Thought I would run this by you guys. I have the VM26 carb. I called 2bros and see what they ran for a starting jet. I have played and played with it. The only way I can get it to run right is by pulling the choke out. This means its running lean but...... The motor revs up with its pushed it. Almost like the choke is installed backwards. Are these carbs suppose to run with the choke out? Seems to be the only way I can get it to run right. Or is it installed wrong?
VM26 question
jmurray192
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Thought I would run this by you guys. I have the VM26 carb. I called 2bros and see what they ran for a starting jet. I have played and played with it. The only way I can get it to run right is by pulling the choke out. This means its running lean but...... The motor revs up with its pushed it. Almost like the choke is installed backwards. Are these carbs suppose to run with the choke out? Seems to be the only way I can get it to run right. Or is it installed wrong?
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I think so, I does have the button style choke. Linky
Two Brothers Racing, add an item to your shopping cart:
Pilot is 15
Main has been changed from 170 to up to 190. Now its a 170 and only runs correctly with the choke pulled. But only runs correctly at all jet sizes if its pulled. My top end only suffers with the big jets.
Two Brothers Racing, add an item to your shopping cart:
Pilot is 15
Main has been changed from 170 to up to 190. Now its a 170 and only runs correctly with the choke pulled. But only runs correctly at all jet sizes if its pulled. My top end only suffers with the big jets.
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Go to www.sudco.com, they have all the specifications on the Mikuni carbs and replacement parts should you need them.
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squidwell said:
My VM26-665 runs well with pilot 20 @ 124-150cc
However, with 150cc it runs better with pilot 22,5.
And yes I have to pull the choke when cold, but not long.
edit: btw. I run it with a K&N Filter and needle 4J13 (= the standard needle for a 665)
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Motor is a 106 takegawa motor. Im going to have to strip this thing apart I guess and see if its plugged somewhere.
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Ill have to get a 22.5. What elevation are you fatcaat? 22 just seems HUGE for the little 106 but its got to be the problem.
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The general consensus with mikuni/keihin jets is that the keihin jets are usually higher in number compared to the mikuni jet number. I.E. a mikuni 100 is a keihin 110) So if you run a 35 pilot(stock) with a keihin then you definitely have to assume the 15 on the mikuni is way too lean. Even the 22.5 might be on the small side. BBR actually suggest a 30 pilot and 170 main if you're running a vm26 on a 106 with pipe/filter. I think a 175m/30p would be ideal for a 108 at sea level and 70-80 degree weather.
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sounds like a air leak....check your boot and both intake and carb gaskets.
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I called two brothers they told me only run a 15 couple of weeks back. I dont think a 15 is correct at all. I have a 20 on order also they had a 30 in stock I can give it a shot.
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jmurray192 said:
Buy the jet kits for the VM26 from Trailbikes. Much cheaper and you get a whole kit to work with.
Honda Trail Bikes
17.5 and 20
Mains:
Honda Trail Bikes
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pilot was the issue. I am now running 25 pilot. When I flip throttle it boggs down. which is probley to rich (main). I have installed a 160 main and still bogs. bottom end is perfect but this bogging may be cause by still to big of a pilot? Couldnt see going smaller than 160.
would have loved to buy TBs but dan you know I need to have it now lol. Yamaha has these in stock about 2 mins from the house.
would have loved to buy TBs but dan you know I need to have it now lol. Yamaha has these in stock about 2 mins from the house.
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Also I am running a takegawa chrome case filter. Im going to swap it out for a duel layer normal filter this may help let in alot more air. Cross my fingers this helps so I dont have to keep buying jets.
JETTING = PULL YOUR HAIR OUT :-x
JETTING = PULL YOUR HAIR OUT :-x
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jmurray192 said:
LOL! I would like to say, "been there, done that" but I'm still there!
I can tell you what I have learned from my VM26-606 and here: Welcome to Mikuni Power - VM Series Carburetors . Go there and download the tuning manual for the VM series. Print it, read, it, then throw it in the recycle bin.
First off, all of the VM26-606 sold in the U.S. come with 22.5 pilot and 190 mains. It does not matter where you order it, if it is true Japanese Mikuni, this is how they come. The knock off carbs work just fine, but their jetting will be different.
A takky air filter lets in plenty of air, BTW. Also all jet sizes are industry standard, there is no "one brand runs bigger and the other brand runs smaller". Main jets are sized millimeters: A 190 main jet is exactly 1.9mm diameter. Pilot jets follow a different sizing standard (that I don't know) but are all the same.
I have the Takegawa 124 Superhead and after trying many jet and needle position combos, I am back to the stock 22.5/190 jets.
Remember, the main jet ONLY comes in to play at 3/4 to WOT throttle. It is best to start jetting there, under load, in top gear, on a straight away. The thing may not idle and will probably burble and sputter until you get up to WOT. After that, the pilot jet and needle have nothing to do with how its running. After trying from 155 to 200 main jet, I felt it was smoothest at high speeds with a 190.
After you get the WOT dialed in, sputter your way back to the garage and do the low speed system jetting. If this is in a ZB, I highly recommend some sort of test tank apparatus that allows you to get to the carb while you are testing. You will move that little clip on the needle 3,547 times (if you order new jets, order another needle clip too) and you have to take the ZB tank off for that.
A VM carb should not run with the "choke" on at all. It does not have a choke, it has what they call a "starting" circuit. It does not work like a choke by controlling airflow, instead, it allows a small burst of extra fuel to fly through (I read that in the tuning manual). So if you are running with the "choke" on, you definitely have too small of a pilot.
Always try to tune the pilot with the needle clip in the middle to begin with. Set the throttle position screw (the knob with the spring on it) in until you get a high-ish idle. Back the air screw(the small brass flathead screw next to the intake) out about 1.5 to 2 turns to start. Then, tweak.
Getting it to idle well is the easy part. Now, burp the throttle and let go - if it bogs or hesitates, you are too lean. Turn the air screw in .25 turns at a time until the burp-bog gets better. If that wont fix it, go to the needle clip.
The needle clip position only effects the 1/4 to 3/4 throttle position. Nothing else. Below that throttle level the carb runs on the pilot jet. The tuning manual has a graphic that explains this very clearly. This throttle area is where you do most of your acceleration and shifting. If you move the needle clip down, it raises the needle or rich ens the mix, if you move it up it lowers the needle and leans it.
This is all basic science that should be easy, but my Monkey-R is still not tuned right. After doing these jetting gyrations for a couple of months and doing more research on tuning, I am beginning to suspect timing and ignition. I have no idea what to do about that....yet.
Hopefully, you will get yours dialed in easier than mine but yes, you will lose hair one way or another. Good luck!
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