78 GS1K Carb Rejet? Bad Fuel Economy - KEITH KRAUSE!

[KEITH KRAUSE]

OK Mark. First thing though I gotta say, viewing the plugs and reading what you say they ACTUALLY look like makes it very hard to get an accurate idea of what needs to be done. All the pic's have been this way. I mean, I see what looks lean and you say it really looks richer than what I'm seeing... I never knew pic's could create confusion.
It's obvious that the plugs are darkening more at 1/3 throttle than less opened throttle. You say they look good in person, the only concern is a little uneven color between 1/4 and 2/3. I don't see any significant difference between 1/4 and 2/3, except 4 looks richer, but I can't say how much. Since you say they look OK I'll call 4 good too.
The reads could suggest the synch is off a little, (I know you've set them) simply because the levels can fluctuate while setting. Sometimes you swear you've set them just so, but a double check will show they moved a little. Again, hard for me to say for sure, you've got the better view. You can also tweak the levels a little to even things out a little more. A 1/2" change in #4 level may be what it needs. This would NOT cause your synch to be unacceptable. I know all about how the closer the levels, the better...but a 1/2" change will not cause a problem as long as they were pretty even to begin with. You won't notice a difference, but the plug may lean up just a little and things will be more uniform. Synching is actually an area where you can "cheat" just a little, just like float levels. As long as both are in their "acceptable range", you're still OK and this adjustment may be just what's needed. Otherwise, we've covered everything else that would cause uneven reads. According to past posts, everything else is in good condition/set correctly.
As for the leaner burns at less throttle, just follow what I previously posted. That should get you there. Hopefully, you'll just need to make very small pilot fuel screw adjustments from there, if necessary.
We know the jet needles are where they need to be. 1/2 position leaner (where you had them) caused lack of power. And 1/2 richer would for sure be rich. So the needles are set. You seem happy with the top end and roll on, so the mains are set. The pilot fuel screws should fix you up with the pilot circuit. Adjust as I said earlier. Whatever adjustments you have to make, ALWAYS have the side air screws adjusted for highest rpm. Don't under/over adjust the air screws or try to make them do the pilot fuel screws job.
I'm off for vacation until about next Tuesday. I may be able to check in tomorrow night, but I don't know. I see no reason you won't be able to fine tune things with this info. Don't expect perfection though. A little decel' pop is acceptable. But there should be no real problems.
Hoping for great news when I return. Then we can officially retire this thread. See ya!

[Hoomgar]

Keith. I adjusted the pilots as you described. 1/2 turn out on 1 & 2 and 1/4 turn out on 3 & 4. I readjusted the air screws.

Not sure what to think. It definately made the mixture a little richer because it greatly reduced the spitting into the air filters and the decel pops have reduced. But now it is irratic? It idles funny like it isn't running on all four cylinders but as soon as you hit the throttle it wakes right up. When cruising at minimum throttle openings it acts like it is running out of gas now :x

The air screw adjustments really torque me off. I guess maybe I am expecting too much? It never seems they make much differance at all. I turn those damn things in the whole way to the stop to get a noticeable change. When fully seated of course the bike will choke out if you leave it there. I turn it about 1 full turn out to make it idle again. Back it down to ? turn out, ? turn out, go back the other way to 1 turn, 1 and ?, ?, ?, 2 turns, 2 and ?, etc? it?s all the same man. It makes no difference at all, ever. The whole time we have been working on this tune up and with both sets of carbs I swear it seems it is always like that. I may get about a ? RPM change at best but that is really hard to tell as the bike doesn?t idle smooth enough at 1k to be able to tell. There has to be something wrong here? I mean, from your instructions it would seem that the air screw adjustments should make at least a half an RPM to a full RPM difference or more but I never see that. That said, setting the sir screws is always just a guess. There is no sweet spot that is discernable. What do you think may be the problem there or do I need to be able to read those ? RPM changes better?

I mean we?ve been through this so I don?t know what is left to check? The boots are good, o-rings sealed, no cracks or air leaks of any kind there. No vacuum leaks on the petcock vacuum tube. All passages in the carb are as clean as the day the dern things were made. I just don?t get it? And I feel at this point that this thread has become a pain in you?re a$$ and I?m just wasting your time. If you don?t feel like pouring anymore thinking into this I don?t blame you my friend. I?ve appreciated all the help but am finally getting to my burn out point. Which as you can see took quite a bit as I can be very determined but this thing is *@%^$*@%^$*@%^$*@%^$ing me off. I feel like just riding it the way it is. Which is not even close to right.

Do you have any more energy or ideas or are you tired of this GS? This thing is a pig. I never had trouble like this with my other GS. I?m thinking this motor just has issue. Maybe we have it as good as it is going to get?

Thoughts?

[wrench]

I think Frosty should take your screw driver away

[Hoomgar]

I think Frosty should take your screw driver away

He can have it! But he will have to find it in the woods across the street!

[wrench]

I think Frosty should take your screw driver away

He can have it! But he will have to find it in the woods across the street!

Stock jets and air boxs Rock

[frosty5011]

Keith wrote:

I'm off for vacation until about next Tuesday. I may be able to check in tomorrow night, but I don't know. ...

Needs "another" vacation so soon???? 8O 8O 8O Wonder why?

[wrench]

Keith wrote:

I'm off for vacation until about next Tuesday. I may be able to check in tomorrow night, but I don't know. ...

Needs "another" vacation so soon???? 8O 8O 8O Wonder why?

LOL

[KEITH KRAUSE]

First of all, I'm not frustrated or anything over this. I admit this jetting over the internet can be more difficult than doing it myself. There's simply no way to expect you to do things the way I do. That doesn't necessarily mean you're doing something wrong, it means there's the possibility of error and I simply can't do anything from here. Remember the simple mistake about plugging the vacuum during a synch? It seemed obvious, but it still happened. You also described over the phone once a "modified" shall we say, thin brass plate with a dimple that goes over the jet needle assembly. Things can happen that can cause problems I can't possibly trouble shoot around.
It also can get confusing and something can be lost in describing problems. For example: earlier, you said the bike ran well (except for decel' pop and spitting. So you richen the pilot fuel screws. The pop and spitting improves a lot, BUT, now it feels like it's running out of gas at minimal throttle.(?) Richening those screws couldn't cause a running out of gas sensation...but that's what you call it. This makes no sense to me and it can be frustrating. I have to try to guess what's REALLY happening and make a suggestion. But you're not the only one. I read it here all the time between two people.
Before these simple pilot fuel screw adjustments, you were pretty happy with the bike, except for the spitting and decel' pop. Now, with a richening adjustment, those obvious lean conditions have been replaced by erratic idling and a feeling of fuel starvation at low speeds. Sure is a big swing for such small adjustments. 1/2 the results are expected, 1/2 don't make sense.
I also didn't realize your air screws aren't operating as they should, nor does the bike idle well at 1,000 rpm's, which could be one and the same problem. A '78/79 GS1000 tuned correctly will idle perfectly at the factory suggested setting...1,000 rpm's. I'm not sure what you mean by "1/4 rpm" change regarding turning these screws??? Every GS 750/1000 I've tuned has a very noticable sweet spot while tuning these screws. Only if the idle was too high to start the adjustment or if the carbs are dirty/unbalanced or some mechanical problem, would there be a problem fine tuning them. But yours are basically unresponsive after 1 turn out? Yes, there's something wrong, but what? What WILL the bike idle well at? The rpm gain is small but easily noticable with these screws, but you can't accurately set them on a bike idling at 1,300 rpm's, etc. And again, if your bike won't idle at 1,000 rpm, then something's wrong.
Many things effect adjusting by the highest rpm method. Vacuum levels, valve clearances, ignition timing, compression, float levels...and much more. I don't know what's not right on your bike, but the screws expose a problem.
If the bike was here, I'd go through the whole "basics" list. But you say everything you know of is right. You're at a spot where the bike runs well, except for the pilot circuit. Either way you turn the pilot screws, you have a problem. Richening them just a 1/4 to 1/2 turn causes a problem. Leaning them the same amount causes a problem. The pilot screws are obviously in their range of effect, so a larger pilot jet makes zero sense. The carbs are synched and clean. Floats adjusted correctly. I don't know.
There are times that typical re-jetting just gives poorer results than expected. Jet kit makers warn you with the word "driveability". All your problems could go away with a simple pipe change or who knows what. It DOES happen. Sometimes the cut-away that works well in most set ups, has to be changed. Sometimes needle jets, etc. Jet kits themseleves say these changes are only RARELY needed, but they do happen. I don't believe (from past experience) that your bike is one of the picky ones. I think something's been over-looked or done wrong.
I'll take a little time off before the wife kills me and try to reply with something to help you. Talk to you in a bit.

[frosty5011]

First of all, I'm not frustrated or anything over this. ............

LOL, not saying you're frustrated........just thought that your fingertips might need some time to heal........they must be raw from all the typing!

[KEITH KRAUSE]

No, it's not a big deal. Nobody's twisting my arm.
I try to help because I want to.
Mark may not believe it, but many people, some members here even, have put in a lot more time and effort into a re-jet and still have problems. Nobody said it's easy, especially when it's new to you, and this is all new to Mark.
I've stuck with him and will until he gets it right or gives up trying.
I wish this re-jet was simpler, but that's the way it is.
I will say that this thread would probably be at page 1 or 2 still if advice was taken exactly. My very first post said to get a DJ kit. Then if you jump to the installed kit as I said to set it up, the tank would have been off this bike just ONE time at this point, except for the problem he had with learning to synch. ONE. We would still have this pilot circuit problem(?) to get right, but Mark would still have patience.
But what's happened during this thread isn't unusual. We all have to try what makes sense and just learn by trial and error. Sometimes we take advice, sometimes we re-arrange it and hope it works. Sometimes we read something and take it the wrong way... on both ends.
I've put a lot of time into this re-jet and I don't want to see final results that make me look bad or cause others to shy away from modifying their motor. I want this bike to run right just as much as Mark does.
I see that this thread has a lot of readers and I know some valuable things are being learned. That alone makes this thread a success.

[frosty5011]

Keith wrote: (actually he typed it)

..... this thread has a lot of readers and I know some valuable things are being learned. That alone makes this thread a success. Smile

Ain't that true! The most valuable being: DON'T LET HOOMIE NEAR A SCREWDRIVER!!!

(Had enough yet, Mark? You said to keep 'em coming, LOL)

[KEITH KRAUSE]

OK Mark. New day, new hope, right?
I'm sending this hoping you're working on it and I hope this gets to you in time. Let's try a little fine tuning.
This is an easy adjustment that I hope will work.
First of all, be sure the K&N's were oiled just like the can says. Exactly.
Don't re-oil them if you're positive you did it right, they'll just drip and make a mess for days. Second, be positive the plugs are gapped correctly.
Then adjust your side air screws out to 1 1/2 turns and leave 'em for now. No motor running/highest rpm stuff, just adjust 'em out to 1 1/2.
Now adjust the pilot fuel screws at 1 and 2, IN 1/4 turn from where they are now. Be precise in the adjustments. Leave 3 and 4 where they are.
Test and let me know how it goes.
If you still have a problem, we still have a little fine tuning we can do, though not much with either the air or pilot fuel screws. But we still can try. If those adjustments don't help, we have to try something that's a little more work and may work.
What we can try, (what I would do if the bike was here) is a re-synch. I would still hook up the tool first to verify the levels are as I last adjusted them. If they are, here's what I'd do.
I'd raise or lower the levels across all four cylinders at the same rpm (as close as possible) that you last synched at. Deciding to raise or lower the vacuum levels depends on the results you report back from the above re-adjustments and tests. During testing, I'd like to see another 1/3 SOLID plug read, THEN followed by the very minimal throttle/steady cruise read. I know this is a pain, but I'm trying to do things as if the bike was here.

[Hoomgar]

Keith wrote: (actually he typed it)

..... this thread has a lot of readers and I know some valuable things are being learned. That alone makes this thread a success. Smile

Ain't that true! The most valuable being: DON'T LET HOOMIE NEAR A SCREWDRIVER!!!

(Had enough yet, Mark? You said to keep 'em coming, LOL)

This is nothing! :roll:

I worry about people who hold their peace Ron, I don't know what they are thinking :twisted:

[Hoomgar]

Keith, you are a true champ buddy. I?ll get back to it. I haven?t touched or ridden the bike since my last post in this thread. I was mad enough at it to beat the crap out of it so I let it sit. I?ve read what you said and will give it a try and report back in the order you ask. I don?t have any evenings right now so it will most likely have to wait until the weekend.

Thanks again man. I?m not done yet. Just getting close :?

[KEITH KRAUSE]

Whenever you're ready Mark. Don't get mad at the bike. There's always a reason for something not going right. I really hope we find any problem and get rid of it.
We'll see what the small adjustments do for the bike. If you still aren't happy with it, we'll try to get as detailed as possible about the problem/symptoms and hopefully pin it down.