Polish Carb Throats

[catbed]

Would polishing the carb throats make any performance boost? i did it on my car throttle body to cut down on the oil build-up and i noticed a slight increase in gas mileage. if it doesnt do anything, it would sure look nice.

[Steve]

Would polishing the carb throats make any performance boost? ..., it would sure look nice.

Assuming that you are talking about polishing the inside of the throats, and that you are running any type of filtration (stock airbox or pods), how are you going to see them?

If you have a severely-built high-performance engine that simply has to have every bit of air possible, polishing the surfaces might reduce turbulence ever so slightly. Performance gains might be minimal, maybe not even measurable, though. However, for better street driveability and gas mileage, leaving them alone or even putting a slightly rough finish in there (think cross-hatch honing in the cylinders) will produce a little turbulence that will help keep the fuel droplets from puddling. Of course this is after the jets have added fuel to the air flow. Polishing before fuel is added probably won't hurt anything, but I don't think it will help, either.

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[catbed]

just an idea. thats all.

[Old Colt]

Yes it will help. You will want to blend in any un-needed lumps and bumps.

[blowerbike]

nope nope and nope..
the intake trac needs to be a little rough to atomize the fuel.
there's more performance to be had by regapping your spark plugs.
you always hear about port and polished heads..
thas a good bench racing sales pitch.
to shiney is not good.

[Shaughn]

The reason it works so well in your (presumably fuel injected) car is that
at idle, the throttle plate is almost entirely closed, and that little bit of
grime can close it off entirely, causing the computer to adjust the throttle
open in order to idle properly. Cleaning the IAC circuit at the same time also
yields benefits. This is a very good thing to do in your car for minutes and zero cost, probably about every other oil change.

[Mark M]

the intake trac needs to be a little rough to atomize the fuel.

He is talking about the carb throats AHEAD of the jets, not the intake ports.

To TS, a polished surface is considered optimal for dry flow, such as the intake before fuel is added and the exhaust ports. As blowerbike says, surface roughness is desired for keeping fuel droplets off the intake port walls and mixture consistency.

Whether any measureable gains would be made or not would be doubtful.

Mark

[blowerbike]

He is talking about the carb throats AHEAD of the jets, not the intake ports.

To TS, a polished surface is considered optimal for dry flow, such as the intake before fuel is added and the exhaust ports. As blowerbike says, surface roughness is desired for keeping fuel droplets off the intake port walls and mixture consistency.

Whether any measureable gains would be made or not would be doubtful.

Mark

what mark says..
i was using the intake tracs as an example of over polishing.
i can see where someone would get confused with my above statement.
in the end we both agree, there's nothing extra to be had by polishing the carb throats.

[Steve]

Catbed, if you feel that you really must polish ... at least do it where it can be seen.



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[mighty13d]

there's nothing extra to be had by polishing the carb throats.

aside from hidden prettiness!

[blowerbike]

aside from hidden prettiness!

very true..
anything is better than sitting on the couch eating bon bon's and watching Oprah during these winter months

[Old Colt]

nope nope and nope..
the intake trac needs to be a little rough to atomize the fuel.
there's more performance to be had by regapping your spark plugs.
you always hear about port and polished heads..
thas a good bench racing sales pitch.

BS!
You clearly have never seen a proper port and polish and the true results that it gives.
The porting work is done for a reason and skill and knowledge is required. The polishing is done with specific surface finishes in different areas of the flow tract. The flow tract is considered to be from the first part the air enters to the tip of the tailpipe. Consideration of surface finish takes into account if the area is wet or dry, warm or cooled, laminar or turbulent, clear throat or divergent as in going around the valve stem. On a wet intake the flow stream can be steered to move the fuel droplets into a desired portion of the streamflow with small changes to the surface area.
It all matters for a proper porting job.
Saying that there is no performance gain is the biggest and most narrow minded BS I have ever heard.

If CB wants to cleanup and polish the carbs on his bike, it surly is not the wrong thing to do.

[blowerbike]

BS!
You clearly have never seen a proper port and polish and the true results that it gives.
The porting work is done for a reason and skill and knowledge is required. The polishing is done with specific surface finishes in different areas of the flow tract. The flow tract is considered to be from the first part the air enters to the tip of the tailpipe. Consideration of surface finish takes into account if the area is wet or dry, warm or cooled, laminar or turbulent, clear throat or divergent as in going around the valve stem. On a wet intake the flow stream can be steered to move the fuel droplets into a desired portion of the streamflow with small changes to the surface area.
It all matters for a proper porting job.
Saying that there is no performance gain is the biggest and most narrow minded BS I have ever heard.

If BB wants to cleanup and polish the carbs on his bike, it surly is not the wrong thing to do.

charlie,
your gonna have a damn heart attack.
calm down man!
he can rub on his carb throats till his fingers bleeds if he wants..
geesh.
i have seen plenty of quality 4 stroke port jobs, im not the typical member here that has little hands on experiance.
i am the exaxct oppisite.
my point is that you dont want a smooth, chrome looking intake tract.
also, there will be no noticable gains from polishing the carb throats.
trying to type this stuff and have eveyone understand what you mean is diffacult at best.
enjoy the rest of your weekend charlie...

[Steve]

BS!
You clearly have never seen a proper port and polish and the true results that it gives. ... The polishing is done with specific surface finishes in different areas of the flow tract. ... On a wet intake the flow stream can be steered to move the fuel droplets into a desired portion of the streamflow with small changes to the surface area.
It all matters for a proper porting job.
Saying that there is no performance gain is the biggest and most narrow minded BS I have ever heard.

Ahhh, very true, and, as you have said, that is the difference a proper porting and polishing job can do. A good porting job will do its best to minimize unwanted turbulence that is caused by mis-matched joint surfaces, protruding gaskets, etc.

Alas, this is the first mention of porting. Catbed's original question only asked about performance gains due to merely polishing the throats. I think you might agree that merely polishing the carb throats would yield negligible improvement.

.

[Shaughn]

Minor Thread Hijack

Steve!

Those float bowls look great! I meant to comment on that trick
penny reflection shot when I saw it in another post. What do you do
post-polish to keep them looking good?