Modern Buddy

Well I opened up the intake today to check the condition of the airfilter. Looks to me like a restrictive maze. It's been my experience that on working with scooters intakes are almost always restrictive, usually to meet some sort of noise compliance. And that a performance intake helps more than a high performance pipe. I also took out the little rubber tube restrictor/silencer and just the same as with my metropolitan it needs to rejet richer which means more power can be had. Does anyone make a performance intake for the Buddy? And has anyone had any experience with the Buddy with a performance intake or a rejet with the tube removal?

Put the tube back in

Dude, the issue you are going to face by altering the intake is one of vacuum changes. When you do ANYthing to the intake, it changes the vacuum characteristics of the fuel system. The Buddy utilizes a CV (Constant Velocity) carburetor that operates on vacuum. Any change, therefore, to the vacuum characteristics will also change the operation of the throttle slide in the carb. Unless you are a carburetion guru, my recommendation is don't mess with it...

--Keys

Keys wrote:Dude, the issue you are going to face by altering the intake is one of vacuum changes. When you do ANYthing to the intake, it changes the vacuum characteristics of the fuel system. The Buddy utilizes a CV (Constant Velocity) carburetor that operates on vacuum. Any change, therefore, to the vacuum characteristics will also change the operation of the throttle slide in the carb. Unless you are a carburetion guru, my recommendation is don't mess with it...

--Keys

Good to know

Ah that's where I specialize in, I know people who tune carbs and I've learned a lot from them, the carburetor is how I was able to achieve enough power to pull a respectable 45 on the flats out of my basically stock metropolitan and still be able to get off the line performance. I installed a "high performance" intake on it after my mods and took it off because it wasn't as fast top speed or accelerationwise as my modded airbox, even after rejetting it was still slower. Intake is THE number one restriction in the engine exhaust mods won't get you nearly as much power as a proper intake. It's why fuel injection is so much better because you can optimize the intake for flow and not worry about vacuum with a correctly jetted carb. I'm gonna have to experiment with different main and pilot jetting plus possibly modding the slide spring or slide venturis, maybe even make some sort of velocity stack for it because right now it needs a vacuum to properly draw fuel into the air channel (rubber hose), but a properly tuned intake system on a carbureted engine will instead use a pressure differential (bernoulli's effect) set up by a fast moving intake airstream to suck the fuel, hence the velocity stack. I got a cool 3 miles an hour on my metropolitan which by some math translates into about a 1/2 horsepower increase. So displacementwise counting that the buddy has lower compression and is aircooled I should be able to squeeze another 3/4 horsepower out of this engine which translates to an increased top speed of about 2 mph, not much eh? Every mph counts though. Hope those ponies don't mine giving birth to some freakish 3/4 horse Gosh darn these PGO engineers don't make tuning these Buddies very easy.

Try looking for an intake intended for a Chinese GY6 150. Most of them should fit the Buddy. The carbs are very similar. Check out MRP or Scootdawg.com. I made one out of some large rubber hose from Home Depot.
Tuning the CV carb is not that bad, just takes some patience and a good selection of jets.

My tuning is different. I can get any carb to run decent with any intake with just jets, the trick is to get everything just right so that airflow is maximized along with intake velocity, like I said I put on a high flow intake and filter on my metropolitan and couldn't get as much power as I got with a modified stock airbox. The inlet is specially shaped on the metropolitan to act like a velocity stck so I got better performance with that than the short straight pipe intake. I'm gonna have to crunch some numbers and do some tests but I should be able to get some better performance, I do think the stock intake has to go. Modding it to work will be a lot harder because it looks like it was engineered to keep rain and water out as much as possible with all the bends and baffles and intake positioning it has. I'll take a look at the gy6 intakes and see If I can get an over size one and design some velocity stack to fit in. Opened up the carb right now and the carb and intake runner could use a polish and port match. Funny that this is all just for fun I'd hate to have to do this as a job, those PGO enginerds looked way too serious testing out their bikes in the video.