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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I have found the opposite works for me!
Everything from the slide cutaway, pilot, fuel nozzle, needle size and position affects WOT so don't kid your self into thinking start with the main then work your way down......
If you have the main perfect at WOT then tune the pilot you affect the total amount of fuel at WOT.... JUST SOME ADVICE! you shluld work your way up if anything.....main jet and needle affect off idle throttle response greatly.......
Everything from the slide cutaway, pilot, fuel nozzle, needle size and position affects WOT so don't kid your self into thinking start with the main then work your way down......
If you have the main perfect at WOT then tune the pilot you affect the total amount of fuel at WOT.... JUST SOME ADVICE! you shluld work your way up if anything.....main jet and needle affect off idle throttle response greatly.......
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WOW.... this is becoming a very good thread not only for me but anyone with issues. thank you guys for taking your time.
Bike idles perfect this is in the zb and has a 5 speed tranny it is being push started to help save first gear. So perfect it starts with no throttle and very little pushing to start. (well a hell of alot better than when I had the 15 pilot in there).
Issue now is when I go from 1/2 on up with it resting at idle completly boggs. Points to me that main is still to big. Lowest I have tested is 160. I will be getting a 150 and 140 tommorow if in stock if not ill have to order from dr or tb.
I have jetted a few bikes in my short time and have had no problems. This one is giving me alittle trouble. Alot has to do with I just cant belive how low on the main and how high on the pilot. I just didnt seem right. But all motors are not alike. I should stick with instints rather than other companys experiences
Bike idles perfect this is in the zb and has a 5 speed tranny it is being push started to help save first gear. So perfect it starts with no throttle and very little pushing to start. (well a hell of alot better than when I had the 15 pilot in there).
Issue now is when I go from 1/2 on up with it resting at idle completly boggs. Points to me that main is still to big. Lowest I have tested is 160. I will be getting a 150 and 140 tommorow if in stock if not ill have to order from dr or tb.
I have jetted a few bikes in my short time and have had no problems. This one is giving me alittle trouble. Alot has to do with I just cant belive how low on the main and how high on the pilot. I just didnt seem right. But all motors are not alike. I should stick with instints rather than other companys experiences
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TRT said:
Awesome!
TRT said:
This is incorrect. At wide open, the slide and cutaway are completely out of the way and have nothing to do with what is coming through the main jet and needle-jet. The needle size and position (clip) itself is also out of the equation at WOT because it, too, is completely free of the jet needle and hanging in the air stream This is why it is called Wide Open Throttle. The needle affects only mid-range transition from pilot to main jets.
Only the main jet and needle-jet effect WOT, the pilot jet is bypassed by the time you are at 1/2 throttle. Since we are only talking about testing different main jets, I did not even mention the needle-jet here. Nor did I mention changing the size/shape of the needle for obvious reasons.
TRT said:
This also is wrong for this carb.
The shape of the needle is designed to sort of "cork" the main jet until about 1/4 throttle. Main jet has nothing to do with idle.
Lots of guys like TRT are experienced enough to tune by the feel of the bike. I'm an engineer and I don't kid myself, people could get killed.
I like to read the manual. Everything I have written is validated there. Of course it is ony a guide.
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142 Posts
VM manual is great... Thanks.
I have a lot to learn when it comes to tuning. I started with this simple layman's guide, and along with this dellorto tuning guide, learned what each circuit of the carb was or was not doing.
Dellorto Motorcycle Carburetor Tuning Guide
I have a lot to learn when it comes to tuning. I started with this simple layman's guide, and along with this dellorto tuning guide, learned what each circuit of the carb was or was not doing.
Dellorto Motorcycle Carburetor Tuning Guide
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Alright Im thinking it may be something else. I have tried pilot at 15-30 and a main at 40-80 and I am getting the same response boggs when I get on the throttle. Would the slide cut to lean cause this. I though the slide and needle would be a fine adjustment and I should be able to get it close with out having to replace it asap. Float level was checked perfect. valves checked perfect. hmmmmm
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jmurray192 said:
It could be the slide cut.
Like you, I always thought cut shape and needle shape were fine tune things for serious racers and I figured since so many people use the VM26 on minis, that close to stock adjustments would be all I needed.
Funny you mention slide cut because last night a friend convinced me to experiment with the slide. I had a 1/4 to 1/2 throttle response bog, just as you describe, that I could not get around. So I took the edge off of the cut. I did not change the angle of the cut, I just chamfered about 1mm on the edge of the slide cut. See pics below.
I dont know if the Voodoo gods are with me today or if my Chi is inline with my karma, but I'll be dammed if that did not almost completely eliminate my response bog. All of that horse crap about reading the manual only matters if your Chi is in line.
I still have a bowl starvation isue at the top end but at least half of my worries are over.I had to be convince myself that I was doing everything correctly (100 times) before I decided to modify the slide. JMurray, before you file your slide, try just putting the 22.5/190 jet combo in there and play with the needle clip until you have chased your tail around the ZB enough to be sure.
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Well taked to bbr tech. for awhile. I guess with running the yosh pipe (Alot bigger than most aftermarket pipes) A 26 is just too big of a carb. I have tryed every jet combo and it just boggs at 1/4 to 1/2. He said they do run this carb on a few bikes but only on tracks where they need top end and dont care about low end bogg. Im running street so this is a huge issue to me. Im throwing in the towel and going to a keihin carb.
Again this is a takegawa 106 high comp piston with a takegawa head (Not Superhead).
Again this is a takegawa 106 high comp piston with a takegawa head (Not Superhead).
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I really feel bad for you having to deal with this frustrating issue.....I had the same problem with my mikuni 22mm on an 86cc GPX. But on another note, my yx 184 has a VM 26 and its awesome thru out the power curve........no bog, hesitation , sputter, or popping. It may just be a lemon:-(
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1,420 Posts
nielspbr said:
well its just too big of a carb screams at full T. But it still has a bogg that I cant get rid of. This is only a street bike so I need to just go will a smaller carb for over all good power.
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Z said:
lol what I need is a 124 kit and yoshimura. Will come at some point.
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Z said:
Does anyone got one for sale?
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