carb adjustments

[Anonymous]

I have a 1979 gs 1000e. I just put on a dyna 3 ignition, pod filters, and a 4 in 1 pipe on my bike at the same time.':roll:' I put size 115 jets in. What i need to know is where should i set my mixture at as a starting point?
the bike was completely stock before.

 

[earlfor]

Re: carb adjustments

Fuel pilot 1 1/4 turns out. Airscrew 1 3/4 turns out. Synch the carbs to
10 in Hg @ 1200 rpm.

Earl

I have a 1979 gs 1000e. I just put on a dyna 3 ignition, pod filters, and a 4 in 1 pipe on my bike at the same time.':roll:' I put size 115 jets in. What i need to know is where should i set my mixture at as a starting point?
the bike was completely stock before.

 

[KEITH KRAUSE]

Re: carb adjustments

I have a 1979 gs 1000e. I just put on a dyna 3 ignition, pod filters, and a 4 in 1 pipe on my bike at the same time.':roll:' I put size 115 jets in. What i need to know is where should i set my mixture at as a starting point?
the bike was completely stock before.

I have the same bike, similar mods. Your main jet selection may work, depending on the brand of pipe and filters. I have a V&H pipe and K&N filters which work well with 138 DJ jets which are about the same as 130 Mikuni main jets.
You WILL need to raise your jet needles. Probably 2 positions, by lowering the e-clip two positions. Then I suggest a step up in pilot jet (2.5) increase. You may be able to adjust your pilot and air screws to make the pilot circuit work with the stock pilot jets.
A GOOD carb synch using a vacuum tool is a must. Also, re-synch every time you move the needles.
If you can't get the stock jet-needle to work, you'll need a jet kit such as Dynojet, p/n 3304.001, about $125.

 

[Anonymous]

the only adjustments that i can see to make is on the side of the carbs. there is an adjustment screw. i dont know if i have a different air and fuel screw. i think that my carbs are 33mm mikunis. I know that they are the stock ones. right now i have a great mixture up to 6000 rpms, but then it starts to bog out. any ideas?

 

[KEITH KRAUSE]

the only adjustments that i can see to make is on the side of the carbs. there is an adjustment screw. i dont know if i have a different air and fuel screw. i think that my carbs are 33mm mikunis. I know that they are the stock ones. right now i have a great mixture up to 6000 rpms, but then it starts to bog out. any ideas?

Stock carbs (U.S.) are VM26SS. I don't know if Canada bikes got 26mm or possibly 28mm? I do know 33mm are not stock anywhere. Sounds like your bike is starving for fuel above 6,000 rpm's. The jet-needles need to be raised and the main jets increased and probably the pilot jets increased too as I posted.
Your jet-needles are inside your slides.
As for the screws...the PILOT screws are reached from underneath and are engine side of the floatbowls. Use a mirror too see and adjust them. Turning them OUT (counter-clockwise) richens the mixture. They can be tight if never moved before and it's easy to strip the head off. Use a good fitting tool. They are sensitive to adjustments and even 1/8 turn can change the sparkplug color. For a starting point regarding the pilot circuit, I would adjust each pilot screw out 1/4 turn and test. When plug reading for the pilot circuit, ride the bike a few miles in 4th or 5th gear at about 40 mph. Just have the throttle open just past "idle". Do what the plugs/performance tells you. If you find yourself adjusting these screws more than a full turn out further from where they are initially, then you most likely need a step up (2.5) in pilot jet size and of course turn the pilots back in to where you started. You may even have to try larger pilots and turning the pilots out a little. It's suggested you start with fresh plugs or at least clean yours well.
For the SIDE AIR screws...adjust as follows. Put the bike on the centerstand and warm it up first. Turn the screws on both carbs facing you in 1/4 to 1/2 turn increments until you achieve the highest possible rpm's. Fine tune these two screws. Do the other two screws the same way, until you achieve the highest rpm. Now re-set the idle to 1,100 rpm with the idle screwknob. They usually end up about 1 1/2 to 1 3/4 turns out. Turning these screws OUT leans the mixture. Careful, these screws strip easily too if never moved.
Do the pilot screws first and then the side air screws. Jet needle adjustments must be followed with a vacuum tool synch. Then test.
A good carb synch is important with these carbs and re-jetting is too difficult without a good synch. Raising the jet-needles is the most work.
Test for the jet-needles at 1/2 throttle and the mains at 7/8 or wide open throttle.
I forgot to mention, remove the two float bowl vent tubes so the bowls vent better. The increased air intake creates a vortex in the tubes and this cause fuel starvation. Removing the tubes helps the jets draw fuel easier. This is recommended by jet kit makers regarding stage 3 kits, especially with VM carbs.

 

[Anonymous]

you said that i should raise my jet needles by moving the e clip a couple positions. I opened up the float bowls to look for said e-clips and i could not determine where they were. I have tried all the other adjustments and i am getting close. at least now i understand what the adjustments do. This is my first attempt at anything like this but without your help i know i would be COMPLETELY lost. so if i haven't yet ..thanks.

 

[KEITH KRAUSE]

you said that i should raise my jet needles by moving the e clip a couple positions. I opened up the float bowls to look for said e-clips and i could not determine where they were. I have tried all the other adjustments and i am getting close. at least now i understand what the adjustments do. This is my first attempt at anything like this but without your help i know i would be COMPLETELY lost. so if i haven't yet ..thanks.

With pods and 4-1 pipe, you MUST raise the jet needles or your bike will run very lean between 1/5 and 3/4 throttle. Adjusting the jet needles is the most work and ALWAYS requires you re-synch the carbs with a vacuum tool to avoid mixture problems. The jet needles are inside the middle of the slides, access is under the top cover of the carbs. To get them out you need to pull the throttle shaft. If you look in either side of the carbs, you will see the jet needle go up and down when you turn the throttle.
The jet needles are adjusted by pulling out the e-clip and re-installing it in a different groove or notch. Your stock needles should have 5 grooves. If your clip is in groove #3, then I suggest installing the e-clip in #5 groove, the bottom one. Lowering the e-clip position, raises the needle. You may have to make needle adjustments more than once. If your stock needle does'nt richen the mixture enough, you'll need to buy a jet kit.
The procedure is a bit involved if you've never done it before. You should have a manual. Do you? If you need help, I'll check with you in the morning. I'm a slow one finger typer, but I can try to walk you through it. The carbs need to be manually synched too. This involves the fully closed and fully opened slide positions. The manual synch needs to be followed by a vacuum tool synch. Do you have a tool?

 

[Anonymous]

hey keith if i don't get back to you for a week or so it's because i am on vacation. the bike trip turned car trip.
but where i am at now is, i've got the bike to run and idle well. where i am having a problem is when i crack the throttle hard it bogs out and has no response. when i turn the throttle smoothe it picks up and responds like it should. the last change i did that had the most effect on the engine. I raised the level on the float bowls although i do not know how much exactly, but they are all the same. the plugs were white and now they are more black than tan. i do have a synch tool but i thought that i would only use it when i got it running at least half way decient.
any idea of where to go from here?

 

[KEITH KRAUSE]

Hi. You've said nothing about raising the jet needles.
There's no way you'll get the bike running correctly unless you raise the needles. Honestly, if you will make the effort I'll explain the procedure. If you're planning on trying to change just the mains and maybe the pilot jets, then you're wasting your time. Your bike might feel "OK" to YOU, but it will really be running way too lean whenever you're on the needle circuit, which is the majority of the time.
As for the float height, they should be set between .90-.98". I like to set them at .94. Your adjustment method sounds incorrect. You've got the plugs running too dark on the incorrect float height alone, despite a lean jet needle setting. You're making this too hard on yourself. Get some verniers and adjust them right.
As for carb synching, the VM carbs demand a good synch. You simply can't jet carbs that are not reasonably in synch. Synching is a part of jetting. You can have a bike perfectly jetted, but if just one carb is pulling too much vacuum compared to the others, that carb will run too rich.
Again, if you're going to do the needle/float/synch work, I'll help you. You also have to make the other adjustments I explained in previous posts. If you don't think you can do the work, then I'll give you the option of sending the carbs to me. No charge. I'm guessing the shipping could be $40 or more round trip? If the carbs hardware is in good shape so things can be taken apart, I'll adjust the floats, raise the needles and do a MANUAL synch in preparation for a vacuum tool synch. In regards to raising the needles, keep in mind that this is trial and error. Based on your info, I would raise the needles two positions. If they don't perform well, then they would have to be adjusted again and possibly only a jet kit would work then because your needles would be adjusted as rich as they can go. (You did say that the bike was stock, so your needles would be in groove #3 and your needles only have 5 grooves.)
Let me know what you want to do. Keith.

 

[Anonymous]

What is a "manual" synch, and do you have to do that to my '83 CV carbs? :twisted:

 

[KEITH KRAUSE]

What is a "manual" synch, and do you have to do that to my '83 CV carbs? :twisted:

A manual synch is synching the carbs by sight. On your CV carbs, you try to set the throttle valves to open up at the same time. You should always follow this by synching with a vacuum tool for better accuracy. A good manual synch makes the vacuum tool synch much easier/quicker. Your bike will run much smoother and get better gas mileage after a good vacuum tool synch.

 

[Anonymous]

OK, that is what I thought. I did that by using a micrometer and measured from the bottom edge of the carb, to the bottom edge of the butterfly plate. I dont have the kind of vaccumm sync tool that goes into the little holes after the carb. The closest thing I have is the old school kind thawt goes onto the back side of the carb, will that work? I wont be able to do anything else until I get a new set of mixture screws (they are $10 each!!) Then I will go from there. I cant afford a Dynojet jet kit right now, like you told me to get, but I have shimed the needles up using some very small washers. I did some research on the Dynojet page, and they say thier kit uses 124 dynojet mains for pod filters, and 130 dynojet mains for pods and good pipe. I think my Mikuni 120 main is a good compromise right now untill I can get the jet kit, but I wont know for sure untill I get the mixture screws, and mount my katana pipes permanantly.

 

[Anonymous]

hey keith i am back from vacation and i am now ready for round two. I thank you for your offer but i want to do this . Keep in mind that this is all new to me and i am ready to put in as much time as needed.
The needles, they were at #2 position when i first opened the carbs so i put them to the#4 position. Then after raising the float bowls i moved them to the #3 position and that is where they are at now. If i was to try a jet kit how would i know what one to get?
I am going to adjust the floats when i take off the carbs tomorrow.

 

[KEITH KRAUSE]

Hi. I hope you do have the stock VM26 carbs or some of my info could be incorrect. You mentioned at one point you thought you had 33's?
For a quality 4-1 pipe and pod filters, one position on the needles won't be enough. I don't know how well your pods flow but trying the needles in the 4th notch from the top is better. You may have to try the bottom groove. Remember, to test the jetting right, you must vacuum tool synch these carbs every time you disturb the needles. Don't mistake poorly synched carbs as jetting issues. If you can't get the stock needles to work, then the correct Dynojet jet kit is # 3304. The VM26 float height range is .90-.98" I like to set them right in the middle.

 

[Anonymous]

Keith, sorry to confuse you, I do have the stock carbs not the 33's. I will adjust a few things today and let you know how it turns out.

ps when i say the position of the clips on the needle i count up fron the point of the needle.

 

[KEITH KRAUSE]

Keith, sorry to confuse you, I do have the stock carbs not the 33's. I will adjust a few things today and let you know how it turns out.

ps when i say the position of the clips on the needle i count up fron the point of the needle.

Well, you're the first to say they do that, at least to me. That will cause confusion. You said the bike was stock but of course someone could have made needle changes in the past. I'm not sure about the needle settings for Canadian carbs, but I'm now thinking the needle clip was originally in the 3rd position FROM THE TOP. (It would be nice to know). Normally with your mods, the needle must be raised at least two positions from the factory setting. That would put your clip in the #5 or bottom position. This would be the richest setting you can have with the stock needle. Many find that the stock needle won't work and they go with a jet kit. There are also jetting spacers you can install to make 1/2 position adjustments.

 

[Anonymous]

I was definetly moving it the wrong direction. I have now moved it to the bottom but the weather is too ugly to test it. I also replaced the fuel valve but it still leaks so i have another problem to fix. I let the bike sit for 2 weeks when I went on holiday, and when it got back all my fuel was on the garage floor. One step foreward and two back.

 

[KEITH KRAUSE]

Well, keep trying. You'll get it right if you have patience.
Pingel makes a great fuel valve for about $90 (U.S.) including adapter plate for your tank. No more vacuum/failing stock petcock stuff. You do have to turn the fuel on and off. I recommend it. I've got the part # if you like and phone #. They're also on the web. You have to ream out the existing petcock hole just a little with a file. Very easy upgrade in my opinion.
If you want to see a close pic' of the valve then visit my website photos.
Just click the WWW symbol below.

 

[KEITH KRAUSE]

And don't forget to have those floats set between .90 and .98".
I like to set them at .94"
Also, make sure the floats are "even". Many times the float will be tweaked, one side different from the other. Even them out and then set to .94"