alternate between actually shutting off and leaking; moving the lever back and forth a few times would usually free it up.

You might also want to check out your ignition system. I had a similar issue where the bike would run great until it warmed up, then sputter and die. Wouldn't restart again until it was quite cooled down. In the meantime, trying to start it would sometimes result in some nasty backfires (like gunshots). Replacing the plug boots and increasing voltage to the coils (via a relay and direct feed from the battery) seemed to clear that up. But you'd also want to check your pickup coils and igniter and coils.

[jayz]

Now I'm thinking it must be electrical. I charged the battery up to 13.8v, stuck it in and it fired right up. I let it run for five minutes and turned it off. Five minutes after that I tried to start it and no fire! I decided to see if I was getting juice to the plugs. I pullled the boot off of the number one plug and stuck a screwdriver in the boot to arc it to the engine. I got a shock. I tried the same in number 2, NO ARC! I went to the other side and pulled the boot off of the number 4 plug put the screwdriver in, hit the start button and the DANG THING STARTED!

I drove it home, let it sit for five minutes and it started again. I tried it again an hour later and it started again.

These intermittent things are the most maddening of all.

Coils?

[jayz]

Another odd thing, while it's idling, if I pull the plug boot off of number one, the idle does not change at all. If I pull the boot off of 2, 3, or 4, the idle changes drastically as expected. I expected to find the number one plug to be fouled, but it doesn't look any different than number two.

[jayz]

Could one bad plug boot keep it from starting? My number 4 plug boot gets oil on it from a small oil leak (I'm pretty sure the leak is from brittle cam end plugs). I'm asking this because the bike started when I pulled the number four plug boot, but maybe that was just a coincidence.

[t3rmin]

Get new boots. It's cheap and easy and eliminates one possibility. z1enterprises.com has nice NGK boots for cheap.

[jayz]

Happy Ending Update:

Went through the electrical system. Checked the plugs, coils, signal generator and igniter. Everything checked out except for the igniter, but I wasn't real sure we were doing the test correctly, so I couldn't be 100% sure the problem was the igniter. Then I priced igniters...WOW! $370! I paid $600 for the bike! I found used ones on ebay in the $150 range, but not knowing if they were any good and not sure that was even the problem, I wasn't ready to go there. Considered switching to a Dyna S. Then my son found a perfect fit at a local junkyard for fifty bucks. He slapped it on and now I'm back on the road!

I'm still going to clean the carbs. My son just bought a 1980 GS550E and we are cleaning his carbs now, so we'll have experience before I pull the carbs off my bike.

[jayz]

Not So Happy Now...

After I installed the new (used) igniter it ran fine for a week. Then one morning I made it about a half-mile down the road and it suddenly backfired once and stopped running. I hit the starter button and it turned over but it sounded like it did before when it wasn't getting spark. I tried the starter again and it started, went another quarter-mile and backfired and died again. It started right back up. It did this a couple of more times before I made it back home and parked it.

With the old igniter, it wouldn't start sometimes, but once it started it would keep going--it wouldn't die on me. Now it will start but it suddenly dies going down the road. These intermittant problems are tough to test.