Who out there has a 28mm Mikuni???
- Thread starter EZRider76
- Start date
Thanks man, but I'm really looking at what the needle is that someone with a Mikuni is running. I'm having a SOB of a time getting that 1/2-3/4 range running right.
thats the stock carb right? been a while since i thought about my blaster lol.
270 main jet, stock pilot, stock needle position.
fmf fatty/powercore2, no airbox lid.
bump the main to 280 for winter.
270 main jet, stock pilot, stock needle position.
fmf fatty/powercore2, no airbox lid.
bump the main to 280 for winter.
im thinking bro, with all the headaches this 28mm has caused you, you need to invest in Advil and a fifth of something smooth!!!! then re-approach the jetting with a whole new outlook!
have you tryed jetting the main down from the 270?
have you tryed jetting the main down from the 270?
That is tonight's agenda...the rejetting downward. Talked to my buddy last night that has been riding two strokes since he could talk, working on them before he started school. He pretty much told me 270 sounded a bit high with my characteristics, and to reset my needle to mid clip and drop to a 260. If that works, the "smooth" will be consumed as celebration. I:I
:-[ Size doesn't matter...as long as it runs and keeps going, that's what's important. 8-|
dont ask me why i think this, i have no idea...
i was just thinking, if a stock 26mm(like my old one) runs with the same mods, a 270 main, it wouldnt stand to reason that a bigger carb, 28mm would flow more air requiring a slighlty smaller jet like a 250-260. doesnt more air usually mean more fuel? idk, im just throwing things out there trying to help. i hope it works man!!! as im STILL waiting for my needle to come from CPW, im not looking forward to my jetting issues either. so, i know how you feel!
I thought we were talking about carbs. If you wanna have a flop off, I'll be more than happy to go first so you don't need to embarrass yourself.
Don't worry, we know it has to do with the cold Canadian Weather. dont ask me why i think this, i have no idea...
i was just thinking, if a stock 26mm(like my old one) runs with the same mods, a 270 main, it wouldnt stand to reason that a bigger carb, 28mm would flow more air requiring a slighlty smaller jet like a 250-260. doesnt more air usually mean more fuel? idk, im just throwing things out there trying to help. i hope it works man!!! as im STILL waiting for my needle to come from CPW, im not looking forward to my jetting issues either. so, i know how you feel!
Ok, WHAT made you think that? Bahahahhaahaa...wasn't WHY??? Just kidding.
Anyhow, I get the reasoning, and I have been over it 1,000 times in my head, but I don't get why mine is acting this way...other than the fact there could be the difference in the needle. Mine could be a bit shorter than the stock needle (remember from my other thread, this carb came off a Russian Sportster Motorcycle), plus, I'm not 100% sure if I have stock reeds or not. I just have to play with the characteristics of what my little engine wants from this carb. Usually though, by the very CALCULUS formula of AFR to get the proper mix, more air would mean more fuel. That is the theory I was playing with, with the variable being that stupid needle. I will see tonight and report back.
yeah, i guess my question would be, if the 28mm needed to be jetted smaller than the stock 26mm, why not just get a stocker and run it??? no more fussing with this PITA 28????
You know the slides have different cut out sizes too right? That will also affect jetting in the lower throttle position ranges. On keihin the slides are numbered inside where the cable hooks up. 4-8 is the numbering and 6 is the standard for most of the carbs I believe. I'm not sure if the slides are interchangeable on the Small mikunis like they are on some keihins...
Yes, I did notice that my round slide was stamped 1.5, I think on the cut out though. I was really trying not to go there, just more confusion. I'm confident that I can make this work, I just need more diligence and ass time on it.
If this is the case, then why do any of us get a larger carb, and see big performance gains?
Look at it like this , not that this is just as a reference , I have no idea what actual flow tests are per carb nor could I find any.
But as an example, lets say a 26mm carb can give 500cfm a minute with whatever jetting,
Now a 28mm carb can flow 700cfm a minute again with whatever jetting, you are getting more air/feul mix, in the motor with the 28mm than you would a 26mm.
You really are using more air/feul mix than you think when you increase a carb!
I hope this helps ya understand.
Best advice is plug chop to perfection! The plug dont lie!
ok, now i get it! i couldnt understand the jetting relative to the cfm. thanks slicker!!!!
No problem, homie!
I agree with your buddy you should do a plug chop to confirm however, but i bet with the 28mm you will drop a size or so. I:I
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