Still runnung rich, '79 GS1000S with slide carbs

[robinjo]

Bike: totally stock 1000S with new stock filter

Problem: running rich, stuttering if given to much throttle at low to medium enginespeeds
pulls good if throttled gradually except at 4 to 5k rpm.

carbs cleaned well, weren't dirty to begin with
new main jets, 96s couldn't get stock 95's
needle in middle groove as per manual
floats set at 24mm, 23 to 25mm says the book
air pilot screws set at 1 1/4 turn, doesn't make much difference where I set them for
the ridability but got the highest idle at that point
fuel screws allmost closed, one totally closed, set by riding the bike pretty fast and
then checking the plug color with the jet chart with the numbers posted here once.

What should I do??? nr 94 main jets? lower the needles? go up 1mm on the float bowls? Problem got worse when the temp went up from 65 to 85 degrees outside.

 

[Anonymous]

Try lowering the needles. When in doubt, try the simplest & cheepest things first

 

[robinjo]

Dammit, misspelled the title... :roll:

That's it, Dutch class for everybody, much easier :twisted:

 

[saaz]

Preferrably it would be beter to get the main right first, then play with the needles. As the mains are close to standard, try lowering the needles as they have the greatest effect in the mid throttle.

 

[SqDancerLynn1]

79GS1000e specs float height 23-25 mm air screw 1.0 Piolet air jet 1.2 pilot jet #15 cutaway 1.5 ? jet needle 5DL36-3 needle jet O-4 main air jet 1.5 Main jet #95 I would check and make sure that it has the correct needle jet and correct needle. If at some time it was changed you could be chasing the problem forever if it doesnt have the correct parts

 

[KEITH KRAUSE]

Not to argue with the above advice, but a stock engine should not need a needle adjustment. Something is not allowing enough air into the engine. And the pilot screws underneath should not be closed or near closed. This is only an attempt to try to mask the problem and make it run leaner. Try turning the side air screws out to 2 1/4 turns. The pilots cannot be reset but generally should be out 1 turn. Considering the info you gave us, are your plugs NGK B8ES or equivalent? If all carbs are clean and new air filter, I would suspect a weak spark not burning the mixture right. KK.

 

[robinjo]

Plugs are indeed NGK B8ES and filter is stock and new, the bike has Piranha electronic ignition with what look like new coils. Checked the spark a while ago and thought it was a bit weak (engine turning over on the starter but not running while checking the spark) but without the sparkplug cap screwed on it gave a big fat blue spark about 1/4 inch long so I replaced the old plug caps with new NGK ones but that made no differance to the spark.

Turning the airscrews on the side out only affects idle and a little off idle mixture right??? can't understand how that would help but will try.

 

[Don Lobacz]

The screws on the bottom of the carbs should not be closed off. Try them at 1 turn out.

 

[earlfor]

The first thing I would do is verify that the float needles do actually shut off fuel. If they allow fuel to continue to seep, float height adjustment means nothing because the bowls will continue to fill until the floats are wedged against the top of the chamber. The result is the same at trying to operate your carbs without a float in the float bowl. (you would be rich no matter what you do)

 

[KEITH KRAUSE]

I did some jetting lately and found that because of 'overlap' effect, the air screw will have a definite effect on plug color at typical city speeds and some 55-65 mph mixed in. I used my 10 mile ride to work which I just described, as a chance to check plugs each day after making each adjustment. For an example, on 2 different days with identical weather, with the pilots out 1 1/2 turns and the air screws out 1 1/4 turns, my plugs were dark. On the next day I did'nt touch the pilots and turned the air screws out to 2 1/4. The plugs lightened up considerably. Same day temps and running conditions. As for the float height mentioned above, do you have any fuel coming out of the bowl overflow tubes or do you smell gas fumes?
PS:Just for the heck of it, I'll throw this in. A friend at work asked me why his Honda Nighthawk was running fine until he got to about 50 mph, but then would bog down and the problem started suddenly. We opened his seat and found a shop rag inside the filter housing. It was left by his mechanic who had just serviced the bike the day before. The bike then ran fine. Let us know if turning the air screws out helps.

 

[robinjo]

If I take of the rack of carbs, turn them upside down and level and then try to blow air through the fuel line they should seal right Earl??? Checked the float needles when I cleaned them and they looked perfect but where is this o-ring I allways hear about supposed to be, inside the bit where the needle goes when the floats go up??? If so I don't think it's there, will double check to make sure.

If there is no ring in the place it belongs than I think you have found the problem.

Right now I have the air jets turned out 1 1/4th of a turn from lightly seated, if I turn them out more the bike pops on warmup and a little when idling and I would like to avoid that. I don't have fuel overflowing and don't smell any gas.

Oh and I don't have a shop rag in my airbox 8O the only one working on this bike is me with help from the forum and my trusty manual wich by the way is very limited on info about carb settings.
Air screws: DONT TOUCH!!!
Fuell screws: DONT TOUCH!!!

Must be some gouverment rule or something.

 

[earlfor]

Since I dont have a GS1000, I cant say from experience whether you should have an "O" ring in the needle assembly or not. If on turning them upside down with the float weight resting on the needles, you find that you cannot blow air through the fuel line, I would assume that they are verified as sealing properly.

Earl

If I take of the rack of carbs, turn them upside down and level and then try to blow air through the fuel line they should seal right Earl??? Checked the float needles when I cleaned them and they looked perfect but where is this o-ring I allways hear about supposed to be, inside the bit where the needle goes when the floats go up??? If so I don't think it's there, will double check to make sure.

If there is no ring in the place it belongs than I think you have found the problem.

 

[KEITH KRAUSE]

Did you try turning the air screws out to 2 1/4 AND turning the pilots out 1 turn? You should not get the popping. You obviously need to get more air into the mixture and having the pilots closed or near closed is not the way to compensate for a rich mixture. There is no o-ring on the needle valve. The brass needle valve seat does have a red fiber washer. (Mikuni VM26SS carbs)Two times I have had trouble in the past with needle valves leaking when they looked good. Both times I installed genuine Suzuki parts and the leaking stopped. They are expensive($37 each) but I bought 4 'bargain' brand valves and had 2 of them leak so I sent them all back. This one really has me scratching my head. I know these carbs very well and I have owned my 1000 since new in '79. I've got 117,000 miles so far. Are the plastic spacers that go on top and under the jet needle clip in the correct order? The thicker one goes on top and the thinner one goes under the clip. Is your ignition timing correct? If I can think of anything else I'll let you know. KK.

 

[robinjo]

Did you try turning the air screws out to 2 1/4 AND turning the pilots out 1 turn? You should not get the popping. You obviously need to get more air into the mixture and having the pilots closed or near closed is not the way to compensate for a rich mixture. There is no o-ring on the needle valve. The brass needle valve seat does have a red fiber washer. (Mikuni VM26SS carbs)Two times I have had trouble in the past with needle valves leaking when they looked good. Both times I installed genuine Suzuki parts and the leaking stopped. They are expensive($37 each) but I bought 4 'bargain' brand valves and had 2 of them leak so I sent them all back. This one really has me scratching my head. I know these carbs very well and I have owned my 1000 since new in '79. I've got 117,000 miles so far. Are the plastic spacers that go on top and under the jet needle clip in the correct order? The thicker one goes on top and the thinner one goes under the clip. Is your ignition timing correct? If I can think of anything else I'll let you know. KK.

OK first I will check if the floats close correctly, I think so cause I don't have any flooding but I'll check anyway never hurts, check the fiber washers and the plastic spacer for the correct order, put them back the same way they were when I lowered the needles but can't remember now how they were installed yet again manual very unclear. Pilots out 1 turn from seated right??? If that doesn't help I'll get the timing checked at the shop.

Thanks for the info so far.

 

[robinjo]

Took out the rack and here's what I found out...

1 loose main jet allmost out of the pipe, the carb wich I fully closed the fuel jet on, figures...
Did the blow test for the brass float needle valve seat and heard a little hissing were a little loose, tightened them down a bit more, no more hissing, checked the red gasket rings, they looked good.
Set the floats at 23mm instead of 24mm (23-25mm in the manual)
plastic spacer on the needle are placed correct,thin one below the clip, thick one above it, middle clip.
Fuel screw set at 1 turn out from seated, air screws set at 1 3/4th of a turn, after that some of them started to turn heavy so I stopped at that.

Installed carbs, filter and the gastank en went for a testdrive. Feels good, responds well to throttle and doesn't stutter any more a 4 to 5k rpm. Let her warm up for about 7 miles and let er rip...

Goes like a bat out of Hell to use a well worn clich? straight up to the redline (and into the red if you don't watch the tacho carefully 8O ).
Up onto the freeway, little traffic onto the left lane some throttle and we're doing a easy 115mph with about 1/4 throttle and lots more in store.
I'll check the plugs tomorrow for colour but my guess is that its not far of.

A BIG THANK YOU FROM ME AND MY BIKE WHO IS NOW COOLING OFF AND TICKING HAPPILY IN CONTENT

Lesson learned today is not to be TOO carefull when tightning little carburator parts or they will fall out or leak

 

[saaz]

Good the hear )

With carbs always double check that you have done what you think you have done! Thats why it is hard to give advice on here, as you assume certain things have been done.

The pilot/slide cutout/needle/main ranges do overlap quite a bit, particularly at gentle throttle openings. I don't think we need get into slide cutout theory here!

My experience is - get the mains right (this includes getting the flost height rigt) first as they affect everything....

Then the needles right in the middle to upper throttle...

The pilot/slide/needles interact for cruise conditions.

Thgis does not incluse CV carbs, as I have never had a bike with them!!! You have to worry about diaphrams etc with them...I think I will jump straight to fuel injection...