1982 GS550L lean

[mizz0313]

started a post in the performance/tuning section but it should probably be posted here. Having issues with lean condition on my gs550l on cylinders 1/3/4 with pilots turned out 4 turns. Bike has been converted completely back to stock. Being honest i did everything in the newb section from carb tear down to valve adjustment and looking over all air intake parts. I ordered O-rings from Robert Barr but made a mistake with size so i put bike back together. Just ordered correct size after spraying carb cleaner and getting a very small idle change only on 3/4 side. Days ago I had carb off again after having issues with getting bike to idle when setting mixture screws, did bench sync while they were off. Jets are all stock and i know the carbs are clean, also set float bowl to correct spec after seeing they were not set correctly causing no fuel. Took it out this morning at 4 turns on pilots it idled nice but in 1st trying to take off it needs a lot of throttle to even start moving. In 2nd once moving it seems nice at part throttle gets moving and then has a flat spot, wide open it pulls nice and hard but that's after rpm come down for a second. After pulling hard in 3rd I killed engine and checked plugs 1 rich(was lean yesterday when tested) 2 golden color, 3/4 lean. Can't go higher than 3rd where I live unless on big road, does that make plug chop ineffective?

Should I be adjusting float to allow more fuel or change some jets? With all the research I've done these pilots shouldn't be out that far. While waiting for correct O-rings i will be looking over my air intake system again, i did weatherstrip airbox cover and there is a rubber o-ring between airbox and secondary airbox so i believe that is sealed too but will double check. Please let me know what you think. If i should change jet sizes i will need help choosing. I may adjust float bowls to have more fuel either way, cant hurt. I made a airbox cover to ride before i got the factory cover in the mail, that cover was pretty restrictive and i now have too much air with factory cover so im going to put that on and see if it riches up enough to turn pilots back in and do more testing.

 

[mizz0313]

here again to ask for suggestions from the gs gods. Got Intake o rings installed redid bench sync and also vacuum sync, adjusted pilot screws by ear (hope I did it correctly) all after adjusting float height to .900 to rich mixture. Bike idled nice and also had great power through all circuits so I took it to work. About a mile out it started stalling but started right up, continued on and a quarter mile from work it lost all power with full throttle it wouldn't pull anymore and also shut off while making a turn so I had to coast it the rest of the way. Got to work let it sit about a hour and it fired right up idled nice and redlined. Leaving work it was very troublesome had a hard time getting any power and going up hill it barely moved with full open throttle then would start losing even more power till or eventually shut off. Let it sit it would start and I would go a little further till it shut off again. Did this all the way home took about 2 hours for a 15 mile drive. PLEASE PLEASE any help or suggestions are welcome. During trying to get it home I adjusted the mixture screws from 2-3.5 turns hoping it would make a difference and it didn't. I've dipped carbs and gone through them again multiple times but does this sound like a carb issue? I'm ready to call it quits with it so ANY SUGGESTIONS WILL HELP! ANY! Lol

 

[Nessism]

Sounds like an ignition issue or maybe the petcock. Mixture screws don't cause the types of issues you mention here.

 

[mizz0313]

Okay I will try petcock it's the one thing I have not changed on the bike. It has dyna and stock coils but does have spark once hot. But once hot, bike does act like fuel is shut off/restricted. Thanks

 

[mizz0313]

Would I still get these symptoms from a bad petcock that is set to prime?

 

[tom203]

Would I still get these symptoms from a bad petcock that is set to prime?

Maybe if the petcock was internally clogged.. But gas cap might not be venting (so fuel flow is restricted). Try loosening the cap and go for ride.

 

[mizz0313]

just updating that i still haven't got the chance to get the bike out with the rain here in PITT, i will try to get it out today with gas cap loosened and see if if it drives any better once warm. I also need to try syncing the carbs closer. Made a manometer that is a little twitchy and still trying to get how it works down pat. will let you guys know how it goes. Thanks

 

[mizz0313]

Soaked gas cap parts to clean, tested petcock and its bad. Fuel flows in ON and RES without vacuum applied.

 

[tom203]

Skip rebuilding it- just get new, bunch on ebay right now for $40 to $50 . Note outlet directions and make sure that it comes with the o-ring. Here's a typical

http://www.ebay.com/itm/Suzuki-fuel...ash=item44085df11e:g:03oAAOSwDFNWFXo8&vxp=mtr

 

[mizz0313]

ordered petcock from the link you posted, will have new petcock here tomorrow to install. One question i have been trying to get answered through research is "what symptoms do you get from a petcock that constantly flows"? I have become familiar with the way these petcocks are supposed to work and have found main symptoms of them failing, but not symptoms of them failing in this manner. One thing i have noticed while working on this bike with a bad petcock is i see a pulsing from fuel line while bike is running, I assumed that was the vacuum system doing its job but its not. Will I still get fuel starvation like issues with a petcock that flows in on and res without vacuum applied, what happens when vacuum is applied? I do know i tried running the bike in prime when having issues and it didn't make a difference from what i was able to tell. Its getting replaced either way but figured id ask to have a better understanding of whats going on with my bike or if i should still be looking elsewhere also to fix my issues. Thanks

 

[tom203]

getting these things running right is a step by step process. Your vacuum petcock needs to functioning correctly... flowing fuel at all times will overwhelm float needle seats and likely lead you to overcompensate somehow. Install the new petcock and then reset the mixture screws carefully to 3 turns out and go from there.

The petcock mounting screws need a special washer underneath their head. These washers have rubber bonded to metal - when tightened they insure a tight seal. A good hardware store should have them in plumbing section....1/4 inch size probably will work with the 6mm screw. Bring the screw to store to get a good fit!

 

[mizz0313]

Back again! Got the petcock on and it is working correctly, vacuum sync carbs using gauges. Had bike running and after getting a hanging idle I checked idle screws and plugs, screws we about 2 turns out and the 1/4 plugs were kinda brown with fuel while 2/3 were white and ashy. Go out this morning hoping to ride after tuning screws, and I couldn't get bike to start right away no matter how much choke. Took plugs out after cranking didn't seem to have fuel on them. Went out 3 turns in idle screws and got bike started. while adjusting screws it didn't have much change on the idle bike idled okay but when given throttle rpm dipped and bike wanted to shut off would keep running if i let go of throttle. When it would dip low I would touch choke and it would rev back up. But it did this no matter where I had idle screws set, turn out to 3 turns after pulling plugs and when given throttle it still dipped if I eased on throttle it revved up but only to about 2500 with the sound of not enough power to rev higher and would hang a little. Back at idle if I blipped it would dip again unless I was really easy on it. Are my carbs still gummed up? Last time tearing carbs apart I unganged them and sprayed carb cleaner through idle circuits and choke holes and watched fluid shoot out, I have dipped these carbs already. Ive gone so far with this bike not knowing anything at all about them when I bought it but can't seem to figure out the lean/rich conditions

 

[tom203]

Firstly..... This in your cold start

"and I couldn't get bike to start right away no matter how much choke. Took plugs out after cranking didn't seem to have fuel on them."

I'd suspect the "choke" is not supplying enough fuel up to carb throats... With all your poking and blowing carb passages, did you clean out the passage in the fuel bowl itself, cuz this often gets clogged?

At this point, before your gauge carb sync, I'd doublecheck my bench sync carefully - done right, this will get you real close with all carbs sorta happy... engine should rev eagerly from idle provided enough mixture is available as throttle is openned.

 

[mizz0313]

yes when bowls were off i watched carb clean stream from float bowl holes to across the room, unless they are clogged again. i will be taking carbs off again then. thanks

 

[tom203]

Lucky you! Make sure that "choke" lever pulls out plungers on carbs 1/2 inch fully (I just checked mine)-otherwise cold start won't be quick!
Inspect/ compare mixture screws - make sure their o-rings and washers are intact- and look for blockage from old parts jammed in carb throat orifices.

. once you get these carbs running right, they will stay that way for a long time with with little additional effort.

 

[mizz0313]

okay! Thanks for all your help tom you have helped me learn this bike in a matter of a few months and by just a few post. Thanks for all your time and effort. Will keep you updated on this.

 

[mizz0313]

okay another update. tore carbs apart and dipped them again, bowls had little rust making its way through my old screen that had a slight tear(new petcock was installed but bowls weren't drained) . Another thing i kept avoiding was intake boots, looked okay and after purchasing new ones looking over old ones they were not okay and allowing air. installed cleaned carbs and new boots while carbs are also benched synced. Decided to take bike out to warm up before vacuum sync and it drove great, idle moved around a bit when coming to a stop and after turning it back down and going it continued on fine. Came home parked and let idle throttle was very responsive and came back down nicely to 2k, couldnt get it down to 1100rpm with backing out knob. Went around again and got it into 3rd gear coming up over a hill it shut off. Coasted down to gas station where i fooled with getting it to start again for the next 20 minutes. Finally got it started again but would not idle and would shut off, kept it throttled and got it home but going up the hill it didn't produce power like it did going up the same hill 40 minutes before this (gas cap off this time to check for it not venting). once i hit a flat spot the rpms jumped back up and the bike pulled but once i hit another hill it just bogged till pretty much coming to a stop. Got to top of hill it just took awhile with wide open throttle in 1st, 2nd gear didnt help at all. Got it in the garage and noticed that there was no fuel in the line and turning it to prime then filled the bowls again, also gas in the tank. the bike had a hard time starting again and if i got it running it wouldn't idle at 1100 rpm without shutting off but when giving it gas it sounded great and responsive. Any ideas on this? carbs are clean, new intake boots and o-rings, new petcock and cleaned gas cap venting hardware. Seems like when cold it pulls hard and runs good but once hot it doesn't keep getting fuel, is that because its already running lean so fuel delivery becomes a issue? Maybe im looking at how fuel delivery operates incorrectly. Another thing i noticed is the headers on 1/4 are not flush to the head like 2/3, not sure what that does but i know it cant be good (seen pic on forum where it shows them being flush) . I will be unbolting clamps and see if i can get them seated to the head, flush. I did do a plug chop coming down hill in third and 1 is tan while 2/3 still white and 4 looking slightly coated in fuel. I will vacuum sync when i get home and see if that helps, in the meantime should i be looking at fuel system faults? Fuel line was a little long i did shorten it up before walking away. Bike ran good through all ranges when it ran GOOD. I also adjusted throttle cable above carbs a few months back never adjusting at throttle side now not sure where it should be or if this is maybe affecting my idle. Cable had some slack in it with about a 1/8 inch of play on throttle before throttle plates started moving, today after getting it home i adjusted the cable tighter so there is almost immediate movement from plates is this correct?

 

[tom203]

Let's not worry about vacuum sync just yet....we need to keep fuel in bowls when bike is running. There should be enough vacuum from #2 carb throat to feed all 4 carbs,but something is wrong. Just leave petcock in prime spot for now when you are test riding it. But remember to turn petcock to on or res spot when you ain't running.

" Got it in the garage and noticed that there was no fuel in the line and turning it to prime then filled the bowls again, also gas in the tank"

There should be some slack in throttle cable ,before throttle plates start to open. Idle stop screw should hold position (you can feel plates thud as they rest on it.). Erratic idle when warm suggests air leak (or poor bench sync). Good call to get new boots... did you get new boot o-rings too, cuz I don't remember?

 

[mizz0313]

yes boot o-rings have also been replaced.

 

[tom203]

yes boot o-rings have also been replaced.

I figured that ,but my memory is poor! Keep at it, your persistence will pay off.