Curiously annoying problem-Backfire

[camdel]

Hi Thanks for looking,

Ive been doing alot of research on this site with alot of information. I bought a 1986 suzuki gs 550es. When i first bought the bike it ran fine but had a high idle then it would go down and idle. Occasionally it would stall at a light. Would hesitate around 3-5k rpm. Decided to take it apart and make sure everything was good. It rode and drove ok.

Followed what was recommended such as new o-rings from the cylinder head to carb mounting pipe. Good boots and clamps, good airbox, new battery, plugs, air filter, in-line fuel filter, and throrough cleaning of carbs.
I did have a 2AMP charger hooked up to the old battery as i tried to start the bike. Looking back as it seemed like it was a bad idea.

Its all back together and starts but backfires at idle LOUD!!!! Almost like a 9mm handgun at times. The right exhaust pipe is popping while the left has small amounts of smoke, smells like gas. I read an article about bench synching the carbs and did that. The idle screws i found 3 had no springs or o-rings. Installed new o-rings but no springs. There was no specs for the idle screws in the service manual and read that anywhere from 1-2 turs out from beeing seated was acceptable currently at 1.5 turns.

The 2 left cylinders, while sitting on the bike, were found to have hot header pipes while the other 2 (right) were cold. Took plugs out and long and behold the 2 (Right) cold cylinders had wet plugs while the other left 2(Left) were dry. Stuck a jumper wire to each plug and to the block and they all had spark. Not sure if it was strong enough though.

I am at my end and dont know what to do. Dont want to hurt the bike even more. I appreciate the help.

[terrylee]

Bikecliff should be along to welcome you soon, his site is full of info. you'll need. I'm no expert but try setting the screws at 3 turns out and then do the highest idle method and adjust each screw, usually will end up being around 2-2 3/4 turns, and each carb. can be alittle different. Also did you make sure your float levels are within specs.? If not pull them back off and do that. And do the bench sync. before putting back on. Then you'll need to get the carbs. synced together. Of course this will involve a sync. tool. All this info. is on Basscliffs' site. Hope this helps. terrylee

[Big T]

Did you reinstall the plug wires correctly?

[BassCliff]

Greetings and Salutations!!

Hi Mr. camdel,

Does your bike have the siamese carbs? Did you completely disassemble them and dip all the metal bits and carb bodies? Any leaks in the exhaust or the air intake? You might have to order the missing parts from Sudco or other carb specialty vendor. Partsnmore.com might be a good place to look too.

Anyway, let me dump a TON if information on you and share some GS lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[smarzinski]

From what you have explained it sounds like your talking about the Pilot screws ( what you called the idle screws). First off you will need to have the springs and washers on them. The springs actually push down on the oring to seal them. Those screws adjust the mixture and if they are out of whack then you will get popping. I just ordered a new pilot screw from Z1 enterprises and it comes with the spring, washer, and oring. A little pricey at 11.40 a piece but worth it if it fixes your problem. Just my two cents, hope it helps!

[frozenfish66]

did you adjust the valves? that's step one

step two you need to vacuum sync the crabs

only after that can you adjust your piolt screws.

if you don't follow those steps you will be chasing your own tail and never make progress. you cant really take short cuts on these bikes ask me how i know.

[Nessism]

Dude posted this thread two days ago and hasn't been back to check responses.

Sounds to me that the pilot jets are plugged. It's necessary to hold them up to a light to make sure they are open. That's the first thing I'd try. Also make sure the airbox is sealed.

[camdel]

Sorry for the slow response work keeps beating me up. Terrylee ill try to turn them out a little more. As for the float level, the service manual specifies for a carb that is not on the bike so its a guessing game at the moment. Bassclif's site had a nice article about bench synch so i followed that and ended up using feeler gauges on each throttle blade. Also, i dont have a vacuum synch tool but ive attempted to make my own with a meter stick some tubing and ATF.

Big T, the manual says that the firing order is 1,2,4,3 im not sure if thats from left to right or right to left. i assumed that its left to right.

BassCliff i do have the siamese carbs, i have not dipped the entire carb bodies but have cleaned and inspected all metal pieces. The exhaust doesnt leak but the airbox came with a drywall screw in it when i bought the bike. One would think that some RTV or something can plug that up im not sure. Ill look into the vendorsr and see what they have to offer.

Frozenfish, i have not adjusted the valves.

Nessim, the pilot jets have light shining through them and are cleaned out. Ended up using gumout carb cleaner with the straw and blasted all jets and passages in carb body with it.

From what i can i have a list of things to do:
1.adjust the valves and get a new gasket for the valve cover
2. fix the hole in the airbox that was caused by a previous owner
3.make sure pluf wires are in their correct place
4.find a way to vacuum syn the siamese carbs with my home made synch tool
5.adjust the pilot screws

correct me if i missed something.

[cowboyup3371]

You really should dip the carb bodies and your jets for 24 hours just to get everything out. It will save you tons of heartache later.

[camdel]

Ill get the carbs and jets dipped tonight.

[camdel]

it ended up being some boogers in the carbs. After dipping and an extensive cleaning, it runs.

[cowboyup3371]

Congratulations. I'm glad you were able to sort it out.

[BassCliff]

Hey Mr. camdel,

Nice going! When are we going to see some pictures?


Thank you for your indulgence,

BassCliff