New to me GS550 won't run without choke

[Isoparmesan]

Where do you have the vacuum line connected?
One end on the petcock and the other?

Vacuum line goes from the petcock to the nipple on the left side of carb 3. Fuel t is between carbs 2&3. I think what is normally the carb air vent line is just connecting carbs 2 & 4 (I have to look to verify this).

[allojohn]

I think what is normally the carb air vent line is just connecting carbs 2 & 4 (I have to look to verify this).

The vents from 2 & 4 carbs are not connected. The two tubes should vent into calm air behind the airbox or pods.

[Isoparmesan]

The vents from 2 & 4 carbs are not connected. The two tubes should vent into calm air behind the airbox or pods.

Ok. I’ll set it up that way. I’m assuming I should also install a crankcase breather hose, even though I’m not using the air box.

what are possibilities for the smoke. I’m assuming it’s atomized oil, and hope routing a breather hose with a filter on the end will mitigate it. but I’m just wondering how concerned I should be about it, and what things would affect it. I still need to balance the carbs. I also have yet to check compression as I don’t have the gauge for it.

[allojohn]

Ok. I’ll set it up that way. I’m assuming I should also install a crankcase breather hose, even though I’m not using the air box.

what are possibilities for the smoke. I’m assuming it’s atomized oil, and hope routing a breather hose with a filter on the end will mitigate it. but I’m just wondering how concerned I should be about it, and what things would affect it. I still need to balance the carbs. I also have yet to check compression as I don’t have the gauge for it.

Yep, do exactly that. You won't notice a thing, just clean the filter every now and then.... I do once a year.

[Isoparmesan]

Yep, do exactly that. You won't notice a thing, just clean the filter every now and then.... I do once a year.

Will do. If I install a breather hose and it still smokes what would the next possibility be?

[allojohn]

How much smoke are we talking about here? When the engine is good and hot you will see a little smoke but that's all. If you're clouding up your garage there's a serious problem...

[Isoparmesan]

How much smoke are we talking about here? When the engine is good and hot you will see a little smoke but that's all. If you're clouding up your garage there's a serious problem...

here’s a video. This is after riding around town for 45 min or so. https://drive.google.com/file/d/1N-a...w?usp=drivesdk

[Isoparmesan]

Update:

ran some tubing from the air vents on carbs 2 and 4 to just behind the battery.

I had noticed that the petcock was a bit leaky. In the box o parts that came with the bike was a spare petcock that looked to be identical. Swapped them, and transferred the petcock filter with a new gasket to the replacement. Only to discover that the replacement leaks in both non-prime positions. Returned original petcock (with new gasket) and hooked everything up.

ran the bike to see how long it would take the smoke to start coming, and to see if it was really coming out of the crankcase. After the bike was warm, it started spewing gas from the petcock in the non-prime positions. Shutting the bike off stopped it, although it does slowly drip when not running.

so, I’m thinking I need a new petcock, or at least need to clean and replace all the rubber bits in this one. I’m also thinking it’s possible that the smoke I’m seeing is just gas hitting the crankcase/exhaust pipe.

What I don’t understand is why the petcock suddenly gave way like that. Would changing the configuration of the carb vent hoses change the vacuum properties that extremely?

[allojohn]

here’s a video. This is after riding around town for 45 min or so. https://drive.google.com/file/d/1N-a...w?usp=drivesdk

That's more than you should expect, but it may be excess moisture in the crankcase as the bike has not been running frequently.
I'd keep it running for 30 mins to see if the vapor deminishies. Also, you need to put a fan in front of the bike to cool the engine when doing this.

Update:

ran some tubing from the air vents on carbs 2 and 4 to just behind the battery.

I had noticed that the petcock was a bit leaky. In the box o parts that came with the bike was a spare petcock that looked to be identical. Swapped them, and transferred the petcock filter with a new gasket to the replacement. Only to discover that the replacement leaks in both non-prime positions. Returned original petcock (with new gasket) and hooked everything up.

ran the bike to see how long it would take the smoke to start coming, and to see if it was really coming out of the crankcase. After the bike was warm, it started spewing gas from the petcock in the non-prime positions. Shutting the bike off stopped it, although it does slowly drip when not running.

so, I’m thinking I need a new petcock, or at least need to clean and replace all the rubber bits in this one. I’m also thinking it’s possible that the smoke I’m seeing is just gas hitting the crankcase/exhaust pipe.

What I don’t understand is why the petcock suddenly gave way like that. Would changing the configuration of the carb vent hoses change the vacuum properties that extremely?

Suzuki petcocks are a pain in the a$$ when they fail and almost impossible to repair. Replace with new. Your vent tubing is correct.

[Isoparmesan]

That's more than you should expect, but it may be excess moisture in the crankcase as the bike has not been running frequently.
I'd keep it running for 30 mins to see if the vapor deminishies. Also, you need to put a fan in front of the bike to cool the engine when doing this.

Suzuki petcocks are a pain in the a$$ when they fail and almost impossible to repair. Replace with new. Your vent tubing is correct.

Just ordered an OEM petcock. It's really too bad that the much aftermarket ones seem to all be terrible. Also, I've seen some mention of special sealing washers for the petcock mounting bolts. Is that something that I need to find? I currently don't have any washers on those bolts.

And yes, I would not run the bike for 30 minutes stationary without a fan. That video was taken after riding around for 45 min or so and pulling back into the garage. where I let it idle for a couple minutes to try and find the source of the smoke. I really hope it's mostly just gas vaporizing on the crankcase and exhaust.

[allojohn]

The rubber gasket makes a good seal on the petcock, not sure what adding washers would do. Make sure both surfaces are clean.
Pop a small filter on the breather hose, a little back pressure will help reduce the flow.

[steve murdoch]

The gasket/washer for the petcock is also called a "dowty washer".
#6 on the schematic and yes i would acquire them.

https://www.ronayers.com/oemparts/a/suz/50d3f55ff8700230d8b4c5ec/fuel-cock

[Isoparmesan]

Alright. The petcock was backordered, so in the meantime I replaced the diaphragm in it with the one from the spare I had. Cleaned the filter, soaked the main body in chem dip, and reassembled with a new gasket and sealing washers around the bolts. No more gas leak! I've also since received the replacement petcock, and will hang on to it in case this one ends up failing.

I also balanced and synced the carbs and it idles and runs really well now.

The only issue I have now is the kind of excessive blow-by. It doesn't happen on startup, but after the bike has been running for 20+ minutes. I didn't have time to do a compression test, but that's something I'm going to do soon.

After doing the carb sync, I attempted an "Italian tune-up". I took it to a large lot and went back and forth accelerating hard in 1st and 2nd gear (not enough space to go beyond that). No change. I haven't taken it on the freeway yet to get it above 60mph for any length of time (I actually attempted this, but there was traffic, lol). If I do that, and I'm still getting the blow-by, is my only recourse to pull the head and do piston rings, valve seals, and lap the valves? I'm not sure how concerned I should be about operating the bike with that amount of blow-by coming out of the breather.

I currently just have a hose coming off the breather with a Uni crankcase filter on the end of it. The filter lands around the pod filters, but I want to get a longer hose so it goes further down, unless It's better for it to go above the where the airbox generally is.