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Yerf Dog 3206 |
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Yerf Dog 3206
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Yerf Dog 3206 GX150 Go Kart had a 150cc engine making around 10HP.After selling a Yerf Dog 3203 go kart, I picked up a Yerf Dog 3206 (aka GX150) at a local Sam's Club store. The engine and overall kart design appealed to me more than the 3203 kid's go kart design. At the time, this kart offered a lot of machine for the money. It was assembled in the USA by Yerf Dog using some components from Asia - including the Chinese made GY6 engine that was a clone of the original Honda GY6 design. I really liked the looks of the US made frame design. Yerf Dog referred to the frame design as "Spiderbox". The frame was one of the better parts of the Yerf Dog 3206 off road go kart.
Modified Yerf Dog 3206 Go Kart The picture shown above is not what the Yerf Dog GX150 looked like in stock form. As usual, I couldn't resist the urge to try to improve on the design and make the machine better. I bought a used set of aluminum wheels with Holeshot tires for the rear. Up front, I installed spindle adapters and ran with larger wheels and tires. This gave my Yerf Dog 3206 a nice boost in ground clearance and off road handling. In the pictures below, you will see the stock turf tires that the go kart came with from the factory. In addition, you will see some shocks that I was experimenting with on my Yerf Dog GX150. The stock shocks were too stiff in the rear and had too little travel. The stock front shocks were also cheap quality, so I decided to experiment with different used shocks that I bought on eBay. Experimenting with Different Shocks In the rear, I finally settled on a set of Kawasaki Tecate KFX250 ATV shocks. They were about 2 inches longer and offered plush wheel travel. They were a great addition for the rear of my kart. On the front, I tried various different shocks and had a harder time of finding something that would work well. Once the suspension was improved, it was time to try to improve the performance of the 150cc GY6 engine. Ported Intake and Exhaust Ports on GY6 Head One of the things that I did was to pull the cylinder head off and port the intake and exhaust ports. I mainly removed casting flaws and shaped the valve guide hump a little. Nothing too radical. On the exhaust side, I also opened up the port diameter more to match a larger exhaust header that I made.
Stock (Top) & Custom Exhaust (Bottom) The stock exhaust had a tiny primary header diameter that later stepped up to a larger diameter. Because of the short header length, I suspect that they made a tiny primary header to try to boost low end power. This engine really needed a longer header to be tuned optimally for max power, but the space constraints of the Yerf Dog 3206 required a shorter exhaust. I picked up an old Supertrapp muffler and re-packed it. I used the stock exhaust flange as a pattern and marked up a piece of 1/4" thick steel stock that I had laying around. I then used a hole saw, hack saw, drill, & bench grinder to form the new exhaust flange that I needed for my custom exhaust. Hey, I don't have access to a machine shop, so what I lack in terms of equipment, I have to make up in terms of sweat and time. After shaping the flange by hand, I used some mandrel bend U pipes and cut out the angles I needed to form the header. I then welded it all together. The result was a much freer flowing exhaust system.
Custom Exhaust Installed on Yerf Dog 3206 With these modifications, the GY6 engine in my Yerf Dog 3206 really woke up on the top end. I had a tach installed on the kart, and in stock form the engine really hit a wall around 8000RPM. It would really strain to rev up higher. After my modifications, the engine revved up easier, and I even saw 10,000RPM on the tach on some long WOT runs. The engine screamed (at least as far as a little 150cc 4 stroke engine can "scream"). Going with the larger header gained more top end power, but I did loose some low end power with this exhaust. After much tinkering and playing, I eventually sold my Yerf Dog 3206 prior to a cross country move that prohibited me from taking it along. Even though it was a low performance machine overall, I had a lot of fun and learned quite a bit while working on my Yerf Dog 3206 off road go kart. Click links below to see some of the other machines I've played with:
Honda Odyssey Yamaha Rhino Twister Hammerhead Yerf Dog 3206 Yerf Dog 3203
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