What size Carb for 300ex?
Nov 1, 1999 | 06:18 PM
#1
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Weekend Warrior
Joined: Oct 1999
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What size/brand carb should I run on my 300ex to maximize performance? If it makes any difference, I ride around 4500'-6000' the majority of the time. I here the stock carb is fairly restrictive.
Thanks.
Thanks.
Nov 2, 1999 | 04:33 AM
#3
Range Rover
Joined: Oct 1999
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What kinda 300EX can handle a 38mm keihin carb? Are you thinking of a 250R? Anyway, unless you have that thing built-to-the hilt, there is no way a 300EX will run well with a 38mm. You would get too much fuel.
If you are looking to make it run better, do the most important things first. Pipe, filter, and a 350X 3-wheeler boot helps also. But if you have that stuff done, then you may be able to do something with the carb. What I suggest is to send the stock carb to a builder like Curtis Sparks Racing, or TC Racing, etc. They actually bore the stocker out for $100. That's what I did and it ran much better. Curtis Sparks even said thats the best and chiepest way to go with a mildly tunned 300EX. Too big of a carb can be worse than too small of a carb.
If you are looking for other ideas, here is what I had on my 300EX to make it more fun to ride, yet retain close-to-stock reliability. It was a lot more fun to ride, I also won many races with it when I was done. Here's the list from what should be done first to last. Pipe, filter, 350X 3-wheeler airboot (between airbox and carb), modified carb, ignition advancer key, and then get in the motor. Do everything in the motor at the same time because it all works together. High compression piston, cam, valve springs, and port job(very important for improved performance).
IMPORTANT: if you do ever put an aftermarket cam in it, get new heavy duty rocker arms also (not stock, but ones resurfaced by a builder). I found out the hard way that Honda changed rocker arm manufactures when they went from the 250X to the 300EX and their surface is too thin, thus detroying the cam and rockers. A 250X does not have this problem, and Curtis Sparks actually first discovered the problem with my motor, so I was actually the first person to use new rockers. And I saved other people the grief I went through.
A stock 250X cam will also make it run better, so if you know of somebody that has a good one laying around, that will also work.
Hope this helps,
Sickman
If you are looking to make it run better, do the most important things first. Pipe, filter, and a 350X 3-wheeler boot helps also. But if you have that stuff done, then you may be able to do something with the carb. What I suggest is to send the stock carb to a builder like Curtis Sparks Racing, or TC Racing, etc. They actually bore the stocker out for $100. That's what I did and it ran much better. Curtis Sparks even said thats the best and chiepest way to go with a mildly tunned 300EX. Too big of a carb can be worse than too small of a carb.
If you are looking for other ideas, here is what I had on my 300EX to make it more fun to ride, yet retain close-to-stock reliability. It was a lot more fun to ride, I also won many races with it when I was done. Here's the list from what should be done first to last. Pipe, filter, 350X 3-wheeler airboot (between airbox and carb), modified carb, ignition advancer key, and then get in the motor. Do everything in the motor at the same time because it all works together. High compression piston, cam, valve springs, and port job(very important for improved performance).
IMPORTANT: if you do ever put an aftermarket cam in it, get new heavy duty rocker arms also (not stock, but ones resurfaced by a builder). I found out the hard way that Honda changed rocker arm manufactures when they went from the 250X to the 300EX and their surface is too thin, thus detroying the cam and rockers. A 250X does not have this problem, and Curtis Sparks actually first discovered the problem with my motor, so I was actually the first person to use new rockers. And I saved other people the grief I went through.
A stock 250X cam will also make it run better, so if you know of somebody that has a good one laying around, that will also work.
Hope this helps,
Sickman
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