lean on #1 and #2, perfect on #3 and #4, 1981 gs1100ex

[RipRoaringFun]

I just installed new intake manifolds because all 4 cylinders were lean and the old manifolds were shot.

But cylinders 1 and 2 are still way lean.
It's not the coils since 2 and 3 use the same coil and cylinder 3 is fine, vice versa for cylinders 4 (which is fine) and 1.

Any ideas what could be happening? Just to be sure I re-tightened the hose clamps on all 4 cylinders.

[cowboyup3371]

How far out are your screws?

[RipRoaringFun]

How far out are your screws?

You know I thought about that -- I haven't checked.

I don't know where they are on this bike's carbs, haven't had the bike long.

I notice what *may* be a brass screw in a deep hole at the front side (intake side) of each carb -- the hole in the carb body is vertical and I'd have to lower a narrow flat blade screwdriver in to adjust them.

Are these the pilot screws and if so, do you know how many turns out they should be?

[cowboyup3371]

I know some will start with them 2 to 3 turns out and then adjust from there. Have you also synced them lately with a carb tuner?

[RipRoaringFun]

I know some will start with them 2 to 3 turns out and then adjust from there. Have you also synced them lately with a carb tuner?

The 'pilot screw', that's what the shop manual calls the screw I mentioned that's at the top front intake side of each carb -- well on my #1 carb it is STUCK. I sprayed some Amazing Blaster down there and waited a bit to let it seep in but that #1 pilot screw won't budge.



Also, I may still have an air leak somewhere on #1 and #2 --- is it SAFE and correct to use WD-40 as a spray to find the air leak with the motor running or will I blow myself or the motor up ?

[spyug]

The 'pilot screw is the only one you can adjust. About 2 1/4 to 2 1/2 turns out from bottom.

If the bike is new to you , you may need to clean and rebuild the carbs and replace all the o-rings. Once the carbs are done you need to synchronize them and for that there are two procedures 1) static or bench synch where the butterflies are all set to be slightly open when the throttle is "at rest" and 2) dynamic synch for which you need a manometer (vacuum guage) to set them with the engine running.

Please read up on the carb cleaning tutorial. From what you have described it is most likely that your carbs are out of wack. I experienced exactly the same thing recently with my Kat project bike. I had cleaned and rebuilt the carbs in the spring and the bike ran fine. It sat for the summer and fall and when started again had those symptoms. I recleaned and put in fresh 0-rings and now fine again.

Good luck freeing up that stuck screw. I would use lots of penetrating fluid and an impact wrench.

Let us know how it goes.

Cheers,
Spyug

[RipRoaringFun]

The 'pilot screw is the only one you can adjust. About 2 1/4 to 2 1/2 turns out from bottom.

If the bike is new to you , you may need to clean and rebuild the carbs and replace all the o-rings. Once the carbs are done you need to synchronize them and for that there are two procedures 1) static or bench synch where the butterflies are all set to be slightly open when the throttle is "at rest" and 2) dynamic synch for which you need a manometer (vacuum guage) to set them with the engine running.

Please read up on the carb cleaning tutorial. From what you have described it is most likely that your carbs are out of wack. I experienced exactly the same thing recently with my Kat project bike. I had cleaned and rebuilt the carbs in the spring and the bike ran fine. It sat for the summer and fall and when started again had those symptoms. I recleaned and put in fresh 0-rings and now fine again.

Good luck freeing up that stuck screw. I would use lots of penetrating fluid and an impact wrench.

Let us know how it goes.

Cheers,
Spyug

Thanks for the tips.
Actually I had the carbs off and they looked spotless, none of the jets were clogged.
I set the float heights per the manual.
However just because the jets weren't clogged doesn't mean the tunnels in the carb body are fine.

I'm thinking about trying 2 things before pulling the carbs again:

1) use a clear tube to assess the fuel level -- the manual calls for 5mm +/- 0.5mm on this bike. Maybe I've got a bad needle valve or stuck float issue.

2) check for air leak using WD40


(2) here is the MOST IMPORTANT. This bike will not drop down to idle consistently (air leak) -- it hangs at 2500 to 3000rpm at stop lights. AIR LEAK says my brain.

So is WD40 the best thing to check for air leaks?

[spyug]

You can check with WD but the more you tell the more it seems its the carbs themselves and I am thinking leaky o-rings. I don't think you discover that with the spray but give it a whirl.

You haven't mentioned the airbox or pods. What are you running? The problem could be at this side if the airbox rubbers are split or the box is not sealing or pods are not restrictive enough. GSs seem to like good sealed airboxes or somewhat restrictive pods. I have found that some cheaper pods like emgos just don't do a good job as they are too free flowing.

I'm thinking you are going to have pull those carbs and strip and dip them. as you noted, the jets are clean but you would be surprised what gunk comes out of passages.Notwithstanding that I'd still bet that your o-rings need replacing. Dollars to donuts air is getting in past a cracked or shrunk ring. You really also need to get that screw out as its likely contributing to the probs.

Good luck with it.

Cheers,
spyug

[cowboyup3371]

As someone else here says RipRoaring, you cannot see everything inside of those carbs. There are passages that can become quite blocked and you'll never know it. You might want to strip them down, dip EACH one for 24 hours EACH in Berryman's carb dip, get new orings from cycleorings.com and go from there. Be careful about doing too much playing with those air screws as they may not remain whole.

You'll want to change out your intake boot orings as well since that bike is so old.

Read up on Basscliff's site (see your welcome post) and have fun.

[RipRoaringFun]

You can check with WD but the more you tell the more it seems its the carbs themselves and I am thinking leaky o-rings. I don't think you discover that with the spray but give it a whirl.

You haven't mentioned the airbox or pods. What are you running? The problem could be at this side if the airbox rubbers are split or the box is not sealing or pods are not restrictive enough. GSs seem to like good sealed airboxes or somewhat restrictive pods. I have found that some cheaper pods like emgos just don't do a good job as they are too free flowing.

I'm thinking you are going to have pull those carbs and strip and dip them. as you noted, the jets are clean but you would be surprised what gunk comes out of passages.Notwithstanding that I'd still bet that your o-rings need replacing. Dollars to donuts air is getting in past a cracked or shrunk ring. You really also need to get that screw out as its likely contributing to the probs.

Good luck with it.

Cheers,
spyug

I'm thinking by 'orings leaking' you mean the intake manifold orings -- but this model, the 1981 GS1100Ex does not have them. I found that out when I started trying to solve this problem a while back. It woulda made things easier on me if that was the problem! Thanks for the suggestion. Here's the parts diagram for my 1100E head. The intake manifold ports are cast with the head itself -- unlike what I've heard other Suzuki fours have, you cannot remove 2 large Phillips screws to get metal manifold ports off the head and find an oring behind there. As you can see from this diagram, there are only 3 parts connected to the intake port: a rubber boot (part #23 for cylinders 3 and 4, part #24 for cylinders 1 and 20 and two clamps, part #25. No oring, no removable metal intake porthole:


Also, this bike's rubber intake manifold boots were cracked and all four plugs were white. So I bought new manifold rubbers from the local Suzuki dealer and installed them, and that's when I had the carbs off and after putting carbs back on plugs #3 and #4 are now golden brown.

But the 'idle will not drop consistently to 1200rpm at stoplights' problem is still there. And plugs #1 and #2 are still chalk white.

I tightened the hose clamps today on the intake and airbox sides of all 4 carbs today then re-checked, same high-idle problem, same chalk-white plugs on #1 and #2.

Here's a picture of my airbox. By the way, the bike has a Supertrapp 4-into-1 and the prior owner drilled the main jets out to 150 or so, I think in an attempt to resolve the lean running problem, but he missed the cracked intake manifold rubbers. I found and fixed that issue but pretty sure I still have a leak somewhere, perhaps. I'm not at all afraid to pull them carbs again but before I do I want to try to find the air leak.

HERE'S THE AIR FILTER -- prior owner had removed the black plastic surround box to leave the air filter exposed like this when I bought her:





Here's the SuperTrapp with lots of donuts on her, she is not too loud I reckon due to all them donuts:

[cowboyup3371]

I think you are sucking in too much air with the air box missing like that. Someone else here with more experience than I can dive into this further but IMHO you need to find the rest of your air box and go from there.

[Suzuki_Don]

Cowboys right find the rest of that airbox and return it to stock.

[spyug]

Is that filter oiled? If its not its going to flow too much air as Don and Cowboy say which is not going to help matters. Foam filters need a special oil to make them work properly and you should be able to get a can at the local auto store (K&N makes some).It doesn't explain the leaness on 1 & 2, however.

When I was talking o-rings , I wasn't speaking about intake boots but o-rings in the carbs themselves. If 2 of the 4 carbs are producing lean conditions then it more or less stands to reason (IMHO) that the problem lies in the carbs themselves.

The more I read this post, the more convinced I am that your problem copies the issue I had as I described. You do need to dip and rebuild those puppies my friend. Just make sure that you get that stuck screw out first as there is a tiny o-ring in that tube.

spyug

[Octain]

Correctly clean the carbs, find the rest of the air box, make sure intake rubbers on both sides of the carbs are good. Then go from there.
If you dont PROPERLY clean the carbs per "THE" tutorial you're just chasing your tal.