As if we don't have enough carb threads already.........

[frosty5011]

For the carb guru's out there, I have a question.

I have a set of carbs on my GS1000 ( '78 ) that I just cannot get adjusted quite right. This set (which is perfectly clean) that is currently on the bike has little red plugs/inserts in the carb throats where the pilot jet hole enters the throat. These plugs have a small hole in them, to allow fuel to come through for the idle circuit.

The pilot screws themselves do come to a needle point, but are shorter than what I am accustomed to, and which I had on my 750 with VM carbs (around 1/2 cm shorter). It appears that at one time, one of the pilot screws may have been screwed in too tight which kind of forced this reddish plastic/nylon plug mentioned above to potrude out further into the carb throat. (I really don't want to try too hard to push this plug/insert back like the others, for fear of squashing the pilot hole that is in it)

Again, the 750's VM carbs (of which I still have an extra set handy, but not in good shape) with which I am more familiar, have no inserts whatsoever in those holes, and if you screw the pilot screws(s) to where they bottom out, the points of the pilot screws would potrude ever so slightly through those holes..........but not on this set that I am talking about.

If anybody is familiar with those carbs, do you know if they maybe have different baseline settings? Maybe that is my problem -- I haven't been willing to adjust them "too far" from the baseline (1-1/4 turns out for fuel pilot, and 1-3/4 out for the air mixture screws). Other than those differences, the carbs seem to be identical to me.

My adjustments keep leading to the bike feeling like it's running lean, yet plugs saying it's on the rich side.

I have NOT yet had a chance to have the carbs vacuum synched (I know, big boo-boo) but with every other set of carbs I have ever disassembled, and put back together with only bench synching, I have never had a bike run with hesitation/stuttering like this before - maybe just a little vibration, which was taken away with a vacuum-synch later on.

Sorry for posting another carb thread, but this set has me confused.

 

[SqDancerLynn1]

SOunds like you may have the blunt mix screws that Keith was talking about check thread -- Broken mix screws ??
http://www.thegsresources.com/_forum/viewtopic.php?t=38221

 

[frosty5011]

SOunds like you may have the blunt mix screws that Keith was talking about check thread -- Broken mix screws ??
http://www.thegsresources.com/_forum/viewtopic.php?t=38221

Lynn,

No broken tips on these carbs at all. The pilot screws (that were in the carbs) all come to a nice point (very sharp). The length of these pilot screws is 25 mm's (I just measured them - and the length of the pilot screws from previous set of carbs was 28 mm's). The pilot hole is not clogged with any kind of tip in it at all, just this reddish nylon insert that has a very small hole going all the way through it (you can squirt carb spray or shine light through it).

I wish I could take a picture, but because of the space/angles, you just wouldn't be able to see it (at least with my crappy dig. camera).

Unless maybe the nylon inserts previously held some tips in them.....and someone prior to me removed those tips, and put in new screws??????????

 

[Buffalo Breath]

plugs

plugs

Fuel restrictor plugs

 

[KEITH KRAUSE]

I've never seen the red inserts before. Fuel restrictors must be right.
I'm not sure why they are used though. For the sole purpose of restricting flow on an otherwise perfect carb wouldn't make sense to me. The standard pilot fuel screw and the "normal" passage in the carb body handles that job.
I can only guess that they could be part of a repair job. If someone broke off a screw tip, the passage could be enlarged/damaged by removing/drilling the tip out. The larger hole could then have the insert pressed in and that would fix that part of the repair. Then, I'd assume the insert takes up a little more space and the standard length pilot screw would be too long. So a shorter pilot screw would fix that and the whole assembly would work like the standard assembly.
I've never heard of a "repair kit" like this though. But if it has nothing to do with repair, what are they for? It wouldn't be for smog purposes, because the standard set up can be adjusted until it's running too lean.
The one insert could be pushed out a little because someone installed a standard length screw or tightened the shorter screw too much?? I don't know, 27 year old parts can have an interesting history. The tip protruding out a little would effect flow, but I can't say if it's significant enough to cause trouble. I wouldn't want to try to push it back in either.
As for your running problem, you think the bike is running lean but the plugs are dark? Why do you think it's lean? How are you taking plug reads? At what throttle position? Is this bike completely stock? Air box lid still on? The pilot fuel screws can be set anywhere from 1/2 to around 1 1/4 from the factory. A 1/4 turn can have a big effect. If stock, I'd re-set them to 1 turn and then set the side air screws for highest rpm, not just set at 1 3/4 and assuming that's good, if that's what you did. Whenever you make significant pilot fuel screw adjustments, you must re-check the air screws for highest rpm too. Sometimes small adjustments are needed.
Your problem still depends on throttle position too. Just off idle, the jet needle starts overlapping. Also, as you know, the carbs must be vacuum synched and clean, etc, before accurate plug reads can be taken or fine tuning the screws is possible.

 

[frosty5011]

OK, still don't know what the deal is with the carbs' inserts. But I got the problems worked out.

The hesitation/stuttering kept getting worse to where it was happening all the time at all throttle settings. New points didn't solve the problem - but replacing the condensers made a world of difference.

Didn't want to wait until mid-next week to have condensers shipped to me, so I bought a set of automotive condensers from Advance Auto, found a place to mount them under the ignition cover, and the bike purrs like a kitten now. (Not quite perfect, a cold engine start requires about 3 seconds of choke upon startup )

I would be curious to know if anybody else ever comes across another set of carbs like this though. If you do, please let me know. I'm actually VERY happy with them.

 

[robinjo]

I told you it was ignition! :lol:

 

[Hoomgar]

Rock on buddy

 

[frosty5011]

I told you it was ignition! :lol:

That's not true...........you told me to sniff some tulips! 8O 8O 8O 8O

 

[Jethro]

Whats a condenser?

 

[KEITH KRAUSE]

Whats a condenser?

You ain't got no condensers on your bike, so don't worry about it.
The condensers are used on points ignitions. They work like little storage tanks for electricity. They keep the points sparking correctly. If the condenser goes bad, you generally pit or burn up the points quickly.

 

[duaneage]

I fixed quite a few carb problems witha new set of plugs and fresh points/condensors

 

[Hoomgar]

Whats a condenser?

It's a capacitor.