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

[Hoomgar]

OK Keith here it is. I did as you mentioned above which affectively put me at 1 ? turns out on the pilots and I noticed that the erratic behavior seemed to calm down a bit. That was with the air screws at 1 ? turns out like you said. But it was still spitting into the filters and popping on decal so I got to thinking maybe it needed the air screws adjusted anyway and I figured I would try that. I was going to set it back then and perform the tests you asked but listen to this.

After I had taken that little spin and tried adjusting the air screws I finally got to see what was going on. The air screws have been making a difference all along. The problem was that the pilots were so lean that the ?sweet spot? as you call it was only about ? to ? turn out before most likely because now I found it at around 1 to 1 ? turns out with the pilots at 1 ? turns out. The erratic behavior must have been from having the mixtures greatly different on 1 & 2 than they were on 3 & 4 because that hasn?t come back.

Anyway, what I did was this and found the theory may be right. I now have the pilots at 2 full turns out on all four carbs. I did a full reseat and set just to make sure. They were right though. After that I found that the air screws maxed out my idle (still only varies about 1 rpm but enough to tell) right around 2 to 2 ? turns out. I went by max idle and not a quarter turn increment. They are probably all at about 2 1/8 but I know they are between 2 and 2 ?. That seemed to be pretty much the same on all four carbs.

Here is the good news. It only needs a little choke now to start when cold (found that out this morning) but after about 30 seconds it runs without any choke and it no longer coughs or spits into the filters at all anymore. And the popping on decal is almost gone. Only the slightest little bit yet. Not enough to worry about. It runs smooth again. No smoke that I can see. I think this is really close. If anything, the pilots could maybe go out another ? turn but I think with the air screws where they are that I may be as close as I want to get.

This is the way the evening panned out for me with the time I had. I was very pleased. I don?t have plugs or time to get plug reads right now so I am going to let this be finished at this point. If it needs more fine tuning later on I?ll start a new thread.

I am going to be putting electronic ignition in it this winter and some new coils so next spring may bring new things. I also have my hopes on a set of 29mm smoothbores that if I can get them may be going on this bike. For now though, I think it is the best it has been and is way better than it was when I bought it in April.

What?s your spin on this? Thanks for all the help mate.

[KEITH KRAUSE]

I think if you're happy with it Mark, that's all that matters.
Tinkering with the screws is one of lifes little joys. They are precision and it can take some tinkering. You may find you want to play with them (just a little bit) when cold weather hits. My bike likes the pilot fuels screws out an additional 1/8 turn in winter. Not much I know, but seems to give it just that little extra fuel, most noticable during warm ups.
And going back, I always make a larger/un-uniform pilot fuel screw change if the plug colors are different enough between cylinders, as your latest ones were. With the initial setting, we were at one end of adjustment, (lean, it turned out) so going with a large richening adjustment actually cuts down the time it takes to narrow it down. If you get mixed results, as you did, then you've now established a "range" (too lean to too rich). If all goes well, you just work within that range to fine tune. Most bikes end up with the pilot fuel screws out at different points. Works for me.
I gotta get to work. Talk to you later. I may add a last note to officially end this thread later.

[Hoomgar]

Thanks mate

Soooooooooo many lessons to be learned here. I wish it could be condensed to help others without having to glean it from 30+ pages..

[frosty5011]

Keith wrote:

....I may add a last note to officially end this thread later.

So a snowball really does have a chance of surviving in Hell......:

[KEITH KRAUSE]

Thanks mate

Soooooooooo many lessons to be learned here. I wish it could be condensed to help others without having to glean it from 30+ pages..

As I said earlier, this thread could have been condensed by going with the DJ kit from page one. But we all learned some things. I love projects.
I must admit this jetting over the internet and trying to communicate well is harder than working on a bike by myself. Considering all things, this re-jet was not that tough. Many people struggle for a long time and end up wishing they never started. I'm glad this bike didn't end up that way.
You asked for me to help you with this bike and we got it done. I take this tech section seriously, maybe too seriously if you ask my wife. This thread got a lot of attention, which really surprised me. But it's cool to know this thread will help others as long as it's still around. I spend time at this site for these kinds of moments. Might sound kind of silly, but that's the way it is.
Enjoy the bike Mark!

[Hoomgar]

Well Keith all your help was greatly appreciated too. You were a real champ and I am confident that I would have quit without finishing if I had tried to do it with a manual and not had help. To be honest this engine runs really well and strong. Ask Luke, even he was surprised at how well this old iron fought to keep up with the ?big guns? on the highway when coming back from Asheville. And it was running worse then than it does now. I tend to be very anal about things once involved and I know you were the right person to help me sort this thing out. Most of the conditions I described throughout this thread would most likely have gone unnoticed by a lot of other riders. I don?t expect perfection from an old goat like this bike but I try for it just the same.

Right now the bike runs great. Fuel economy is almost doubled and I have learned more in one summer than I thought I would ever learn about VM carburetors.

The bike is old and cranky at times and continues to have ?issues?. All of which I intend to keep after. I can take care of this old beast. It really just needed an owner who would take care of it. It had been neglected too long.

This past week it got a re tuned front rim and a new tire. It also got a new set of SB grips and front brake pads. It?s soon to get a new seat

It really does run strong and I have learned to love the GS all the more having taken the time to learn jetting on this bike.

Thanks again my friend. Kudos to you!

8)

[KEITH KRAUSE]

You're welcome! If you need help with anything, let me know.
The seat should be going out by Tuesday or Wednesday. It's all packed, but my work/chores hasn't allowed me to get to UPS. But maybe tomorrow or Wednesday. I took Wednesday off because I'm sick of working extra and need a day off. :roll: