Help Tuning A Stock '83 GS1100GL

[carusoat]

Hey guys,
I've been here for a while, but have a new user name....and a new (old) bike!

I picked up an '83 GS1100GL and have been doing the typical things to tune it up. Here's a list:

-Cleaned carburators (dipped, sprayed out all the holes, followed the helpful guides here).
- New fork seals
- Oil filter and oil change
- New spark plugs (e3.31...I'm a fan of E3 after putting them on my 650).
- New front tire
- New o-rings in all the carbs and the carb boots.

So anyways, I'm having some trouble and I just can't seem to figure it out. The bike is running rich. It backfires, farts, hangs the idle, bogs, etc. The pilot circuit seems alright, i can achieve a decent idle, and the top end seems ok. But it bogs hard at about 1/4 throttle then screams to red line, but it doesn't pull. I don't really understand why it shoots up to like 9k RPM but the bike isn't really pulling. Everything is stock. Stock airbox, everything in the carbs is stock except i replaced the float needles and the things they sit in with ones from a rebuild kit (K&L) because one of the stock ones was messed up. And new seals for the float bowls. I've checked the float height, synced the carbs (both bench and vaccum) and adjusted the pilot screws a little. It seems to me the problem is the jet needle, but that's stock too so I can't really adjust it.

Hopefully one of you guys can help. It's driving me crazy.

thanks

 

[eil]

What is the status of your air box, air filter, and exhaust? Stock or aftermarket and what, if anything, have you done with them?

I don't really understand why it shoots up to like 9k RPM but the bike isn't really pulling.

Worn out clutch?

 

[carusoat]

Stock airbox in good condition. It has a Uni filter in it that I washed and reinstalled. It wasn't too dirty though. Stock exhaust. Haven't done anything with any of that other than clean the airbox and filter while the carbs were off.

I doubt the clutch is worn out, the surge in rpm im talking about has nothing to do with the clutch. I'm talking about riding down the road in say 3rd gear and then ripping the throttle and the bike bogs, studders, then the rpm shoots up, all the while not really pulling.

 

[gustovh]

Drop cheff1366 a note and see what he thinks. Start with pilot needles at 2 turns out and adjust for lean best idle, what do your plugs look like when the bog/surge happens? do a plug chop, might help.

Have you checked your valves, looked for vacuum leaks?

V

 

[carusoat]

The new plugs dont look like anything...they've only got like 5 miles on them though. But the old plugs are black.

by "pilot needles" I'm guessing you mean the air mixture screws...they're at 2.5 turns out right now.

Shouldn't have many leaks. I replaced the o-rings behind the carb inlet boots. the airbox is what it is, but seems fine.

Not sure about valves. I've never checked that before.

 

[gustovh]

Adjust for lean best idle with the pilots then by turning them in one at a time this leans the mixture, until the rpm's drop off then back off about 1/4 turn, you may have to adjust the idle back down when you do this. Adjust each carb by itself. Given a stock set up and synced carbs and valves in good adjustment, this should get you running.



V

 

[carusoat]

Update:

Checked the float heights with a piece of tubing. All are good.

Noticed the fuel filter was upside down. Fixed that, so it should flow better.

I just did the adjustment for lean best idle with the mixture screws and i definitely got a response from all but 1 of the carbs. no matter how i turn that last one, it doesn't do anything. I checked for intake leaks by spraying wd-40 on the intake boots and that carb didn't have a leak.

I'm not sure where to find valve shims locally so i haven't adjusted the valves.

still dies hard when i try to get on it, then shoots up in rpm. It starts pulling when it's at full throttle so the stock main jets seem right, and idle is ok. It really seems to me that the problem is in the mid-range and from what I understand that's all about the needle jet and the jet needle. shimming the needle only makes it richer, so idk how to lean it out. Or do my symptoms seem like it's too lean? Idk I'm confused and frustrated. Not sure what to do short of buying pods and a dynojet kit.

 

[tirebiter]

Sounds like to me also, the clutch is slipping. How else can the RPMs "scream" up to 9,000 without the bike pulling ?

Is the engine achieving 9,000 RPM slowly or extremely quickly, after the initial bog and hesitation ? Is the bike accelerating at the same rate as the RPMs climb ?

 

[carusoat]

It's getting up there pretty quick after the hesitation. By not pulling I meant the bike doesn't seem to be accelerating at the same rate as the RPMs climb.

I'm gonna order new carb holder boots since I found a leak in one, and can't get the thing to sync because of that leak. Maybe that's the issue.

 

[Nessism]

You should consider adjusting your valves and checking your spark plug caps to assure the resistance it correct. Snip off a small section of the wire before screwing the cap back on too.

 

[gustovh]

Ahhhh, run down and get yourself a new set of clutch springs, bet yours are below tolerance and allowing slippage during hard acceleration. Check your valves, you can join the shim club and get the shims that you need from Ray, his member handle is Ghostgs1. It took less than a week.

Then you could re-sync your carbs after you install the new mounts. You will find as you fine tune the engine runs smoother and pulls harder and gives better mileage.

V

 

[Steve]

Noticed the fuel filter was upside down. Fixed that, so it should flow better.

Please explain. :-k

What fuel filter? The stock filter is the mesh around the fuel intake inside the tank and there is also a filter at the input of the float valve, but neither one can be installed upside down.

.

 

[carusoat]

Steve, I thought I mentioned that the previous owner installed an aftermarket fuel filter. I guess I didn't. I left it on cuz I figured "why not". It's an inline filter. It was mounted upside down to the direction of the flow from the tank though.

New clutch springs? I guess I don't understand why the clutch springs have anything to do with acceleration while I'm not using the clutch. I do understand that if the clutch was pulled the RPMs would climb like I'm revving in neutral. I don't think this is the case considering I can't even move the bike in 1st gear with the clutch pulled in. I have to move it in neutral. So if anything, I would figure the clutch is engaged too much.

It seems everyone is suggesting to adjust the valves...I think I have some feeler gauges that might be the right size. If I adjust one shim, won't it effect another valve? I like the idea of measuring my valves and ordering the shims that I need (if any). But if I do that, install the new shims, and re-measure, will they all be good or could some others be off now and need different shims?

My carb boots should be here Thursday so I'll see how that helps it.

I just wanted to say thank you to all of you for posting your thoughts and attempting to help me. This site is amazing and I am very grateful.

 

[gustovh]

New clutch springs? I guess I don't understand why the clutch springs have anything to do with acceleration while I'm not using the clutch. I do understand that if the clutch was pulled the RPMs would climb like I'm revving in neutral. I don't think this is the case considering I can't even move the bike in 1st gear with the clutch pulled in. I have to move it in neutral. So if anything, I would figure the clutch is engaged too much.


This statement makes me believe that you have clutch spring issues. It is post #9

"By not pulling I meant the bike doesn't seem to be accelerating at the same rate as the RPMs climb."

What happens is, as the springs begin to give up, the clutch slips and gets adjusted and slips and gets adjusted, you see where this is going. Eventually there is no real adjustment left, the clutch still kinda works, but when you put it under load it allows slippage, thus the result of your statement.

It doesn't take much to find out, you can even do it without dumping your oil. To measure is to know.

V

 

[carusoat]

Thanks Gustav. The clutch springs are pretty cheap and doesn't seem like too much to replace them so I guess I might as well. What about the clutch discs?

 

[gustovh]

Inspect em, see if the steels are burnt and measure them as well as the fibers, you will probably be Ok on those items.

V

 

[carusoat]

So I sent my dad to pick up the carb holders when they came in and he asked about the clutch springs and the guy there basically talked him out of ordering some. Now, I just put the carb boots on and took it around the block. It idles waaaay better now, but def still has that slippage. If I give it maybe 1/8 - 1/4 throttle it doesn't really slip, but if i go any more than 1/4 the rpm shoots up and it doesn't wanna move. From what you've said that's the definition of the clutch springs needing replacement right? I don't know if I'll be able to find any locally stocked so I'll have to wait for them to come in...

I never would have thought of the clutch spring thing, thank you very much!

 

[gustovh]

Your welcome, still check the steels and fibers before ordering the springs, they may be bad as well and there is only one way to tell.

V

 

[carusoat]

Results from the garage:

The springs all measured about 1.53", which according to the service manual is the limit. So I guess I'll order some springs.

Measuring the fibers and steels, they were all within tolerance. The steels all at .078". According to the service manual the range is .078" - .082". The fibers all measured about .615", service manual says .61" - .62" so those are perfect. They look brand new too.

The last steel plate that is behind the piano string measures about .076" and has a little more marking on it than the rest. Should I replace this one? I can tell getting that piano string back on is gonna be annoying. And I'll need a new gasket for the housing.

 

[gustovh]

Pretty hard to advise on getting new without laying eyes on. So you get lucky and only need springs and gasket. Make sure you get everything back in proper order. How do your valves look?

V