Seafoam cause poor running?

[Nessism]

My ’81 550 is a full time garage queen since I haven’t gotten the title business sorted out yet. It sat for a lot of years before bought it and needed the typical carb rebuild which I did about a year ago. I’ve been pretty bad about running it regularly so I recently dumped some Seafoam in the gas because the label says it stabilizes the gas. Shortly afterward doing this the engine started running poorly so I pulled the carbs and did a quick spritz out which took care of the immediate problem.

The bike currently runs good other than a hanging idle problem; rpm does not drop as quickly as it should and when blipping the throttle it tends to hang at about 2000 rpm. If I set the idle speed lower, it tends to go too low and stall – can’t find a happy medium.

The carb boots are nice and soft and there are fresh O-rings installed so I don’t think this is a vacuum leak issue. Bike is 100% stock. I’ve check the throttle linkage closely and did a vacuum sync – set the two inner cylinders slightly lower than the outers. Idle mixture screws are set at 2 turns (can’t detect any idle speed variation when adjusting).

My understanding is that a lean mixture leads to a hunting idle. I really don’t understand what has changed on the bike other than the Seafoam. Does it mess up the mixture that much to cause the problems I’ve described? I’m going to dump the gas this week and try with fresh stuff but any input is appreciated.

[zuzu]

Just a thought. But I would run the tank of gas in it. The fill up with your regular brand. Give the sea-foam a chance to clean out the combustion chambers.

IMHO

Tony

[Mark whiz]

Heck, everything I've put Sea Foam in has responed nicely within just a few minutes. The idle speed went up on the bike and my mowers have turned into grass eating machines.

It sounds like you have taken all the quick measures to make things right. Have you checked your plugs for possible mixture issues? If you haven't actually rebuilt/thoroughly cleaned the carbs internally, you might find your issue there. The float needles, seats, and gaskets wear and deteriorate with time and may need replacing. I've found that needles have been required on my GS every 30K miles or so as they can leak a little gas, raising the fuel level in the bowls and causing richness - even flooding the crankcase with gas 1 time.

Oh, if the gas in the tank is more than a month old - dump it and refill with fresh gas. Adding the Seafoam after the gas has already deteriorated won't do any good.

[AOD]

I’ve been pretty bad about running it regularly

This is your problem. I use Stabil in the winter and run my bike at least every other week to keep the fuel moving. You will have less problems if you at least fire it over every once in a while.

~Adam

[t3rmin]

You may still have clogged idle circuits, making things lean. The SeaFoam may have loosened some crap which flowed downstream and clogged something...?

Also consider that lots of SeaFoam in the tank may change the fuel composition enough to alter engine behavior. I noticed this the other day using a bunch of water remover (alcohol) and MMO in the tank. Once I ran it through and put in fresh gas, the bike ran more normal. So although it had a good effect in the long run, while it was still being burned through, things weren't quite right.

[Nessism]

The bike started to run worse after adding the Seafoam. I'm not sure if it caused the problem by loosening crud but I subsuquently pulled the carbs and sprayed them out with carb cleaner. Bike ran better but I can not get rid of the hanging idle - thus my reason for this thread.

I'm going to change the gas and see what happens.

[t3rmin]

Well I'm just suggesting maybe the SeaFoam knocked something loose that wasn't cleared by a quick spray out. Did you poke out the little idle holes in the throat? Spray hard through pilot jet, main jet, and air jets?

Just bouncin' stuff off ya. ;-)

[the_journeyman]

If you get too much Seafoam to your amount of gas, it will run poorly. There may be some smoke though. If you pour it directly in the intake like I can on my M750, the motor will almost stall. Most likely, the combination of not 100% gas with a bit too much Seafoam in the fuel AND the crud being knocked loose is just making it a little grumpy ~

JM

[BassCliff]

Use it or lose it!

Mr. Nessism,

Whenever I use Seafoam I like to put it in the tank just before a long trip when I know I will use most, if not all, of that tank riding that day or the next. Then I fill up with regular gas. Seafoam has always helped. I concur with Mr. t3rmin's speculation that debris may have dislodged and gotten stuck somewhere else. This could happen if you run a "Seafoamed" tank for just a little while. You have to run it for a good long time and let it do its "magic". \\/

Thank you for your indulgence,

BassCliff

[Nessism]

Well I'm just suggesting maybe the SeaFoam knocked something loose that wasn't cleared by a quick spray out. Did you poke out the little idle holes in the throat? Spray hard through pilot jet, main jet, and air jets?

Just bouncin' stuff off ya. ;-)

I removed the pilot jets and poked them through with a wire - none were plugged. Same thing for the mains. I didn't do anything with the air jets. Bike runs pretty well but has a hint of low speed leanness. Air filter is brand new as are the plugs.

Thanks for all the suggestions.

[jimcor]

I'd take zuzu's advice and tell you to run at least a tank full thru the bike, but understand the title thing might make that a little hard to do. Drain, put the old gas in your car and refill the tank with Sta-bil-ized gas.

[smagnusen]

Nessism,

I've had similar issues with my 550. I see that you mentioned that your mixture screws 2 turns out. Accourding to this site, in the carb setting section, the factory settings are 3.5 turns out. This seems to be where mine are happiest. Perhaps your running a bit lean now which might explain the slow return to idle.

[Nessism]

Nessism,

I've had similar issues with my 550. I see that you mentioned that your mixture screws 2 turns out. Accourding to this site, in the carb setting section, the factory settings are 3.5 turns out. This seems to be where mine are happiest. Perhaps your running a bit lean now which might explain the slow return to idle.

Do you have a link to where you read 3.5 turns? I always that they were supposed to be in the 2 turn range.

[smagnusen]

No problem, it's actaully the first sticky in the tech forum:

carb oem spec as per factory manuels

http://www.thegsresources.com/_forum/showthread.php?t=73723

[tconroy]

I removed the pilot jets and poked them through with a wire - none were plugged. Same thing for the mains. I didn't do anything with the air jets. Bike runs pretty well but has a hint of low speed leanness. Air filter is brand new as are the plugs.

Thanks for all the suggestions.

Check your bands on the intake and airbox boots to make sure they are snug and also check the intake boot screw to see if they are torqued the same.It sounds like you may have a air leak.Also check your airbox to make sure it is sealed properly.Clean your plugs and air filter.