No 1 Cylinder not getting warm

[sedelen]

Well I don't have a compression tester, maybe I could find some one with one. I have a couple of friends that work on bikes for a living, surely one of them would have one.

Yes, I did leave on prime, in fact its there now, I will go out in a few and switch it to on..

I did change the oil, it had a really strong gas smell.. I drained the oil tonight and according to the manual it should take 3 quarts, so I followed the instructions and its only just showing in the window, so I will let it sit over night and see where it is in the morning.

Its still putting out blue smoke from the exhaust on the left, that goes to no 1 and 2 cylinders, when I rev it up. Not a lot of smoke out of the right side exhaust. I could not take it for a ride tonight, so I will do that Friday when I am off and see how it acts after riding it around. Maybe I will have a compression tester by then.. Stay tuned...

TTYS,
Scott..

Leaving it on Prime can overflow your carbs with gas, and allow gas to get into your crankcase increasing the volume of oil/gas in your crankcase.
Oil capacity is 3.2 quarts without changing filter or 3.5 quarts if you replace filter. Put bike on centerstand and check the level in the sight glass. Once you get the required level run the bike a few minutes and let it sit awhile then recheck the level again and add if needed.
I like to keep mine just below the upper level mark.
Do not leave your petcock on "Prime" without the engine running for too long a time, just asking for trouble if you do.
Check page 16 in that owners manual (the link is in a previous post in this thread) and it shows the lever for the petcock positions. We've had several instances where people got the Prime and Reserve positions mixed up.

[zaipai]

Leaving it on Prime can overflow your carbs with gas, and allow gas to get into your crankcase increasing the volume of oil/gas in your crankcase.
Oil capacity is 3.2 quarts without changing filter or 3.5 quarts if you replace filter. Put bike on centerstand and check the level in the sight glass. Once you get the required level run the bike a few minutes and let it sit awhile then recheck the level again and add if needed.
I like to keep mine just below the upper level mark.
Do not leave your petcock on "Prime" without the engine running for too long a time, just asking for trouble if you do.
Check page 16 in that owners manual (the link is in a previous post in this thread) and it shows the lever for the petcock positions. We've had several instances where people got the Prime and Reserve positions mixed up.

Thanks, I put back to on. Not really sure why I had it on Prime but just kinda left it there. That would explain the gas smell and really there seemed to be more oil volume that came out of the engine when I drained it then what I put in.. All this explains a lot. Its raining today.. So I will post an update Friday or Saturday depending on weather on how this all plays out..

Thanks for the help all.. I hope this takes care of the issue.

Scott..

[wanrep]

You have a leaking float valve on #1 carb.
The shop that rebuilt your carbs should have replaced all the float valves. If they did, a bit of dirt/rust found it's way to the #1 carb and is causing the float valve to leak and gas to run down the cylinder, into the crankcase.
This causes all the symptoms you describe.

If the float valves are doing their job, you can leave it on "prime" forever without gas leaking into the crankcase.

You can try removing the drain screw in the float bowl, turning petcock to prime and let the gas run out for a few seconds. this might flush any debris off the float needle.
If the float valve still leaks, replace the float valve with a new one.

btw...check your air filter. I'll bet it's gas soaked.

[Steve]

OK, I have taken the time to read through all of these responses and am somewhat surprised that nobody has brought up a favorite topic.

You say the carbs were "professionally rebuilt". Any idea what all they did to them? Did they replace all the o-rings inside? Did they replace any jets?

Most importantly, though, did you synchronize the carbs ON THE BIKE?

A good shop would have attempted a "bench sync" on the carbs before handing them back to you, but that is only a close guess. They HAVE to be synchronized on the bike. It is quite possible that your #1 carb is simply opening just a tad later than the others, meaning that it's not open as far, or not making as much heat as the others.

.

[chuck hahn]

I would also, to add to Steves response, double check theres that washer under each of the float seat, recheck the float heights yourself, And under no circumstances ever leave the petcock on prime or reserve when its just sitting. The only time PRI is needed is i the bike has sat for a week or 2 without running...gas will evaoporate out the vent tubes and you reprime it for a few seconds befote starting. OR if youve completely ran out of gas even on reserve or if you have to drain the carbs for maintenace issues. Other than these reasons, the petcock should always be in the ON position. Also check to see if they put rubber plugs back in on all the pilot jet holes.

[sedelen]

[QUOTE=wanrep;1713459]If the float valves are doing their job, you can leave it on "prime" forever without gas leaking into the crankcase./QUOTE]

I would like to agree with you, but then there's that caution in the owners manual. In fact it's in most owners manuals for the GS series bikes. Now why would Suzuki put that in there for a serviceable bike? I've argued this point before and it's just best to not leave it in "Prime." It very well could be when the bike is on it's sidestand the bike is at an angle and the floats don't come up high enough to provide a good shut off.

[chuck hahn]

Steve...I see he has only 2 posts so far...sooner or later he will see the light. The steel points of the needles arent machined so precisely to seal like say an oring would. Secondly, the needles are steel and the float seats are softer brass..thus the softer brass does inccur wear over a sustained period of time. These two realities in and of themselves are reasons the owners manual warns directly about leaving it on prime. Then you factor in the petcock seals and diaphrams wear and can fail almost at any time...see what I mean???

[zaipai]

The shop that did my work is one I have used before and is a friend. He does really good work, I trust he rebuilt them well. I gave him a rebuild kit I bought for it, he did the rest. Below is a link to a CafeTV that featured some of his work, its short, only 1min or so but you can see he is a stickler for details.

I did put the petcock back to On from Prime. I think I set it on Prime after I put the carbs on and forgot to put it back, this is my first experience with a vacuum petcock so still finding out about them and how they work etc..

He did do a bench sync after he rebuilt them. I have a vacuum carb sync tool I used on my Honda cb550 so I will get to sync'ing these carbs, its really been more a time issue for me. Sounds like I need to do that sooner rather then later..

Thanks for all the advice I am looking all of it and will take all advice that comes my way..

https://www.youtube.com/watch?v=MOF9hyOSEsQ

TTYS,
Scott..

[koolaid_kid]

If the float valves are doing their job, you can leave it on "prime" forever without gas leaking into the crankcase.

I would like to agree with you, but then there's that caution in the owners manual. In fact it's in most owners manuals for the GS series bikes. Now why would Suzuki put that in there for a serviceable bike? I've argued this point before and it's just best to not leave it in "Prime." It very well could be when the bike is on it's sidestand the bike is at an angle and the floats don't come up high enough to provide a good shut off.

Forever is a long time. Whilst I have left it on virtual prime (Using an aux tank while tuning the carbs) for hours, even overnight when I forget to remove it, I would not leave it on all the time.
My GS manual had the warning, my GPz manual does not, and they both use BS34 carbs. But I still don't leave it on prime, that is the whole function of the vacuum petcock.

[sedelen]

Steve...I see he has only 2 posts so far...sooner or later he will see the light. The steel points of the needles arent machined so precisely to seal like say an oring would. Secondly, the needles are steel and the float seats are softer brass..thus the softer brass does inccur wear over a sustained period of time. These two realities in and of themselves are reasons the owners manual warns directly about leaving it on prime. Then you factor in the petcock seals and diaphrams wear and can fail almost at any time...see what I mean???

Chuck,
That's a great explanation of the potentially inherit weaknesses of the float needles and seats. I would also think that the pressure that builds in the tank after riding, or from the bike sitting in the sun would put those needles and seats under more pressure and what would otherwise be a small gravity leak could be compounded even more.

[sedelen]

Forever is a long time. Whilst I have left it on virtual prime (Using an aux tank while tuning the carbs) for hours, even overnight when I forget to remove it, I would not leave it on all the time.
My GS manual had the warning, my GPz manual does not, and they both use BS34 carbs. But I still don't leave it on prime, that is the whole function of the vacuum petcock.

Forever is a long time.
And it also has been a very long time since I clearly remember entering into a discussion with you on this very same subject.

[MisterCinders]

If the float valves are doing their job, you can leave it on "prime" forever without gas leaking into the crankcase.

That's a pretty big "IF." Why would Suzuki bother with a vacuum petcock, if the float valves are so reliable? Why do other bikers turn off their gravity fed petcock when they park the bike? Superstition?

If the float valve still leaks, replace the float valve with a new one.

If I follow you, he should flush the bowl, check for leaks, and then replace the "float valve." That's pretty expensive, depending on what a "float valve" is. An OEM float needle/seat assembly is pricey. The ones in the kits are junk.

Before you shell out for a new float needle and seat, there are a few other things to inspect for leaks.

1. Clean the seat and the float needle to make sure nothing is blocking it.

2. Check the float needle for wear. If you can feel a ridge on the point, replace that needle (you can get replacement float needles from Z1).

3. Check the needle and seat together for seal. Blow into the bottom of the seat as you slowly slide the needle into it. You should feel it close as your cheeks puff out like blowing up a balloon. If it doesn't seal, then you might need to go back to the needle or replace the set.

4. Check the float itself to make sure it is not catching on something like a bowl gasket edge).

5. Check the washer for the needle seat. These can fail, and let gas flow unchecked. If so, replace that washer.

[wanrep]

I'm new here but not to motorcycle carburetors. I've rebuilt more sets of GS carburetors than I can count.
Fact remains, it doesn't matter if the petcock is on "on" or "prime", if the float valve's leaking, that cylinder is going to flood and run rich when it's running.
No, it won't flood the crankcase if it's on "on" while sitting (until the petcock starts leaking which they all do at some point) but it's still not going to run correctly.

If Zaipai fixes the #1 float valve, it won't matter if he accidentally leaves the petcock on prime. The other 3 plugs looked good, right?

Just a side note...I've replaced the vacuum petcock on every bike I've had with a Pingel, manual on/off/reserve, petcock and I do turn it off.

[tom203]

I'm new here but not to motorcycle carburetors. I've rebuilt more sets of GS carburetors than I can count.
Fact remains, it doesn't matter if the petcock is on "on" or "prime", if the float valve's leaking, that cylinder is going to flood and run rich when it's running.

But when engine is running, fuel is dribbling thru seat and into bowl at all times, so slight leakage at needle seat would not cause the cylinder to run rich. I bet lots of these old carbs (like mine) probably have worn seats- unnoticeable provided we don't leave it in "Pr" and petcock is working right

[wanrep]

That's a pretty big "IF." Why would Suzuki bother with a vacuum petcock, if the float valves are so reliable? Why do other bikers turn off their gravity fed petcock when they park the bike? Superstition?



If I follow you, he should flush the bowl, check for leaks, and then replace the "float valve." That's pretty expensive, depending on what a "float valve" is. An OEM float needle/seat assembly is pricey. The ones in the kits are junk.

Before you shell out for a new float needle and seat, there are a few other things to inspect for leaks.

1. Clean the seat and the float needle to make sure nothing is blocking it.

2. Check the float needle for wear. If you can feel a ridge on the point, replace that needle (you can get replacement float needles from Z1).

3. Check the needle and seat together for seal. Blow into the bottom of the seat as you slowly slide the needle into it. You should feel it close as your cheeks puff out like blowing up a balloon. If it doesn't seal, then you might need to go back to the needle or replace the set.

4. Check the float itself to make sure it is not catching on something like a bowl gasket edge).

5. Check the washer for the needle seat. These can fail, and let gas flow unchecked. If so, replace that washer.

You're right. All the aftermarket float valves I've tried over the years are junk.
I always use Suzuki's but yes, they are pricey at $33. Never had one leak though.
When I rebuild an old set, I replace all the float valves with new ones.
I put them on a carb rack with a remote fuel supply and let them sit for an hour with the gas on to make sure there's no leaks.
It's pricey but I've never had a bike come back with carb issues.

Zaipai's issue may very well be a speck of dirt in the float valve causing it to hang open. I'd start there first. If, after all cleaning and adjusting fails, then replace the float valve.

By all means fella's, turn those petcocks off. I still turn mine off.
BUT...it shouldn't be disastrous if you accidentally leave it on. That's all I'm saying.