Blueprinting for methanol

Anyone on here know what to.do to blueprint a mikuni carb for methanol.
One thing, the jets(Fuel passages) need about 104% increase in area. Never drill, use a reamer! Area equals pi R squared. A lot depends on what carburetor you're using. The Mac 91 carb (intended for gas) with some tweaks, could run 100% alcohol.
 
My thought is the animal carb runs methanol the lo206 runs gas , same carb different jets .
Set it up like an animal of course a little richer to feed it more fuel .
The inlet needle could be a choke point .
 
I'm going to assume you're talking about a Mikuni round slide? I've dabbled slightly with running methanol through a Mikuni, but I'm still on the beginning edge of the learning curve. I started with putting a main jet in it twice the size as what came in it, being that it takes roughly twice as much methanol as it does gasoline for the same engine. To be honest, I don't remember now where I ended up with jetting, but doubling the main jet size got it really close. Unfortunately, Covid has severely cut into our karting time, so I haven't done much with it. My biggest issue has been the fuel pump over-pressuring the needle and seat and flooding it out in the corners (we're sprint/road racing). I think I figured out a cure, but again, we've had almost no testing time to try it out.

One bit of advice I can give you from many years of snowmobile racing - don't use anything but genuine Mikuni parts in a Mikuni carb. The aftermarket stuff is all junk.
 
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I'm going to assume you're talking about a Mikuni round slide? I've dabbled slightly with running methanol through a Mikuni, but I'm still on the beginning edge of the learning curve. I started with putting a main jet in it twice the size as what came in it, being that it takes roughly twice as much methanol as it does gasoline for the same engine. To be honest, I don't remember now where I ended up with jetting, but
Clear something up for me, when you say twice the size, what does that mean exactly? Twice the diameter or twice the area?
 
This will give you an idea what I'm talking about.
 

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Clear something up for me, when you say twice the size, what does that mean exactly? Twice the diameter or twice the area?
I have no idea. I'm just going by the numbering system on Mikuni main jets. I believe my carb came with a 130 main jet, so I put a 260 in it to start with running methanol. I've been told that with Mikuni jets, going to double the number size flows twice as much fuel, so based on that I would assume it's twice the area.
 
Duh! I missed your post that you're using the PZ27 carb. That's the World Formula carb isn't it? Doesn't Briggs make an alcohol jet kit for that? We use the kit for the stock Animal carb and it works great. No muss, no fuss! I'm thinking I saw a jet kit listed for the WF carb too, but maybe not.
 
I don't know about their numbering system, you may be right, they may be indicating flow numbers, Briggs numbers their jets by the diameter.

Let me assume something else, 130 might mean .130 MM. Is that right? If that assumption is right, 260 means .260 MM. In that case, you increase your flow by 300%.

If those 2 numbers indicate area, then your close. You need some measurements!
 
A PZ carb is a Walbro, not a Mikuni. That may be where the start of the confusion occurred.
We build both Mikuni and Walbro carbs for alcohol.
Al is correct; start with doubling the "area" of the main jet.
The jet sizes that I believe you all are talking about are measured in millimeters diameter. This is NOT area or flow numbers.
For instance, a 95 main jet is mm size for a stock gas animal or L206 (22 mm) carb.
And if you're working on one of the $15 ebay import copy carbs, all bets are off, as the quality and air circuits are all over the place on these carbs.
Who knows, you might get lucky, but then again, you probably won't.

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Do the math and double the area of the jet for starters but be aware that the size of other components in the carb also make a difference.
Examples: the size of the air bleeds, the size of the holes in the emulsion tube, the size of the nozzle and needle clip position.
A 95 (gas) main jet is .95 mm, a 137 (methanol) main jet is 1.37mm
Briggs does not make a methanol jet kit for the PZ 27 WF carb.
They do make one for the PZ 22 Animal carb.
 
Just for reference a Mikuni 130 main jet is .040 and a 260 main is .055. These are inch measurements.
The numbers now make sense. Actually the starting point for going from gas to methanol from a .040 jet, would be .05656. or a .056 or. 057
And going from a 36 gas jet would be .0509 or a .050 jet
If my calculations are correct?
 
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:)
The numbers now make sense. Actually the starting point for going from gas to methanol from a .040 jet, would be .005656.
And going from a 36 gas jet would be .509 or a .51 jet
If my calculations are correct?
;) ;):eek: fat fingers an decimal points . Or mm and decimals .
I'm totally confused now !
 
The high-speed jet needs to be bigger, but don't forget the low-speed jet, it needs to be bigger also.
 

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:)

;) ;):eek: fat fingers an decimal points . Or mm and decimals .
I'm totally confused now !
Thank you for pointing out my error. I have now corrected the mistakes. with the floating decimal point.
.050 for the .036 gas jet and the .040 would be .056.

I thought I was perfect but I guess some days you are off a little.
.56 jet might just run a tad rich.?
 
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