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

[Anonymous]

Too much to read so if this has been covered I am sorry. Could your odometer be out to lunch? They can be off by a huge amount on these bikes which results in a really bad mileage calculation.

Steve

 

[KEITH KRAUSE]

OK Mark. Hope I have this straight. You want to keep the carbs on the "new" bike the way they are for now, so you have a bike that runs. That means we can service the carbs that came with the other bike and already have a DJ kit. Sound good? I think there's no pressure or rush this way.
We can set up the carbs and just hope that the other stuff I mentioned is good or will be later on, such as the timing, etc. I was just trying to do things in order, but we can work with what we have if you like. I just didn't want to see you spend time and money on the bike and find out you have major problems that would make you want to forget the whole thing.
By valve clearances, I meant to check the tappet clearances. A search here will give you detailed info on a quick compression check.
As for the carbs, the leaking you just discovered will probably be the main reason for the bad gas mileage. A simple cleaning/ inspection and maybe some replacement parts will fix this.
Let me give you an option. I can try to walk you through the carb work if you like. I realize I'm not the only help you have but I will be busy this weekend and I'm not sure how much I can help. So if you're relying on me, I apologize. The option is, I can do this carb work for you and not charge you an arm and a leg. I can do better work than any shop around.
Let me know in a PM if you would rather have me do the carb work. If you want to try, that's great. As usual, gotta run off to work. :roll: Keith.

 

[Hoomgar]

Thx guys. Steve, you could be right as I already suspect the speedo is off and they are joined at the hip but it isn't off that much. Not in a 100 mile or less calculation. Even if it is off it is still bad.

Ryan, I am looking into carb dip now. Maybe parts cleaner?

Keith, read the first two posts on this second page. The game plan has changed, I am working on the carbs for the bike now as they are screwed!

I need to get these squared so I can get the bike running.

 

[first timer]

nope you need "carb dip" berrymans should be available at most retail auto part stores if not go to napa tell that you want a gallon tub of berryman and if they don't have it can they order it or order somthing very close. it's a pretty common thing.

-ryan

 

[Hoomgar]

Well I am at that point so out I go. The entire rack is completely disassembled. I mean completely. There isn't a thing left that could be taken apart or unscrewed.

I threw everything together into a big tub of WD40 to soak.

NOT! J/K :lol:

I have every carbs parts each in their own cup. The bodies are stripped, carb cleaner cleaned until all orifices are open and ready to dip.

Oh, the carb boot o-rings are all very good looking. They are soft and pliable, not swollen and quit frankly, look new? Maybe just put in.

Side note. You saw the pic of plug number three? Everything about cylinder 3 is funky on this bike. The spark plug socket is cross threaded about 1/3 of the way in. Carb 3 was gummy while the rest were not. The carb boots all came right off the same except the boot on number 3, it's screws were corroded in places and took some finesse to get out. The float needle in number 3 was particularly gummy.

I am going to clean out my tank, check the petcock screen and get a proper motorcycle fuel filter for it while I am at it.

I'm on this. Thanks for all the help. I have never been more committed to a cycle repair than this before.

What do I need to get in order to sync the carbs? A Manometer? <--spelling

Can I make one?

BBL

 

[Hoomgar]

Who can point me in the right direction for a carb balancing tool?

 

[first timer]

any bike shop can order one, i have heard good things about the carbtune sync meter, basiclly i think you can get a pretty good one from jc whitney, make sure you get the kind that uses mercury they are more acurate.

congrats on getting everything apart you are half way there, was so hard was it.

-ryan

 

[Hoomgar]

No it really wasn't man. I got some carb dip. It's Gunk brand and is environmentally safe? Guess that means it wont work :lol:

No actually it worked nice. They all look nice and shinny new now. All passages open and clean. Every single o-ring in these carbs was tar when I opened them. They simple crumbled out. All of them! Only the boot o-rings were good but upon closer inspection I can see that even they could use replacing. Where is the best place to get all the o-rings I need for these carbs and quick? Bike Bandit only stocks about 2 of them :?

I bought a 4 carb rebuild kit off eBay today for these carbs. Hope I didn't get snookered? Was this a good buy? http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=4543738108

I hope so. I also got another set of bowl gaskets. Time to stock up.

Oh, I also got a compression gauge and got those cylinder pressure reads.
I had to take them cold of course as the bike isn't running but here was the results read after one minute wait on each cylinder. There was virtually no fade at all on all four of them. I think they are good right?

Cylinder:

1 = 110
2 = 106
3 = 112
4 = 118

I just need o-rings and gaskets now in order to reassemble.

I am looking for a carb tune up tool. The Morgan Carbtune II is going to be it if nothing else comes along.

One more, I know I have a lot of questions here but your answers are greatly appreciated guys. How can I tell what size and make these mains are? There is no markings whatsoever on them. But the hole in them just looks really big to me for a jet in a stock 997 engine running 26mm carbs? Here are some pics of them:

I could drink through that hole!!!

What make is this? How can you tell?

 

[KEITH KRAUSE]

Hi Mark. Glad you decided to tackle the carbs.
The rebuild kits you bought look OK from what I can see. Some parts were necessary, some not. If you want to do a complete job on these carbs, I would order the o-rings from Robert Barr, a member here. I think he wants about $16 for all the o-rings. There's at least 5 in each carb to replace.
I use a Motion Pro mercury vacuum tool. It's simple, but works as good as the person using it. Morgan Carbtune costs about twice as much ($80) but uses metal rods instead of mercury. Mercury works well, but if you take a longer time to synch and you turn it off because of the motor getting hot, condensation can get trapped in the mercury columns and make the levels harder to read.
Since you're not going to put the DJ carbs on the project bike, I think you should take out the DJ parts and use them in these carbs. I doubt you can re-jet with the stock jet needle. I can then give you the jet settings I hope will get it right the first time, which is difficult to guess though. Sound like we're on the same page?
Do you have a manual, or hopefully a factory manual? If not, I'll try to peak in during the day to see if you have questions.
After the carbs are cleaned up and blown out with high pressure and any o-rings replaced, you need to get some verniers and measure the float levels. First make sure the floats are not tweaked. Measure both sides of each float and gently bend so they're the same. Then set them to the exact middle of their factory range, which will be .94". Measure from the base of the carb body, without the bowl gasket, (don't place your measuring tool on the small gasket ridge) to the top of the float. Hold the tool straight and slide it across the top of the float so it BARELY touches. Carefully bend the tab that contacts the float valve tip, to get the level you want. Double check your work.
At this point you'll still have to swap out the needle assemblies, check/adjust the needles before installing, install the DJ mains, bench synch the slides for the fully closed and fully open positions, and set your side air screws and pilot fuel screws. Followed of course, by the vacuum synch. Did you keep a record of how far out each pilot fuel screw (underneath) was? If not, set them at 1 1/2 turns out to start. Remember to only seat them LIGHTLY to avoid damaging the sharp tip. The side air screws can also be set at 1 1/2 turns out to start.
Regarding the needle assemblies, use a good fitting tool to remove the two Phillips screws down in the slide. They must be removed to swap the needle and make adjustments. This assembly takes some finger dexterity to re-assemble. Make sure the two plastic spacers, a thick one and a thinner one, go back on the DJ needle in the same order. The thick one goes above the needle e-clip, the thinner one goes below the clip. Any jetting spacer you may still have, (if we used it) would go on top the e clip. I think in your case, we won't use a jetting spacer if you have it. So install the e-clip in position #4 (from the top) of the DJ needle. Be sure the thin brass plate that goes under the throttle valve arm goes back the same way it came out, don't flip it upside down. It has a small tit on it and it fits into the arm. You'll see, just be aware. Don't over tighten the screws, the heads strip if over tightened.
Install the 138 DJ mains, if that's what the carbs have. The DJ mains will have the # stamped right on top. Yours may say 142?? If no #, I don't know what's going on. Mikuni's also stamp the # in the same place and have a little symbol, like a small square inside a larger square. I would re-use the stock Mikuni pilot jets, don't use the pilot jets that came in the rebuild kits.
That just leaves the bench synch for the fully open and closed positions.
As usual it takes me longer than I want to admit to post this. I don't want to take too long because the posts are "timed" or something, and I click submit, and I get an invalid message and lose everything. I'll post the bench synch info, I hope in time for you, tomorrow AM. The synch is very important, you want to get it right to make the vacuum synch easier. Also, the fully open position is important. Later.

 

[Hoomgar]

Thx for all the info Keith. I am moving on and need a few easy questions answered by anyone who knows?

1. Must I/should I clean the floats as well? They have that rusty looking fuel stain on them. If so, how and with what? I didn't want to dip them as that seemed unsafe?

2. All the needles were set at the 4th position down from the top except the one in carb #2, it was set in the middle or the 3rd one down. Does this seem right? Wouldn't they all be in the same position?

3. What is this stuff I removed from my oil plug and the bottom of the pan when I changed the oil today? It is soft and rubbery and is orange/red in color? There was a bunch of it, pictured is just some that I picked out and wiped off for the photo.

Now onto business. Amos (having younger and better eyes) was able to read marking on the mains that I could not see. The mains in my carbs said R and two little squares and the jet size was 132.5

The mains in my other old set of carbs just say 118. I am running the old carbs as is right now just to see what they do. It runs fairly smooth out to red-line with no perceivable flat spots but lacks power. I took a plug read and it is decidedly lean on all four cylinders. Some worse than others and #4 being the best. I noticed that the screw on the bottom of carb number 4 was sitting out considerably further than the other ones. So unless there is a lot of room for adjustment I would say these 118 mains that I though were DJ and am not sure what they are now may not be big enough. Here is a pic of the plug read taken hot after 3+ miles at 1/3 throttle:

Remember, these are vm26ss carbs and are small. But what do I know? It just seems to me that the 132.5's in the original carbs would be big but maybe I am wrong. I am only playing with these old carbs on the bike to see what they did. I feel certain these jets will be too small. Maybe we stick with what is in the bike already?

I will order those 0-rings now.

 

[Hoomgar]

0-rings are ordered and paid for. Hopefully they will arrive soon. I'll need that bench sync info you mentioned Keith? Also, if you didn't see it, can you look at my questions in my last post? Thx

When we figure these babies out and get them right I am going to rebuild the other set of carbs I have the same exact way and leave them dry stored so I have a spare ready to go when the time comes. Sweet

 

[KEITH KRAUSE]

The orange, pliable stuff in the oil looks like a type of sealant that oozed out during engine/case assembly.
Clean the floats with a toothbrush. If the stain persists, don't worry about it. Be sure to set them as I said.
Yes, the needles should all be identical. I hope there wasn't some reason that someone would try to make this compensating adjustment. Maybe just a mistake I hope.
I don't know why, but I keep getting mixed up with which set of carbs you're working with. Neither set really has a DJ kit?? The stock needles many times just don't work. Anyway, going by those plug reads, you should try raising the needles another position. Put the e-clip in the bottom position if these are stockers. If there are only 5 positions, then these are stock needles.
Try 130 Mikuni main jets.
The pilot fuel screws underneath are not always set the same, but are generally within a 1/2 turn of each other. There's no reason to think yours are set wrong at this time, except for #4. I don't know where it's at, but try an additional 1/4 turn in for starters. GENERALLY, these screws are around 1 1/2 turns out with pods/pipe. Use a mirror and light, and don't get crossed up and turn them the wrong way. You want to turn that screw in, clockwise.
Before taking any more reads, I suggest waiting to do the vacuum synch. You'll get more accurate reads then.
Hope I answered your questions. Gotta get to work now.
I plan to post detailed info about the carb bench synch tonight after work. A good bench synch will make the vacuum synch much quicker/easier. Remember, you'll need a couple of larger fans to cool the motor when synching.

 

[Hoomgar]

The orange, pliable stuff in the oil looks like a type of sealant that oozed out during engine/case assembly.
Clean the floats with a toothbrush. If the stain persists, don't worry about it. Be sure to set them as I said.
Yes, the needles should all be identical. I hope there wasn't some reason that someone would try to make this compensating adjustment. Maybe just a mistake I hope.
I don't know why, but I keep getting mixed up with which set of carbs you're working with. Neither set really has a DJ kit?? The stock needles many times just don't work. Anyway, going by those plug reads, you should try raising the needles another position. Put the e-clip in the bottom position if these are stockers. If there are only 5 positions, then these are stock needles.
Try 130 Mikuni main jets.
The pilot fuel screws underneath are not always set the same, but are generally within a 1/2 turn of each other. There's no reason to think yours are set wrong at this time, except for #4. I don't know where it's at, but try an additional 1/4 turn in for starters. GENERALLY, these screws are around 1 1/2 turns out with pods/pipe. Use a mirror and light, and don't get crossed up and turn them the wrong way. You want to turn that screw in, clockwise.
Before taking any more reads, I suggest waiting to do the vacuum synch. You'll get more accurate reads then.
Hope I answered your questions. Gotta get to work now.
I plan to post detailed info about the carb bench synch tonight after work. A good bench synch will make the vacuum synch much quicker/easier. Remember, you'll need a couple of larger fans to cool the motor when synching.

Sorry for the confusion Keith. Yes I am playing with two sets of carbs. Just forget about the set I post about last. That is what that plug read was from. Those are the carbs off my other GS and have what looks like Mikuni 118 mains but there is no marking I can see that designates manufacture. I believe both carbs have Mikuni jets in them. Just forget about this set; let's work on the set off the bike.

That set is the one I have just completely disassembled and cleaned. I just ordered new o-rings from Robert and also a gasket set off eBay. The mains were labeled as 132.5. If you think these are good we'll go with them. Or should I look for something smaller? The needles only have the 5 slots so these are most likely Mikuni parts. The other marking on the 132.5 mains was an R followed by what looks like two squares.

Keith, I can learn anything but it has to click first and those instructions for setting the float levels do not click. I need a picture or something to know what I am measuring. What does "tweaked" mean? Crocked maybe?

I need help with that since that will be next upon assembly. Where did you order your vacuum tool from or what one do you recommend I get for me? I need to get it ordered and have no idea so I will go with your recommendation.

 

[KEITH KRAUSE]

Hi Mark. The tool I have now is a Motion Pro. About $40. Works well. Only negative (with any mercury tool) is you can get condensation mixed with the mercury if you take too long to synch. Not a major problem, just an annoyance. The Morgan Carb Tune uses metal rods and doesn't have this problem. Mercury can spill too if you knock over the tool. The Morgan is about $80? I have no problem with the Motion Pro, but the Morgan is a fine tool if $ doesn't matter.
Yes, you can try the 132.5 Mikuni mains. I guessed 130, so that's close enough to try.
The stock jet needles e-clips will have to go in the botton position and we'll hope that does it.
The factory float levels are to be between .90 and .98". I set mine at .94".
Just make sure you hold the measuring tool reasonably straight up and down. Because of the "range" in the setting, you have a little room for error. As for "tweaked" floats, before starting final adjustment, if needed, make sure both sides of each float measure the same. They're sometimes bent (one side higher than the other). You can't accurately adjust them until they're even. Gently bend one side a little to match the other closely if needed. To measure, you need some verniers.
Float level is CRITICAL to good performance, so do it right. Make sure all the float valves are in good condition. The little pin under spring tension must have no slack in its travel. If you GENTLY press it in a little, it should come back out completely under spring tension. If you can actually pull the tip out a little further (slack), the spring is weak and the valve should be replaced. Also, check the pointed tip of the valve where it seats into the brass seat. If a groove is worn around the tip too deep, the valve will allow gas to leak out the bowl overflow line. Keep each float valve with its brass seat, they wear as a unit. If any valve looks worn out or the spring/tip is weak, don't bother to set the float level to that carb yet, replace the valve.
To measure, make sure the bowl gasket is removed. On the carb body, where the gasket sits, you'll see a small, thin ridge. This helps the gasket seal. Don't let your measuring tool sit on top this ridge. Put the tip of your tool on the flat surface. With the floats resting on the float valve, you want to measure to the highest part of the round float body. With the carb at eye level, slide the tool over the top of the float. It should just barely graze the float, not pushing the float downward any more than a graze. Just be sure to hold the tool straight and double check your work. If you have to make an adjustment, you bend the little tab that contacts the valve tip. In this INVERTED position, bending the tab UP, will LOWER the measurement, and vice-versa. Don't be rough with the float when bending the tab. Hold it so you don't tweak things. I put my middle and index fingers under the float so the tab is right between them. I then push down on the tab with a small screwdriver tip to make an adjustment. If you push too far and need to push it the other way, just flip the float over. A little tab movement changes the measurement a lot. It takes practice sometimes. Be picky and set them right.
Just a thought, in case you don't know: be sure you install the float correctly, not upside down as others have done. You can easily see the little shiny "rub mark" on the float tab where it contacts the float valve tip.
Bench synch info to follow.

 

[Hoomgar]

OK I think I follow you now. I missed the whole "inverted" part in your last post. It makes sense now. Plus I found that in my manuals so I will get-r-done I am going to wait for my rebuild kits to come so I can use the new float valve needles and seats. Then I will do it up.

Right now I am playing around with this other set trying to dial it in. :?
Just something to play with and learn.

 

[KEITH KRAUSE]

Well then, here's something to play around with and learn. The VM bench synch.
FULLY CLOSED POSITION first ('78/79 GS1000): Take the tops off the carbs. Throttle return spring INSTALLED. Be sure the throttle valve arms and throttle pulley are torqued to the throttle shaft and the throttle shaft stopper plate is tightened.
Turn the idle adjuster knob to make a good clearance between its tip and the throttle pulley. Above each slide is the slotted adjuster screw and its holding nut. Loosen the holding nuts. Hold the carbs with the ENGINE side facing you. Look at the small nick at the bottom of the slide. When done, you want these to all look as close to uniform as possible. On the 1000, you can start with any carb. Turn the slotted screw to fully close or seat, the throttle valve. Don't tighten it down. Just seat the valve. When you see the valve stop dropping, stop turning the screw. You'll find that the screws are very sensitive. It does take decent eye sight and a careful hand. Once the valve is fully closed, hold the adjuster screw STILL and tighten the holder nut to 3.5 ft/lb. NO MORE. Repeat to the others. When done, the small nicks should look uniform.
Now the FULLY OPEN POSITION: There's a slotted screw under spring tension mounted on the carb bracket. When you open the throttle fully, the pulley will stop when it hits this screw. Turn the carbs so the FILTER side is facing you. Raise the valves by pushing up the throttle pulley until it stops and hold it. Look up and inside the bore. Note the bottom of each valve. The bottom of all the valves must be between .5mm and 1mm above the top of the intake chamber. Turn the slotted screw in to decrease the gap, out to increase. It usually only takes a 1/2 turn or so, if needed.
Now turn up the idle adjuster knob enough so the bike will idle when you do the vacuum tool synch.
A good bench synch will make the vacuum synch easier/quicker.
Use two fans. Stop if you think the motor's getting too hot. Remember to adjust the side air screws by using the highest rpm method before the synch. This is to be done on a warmed up engine. The ignition timing, tappet clearances, and throttle cable slack must be correct too. Clean and oil those K&N's with K&N filter oil and mount.
Note the initial vacuum levels at start up. I synch at about 3,000 rpm's. Don't rev the bike suddenly or you'll suck up mercury. Easy on the throttle. Adjust the higher level(s) to match the lower levels. Don't over tighten the adjuster screws. Get the levels as close as possible. If you can get them so the difference between the highest and lowest level is about 1/2", that's good. Double check all adjustments by slowly opening/closing the valves. It takes practice. You can do it.
Any questions, let me know.

 

[Hoomgar]

Awesome Keith, thx So yes some quick questions. (I sure hope I am not burning you out? Once I learn this stuff I will be able to help others as well)

The ignition timing, tappet clearances, and throttle cable slack must be correct too. Clean and oil those K&N's with K&N filter oil and mount.

1. Ignition timing is still done via points and condensers. I need tips.

2. Tappet clearances? What is/are they/that? I am out of my element, please help.

3. Throttle cable slack. I think I do this right. I always adjust the cables so that there is only the slightest detectable slack on both cables when the throttle is sitting in the returned position. It feels right that way to me. Is that correct?

K&N filter oil, who would have thought it? I thought they were dry filters? I have been using them for over 14 years and never did or knew that. Learn something everyday I always just cleaned them out with gas, polished the chrome with chrome cleaner and put them back on. I will get some of this oil.

No worries about mercury getting sucked in. I just bit the bullet and ordered this set
http://www.ekmpowershop.com/ekmps/shops/carbtune/index.asp?function=DISPLAYPRODUCT&productid=26

It's a tool investment and I never feel bad about that even though it was a tad pricey. I want to be able to do tune ups that are spot on and help others with the same. The time to learn is now!

 

[Hoomgar]

Hey guys, should I buy this tool for setting my timing or is there another way you suggest? I am pressing the "Ask Earl" button here. I know you know the best way to set timing on these old scoots Earl. Should I use a light like this or do you do it some other way? And if by light, is this a good one or should I look for another product? Give me your recommendation please.

Thanks

Here is the light. It's hand made.
http://cgi.ebay.com/ebaymotors/ws/e...d=1,1&item=4544529879&sspagename=STRK:MEWA:IT

 

[KEITH KRAUSE]

Mark, I can't vouch for that timing tool, but it says it does the job.(?)
It's been a long time since I adjusted points. I've played with some older British bikes recently, but mostly all upgraded ignitions any more. I used to use a regular timing light and seperate dwell meter for the points on my bike (24+ years ago).
You have to have good condition points to begin with, then you set their gap. Then the timing. Earl could probably explain it better with all the experience he's had with 'em. I could, but without pictures to point to the adjustment screws, marks, etc, it would be kind of drawn out and might sound tedious. You don't have a manual of any kind? Even a cheaper manual will show this procedure? If Earl doesn't show up, I'll describe the procedure, but I don't know if I'll make it as clear as he has in the past. A search would show past posts? With pictures, it's easy. Without pictures, a little more difficult. How about a Dyna ignition to bring the bike into the 21st century and really improve the spark and overall performance? If you're going to keep the bike some time, it's $ well spent. You're made of money, right? :lol:
As for tappet clearances, these should be adjusted at the rebuild. The clearances have to be set between .03 and .08mm on a stone cold motor.
The throttle cable slack should be about 1/12" or so on the pull cable. The return cable should be zero or nearly zero slack.
If you have K&N gauze filters, they MUST be oiled and you should only use their oil. Other oils can restrict their flow. NEVER use gas to clean them. Use K&N cleaner or a mild dish soap/detergent. Don't "dunk" them in cleaner either, just a 1/4" deep cleaner in a pan. Lay them in this and rotate them to get them clean. "Swish" them around, back and forth to remove dirt. Also, be sure to always rinse them from the INSIDE-OUT. Never use high pressure water either. Always allow them to air dry, no serious heat. K&N's are bitchen filters but you have to take care of them. I can't say for sure, but yours could have their flow characteristics compromised if they've been handled wrong in the past. Hope not. Don't know how you'd ever know either, unless you tested them against new filters. Hope this helps you out.

 

[Hoomgar]

Thx Keith. I know how to set timing on a car. So I imagine it is very similar on as bike then. My question really was if that was a good light for my bike or not? If your saying I can use my 4-6-8 cylinder light gun and dwell meter from my Chevy days then I am set. I have most likely every service manual made for this bike but they don't know if that light is any good or not That was my question. I think I will follow your advice and use my timing gun for my car. But it is inductive not direct connect and I wasn't sure if that would work on my bike or not?

I still don't know what a tappet is so I guess I'll look that one up. The manuals suck. It's so dang hard to find anything in them. They are about as organized as a city phone book.

One thing, you said to clean the floats with a tooth brush but what is a safe cleaner to use on them? Should I use gas? Carb cleaner? I don't know what that material is and don't want to damage it.

As for the ignition. I may "upgrade" the Dyna ignition in my 1085 someday and when I do I'll put the one that is currently in it into this bike. Until then, it's points and condensers

Still waiting on parts :?

Made of money? You have got to be kidding me! When this project is done that is it! I wont have more cash until this time again next year when the tax man gives my money back once more. Give me a break!

Thx for all the help.