1986 GS550ES running rich after start-up

[Anonymous]

I have a 86' GS550ES that starts great on choke. After about 1 minute of running on the choke it goes rich and then it sounds like the plugs are fouling. When I turn the choke off, it sputters and misses and and engine shuts down. I have cleaned the carbs, set the Pilot screws to 2 1/2 turns out from close, replaced the RR(battery was going flat after 5 minutes). This is happening all through the entire RPM range. I have an in-line fuel filter installed as well. I noticed while the engine was running that the fuel passing through the line looked foggy. Any assistance would greatly be appreciated. Thanks in advance!!!

[KennyJ]

As the owner of an 85 550EF, I can tell you that one of you needle and seats is bad and not closing off completly. This happens when it is running for the vacuum is holding open the petcock.

It is a 2.8 needle and seat. I bought a set up K&L's about 2 weeks ago for 14.95 each. Might as well replace both since you are in there.

I set the floats at 22 mm. If I remember right the specs are 19.5 to 21.5, but 22 works best for me.

Kenny

[Anonymous]

Hi Kenny,
I checked them when I had the carbs out and they held, but then again what do I know, it's running rich. I may as well change them out. Have you played around with the pilot screws and if so what are yours set at? Thanks!

[KennyJ]

My screws are set at approximately 2 1/4 turns out from light bottom. Do you know your float height? If it is too low, that baby will flood easily!

Mine worked well when I clean the carbs 4 weeks ago, put them on the bike and sure as poop, ran really rich once it warmed up. Put the new needles/seats in 2 weeks ago, and it runs super smooth now.

Kenny

Could also be the o-rings on the seat assembly, one of mine was questionable, but I couldn't find a good replacement to try, and I hate pulling those carbs!

[Anonymous]

Hi Kenny,
Well, I know I measured the float height and they were within spec. Im not sure how the float height can change as I have been very carefull around them. But I could see if the needle and seat were worn, this would change the float height as well. Im going to turn my pilot screws in a 1/4 which would put them at 2 1/4 like yours. Is this the factory setting? I can't remember what I counted when I changed mine. Can you give me the link to K & L as I want to order new needles and seats. Thanks!

[KennyJ]

Yes, 2.25 was the factory setting on mine. I purchased mine through the local independent parts dealer. The brand on the package was K&L, they came through Western Power Sports (wholesaller).

Kenny

[Anonymous]

Cool,
Thanks Kenny. I can get the same type through a parts dealer near me. About $18.95 each. Thanks for the tip. If it works, I let you know.

Manish

[Anonymous]

I did some playing around with the bike today. (New Needle and Seat are on the way).What I found was when running the bike on choke above idle speed, it cleaned up enough to run down the road, and it ran better when I applied a little choke. This would lead me to believe the engine is starved. The carbon on the plugs tells me that I have not run the bike enough to clean them out. It ran beautiful when it warmed up enough on a little choke. Now Im totally confused. Petcock?

[KennyJ]

This is somewhat a WAG, but the choke does let air bleed through, it might be enough to lean out your super rich mixture.

In the first part you say it is running rich...are you sure it is rich? Have you replaced the pilot jets yet? I can tell you that I am very bad at winterizing my fuel / draining the carbs. I know that after it sits too long, I can never get the pilot jets clean and thus it always runs poorly without choke. I have just learned to replace them and it always clears back up.

So upon teardown, I usually purchase pilot jets and needles and seats. The $40 or so spent is much cheaper than pulling those blasted carbs more than once.

Kenny

[Anonymous]

Hi Kenny, Yes, I said it was running rich. Based on my observations of the spak plugs. But, as I did some further riding last night, playing around with the choke, Im thinking it is starvation (Maybe Petcock). You may be correct, it may be leaning out just that much to run right! I am going to replace the Pilots as well now along with the needle/seat. Im doing a tankotomy tonight to investigate any rusting going on. Let ya know what I find. Keep on riding, Manish

[dgeorge]

It could be the fuel filter if it is not a free flow filter, it could be starving the bike for gas. Regular auto fuel filters won't flow enough for a gravity feed system. Just a thought.

[SqDancerLynn1]

Another possible problem could be with the choke in richment plunger not sealing allowing fuel to be drawn thru the choke circuit Could also be worn out needles & jets

[Anonymous]

How about the charging system? Ignitor, stator, signal generator, RR? I replaced the RR and the battery is staying charged. Im checking the Ignitor and Im getting no readings. I really don't want to know what this is going to cost! I haven't gone to the stator yet. I know the RR and the stator are part of the charging circuit, and the signal generator and the Ignitor are spark. Just throwing it out there.

[earlfor]

For your battery to stay charged, there has to be stator output. All the R/R does is rectify available AC to DC. Simply, if you have spark on all 4 plugs, then the ignitor is working. When it does malfunction, it is common to lose spark on ignition matched cylinder pairs or all 4 cylinders. No spark on 1,4 or no spark on 2,3 would make the ignitor suspect....or a coil. No spark on 1,2 or 1,3 or 4,2 or 4.3 would not be an ignitor fault.

Ignitor boxes cost about $420. Its cheaper to convert to a complete Dyna ignition system than to replace one. I am not inclined to go with a used unit on ebay for something like this.

Earl

How about the charging system? Ignitor, stator, signal generator, RR? I replaced the RR and the battery is staying charged. Im checking the Ignitor and Im getting no readings. I really don't want to know what this is going to cost! I haven't gone to the stator yet. I know the RR and the stator are part of the charging circuit, and the signal generator and the Ignitor are spark. Just throwing it out there.

[Anonymous]

Hey Earl,
Well I must have had a brain fart last night when I checked the Igniter at 11pm. According to my Suzuki shop manual truth table, the Igniter is fried. But if it was, I would have a nasty running bike with some pretty wet plugs. Ohms out of the signal generator are right where they should be. Back to the carbs!

Thanks for the reply!!!