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

[Hoomgar]

I just rode to work after installing the Stage II jet kit. I needed a test ride after setting the air screws and sync of the carbs. It seems to run good and smooth but I am not sure about the power? No backfires, stuttering or coughing out the air filters. It just seems that it is not as strong. But it has never idled like this before. The idle is now perfect...

What order would you like plug reads Keith?

 

[Hoomgar]

OK here are two chop tests with new plugs after the rejet with the stage III kit.

I also rechecked the intake boots and o-rings. They are good. My high idle thing must have been sticking floats in the other carbs.

I took two reads, one at 1/3 throttle and one at 1/4 throttle.

1/3 throttle chop test:

1/4 throttle chop test:

They look very close. Things to notice different from past plug reads:
1. The number 3 plug that was always lean is now the darkest if anything.
2. The color is very consistent across all the plugs compared to before. 3 and 4 are slightly darker than 1 and 2 and only slightly. You have to look at the insulator to see it.

As best as I can describe it the bike runs like this...

It is smooth. Very smooth and seems to run great as far as even acceleration and no bogging or staging like stuff. No coughing or back firing. It seems about the same the whole way through the RPM range.

It seems weak. It is slightly sluggish to rev off idle but then seems fine. It does require some choke to get it started when cold. Once warmed up it runs smooth. It just doesn't have the power it did before.

Again the photo's don't tell the whole story. Not sure if you could see it or not but the 1/4 read is slightly darker than the 1/3 read. Both seem just a bit on the light side but better than in the past.

WOT seems to pull OK. It has been stronger in the past.

Intake boots cleaned and resealed with good o-rings and some hi-temp grease.

Oil changed - not filter this time around since only 1200 miles since last change.

New plugs, gap checked and set at factory.

Stage III kit installed with the needle clip in the forth spot down from the top of the needle. Spacer on top of the needle but under the stock spacer. DJ138 mains used. Bench sync, air screws tweaked for max idle (barely noticeable change after 1.5 turns out) and carb sync with Morgan Carb Tune II.

The only thing I would like to see at this point would be some of the missing power back. Not sure what the fuel economy is yet?

 

[duaneage]

Maybe the "seat of the pants" feel is not what you had before but if it idles good, runs smooth, gets decent mileage, and causes you no trouble I would leave it alone. The extra power you may have had before could have been due to carb problems that ruined your mileage.

I guess if your after more speed press on but if it runs decent maybe that is how this bike is going to run. I ws tuning a small block years ago and had the carb jetted way off. The car was quick off the line and seemed to be fast but it wasn't right. Other problems I had forced me to tune it the right way and forego some of the performance I had.

 

[KEITH KRAUSE]

Mark, Mark, Mark...what am I gonna do with you? :?
Do I type in Spanish? :lol:
Your lack of power as you put it would almost certainly be a lean condition.
First of all, you didn't put the jet needle position exactly as I suggested. I said put the e-clip in the 4th position with NO jetting spacer. Then be sure to replace the stock plastic spacers the way they are...thicker on top the clip, thinner below the clip. By using the DJ jetting spacer on top the e-clip, you're 1/2 position leaner than I wanted. This could matter a lot. Remove the jetting spacer, leave the e-clip right where it is (4th position from top), and be sure the stock plastic spacers go back as above. Because you have to disturb the jet needles, you must re-bench/vacuum synch again. Re-test.
Also, I'm assuming you did check the float levels? Where are they set? Very important they be at .94" or even .93/.92 works.
Also, floatbowl vent lines must be tossed and vent ports left open.
And are you POSITIVE the timing is correct and advancing right?

 

[frosty5011]

Mark, Mark, Mark...what am I gonna do with you? :?
Do I type in Spanish? :lol:
Your lack of power as you put it would almost certainly be a lean condition.
First of all, you didn't put the jet needle position exactly as I suggested. I said put the e-clip in the 4th position with NO jetting spacer. Then be sure to replace the stock plastic spacers the way they are...thicker on top the clip, thinner below the clip. By using the DJ jetting spacer on top the e-clip, you're 1/2 position leaner than I wanted. This could matter a lot. Remove the jetting spacer, leave the e-clip right where it is (4th position from top), and be sure the stock plastic spacers go back as above. Because you have to disturb the jet needles, you must re-bench/vacuum synch again. Re-test.
Also, I'm assuming you did check the float levels? Where are they set? Very important they be at .94" or even .93/.92 works.
Also, floatbowl vent lines must be tossed and vent ports left open.
And are you POSITIVE the timing is correct and advancing right?

?Qu? dijo usted? 8O 8O 8O

 

[Hoomgar]

Mark, Mark, Mark...what am I gonna do with you? :?
Do I type in Spanish? :lol:

Well you might as well. You know, one of the things I have always been complimented on was my ability to follow directions exactly :?

I read and re-read what you said to do and went off to the garage thinking you said to use the spacer. Shoot me now :roll:

I usually print out your instructions and take that out with me but my printer is down. That's my story and I'm sticking to it! :lol:

anywho...

Your lack of power as you put it would almost certainly be a lean condition.

What I was hoping you were going to say. This is the nicest color we have had yet. It was just a tad lean looking to me.

First of all, you didn't put the jet needle position exactly as I suggested. I said put the e-clip in the 4th position with NO jetting spacer. Then be sure to replace the stock plastic spacers the way they are...thicker on top the clip, thinner below the clip. By using the DJ jetting spacer on top the e-clip, you're 1/2 position leaner than I wanted. This could matter a lot. Remove the jetting spacer, leave the e-clip right where it is (4th position from top), and be sure the stock plastic spacers go back as above. Because you have to disturb the jet needles, you must re-bench/vacuum synch again. Re-test.

Ohhhh!!! You didn't want me to use the spacer?!? :lol: :lol:
All stock spacers were installed correctly and will be again once the DJ spacer is removed.

Also, I'm assuming you did check the float levels? Where are they set? Very important they be at .94" or even .93/.92 works.

Set right in the middle of the range as before. All four the same. I did not test with the clear fuel tubes in the drain holes this time.

Also, floatbowl vent lines must be tossed and vent ports left open.

Gone! I use them as drinking straws to drink beer from long neck bottle now :lol:

And are you POSITIVE the timing is correct and advancing right?

No I am not. I haven't checked them since I set them spot on 2000 miles ago. I hope they don't need checked every couple thousand miles? If so they are going bye bye really quick.

Thanks for your enduring patience Keith. I'll post results after the changes.

 

[Hoomgar]

Maybe the "seat of the pants" feel is not what you had before but if it idles good, runs smooth, gets decent mileage, and causes you no trouble I would leave it alone. The extra power you may have had before could have been due to carb problems that ruined your mileage.

I guess if your after more speed press on but if it runs decent maybe that is how this bike is going to run. I ws tuning a small block years ago and had the carb jetted way off. The car was quick off the line and seemed to be fast but it wasn't right. Other problems I had forced me to tune it the right way and forego some of the performance I had.

I appreciate that Duane but were not talking about an acceptable power loss here. If that were the case I'll gladly pay at the pump.

 

[duaneage]

Points wear out, high speed runs tend to walk them out of adjustment as well, one of the less endearing qualities of mechanical ignition. I would check them often during the tuning process to make sure they are spot on.

Every jetting change or major adjustment should be followed with a quick timing check just so you KNOW they are not causing a problem.

 

[KEITH KRAUSE]

Yes, points and timing have a huge effect and they lose their settings easily. They pit, they burn...always check points condition/gap/timing before vacuum synch.

 

[duaneage]

The plug reads WILL be affected by yhe points. The dwell angle (120 degrees if I recall for this bike) is what sets the charge and discharge parameter for the coils.

Buy this

http://www.7453217467431.com/produc...er_id=3642147&affID=39901&bmUID=1123553111093

Picture here:

http://www.tradervar.com/wwwold/CP7605.jpg

If your gonna play with a points equipped machine you need the right tools. I don't know if this will work for the bike but if you can somehow use it it is worth the money. Reading dwell on a meter is more accurate and faster than measuring the gap (old points are really hard to measure, the feeler gauges never get it right) and then moving the timing around throws it all off.

Keith - will a car dwell meter work if you read the scale differently or is a specific motor cycle one required?

When I worked on Mark's bike last May I had a tough time setting the gap and getting the timing right, I was not able to check the dwell either.

 

[Hoomgar]

Duane, you only needed to ask buddy. I told you I had a duell meter. I have all that old ignition stuff from my old Chevy SS days. Light, meter, feelers. I'll recheck the points and maybe just rape the Dyna electronic ignition out of my other bike. I plan on upgrading that anyway. We'll see. Money is tight so at a pinch new points and caps but I was hoping that by the time I needed them I would to the electronic route.

I was going to work on this last night but was ill and could work around the fuel fumes. Tonight I go to do head work on my other bike so hopefully I can get to this Wednesday night. The PA ride is this weekend. I need to step it up. How do I keep getting into this situation? :lol:

 

[Hoomgar]

Keith. It is hard to believe that those four little spacers can make such a difference in how a bike runs?! But they did. I got my power back! I didn't get a chance to get plug reads yet but I will.

I have a new issue now and don't want it in this thread so I posted a new thread for it here:
http://www.thegsresources.com/_forum/viewtopic.php?p=378132#378132

 

[KEITH KRAUSE]

Keith. It is hard to believe that those four little spacers can make such a difference in how a bike runs?! But they did. I got my power back! I didn't get a chance to get plug reads yet but I will.

I have a new issue now and don't want it in this thread so I posted a new thread for it here:
http://www.thegsresources.com/_forum/viewtopic.php?p=378132#378132

I replied at your other topic too. For a nice guy, you sure have lots of problems. You ARE a nice guy right? :lol: Maybe you're cursed? I dunno.
As for removing the jetting spacers and richening it up a little, that would certainly help but shouldn't cause the "night and day" difference you describe. A 1/2 position on the needles certainly matters, but wouldn't cause the bike to go from smooth but obviously lacking power to what you have now. Not the drastic change you describe. I think, without knowing, you synched the carbs better after removing the spacers. That's something I always stress...double check, triple check your settings. I swear they move by themselves sometimes. Anyway, no matter now. Hopefully, your performance and reads will be good at 1/3 and wide open. You already say the needle reads looked good or just a bit lean, which removing the spacers will help richen just right. Then possibly a little fiddling with the pilot circuit pilot fuel screws and you should be good. The bike should start with a normal amount of choke and warm up quickly. It should idle about 1,000/1,100 rpm's. There should be no dark exhaust after a throttle blip after idling several seconds. There should be no bogs or stutters off idle, etc. The gas mileage should be decent and no raw fuel smells/heavy exhaust. Pilot circuit reads can be a little hard to get. Just cruise around in 4th gear for a couple miles at about 35 mph is good (minimal throttle opening is what you want), then chop off and read. I do this test right after the needle/wide open tests. Then you know the reads aren't effected by choking or excessive idling. As long as you synched correctly and your side air screws are set correctly, then all you have to adjust, if needed, is the pilot fuel screws. If you end up moving the pilot fuel screws beyond 1/4 turn from where they are now, then re-set the side air screws for highest rpm. You may not notice a change, but check anyway.

 

[Hoomgar]

I wouldn't call it night and day or say it has arrived Keith but it is "noticeably" better. Not much gets past me as far as performance. I notice things others don't. I am sure the bike can run even stronger but right now it is back to where it was before as far as power. Before removing the spacers it was down on power. The average rider would have never noticed. I do. I can tell in 1 gear what it is going to be like.

Not sure why this thing has given me so much grief. I never had a bike that required this much tinkering before. My other GS was a dream compared to this one as far as that goes. I just think it needs a lot of TLC to bring it back from where the PO took it :?

I wont have time to fix my fuel leak problem or get plug reads before the ride this weekend so I will just change the oil before we head out and do that stuff after we get back.

I think were really close now. A few more tweaks here and there and she should be good. It definitely runs smoother now.

As always Keith, thanx for the help buddy

 

[Hoomgar]

Small update. Keith, were getting close. The bike ran great for the PA ride this weekend. There is some poping on decel now. It isn't what I would call really bad but it is consistant and always does it as you came down close to stopping.

Here is the best part...


drum roll please ... - ... - ... - ...


I got just shy of 40 MPG on the ride this weekend!!! WooHoo!

That's a 16 to 18 MPG improvment from what it got when I bought it.

I want to fix the gas leaking into the crankcase issue next but then I will be back to fine turn the pilot circuit which I suspect is the culprit for my poping on decel.

Then we'll get some more plug reads and hopefully put this thread to rest

 

[KEITH KRAUSE]

Ahhhh grasshopper. It is good news you bring.
As for the pilot circuit and decel' popping, don't expect to get rid of it completely. I'm not saying you can't on your bike, but I just wanted to tell you that.
My bike (and several others I've jetted) have some decel' pop. Mine has some moderate popping if I shut the throttle off at about 6,000 rpm's, mostly lower gears. It doesn't last long. I knew before jetting my own bike that I may have to live with it. Similar bikes I jetted before had the same thing. This can happen with or without the DJ kit.
The main difference with the DJ kit is the needle and the early overlap effect with the pilot circuit. DJ warns you to leave the pilot jet stock. So of course, I had to play. Increasing the pilot jet to a 17.5 helps decel' pop but causes worse and harder to live with problems. The pilot circuit runs too rich...the bike can temporarily foul plugs with the choke on in the morning...a little puff of dark exhaust when you blip the throttle after several seconds idling...hard starting when hot...I'm sure a small loss in mpg...I'll take the decel' pop anytime.
The 17.5 pilots work better with the stock needle, but as you've learned, the rest of the performance suffers.
Your motor is at it's leanest when it's running at several thousand rpm with a closed/nearly closed throttle. The motor's revved up but it's being fed by that tiny little pilot jet.
What you can do: Be sure the side air screws are set for highest rpm and don't compromise that or you'll see worse things show up. As long as your float levels, synch, etc, are correct, all you can try is a little richer on the pilot fuel screws. But take those reads first at minimal throttle opening. Take them right after the 1/3 throttle run. If the plugs say you can richen them a tad, then go ahead. If not, then I suggest you leave the bike alone. Let me know how it goes.

 

[duaneage]

If not, then I suggest you leave the bike alone. Let me know how it goes.

Considering I was chasing your ass down those back roads near triple digits I think the bike is jetted as good as it will get. Take the masters advice and enjoy it already. It even smelled better.

 

[Hoomgar]

If not, then I suggest you leave the bike alone. Let me know how it goes.

Considering I was chasing your ass down those back roads near triple digits I think the bike is jetted as good as it will get. Take the masters advice and enjoy it already. It even smelled better.

Yeah I forgot to mention that Keith. It doesn't smoke or smell nearly as bad anymore either. And it makes smaller GS bikes with lighter riders work their butts off to keep up with it while it is just mildly scooting along :twisted:


It also seems to top out better now than it did before. Meaning, it hits the needle stop faster than before. Not that it did that on the PA ride mind you. Because it didn't :wink:

 

[Hoomgar]

Keith, I haven't had time yet to do a 1/3 throttle chop test as it requires daylight and I haven't had the opportunity yet. But a 1/4 or less read is easy without looking so I did a "just off idle" test last night on the way in and cut it off. At least we can look at this awhile. 3 and 4 are a tad darker on the insulator than 1 and 2. It is just a bit lean looking.

Here is what it is doing that I have found riding it. It coughs or spits a lot into the carbs while cold. And it does it a bit at stops. It pops a good bit all the time when you leave off the gas. And there is a stutter at times when you go to get back on the throttle until it gets gas and smooths out. Sometimes trying to run with traffic results in stutters.

Can we do anything with this info or do you require that 1/3 throttle chop test first?

 

[KEITH KRAUSE]

Mark, as always, I'm trying to help without delaying you too much.
I only have a minute but wanted you to know I read your latest info.
What happened?? The bike seemed good after that long trip, but now you have stuff showing up? I know you tweaked the floats since to fix a leak.
I'll try to give some help about your problems later tonight. Sorry if you're depending on me and this delays you.