Jetting a Joyner 2008 sandviper

Posts: 13

I junked the stock air box, put on a k&n air filter and rejetted it with a 117.5(my elevation is 57 ft. above sea level)and it ran like a top. During riding on the third day, the junk air intake fell apart. Joyner glues a 1 1/2" rubber ring to the intake tube and mounts it to the carb. No matter what I did, the ring would always come off. I built a redneck intake using 1 1/2' abs with one 90 degree elbow and a 6'' straight piece with the k&n on it. The intake is now bullet proof! While now when I throttle it, it falls flat on its face. The plug was bright white and I jetted it a 125. It runs a little better, not much, and the plug is still white. I don't want to buy a couple dozen jets and make guesses in the dark. Can anybody suggest a start point, Thanks.

Posts: 148

I would go with a 145 jet at your altitide with your intake mods.

Posts: 76

Can you post pictures of the intake. I have the same buggy and would like to see how you installed it. Deser Toys in Ontario Ca. Says that 140 is the most common. (per his website)

Posts: 13

Slopeflyer, here's the pictures. I used two 45's, two 15 degrees, and one 22 degree with a 6 1/2" straight pipe( all 1 1/2 abs pipe). The intake to carb piece is a 1 1/2 plumber's banjo coupling. I welded up a support bracket to hold up the intake from bouncing around. It took some time fitting the pieces together to make it work, don't glue it untill your sure everything clears. Dry fit things together, mark their locations and glue it up! The fun part was jetting the carb. I started with a 145 and when I throttled it, it fell flat on its face starving for gas. I ended up using a 170 main jet for it to run right and for the plug to have a light tan color to it. The reason its so high is from the turbulence (or tornado) effect of the 90 degree bend going into the carb. I guess the best way to describe is the engine is getting more air than it can handle, like a supercharger effect. If you have any questions, I'll be more than willing to help you!

Posts: 76

Thanks for the pictures. You did a great job on that mod. Have you had chance to test out the buggy? Keep us posted on your performance gains.

Posts: 13

SF, I haven't had a chance yet, waiting for some guides. Mods so far are; hotter coil and cdi with a ngk iridium plug, these mods, engine revs up faster and I just tap the key and it starts. Once I put my cvt back together with 17 gram sliders and 2500 spring, I'll being putting through it paces and let you know how it does, Ed.

Posts: 76

Sounds good. I will be starting my mods next month. I need to do the intake, hit clutch, sliders, and spring.

Posts: 15

hey bigdog, any update on the performance? I just did the same intake but haven't taken it out yet. I used a 132 jet. it seems to idle fine.
I posted a question in the mod forum about the vacuum hoses for this setup.

Posts: 13

I junked the charcoal canister and put a check valve on the gas cap. The rocker arm breather hose I put a k&n breather filter on it and zip-tied it to the frame.

Posts: 200

I used a 1 1/2 in. "long sweep" elbow that is made out of rubber and angled right behind the passenger seat. Bought the elbow at Lowes. It's in the plumbing section with the rubber couplers.