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Discussion Starter · #1 ·
Hi everyone, new to the forum here. I have a question about a carbureted go kart engine. I know this is a site for cars, but for my question, an engine is probably an engine. I'm in the process of building a Honda GX200 (and GX270) for an around-the-neighborhood go kart and had a question on the intake. I have a lot of engine knowledge with fuel injected car engines, but not so much with carbs. I know on a FI car, if I want high hp, I should have a short intake tube (before the throttle body), but if I want torque, use a longer tube. My engines will be built for torque since I probably wont get it up to 6,000+ rpm in the neighborhood. My question is, does the tube length have the same effect on a carb engine as it does on a fuel injected engine? Thanks
 

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Discussion Starter · #3 ·
Thanks for the reply. That engine looks awesome. I guess I used 'intake' incorrectly, I was taking about the tube going from the carb/throttle body to the air filter. Sorry. I did stack a couple of 1/4" plates in between the carb and the head to make the port longer though.
 

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More for Less Racer
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The length of a tube from air filter to throttle body or carb has no bearing on power output, unless it gets to a point where the length vs diameter causes it to be a restriction...i.e a 3" diameter x 3" long isn't any restriction to a 2.75" throttle opening, but make that 3" inlet pipe 72" long and it can become a restriction.

This becomes different if we are talking individual port throttle bodies, with no common plenum for all cylinders to draw off of....so a single carb single cylinder engine probably fits the individual runner/throttle body scenario.....length above the throttle plate would then matter and be a tuning aid.
 

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Race it, Don't rice it!
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We did some testing on a predator clone and found the exhaust to be the worst and the transitions between the carb and block to also be an area to improve. We also milled the head and did a valve job with new springs from PAC.
This one got a turbo installed eventually so we didn't look into it further that that and then the crank broke so it's waiting for more parts.
 

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Discussion Starter · #7 ·
I looked into a small turbo, too much work. I milled .065" off the head and did a port job. I'm going to make an adapter so I can put the GX270 carb on the GX200. I'll get a cam and all the other stuff after Christmas. I'd get a flat top piston but that would put me at 13:1 compression, that's a little much when I have a GX270 that can have the same power without running super high octane gas.
 
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