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

[Hoomgar]

OK Keith I have decided to take you up on your offer. First off, my bike is running out of gas at exactly 83 miles no matter if I ride hard or light. I have to switch to reserve at 82.5 to 83 miles. It's like clock work. I do the math when I fuel up and I am seeing a very consistent 24 miles to the gallon.

You say you think it is jetting? I have no idea so I am open to suggestions. I have an idea though that will help us get this done with no risk of rendering my bike inoperable due to my inexperience with carb work. It is simply this:

I have two racks of these carbs 8) I still have the stock ones off my other 1k which are the same carbs. So I figure we pull these off and tape them up and store them while we play. If I can't get it going with the other carbs I can always throw these that came on the bike back in and it will at least run. What do you think? Just start fresh with these other carbs? They were jetted for the same exact K&N pods and for my V&H megaphone pipe. Let me know if this sounds like a plan?

I took a plug read, here they are numbered 1 - 4:

Tell me what you think man?

It smokes black like it is loading up but those plugs don't look that bad. They are tan although #3 is notably whiter than the others.

 

[first timer]

it just looks like you have dirty carbs from those plugs. #2 looks good, 1 is a little lean, 3 is way lean (check the intake boots for cracks or a leaking vacum hose goign to the petcock or a bad pet cock. ) and 4 is rich. if you are happy with the way the other carbs ran and are sure they are clean go ahead and slap them on they should be fine. then take the time and pull the other carbs apart and learn to clean them, especailly for a guy with almost 4 bikes. oh yeah check the intake boot o rings as well. you want to get this all sorted out before you start adjusting your carbs.

keep in mind this is a older bike and probly wasn't reved very high for a while so it may be throwing a little more then normal black smoke/soot when you crank on it. be sure to change the oil and filter soon to especally after riding it hard, it may dislodge some old gunk.

check your oil level while at it, see if you flooded gas into the oil, i'm wondering if you have a bad pet cock.

-ryan

 

[KEITH KRAUSE]

Hi Mark. Sorry for the delay. It's late and I'm a slow typer. I'll try to get back tomorrow night with more info.
Briefly, you should get a DJ kit to re-jet the carb set that's in the best condition. My experience is the stock jet needles don't give good enough results, especially with K&N's and a quality pipe like the V&H.
Remember, I said earlier that as long as the motor is mechanically sound and you have good spark, THEN I believe your poor mileage is carb related.
Your plug reads don't indicate much unless you know what the throttle setting was to produce those reads. Also, if the carbs are out of synch, you'll get uneven reads such as shown. Those reads don't seem to indicate a bike that's getting only 21 mpg though.
If you want to do a first rate rebuild/re-jet of the carbs, which generally includes a DJ kit and all new o-rings too, let me know. If not, I can still try to help you with the jetting, etc, but don't expect as good of results.
One quick thought: any chance the petcock is different on your bike? Some PO could have installed a petcock with a higher reserve tube? Possible. I'm sure your carbs need at least typical maint', etc, but I just thought I'd mention that. The GS1000 tank has 1 gallon remaining when you hit reserve on level ground. Instead of taking out the petcock to check, maybe you could drain the gas out after it hits reserve to be sure the petcock is stock.

 

[Hoomgar]

it just looks like you have dirty carbs from those plugs. #2 looks good, 1 is a little lean, 3 is way lean (check the intake boots for cracks or a leaking vacum hose goign to the petcock or a bad pet cock. ) and 4 is rich. if you are happy with the way the other carbs ran and are sure they are clean go ahead and slap them on they should be fine. then take the time and pull the other carbs apart and learn to clean them, especailly for a guy with almost 4 bikes. oh yeah check the intake boot o rings as well. you want to get this all sorted out before you start adjusting your carbs.

keep in mind this is a older bike and probly wasn't reved very high for a while so it may be throwing a little more then normal black smoke/soot when you crank on it. be sure to change the oil and filter soon to especally after riding it hard, it may dislodge some old gunk.

check your oil level while at it, see if you flooded gas into the oil, i'm wondering if you have a bad pet cock.

-ryan

I'll have to look at some drawings to see this intake o-ring you speak of? Is that in the boot? Seems it would be a nightmare to install if that's the case?

Here is what was just done to the bike before I bought it. Carbs cleaned and rebuilt. Tune up kit (new points and condenser) Petcock rebuilt, oil and filter change, new tires.

There is one of those stupid little lawn tractor clear inline fuel filters on it and you can see it is starving it for gas as the down tube after it going into the carbs is 80% empty when the bike is running. Thats the first thing to go. I just found this last night while getting ready to start this thread. They have it tucked up under the tank in a way that I had to look up under with a flash light to see it. Now I know it's there and it is gone!

There is no gas in the oil. The rider before me puppied it compared to how I ride it. I am sure it's throwing carbon as the oil is black already.

Hi Mark. Sorry for the delay. It's late and I'm a slow typer. I'll try to get back tomorrow night with more info.
Briefly, you should get a DJ kit to re-jet the carb set that's in the best condition. My experience is the stock jet needles don't give good enough results, especially with K&N's and a quality pipe like the V&H.
Remember, I said earlier that as long as the motor is mechanically sound and you have good spark, THEN I believe your poor mileage is carb related.
Your plug reads don't indicate much unless you know what the throttle setting was to produce those reads. Also, if the carbs are out of synch, you'll get uneven reads such as shown. Those reads don't seem to indicate a bike that's getting only 21 mpg though.
If you want to do a first rate rebuild/re-jet of the carbs, which generally includes a DJ kit and all new o-rings too, let me know. If not, I can still try to help you with the jetting, etc, but don't expect as good of results.
One quick thought: any chance the petcock is different on your bike? Some PO could have installed a petcock with a higher reserve tube? Possible. I'm sure your carbs need at least typical maint', etc, but I just thought I'd mention that. The GS1000 tank has 1 gallon remaining when you hit reserve on level ground. Instead of taking out the petcock to check, maybe you could drain the gas out after it hits reserve to be sure the petcock is stock.

No worries mate

I'll give it the go over you say. The other rack of carbs I have are already DJ and needles and were setup for K&N pods and a V&H so it may already have the jets it needs for this Kerker? But! This is the rack that was on my other 1k when it was getting only 22 MPG!!! What else could make for such bad fuel economy?

The plug read was dumb I guess. I simply pulled them out from in the garage so that was after normal riding. Which is always spirited for me although yesterday I was taking my time on the way home being backed up in traffic.

The petcock has a longer reserve tube in it for sure Keith. I can only fit 3.2 to 3.4 gallons in after having to switch. And that is after a few miles on reserve as well. I am not worried about that and the petcock has a fresh rebuild so it is fine that way. But still the math comes out to 24 MPG.

Not good at all. Plus it always smells gasey. Even Amos said he could smell the gas while following me.


Let me pull apart these other carbs and look at them. We'll start there. In the mean time I'll get that inline fuel filter out of these and get a true plug read from a nice 1 or 2+ mile steady run at say 65?

Thanks for all the input!

 

[dgeorge]

Hi Hoomie, the o-ring is between the intake boot and the cylinder head it is part #28 in the fiche.

 

[earlfor]

Mark, before making any jetting changes, I would do a vacuum synch on the carbs. With plug reads like that, youre shooting in the dark.

Earl

 

[Hoomgar]

Thanks George. That makes sense. Can it be any o-ring? Like from a hardware store of does it need to be ordered special? Heat/fuel resistant?

Mark, before making any jetting changes, I would do a vacuum synch on the carbs. With plug reads like that, youre shooting in the dark.

Earl

Thanks Earl. I have been wanting to learn that anyway. What do I need before I start? Is this where I need that funky tool with the four hoses? I may be able to borrow one from Paparo unless it is cheap and easy to find or maybe make?

I have the advantage of this second rack of carbs to play with so I can have at it.

 

[dgeorge]

Mark, I would order an OEM ones, they are not very expensive about $2 each. They do need to be heat resistant and some of the aftermarket ones are not quite as thick as OEM's are. I think that is the problem that I'm having with mine now. I used the ones from a rebuild kit and I think they may be leaking, so I've ordered OEM's from crotchrocket, just got them yesterday so I'll probably put them on this weekend.

 

[Hoomgar]

Would some hi-heat RTV or maybe the non-hardening stuff used on header gaskets be a help? maybe an assist or do you want to leave them dry for a reason?

 

[dgeorge]

Mark, I don't know about using RTV, but I usually coat mine with high temp grease. It helps hold the o-ring inplace and helps make a seal.

 

[earlfor]

Mark, you cannot use RTV in any application where it will come into contact with gasoline.

E.

Would some hi-heat RTV or maybe the non-hardening stuff used on header gaskets be a help? maybe an assist or do you want to leave them dry for a reason?

 

[wrench]

Correct me if i'm wrong :wink:

But i thought it was recommended for a good plug reading, that you should be hauling arse and then hit the kill switch, and take a reading :?:

 

[Jethro]

I've gotten quite good at plug readings. I've pulled the plugs more times this winter than I pulled my....

I take plug readings at three places. At idle (although I check this last), at about 3500rpm in 4th gear going on a flat road for a few miles, and then at wide open in 5th (must be done on the highway).

 

[Hoomgar]

Mark, you cannot use RTV in any application where it will come into contact with gasoline.

E.

Would some hi-heat RTV or maybe the non-hardening stuff used on header gaskets be a help? maybe an assist or do you want to leave them dry for a reason?

Thx again Earl. This is all good stuff.

Correct me if i'm wrong :wink:

But i thought it was recommended for a good plug reading, that you should be hauling arse and then hit the kill switch, and take a reading :?:

That's what i read as well John. I am going to be doing that.

OK, who has a stock airbox for me?

 

[KEITH KRAUSE]

Hi Mark. Finally got some time.
First of all, buy the genuine Suzuki o-rings for the manifolds. Apply some hi-temp bearing grease to them. If you have the Phillips replaced with Allens, torque to 6 ft/lb.
I would use the carbs that already have the DJ kit.
Now as for your bad gas mileage and us blaming it all on the carbs, you have to be reasonably sure the bike is ready to be re-jetted/synched.
Compression, valve clearances, spark quality/timing, clean/oiled filters, all have to be good before tuning the carbs. After all this stuff has been checked, then you can test and re-jet. Don't cut any corners or the jetting is more difficult.
I think you said the DJ carbs were cleaned and rebuilt? Did you do the work? I just want to say that I've heard that line many times and actually nothing was done. I've also heard "the filters are cleaned and oiled", but they were really oiled with motor oil. That right there will cause bad gas mileage. As for a good spark, in a darker garage, the spark will be blue and fat. If it's yellow or orange, you have a weak spark. If the above mentioned checks are good, then there are reasons the carbs are wasting gas. One of them is they're probably not clean enough. Another can be the float levels. Another the jetting/synch. The carbs need to be cleaned/inspected.
Do you have a good manual or do you need specific info?
Are you going to do the work yourself?
Have you ever vacuum synched these carbs?
Do you have the tool?
Do you know how to chop test plugs?
As for a plug read, I do recommend a carb synch to get more accurate/uniform reads. If all the other checks are good, to get a solid read for the needle, mark your throttle housing and grip for 1/3 throttle. Make sure the bike's warmed up well, and go a couple of miles at that throttle setting and do a chop test. Avoid hard accelerating at this time. That can glaze the plugs. Just open her up to 1/3 and hold it. This is high speed, but you say that's not a problem for you. :twisted:
Any questions? Get back with the reads and we'll go from there.

 

[Hoomgar]

Keith, you might as well speak Russian to me. I haven't a clue and have never done anything you just asked and don't know what most of it means. I will need to go through the docs in the garage. But time is a waisting now because alas, I am GS-less once more, again :x For the moment.

Well it's all bad. And down hill from here. As you can expect when purchasing a bike that is 27+ years old there are many "things" that are wrong or rigged or damaged. Here is the list as of what transpired tonight.

I went to put the plugs back in. Well plug 3 (the funny looking one) wouldn't thread in so I stopped. Looked in the hole with a light and it looks as if someone has cross threaded a plug in there at some point about 1/3 of the way down. I took my time and got it in correctly and it seemed to tighten up OK but now I know what that buzzing sound was the last couple days, a loose plug! It was all sooted up on the threads because of it.

Next, I figure we'll put the kabosh on that lawn tractor fuel filter. You know, the one they put on with clear lawn tractor fuel hose? :roll: Had to cut it off as that stuff is like Chinese finger cuffs and would not pull off.

So I put a good piece of fuel line on it, get all the plugs torqued, slap the tank on and go get gas. Coming back it is running really nice but I smell gas :? Yup, sure enough, pull over and look, it's peeing gas out like there is no tomorrow from the overflow tubes.

Apparently this was a precariously balanced system. The inline fuel filter was restricting enough fuel to keep that from happening or the minute I took it out some dirt instantly found it's way into one or more of the carbs and is clogging the needle valves.

Well, the carbs are out! On the bench and bowls off. What now?

In the mean time I will start on some of the things you just said.

Oil the air filters? This is new. What of that? Never heard that before.

 

[Hoomgar]

Hi Mark. Finally got some time.
First of all, buy the genuine Suzuki o-rings for the manifolds. Apply some hi-temp bearing grease to them. If you have the Phillips replaced with Allens, torque to 6 ft/lb.

I can do that, but it will take a while for them to come in. :|

I would use the carbs that already have the DJ kit.

Might as well do the ones on the bike now.

Now as for your bad gas mileage and us blaming it all on the carbs, you have to be reasonably sure the bike is ready to be re-jetted/synched.
Compression, valve clearances, spark quality/timing, clean/oiled filters, all have to be good before tuning the carbs. After all this stuff has been checked, then you can test and re-jet. Don't cut any corners or the jetting is more difficult.

I have to tear the top end apart?!? Valve clearances? Man. If that is true forget it. I don't have gaskets for all that or the time for that matter.

Compression test. I have seen this posted before. How do I measure it? Is there a special tool?

I think you said the DJ carbs were cleaned and rebuilt? Did you do the work? I just want to say that I've heard that line many times and actually nothing was done. I've also heard "the filters are cleaned and oiled", but they were really oiled with motor oil. That right there will cause bad gas mileage. As for a good spark, in a darker garage, the spark will be blue and fat. If it's yellow or orange, you have a weak spark. If the above mentioned checks are good, then there are reasons the carbs are wasting gas. One of them is they're probably not clean enough. Another can be the float levels. Another the jetting/synch. The carbs need to be cleaned/inspected.
Do you have a good manual or do you need specific info?
Are you going to do the work yourself?
Have you ever vacuum synched these carbs?
Do you have the tool?
Do you know how to chop test plugs?
As for a plug read, I do recommend a carb synch to get more accurate/uniform reads. If all the other checks are good, to get a solid read for the needle, mark your throttle housing and grip for 1/3 throttle. Make sure the bike's warmed up well, and go a couple of miles at that throttle setting and do a chop test. Avoid hard accelerating at this time. That can glaze the plugs. Just open her up to 1/3 and hold it. This is high speed, but you say that's not a problem for you. :twisted:
Any questions? Get back with the reads and we'll go from there.

I have never done any motorcycle carb work other than when I tore the Kaw carbs apart and cleaned them then put them all back together. I got lucky.

 

[first timer]

ok homie take a deep breath count to 10 relax, lets do one thing at a time. you go teh carbs off that good, i would start by just going thru the carbs and cleaning them, basiclly take one carb apart at a time and and anything that does look like dirt either romeve or soak till it comes off. this will requre a little bit of memory cause the vms are kinda like a puzzel and you have to remove a bunch of stuf just to get them apart, have some one with a good memory watch you.

don't get stressed out about this that only makes it harder. so for now work on cleaning a set of carbs it will do you good nad get you in a good mind set to start working on other things.

after you have you carbs apart and reassembled then work on replaceing the o ring gaskets whilke the carbs are off. if you look at he whole pictue you will blow your mind so do only one thing at a time, you can do this it's not that hard. you just have to be backed up in a corner and desprate to have a running bike in order to be motivate to to the work. i was there now i look at fixing a bike like i think about breathing.

-ryan

 

[Hoomgar]

Thx dood I know I can do it too. I got you guys

I have them open and yes the two center ones look like they were cleaned out with a knife. Scraped clean. They need cleaning.

I will do just that. I have two complete sets here so here goes.

No turning back now!

 

[first timer]

you will need some berryman carb dip and about 3 bottels of carb spray, don't forget to get some orings for the carbs from robert barr these are all musts, before you dip make sure to remove all rubber peices also let each carb soak for at least a hour or more.

some tricks i learned, use a impact screw driver bit to remove the screws keeps them from stripping. also when removeing the float bowl gasket use a flat razor and lots of carb spray to soak the gasket and slowly see if you can pry off the gasket so you can reuse it. i also found that useing a old tooth brush and warm water and some dish soap to do a intial cleaning helpful before dipping. so to remove the big stuff.

don;t forrget to blast every passage you find with the carb spray red staw stuck in the hole, every hole you find should have another end so when you spray it will squirt out it, other wise you have a clog.

-ryan