Running rich? [Warning: detailed]

[AcidFaucet]

I've searched through the forums (which have been a huge help), so I'm not looking for a "This is the fix!" but just some general guidance as to whether I'm the right track.

The bike
82 GS550M
- 4 into 1 header, K&N filter, vance & hines exhaust (all PO mods)

Condition of the Bike
- Appears to be running rich
- Doesn't want to idle at less than 2k
- Seems to be doing okay with the throttle open, but boggy
- Some smoke out of the exhaust
- Periodic, exhaust backfire
- Detonation seem heavy, like I'm blasting dynamite in there
- Runs smooth when just 2 cylinders are firing (2 & 3 are the ones I did that with)
- There may be an oily residue base on swiping the exhaust gunk and looking at the plugs, tough to discern (at one point engine oil exceeded the sight glass considerably [sigh, my fault filling to level while running])

At first startup
- Smoked heavily for a while, but cleared out, no real definitive color to it (blackish/whitish/bluish)
- Carbs weren't perfectly seated so it was way lean due to a leak at the intake boot, issue dealt with

What I've done
- Thoroughly cleaned the carbs

- Adjusted the valves, all are right around 0.04 - 0.05; smallest shim 2.55; largest shim 2.65

- Replaced ignition coils (3 ohm dynas), spark wires, coils tested at 6.7ish volts, I'm going to do the coil relay mod this weekend

- At one point I didn't have a plug fully in and a older wiser man pointed out that my compression was definitely fine given the hiss and air pressure coming out of it, checked it still the same, good on all 4

- I've taken the carbs out, drilled the air screw plugs (screwed up one drilling out the plug, luckily I bought a spare set of carbs beforehand)

- Float heights good

- I suspect needles may be having issues, fuel line appears to be fully draining when there's no vacuum (determined by the rubber hose hardening too fast and the amount of dried gas on the inside)

- Fresh plugs, fouled quickly, very residue-y

What I have not done that I think I maybe should do
- Check the timing

My inclination is to do the coil mod, check the timing, swap in clean plugs, and fiddle with the air screw.

Does it sound like I'm on the right track?

[posplayr]

sounds like you have been diligent in reading the forum and doing the required maintenance. Unless I missed it you did not mention the main jet sizes or where the needles were set.

When pods and 4:1 are added the bikes normally need a jet kit as especially the pods will lean out the mixture.

The fact that yours is very rich suggests the PO changed yours and put in too big of mains or has the needle set wrong (you did check the float hight right?)

Is there a Dynojet kit for your bike. The parts lists and instructions can be downloaded from the Dynojet website compare those jet sizes to yours and report back.



EDIT:

SUZ 82 GS550 KATANA

Dynojet doesnt list a link for the pdf file for a #3314 kit

Next step is to compare to stock jet size, maybe Chef1366 can offer an educated guess as to how big you should be above stock.

[AcidFaucet]

Haha, that'll teach me! I opened them up to get the sizes, and found that I forgot to put the pilot in carb #1, and cylinder #1 had the ugliest of plugs I've ever seen, the others didn't look particularly bad. Thanks for asking for those jet sizes!

Float height is within spec 22.4 +/- 1 and the air filter is the airbox style, not pods.

Aside from that obvious mistake of my own, the jetting looks really odd.

Pilots @ 40 (that's stock)
Main @ 110 (stock is 92.5) making it richer
Air jet @ 150 [1.5??] (stock is 1.6)

Available to me full sets of (aside from those in the carb):
Pilots: 42.5 and a spare set of 40s
Mains: 102.5 and 92.5
Air jets: 140 [1.4??]

[posplayr]

Haha, that'll teach me! I opened them up to get the sizes, and found that I forgot to put the pilot in carb #1, and cylinder #1 had the ugliest of plugs I've ever seen, the others didn't look particularly bad. Thanks for asking for those jet sizes!

Float height is within spec 22.4 +/- 1 and the air filter is the airbox style, not pods.

Aside from that obvious mistake of my own, the jetting looks really odd.

Pilots @ 40 (that's stock)
Main @ 110 (stock is 92.5) making it richer
Air jet @ 150 [1.5??] (stock is 1.6)

Available to me full sets of (aside from those in the carb):
Pilots: 42.5 and a spare set of 40s
Mains: 102.5 and 92.5
Air jets: 140 [1.4??]

So all the plugs look pretty good now?

Mikuni's have little squares with mark in the corner. DJ usually are not marked. Are some of them DJ? A 92.5 Mikuni is like a 100 DJ (if it even exists)

92.5 to 110 seems like a big step for just a 4:1

[AcidFaucet]

Haven't fired it up yet. I won't get to it until saturday (I'm in the middle of the painting process this week).

They're all mikunis.

I think I've got it sorted out though. I bought the bike at the tail end of winter and I think I recall the PO mentioning rejetting during the winter. He gave me the 102.5 mains, 140 airs, and 42.5 pilots so I'm thinking that he used the 110s in the winter and the 102.5s normally and adjusting the other jets as he saw fit.

I have ridden the bike prior to my decommissioning it before the onset of summer when I started going on the repair/replace/check/repaint onslaught, and it was seeming to get crankier as it got warmer out.

Obviously that missing pilot would have had a huge impact, but I'm guessing that if I put the 102.5s in it'll be much much happier. I'll let you know how it goes.

Thanks for everything thus far.

[chef1366]

I'd use the 102.5 mains and the 40 pilots.

[AcidFaucet]

Absolutely refuses to start with the 102.5 mains and 40 pilots.

40 pilots and 110 mains will start and run fine.

[chef1366]

Absolutely refuses to start with the 102.5 mains and 40 pilots.

40 pilots and 110 mains will start and run fine.

Sorry but the fact it wouldn't start was not due to the jets.

[blowerbike]

Sorry but the fact it wouldn't start was not due to the jets.

don't be sorry...
your just stating facts.
you have to make sure the bowls are full of fuel.
let it sit on prime..crack a drain loose ect..

[Dave8338]

don't be sorry...
your just stating facts.
you have to make sure the bowls are full of fuel.
let it sit on prime..crack a drain loose ect..

For some reason, tonight just seems to be one of those nights where I should just go to bed...


Can't sleep and am seeing NO humor in the obvious...

[AcidFaucet]

Only difference between the two attempts were changing the main jet sizes. Though from my brief read on jetting I gathered that the pilot was supposed to do most of the work when starting/idling.

Air screws at 3 1/2 turns out. Checked for air leaks, intake o-rings still intact and not flattened round, intake boots are a little firm but nothing bad, airbox boots look fine. I'll give it another whirl with the 102.5s if there's any suspicions that I should look into. Spark is strong, coil relay wired in, 11.x volts at coils.

Seems healthy at the moment, tan plugs. Still haven't checked the timing. If timing were off slightly could more fuel than necessary get a kaboom in a case where a bit less wouldn't?

[chef1366]

Only difference between the two attempts were changing the main jet sizes. Though from my brief read on jetting I gathered that the pilot was supposed to do most of the work when starting/idling.

Air screws at 3 1/2 turns out. Checked for air leaks, intake o-rings still intact and not flattened round, intake boots are a little firm but nothing bad, airbox boots look fine. I'll give it another whirl with the 102.5s if there's any suspicions that I should look into. Spark is strong, coil relay wired in, 11.x volts at coils.

Seems healthy at the moment, tan plugs. Still haven't checked the timing. If timing were off slightly could more fuel than necessary get a kaboom in a case where a bit less wouldn't?

yes you could use more gas with the timing off. Would run very poor though.

[BassCliff]

Greetings and Salutations!!

Hi Mr. AcidFaucet,

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", the Carb Rebuild Series, and the Stator Papers. 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

[AcidFaucet]

@ BassCliff, I saw that mega-welcome when I first registered and put it to use. Your site has been a huge help (the valve adjustment pdfs, electrical stuff, and I'll be using your timing stuff later today).

@ chef1366, alright I'll go through and check everything again, valves, timing, ... maybe I'll find something stupid I did (more than likely).

[AcidFaucet]

It was the intake o-rings. I think in checking them I dealt them a death blow. Found fuel in the bolt holes of each boot. Running fine now with your suggested jetting chef, just a few kinks to work out now.