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81 550 carb rebuild

  • Thread starter Thread starter ratchetneck1
  • Start date Start date
R

ratchetneck1

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I have stripped my carbs for acid dip and rebuild.Do the throttle shafts have to be removed before i dip them? I didnt know if there are rubber seals behind the shafts that will get ruined when i dip them.Also what about the air screws.I have the plugs installed that conceal them but have drilled them out.Is there a small o ring behind these that need to come out? If i remove them how many turns out should they be set at? The one that i removed was 1 3/4 turns (factory setting).I have a kerker 4 into one exhaust and k&n direct mount air filters.The stock jetting was in these carbs (92.5 main and 40 pilot) but have ordered 95 main and 42.5 pilot.This will put me one setting above stock on both jets.Does this sound about right? I have refered to the "carb cleanup" series on this sight as well as the factory manual but any other tips would be great.thanks
mike
 
I really wouldn't reccomend changing the jetting. The stock jetting is good really... Going up one size on the pilots is like going up 5 main jets. The main jet.. you might not notice the difference.

I wouldn't acid dip them. Just clean them properly. That just requires some carb cleaner and some time.
 
IMHO, you can't properly clean a set of carbs with a spray can. Well, let me correct that, you MAY be able to clean them with a spray can, but you also MAY go through the whole process and still be questioning if you have a half blocked passage or something. If you've never cleaned them before, I'd do an acid dip, then you'll never really need to again, becasue you know that you will take care of the bike and fuel system. That's my opinion anyway...

That said, no, the butterflys can stay in the carb body, but you should remove the air screws, and I don't know about the 550, but my 1100's have rubber o-rings to seal them. Often they stick in the bottom of the air screw port, fish them out with a pick or something. As far as the setting, try them at 1 3/4 out like you had them.

And as far as the jetting, has the bike ever run well with the pipe and jetting that it currently has, or is this a new setup? As Nero said, the pilot is much more sensative to upsizing than the mains are. And the mains, I'd trust what Nero says, he knows the 550's and has certainly modified them. But I can't understand why the stock mains would be ok with pod filters and a pipe? I would think DJ kit would be in order with new needles and jets- the works!
 
You'll have to re-jet for those pods and pipe. That means larger mains, pilots, larger pilot air jets, raising the stock jet needles by shimming if U.S. model, drilling out the vacuum ports to the diaphragm chambers and possibly lighter springs.
I prefer the jet kits and the adjustable jet needles.
I'm out the door now for work and I never "hurry" any jetting suggestions, but will check in after to see if you want jetting suggestions (if you don't go with a kit...which I suggest you do).
95 mains are not near large enough.
 
WOW, I completely missed the pods and 4-1 sentance. Yeah you need a dynojet stage 3 kit. they will claim they don't have one that fits. You want the model for the GS550M katana. That's the exact same engine as on your bike. :-) Enjoy!

The jet sizes you speced are WAY off for the air filter and exhaust you have. if you were going to go the mikuni route you'd need to start at a 140 or 150!
 
wow lots of info! The bike had the kerker on it when i bought it.It also had a stock air filter.This bike is by no means any rocketship but i just wanted air/fuel to be were it should be.It ran like i think a 550 should in terms of power before i took the carbs off.Since i had the carbs off i just wanted to have the correct jets in there before reassmbly.Seeing as how i am not trying to squeeze every ounce of power out of it and just want a good combustion what is the rule of thumb as far as jumping up in jet sizes when running the 4 into 1 and the k&n pods.I really dont want to have to keep changing jets ,checking plugs etc keeping in mind that this is my daily driver. Thanks for the info!
 
Nerobro, can you spell out what i need to do with this thing? I have the orings that go to the heads ,complete carb rebuild kits (k &l ) ,and 95 and 42.5 jets . I see that you dont think the jets are right though.
 
I'd go with a stage 3 kit. If we guess wrong, the cost of buying separate jets can get pretty high plus you'll be spending more time taking things apart.
The kit supplies everything you need, not just mains and pilots.
It will take some tinkering but the kit is the best option in my opinion.
Maybe try making another thread asking for specific main and pilot jet info from someone who's made this change, but you may be trusting someone who really doesn't know if his bike is jetted right. I think you'll be sorry though.
Just guessing, I'd say 120 mains and raise the jet needles at LEAST .10" (about the same as two full positions richer.) 45 for pilots. Not sure about pilot air jets without seeing the sizes. You'll still need to enlarge the vacuum port to the diaphragm chambers. Lighter springs if you have any throttle response issues. I'd get the kit. :)
 
the 550 has the lightest springs I"ve seen in a carb. :-)

it's definitely 150 with mikuni jets...

And just go dynojet. It's cheaper. I have $120 in jets from futzing around trying to do it myself.
 
I ordered the dynojet kit from dennis kirk last nite. Should i expect to feel any increase in performance? This was not my goal but if there is so be it!! Thanks for the input.The application was for an 82 gs55 m katana.I hope this is the right setup as i already have a bunch of parts to return!
mike
 
Ok, I am also following this thread since it applies to me also, but what DJ kit is for the 1980 550E? I dont see one, is it the 550 M katana mentioned above, just want to be clear.
 
Yes, there are rubber seals along the throttle shafts. They are visible on the microfiche. Do you need to remove them? I didn't when I dipped my carbs on the 550. The seals do leak a little as is evidenced by some accumulated grime around the shaft ends, but I'm not sure if that was happening before the dip.

If there's a simple way to remove the seals before dipping, I'd like to know about it.
 
I just ordered from the info provided by Nerobro.According to the dennis kirk catalog the 82 gs 550m katana and my 81 550 t use the same rebuild kit so i am assuming the info is correct.As far as throttle shafts go i couldnt really see an easy way to get the return springs and shafts out so needless to say they werent removed.I hope that doesnt bite me later.
 
While looking at the microfiche, it looks like the procedure is as follows:
Separate the carburetors from each other.
Remove the throttle valves from shafts (two little screws holding each)
Now you should be able to remove the shaft from the two center carburettors.
The shaft of the right and left carburettor is locked by an E-ring, which is under the cap located on outer side of each carburettor.
According to microfiche, there are seals only on the outer carburettors, the inner ones have a gasket (is it also rubber?)
Correct me if I'm wrong.
 
The two little screws holding the throttle plates to the shafts did not want to come out without stripping so the shafts are staying put.I have drilled out the plugs above pilot (air?) screws on all four carbs.Before removing each screw i turned them in until they just had a little resistance.Carb 1 & 2 were each about 1 3/4 turns, #3 was about 1/2 and #4 was 1/4 turn.This doesnt sound right to me.Is it possible that the factory with their "special scientific epa approved equipment " set them this way?I payed very close attention when removing them to see if there could have been crap down under them preventing me from getting any more turns but they looked good.The factory manual says "do not tamper" and therefore gives no specs on turns out.How many turns out should i begin with? Backing the screw out makes it richer?Does this adjustment only come into play at idle/slight throttle or does it effect it at all rpm's?
 
ratchetneck1 said:
I have drilled out the plugs above pilot (air?) screws on all four carbs.Before removing each screw i turned them in until they just had a little resistance.Carb 1 & 2 were each about 1 3/4 turns, #3 was about 1/2 and #4 was 1/4 turn.This doesnt sound right to me.Is it possible that the factory with their "special scientific epa approved equipment " set them this way?I payed very close attention when removing them to see if there could have been crap down under them preventing me from getting any more turns but they looked good.The factory manual says "do not tamper" and therefore gives no specs on turns out.How many turns out should i begin with? Backing the screw out makes it richer?Does this adjustment only come into play at idle/slight throttle or does it effect it at all rpm's?
Click to expand...
If you're POSITIVE the mixture screw caps weren't somehow pulled up and replaced, then it appears the factory did set them quite a bit differently from each other. Won't matter after you re-jet. They should be set using the highest rpm method. After you install the kit and bench synch the carbs, I'd probably set them at about 2 turns out before initial start up. Then, on a warmed up motor, fine tune them using the highest rpm method. If you have the correct size pilot jets in there, the rpm method will work fine. Then, vacuum synch the carbs before testing for performance or taking any plug reads. You can then fine tune the screws after the vacuum synch if needed.
Turning the mixture screws out, richens the mixture.
These screws assist the pilot jet and effect performance from closed throttle to about 1/5 to 1/4 throttle. The jet needle also kicks in sooner than some think and it begins overlapping with the pilot jet (my opinion) as early as 1/8 throttle. The more you open the throttle the more the jet needle takes over. From about 1/5 to 1/4 throttle, the jet needles take over until approx' 3/4 throttle, then the main jet takes over until full throttle.
 
Also, the jet kits are sometimes lean with their "base setting" suggestions. More often than not actually.
I suggest making a new thread to ask other 550 owners with the stage 3 kit and similar mods what their settings were that worked. This doesn't mean you'll get it right the first time. You'll have to test and read your plugs, but you may have a better idea where to start. Jetting can take time and patience. Hope yours is easy to re-jet.
Make sure all basic tuning is done before the re-jet. That means clean carbs, good carb inner o-rings/diaphragms, good fuel flow, no intake leaks, valve clearances set, ignition/timing/spark all good, correct plugs, clean/oiled filters.....
 
Keith, thanks for the good info.I have been doing a little each nite after work and am still waiting for parts.Although i have ordered the stage 3 kits and "aquired " the brand new pods i dont know if i will go that route or reistall the stock air intake.Both of the inner boots (air box to carbs) kept pinching off of the carb throat when i tighted the clamps.This air box is a real pain to work with as far as there being no room to remove/ install anything in this area so i thought the pods would simplify things.I also have orderd the two boots and 4 clamps so maybe i will go the stock route.I will have to decide soon i guess.I was happy with the bike with just the 4 into 1 pipe and stock intake but it would be nice not to have to wrestle with putting it back on.
 
A little wink of those airbox to carburattor boots, I don't know if this applies to all older GS bikes but it worked well with my GSX1100F. I fighted with those boots until I realized that, when you remove the filter element inside the box, you are able to stick your hand in and aid the boots to the carburettors. It is allways a good idea to check, that if you remove a little more parts than required, it may be easier to complete your job.
 
putting the carbs back on a GS550 is the seccond worst task in motorcycling. Number one being getting to the carbs on a VFR :-) Pods make life so much nicer.
 
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