keihin 28mm jetting
- Thread starter B14573r
- Start date
Well...
That's an impossible question to answer, really. With all the aftermarket goodies you have, you will have to run a fairly rich set up. The main jet I would start out with about 150. Doubt it's lean and if it is a quickie plug check will tell you. Run whatever pilot is stuffed in there. Set the floats a little rich, about 1mm. Run your first tank of gas a tad oil heavy. This should get you to where she will start and idle, then the fun begins. You will need a few spark plugs and do some chops and tweak her in. I bet you wind up around 80-100 on the main, but I really have no clue. I am comparing rough, ROUGH, guess comparing the Keihin to the Mik. Both being 28mm's it's a matter of flow, volume is the same.
Once you get her running, run it flat out and do a chop. Check the plug. With luck it's black and wet. If so, I was right and this set up is rich. Go to your normal gas mix, set the floats at normal and tweak the jets and settings as needed.
About the best I can do. I suggest this as rich doesn't kill engines, lean can smoke one in minutes. Check the plug, it knows what's up.
A
That's an impossible question to answer, really. With all the aftermarket goodies you have, you will have to run a fairly rich set up. The main jet I would start out with about 150. Doubt it's lean and if it is a quickie plug check will tell you. Run whatever pilot is stuffed in there. Set the floats a little rich, about 1mm. Run your first tank of gas a tad oil heavy. This should get you to where she will start and idle, then the fun begins. You will need a few spark plugs and do some chops and tweak her in. I bet you wind up around 80-100 on the main, but I really have no clue. I am comparing rough, ROUGH, guess comparing the Keihin to the Mik. Both being 28mm's it's a matter of flow, volume is the same.
Once you get her running, run it flat out and do a chop. Check the plug. With luck it's black and wet. If so, I was right and this set up is rich. Go to your normal gas mix, set the floats at normal and tweak the jets and settings as needed.
About the best I can do. I suggest this as rich doesn't kill engines, lean can smoke one in minutes. Check the plug, it knows what's up.
A
If you bought a new Keihin 28 pwk it would come with a #38 pilot, a #135 main and a 46JH needle. That would be a good starting point but I think you'll end up with a little larger main.
I looked it up on the Keihin site, that's the standard jetting. If you bought one new that's how it would come unless you got it from someone with enough experience to give you additional jets for your setup.
But...
He's got a pipe and other items that will require a richer mix. It is far safer and easier to start rich and work down.
That said, I don't think dropping down to the 135 is a big deal, but that's working backwards. My opinion is start rich and then lean it out. If you think the 135 is lean it's stupid to start with a set up that will harm the motor. Always shoot rich first.
BTW, what did you "look up"? I can find no ref to the set up he has and any carb settings for it.
No offense, none exist, so I am a little curious to what you looked up. He does not have a stock Blaster, not even close.
BTW there is no 195cc Keihin app. listed for the Blaster. That's just a generic/standard set up.
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He's got a pipe and other items that will require a richer mix. It is far safer and easier to start rich and work down.
That said, I don't think dropping down to the 135 is a big deal, but that's working backwards. My opinion is start rich and then lean it out. If you think the 135 is lean it's stupid to start with a set up that will harm the motor. Always shoot rich first.
BTW, what did you "look up"? I can find no ref to the set up he has and any carb settings for it.
No offense, none exist, so I am a little curious to what you looked up. He does not have a stock Blaster, not even close.
BTW there is no 195cc Keihin app. listed for the Blaster. That's just a generic/standard set up.
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BTW
Not sh*tting on your biscuit, just wanting to know what you have for info. I also am trying to instill a method of 2 stroke carb tuning that I feel is correct.
You can always make it leaner after a good run. Sometimes if it's too lean, you ain't got a shot at getting it to move until you rebuild the top end.
So point being, I am asking to learn. I have done many of thes and am tweaking several Keihin carbs now. I have Mik's down to a near science. I like a bigger carb on a piped Blaster, so this is a little bit of an area i need to learn more about. That said it's real simple in terms of fuel, compression, ignition and exhaust. True for all motors. It's finding the sweet spot.
Anyway, didn't want to sound argumentative as I am more curious. I hold my system and beliefs as sound, but know I can know alot more about it.
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Not sh*tting on your biscuit, just wanting to know what you have for info. I also am trying to instill a method of 2 stroke carb tuning that I feel is correct.
You can always make it leaner after a good run. Sometimes if it's too lean, you ain't got a shot at getting it to move until you rebuild the top end.
So point being, I am asking to learn. I have done many of thes and am tweaking several Keihin carbs now. I have Mik's down to a near science. I like a bigger carb on a piped Blaster, so this is a little bit of an area i need to learn more about. That said it's real simple in terms of fuel, compression, ignition and exhaust. True for all motors. It's finding the sweet spot.
Anyway, didn't want to sound argumentative as I am more curious. I hold my system and beliefs as sound, but know I can know alot more about it.
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I agree about the starting rich and working your way down.
I believe but could be wrong that what I stated was the standard jetting "out of the box". Now if you ordered a new carb from someone that knew what they were doing, you might get jets for your application.
I believe but could be wrong that what I stated was the standard jetting "out of the box". Now if you ordered a new carb from someone that knew what they were doing, you might get jets for your application.
what i think B14573r is getting at is that if the stock carb comes with a 230 and you rejetted it to say a 250 for his mods, why would this other carb be a 135. im very sure that you guys know what you are talking about but i was just wondering the same question because if you read my thread i was kinda wondering the same thing.
I'd follow the advice you got from Pitboss on the other forum, he's very familiar with this setup.
Yup
Pitboss don't talk about what he's not versed on, I'd take his advise, too.
And, yes the Mik's and Keihins are diff. numbering systems.
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Pitboss don't talk about what he's not versed on, I'd take his advise, too.
And, yes the Mik's and Keihins are diff. numbering systems.
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