Bigger carbs or not??

[ATV DRAG RACER]

yes okay for the sake of science
i will do this

i already know what the result is

[Freez]

Ok, more feedback.

I pulled the dyno reports and had a closer look.

Some corrections. Peak power gain between stock, versus bigger carb is actually 0.9HP, not 0.2HP as I stated before.

BUT... here is the interesting part. BOTH, BVH and stroker are correct.

Here is why. I attached the dyno report. Blue run is stock carb, red line is big carb, both on identical bike, no other changes.

On stormer's side, if you look at peak HP output, there is very little gain. Hardly worth the money spent if you are chasing peak HP gains. From 6000 RPM to peak, there is not that much difference in power. Yes there is a power spike and a little gain with the bigger carb from 8000 to 9500 RPM, but then after 9500 RPM, the stock is better. Ok, its after peak power and might not matter much.

On BVH's side, power output from 4000 RPM to just before 6000 RPM is up with the bigger carb. Now, if you go by feel, the bigger carb will respond better at lower RPM, giving you a nice kick in the butt, over the stock carb. That is most likely what you are feeling when you ride the bike. At 5000 RPM there is about a 20% gain in power. When you ride a bike with more low down torque, the bike overall feels stronger and accelerates better from low RPM. The dyno run Stormer posted only starts from 6000 RPM, so it is missing what happens at the low RPM, and what BVH might refer to. My attached dyno runs start from about 3000 RPM, so you can see what happens at low RPM.

So, it depends how you look at it. Overall, for trail and every day riding purposes, yes I can understand why the bigger carb have advantages and why people would feel that the bike runs better. If you are looking at this from a peak power gain, well then there is not much difference.

Also, I attached the air fuel ratio of this banshee with both carbs, so you can see that they are overall identically set up to produce the same A/F ratio at peak power. This bike was jetted slightly rich, since the owner runs it at a much lower altitude and I compensated for that. And yes, my dyno reads low, so don’t start with that again. No matter what HP it produce, you can still compare if the carb is worth it or not. Also, torque wise, it is producing the same peak torque values as the cab motors do.