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Gs1000 vm26 mixture settings with pods and pipe

  • Thread starter Thread starter howardshane2
  • Start date Start date
H

howardshane2

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I'm sure this has all been covered before so I apologize in advance if information is going to be repeated but I did a search and couldn't really find what I was looking for. I just got my 1000 running again from doing a top end overhaul. Running a dyna s ignition and coils, pods, and 4 into 1. Valve clearances are on the bigger end of the spec, timing is set, and carbs are in sync. I originally set the fuel screw at 1 turn out and the air screw at 2 turns which kind of seemed to be the norm for my mods from what people were saying. It started up and idled no problem but if I blipped the throttle I got a lot of popping on decel and some backfiring through the carbs which told me it was lean so I began turning in the air screws. It seemed the happiest when the air screws got to about 3/4 turns out and the popping and backfiring went away. I'm just curious what other people's settings are because I'm not getting the typical "air screws are usually double what the fuel screws are".
 
Forgot to mention that I put a dynojet kit in the carbs and I currently have the needles set in the middle position since I haven't actually rode it yet. Is it possible that I need to go ahead and richen the needle and that is what is causing my popping on decel when I have the air screws 2 turns out?
 
You gotta get the bike out on the road to tune the mixture. Get the bike running down the road well then worry about fine tuning after.
 
A road test is definitely in order. This my first time messing with these vm carbs I'm used to cv's so I think the extra mixture being there is making me over think things. Shouldn't I be able to get a nice clean idle on the stand that doesn't hang up or drop below set rpm without riding it. On the cv's the pilot circuit is for idle and just off idle, the vm's are the same way right?
 
You are correct, the adjustments are for the idle circuit. The fuel screw (the one on the bottom) is usually set and left alone, its setting depends on your setup. In your case, pods and pipe, so 7/8 to 1 full turn is probably in order. The air screws (the ones on the side) are usually recommended to be about double the fuel screw setting, but a slightly-rich mixture will start better than a slightly-lean mixture, so I go a bit less. I would start with them about 1 1/2 turns out as a starting point, then fine-tune from there.

What pods and pipe did you install?

.
 
I put the black UNI filters on it and a delkivic 4 into 1 off of eBay. The air mixture screw is throwing me off. If I set it at 1 1/2 and the fuel screw at 1. It runs and idles but as soon as I blip the throttle it will pop like crazy and the occasionally backfire through the carbs. But if I start turning in the air screw it starts idling better and when I get to a little less than 1 turn out on it the popping goes away but that leaves me with the airscrew being in farther than the fuel screw. Just through trying different things the motor sounds the best and responds the best with the fuel screw at about 2 turns and the air at a little less than 1. But of course if I look at the plugs they are sooty and black.
 
You remember what jets are in the carbs? I know you mentioned a Dynojet kit, but what about the pilot fuel and pilot air jets?

Also, what plugs are you running? If they are a heat range or two too cold, they might not be getting up to temperature.

.
 
I don't remember what the pilot jets were. I will take a look. I assume they would be stock as the bike was all stock when I bought it. And I'm running the ngk plugs that the suzuki manual recommends. Just the standard plug. There's just one pilot jet in the float bowl correct? And the fuel and air screws just control emulsification in that circuit?
 
OK, stock jets should be just fine.

As far as function, the way I see the diagrams (and I could be wrong), the jets will limit how much air and/or gas gets to the mixture. The air screw will further limit how much air is added, which will richen up the emulsified mixture. The fuel screw will then control how much of that emulsified mixture gets to the air stream for the bike to run.

You mentioned that you are used to CV-type carbs, which just use the jets to control the emulsification, then one mixture screw to control how much of that is admitted. With the VM carbs, you get to fine-tune the amount of air. I still have not figured out why the fuel screws aren't adjusted, too, but I don't have any VM-equipped bikes, so it doesn't matter much to me.

.
 
I just took the float bowls off and all the pilots are the stock 15 size and the mains are the dj 138s which is mikuni 130. So just kind of brainstorming here; if I'm having to turn in the air screws less than the amount that the fuel screws are out is that a sign that I need to get a richer pilot jet than stock? Because I'm restricting more air allowing the mixture to be richer. So if I get a richer pilot jet I should need more air from the air screws so the result would be more turns out the airscrew? Seems right to me haha but I could be wrong.
 
up your pilots to a #20 then dial the mixture in with a colourtune, using the air screws. you will get it bang on with that.
Thats how i set up my GS1000 with exactly the same set up you have. (except i have a Harris race pipe, not a Delkevic)
 
Awesome, that's kind of the route I was thinking of going. Do you have a source for buying pilot jets. I usually use jetsrus but I didn't see anything on there website for vm26. Also with that size jet what were your settings on the screws that you ended up with so I can get in the ballpark.
 
howardshane2 said:
Awesome, that's kind of the route I was thinking of going. Do you have a source for buying pilot jets. I usually use jetsrus but I didn't see anything on there website for vm26. Also with that size jet what were your settings on the screws that you ended up with so I can get in the ballpark.
Click to expand...
set the fuel screws to 1 full turn out and dial in the airscrews with a colourtune. every bike will vary slightly so you need to set yours to how the bike likes it best.
 
Howardshane2 what year is your GS1000?

I was doing just about the same thing today and so here's my two cents.. On my '79 gs1000 with the VM26 carb set, I'm just getting it running after the PO said it used to run before it sat... I put in new manifold O rings and cleaned the carbs, running K&N knock off oval pods, a home made 4:1 header, and an open 3" pipe I made myself. the carbs has #20 pilots (stock should be 15) and #112.5 mains (stock is 95). fuel screws set 1 turn out and air screws 2 turns out. After vacuum sync, it idles and revs in neutral. On a test ride, it pulls hard off the line but then as I open it up. it seems to starve for fuel. Someone on here said I needed at least 122.5 and I read someone had 130's (or just over) in his gs1000 with the VM26's.

So I'm preparing to buy more jets but theres got to be a few people on here with GS1000, pods, and 4:1 open pipe// WHAT JETS YOU RUNNING?

Then if I abosolutely my do my own figuring out, I's going to get pretty expensive going up one jet size at a time and buying mikuni jets instead of the aftermarket jets.. ANY REASON WHY I SHOULD BUY THE GENUINE MIKUNI JETS INSTEAD OF AFTERMARKET?
 
Mikuni jets = precision

Maybe order some 127.5 mains at the same time as you get the pilots
 
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