Worn out carburetor

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mbskeam
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Worn out carburetor

#1

Post by mbskeam »

well as some of you know I run a 38mm mikuni. has anybody ever seen a carb just get worn out from use, like the slide, fuel nozzle, fuel needle...etc???

Cotten.........
will a m74 do a 88"

mbskeam
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Re: Worn out carb

#2

Post by Gearbox »

Every thing mechanical has a service life , so your carb may be to that point . We both know that more fuel and air will make horse power , to a point, isn't that why you stroked it? I know this isn't a good comparison to a Pan motor, but what MM are the Twinkie's running in the carb? They be 88ci , right.
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Re: Worn out carb

#3

Post by Cotten »

A big motor can run with a tiny carb, and a tiny motor can run with a big carb.
In other words, pick a size that is appropriate for your riding habits. Smaller bores accent torque and efficiency, whereas larger bores accent flow and peak horsepower.
Consider whether your payload is a light or heavy one, whether passing accelleration is more important than pulling power, and whether fuel prices mean anything to you.
The Factory always stayed conservative on bore size until Pans came along, when they opened them up dramatically with the M74B.
(This coincided roughly with Eisenhower's Interstate initiative.)
It is nearly as large as Pan ports can ever use.

My 86" did great with its M74B, even when harnessed to a hack.
(Come to think of it, I wore out a 38mm MickeyRooney back in the '70s, but it was tired when I got it. It was a fine carb, but too modern for my personal tastes.)

....Cotten
mbskeam
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Re: Worn out carb

#4

Post by mbskeam »

well I picked up a replacement 38 (least amount of work)
well the old carb was shot, let me tell you.
I put the jets that had been runnin in the 88", and they both where way to small, in the new carb. it must have been so loose and opened up that gas just flowed like it was free......
now I have to play the ride and rejet, ride and rejet till I get the plugs to read correct.
I don't like white plugs, this is a bad thing.ran real smooth but to lean for me. got some new jets at the yammy dealer and now its time to tinker some more.....
as if I ever will stop....LOL

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Re: Worn out carb

#5

Post by Cotten »

Mbskeam!

Most modern fuels do not make 'color' upon sparkplugs like the good ol' days. It now takes many many miles just to get a grey color, making plug reading a poor diagnostic of fuel mixture.
It is a real problem.

....Cotten
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Re: Worn out carb

#6

Post by mbskeam »

hhmmm. the gas here in the NW does color the plugs, is it that p4 gas that you keep talkin about, with all it wonderful propertys...LOL
put on about 40 this afternoon, got back and the plugs are a dark/med brown. now to fiddle with the main a bit and it should be good to go.

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Re: Worn out carb

#7

Post by Cotten »

The fuels that don't color the same have "anti-deposit" additives as well as "injector cleaners" , such as Shell and BP pump gases.
And yes, they are certainly P4gas here in the Midwest!
The qwickymart generics are fine if they don't have ethanol blended into them, but they are low octane.

....Cotten
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