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MadAss Motor Shootout!

How much horsepower does the MadAss make? What kind of increase can I expect to see with an aftermarket exhaust? Can I get the performance I need out of my stock motor, or am I better off just replacing it? If so, what motor should I replace it with? Why doesn't the motor I bought off e-bay run?

As with any performance upgrade, the answers to these and many other questions depends entirely on two things: How much power are you looking for, and how much do you want to spend? How much you spend is up to you, but to help answer the first question, Moto-Scoot has assembled Cams, Heads, Cylinders, Pistons, Carbs, Exhausts, CDI's, complete engines, and dyno tested them all. We hope you find this review helpful, should you desire more power from you MadAss.
First bike tested was the stock MadAss 125. Turns out, the stock MadAss is quite respectable. Compared to it's 2.5HP little brother (the madass 50), it's a pleasant surprise. In fact, in it's stock form, it's pretty close to a MadAss 50 with our 88cc Kit. As a daily commuter, 8.5hp works just fine. It's enough to beat a few small motorcycles off the line, and tops out at about 60mph. But if it's more your looking for, read on.


Stock MadAss

Stage 1 The easiest and first thing we did to increase power was free up the intake and the exhaust. By installing our Ass Pipe and Tuneup Kit (air filter and jets), our 125 had a noticeable increase in acceleration, and a comfortable 65mph was achieved......WE CAN ALSO CORE-OUT YOUR STOCK EXHAUST....This simple mod let the engine breath, and made more power at higher RPM's - where the stock engines is literally "choking",

(It's at this point we highly recommend taller gears, either by going to a 17 tooth front sprocket, a 39 tooth rear, or both. An additional 4000rpm's is used to make horsepower, and you want to take advantage of that.)


Stock MadAss VS. Stage 1

The next step, Stage II, follows the old adage- "No Replacement for Displacement". in other words, replace the stock piston with a bigger one. Stock case size is what ultimately limits how large you can make the stock motor. Topping out at 142cc's, the Stage II Kit hovers right around the 11HP mark - approximately 1.5 hp over the Stage I kit, and almost 3 hp over stock. With proper gearing, your speedo will be reading 65mph-70mph with ease.


Stage 1 VS. Stage 2

...and If hard hitting throttle response is what your looking for, and you require the top speed to keep up with the competition, we've assembled the Stage III Kit. With the addition of a larger carb, and the Moto-Scoot selected camshaft/cylinder head combo, horsepower output is just under 14.

We have specifically designed this Kit for maximum horsepower without compromising reliability. The stage III kit allows the stock motor to truly come alive and bring it to it's maximum potential, without self destructing. While there may be ways of going bigger yet, it becomes more cost effective to just replace the motor entirely. With the aftermarket engine, you will sacrifice your electric start, but if your serious about making more power than is achieved with the stage III kit, you probably won't mind kickstart only.


Stage 2 VS. Stage 3

The final run of tests involves two motor options, the YX160 and the Lifan150, In addition, we bolted on some goodies just to see what we were in for. We kitted two motors, a YX160 with a 184 Bigbore Kit, and a YX160 with a172 bigbore kit and 4 Valve head. The results were impressive...


As you may have heard, engine replacements can be a major project, but with an engine specifically designed to fit the MadAss, engine replacement is simple. All of our engines are sold to retain the stock 55W Headlamps, utilize the stock CDI and voltage regulator (plug right in), and work with stock, and most aftermarket exhaust systems.

The Lifan 150 offers a superior clutch,and replaceable oil filter. Built to withstand the extra horsepower a 150 can offer, the Lifan comes with a relatively high compression piston compared to the stock madass, and a hotter cam delivers over 12hp out of the box! With some tweaking, and a few aftermarket components, this motor could definitely see the upper teens, and have the clutch and tranny to handle it. Another feature of the Lifan is it's very "stock" appearance and finished components.


Lifan 150 VS. Stock MadAss

The YX160. With loads of aftermarket components available for this one, it's definitely the racers choice (not to mention the ability to build it up to 184cc's!) This motor shows horsepower potential we've only begun to tap. With it's "KLX" style head, the YX160 offers a larger combustion chamber, bigger valves, heavy duty crankshaft and five plate clutch to handle everything we've thrown at it so far. In it's stock form, the YX160 continues where the Lifan left off, and pulls over 14hp.


YX 160 VS. Stock MadAss

Just how big can you build it? By installing a "Skirtless" piston, 184CC's is achieved. We remain skeptical regarding this design, but decided to test it. In regards to horsepower, this kit is awesome. No doubt with a little headwork and a hotter cam, over 20hp could be achieved. As for the durability, we'll keep you posted. Moto-Scoot plans on running this piston in one of our race bikes.
And last, but not least by any means, we tested the 172cc 4 Valve Kit. The results dispute the old adage regarding displacement, and surprise even us with 20hp!
Get high performance right out of the box, with a custom built madass from team Moto-Scoot.  Choose the different performance options you want,  and Moto-Scoot will build a new madass to your specs, and ship it right to your front door.  We give you a discount for the stock parts that are replaced, even the stock engine,  so go ahead.......dream up a  custom madass, and team Moto-Scoot will build it for you. We should also mention that besides performance work, we are fully capable of adding options such as clubman handle bars, or other motorcycle styling parts  to turn your madass into real a show stopper.  Please give us a call to discuss the details. Cheerz!

And that's about as far as we've taken it so far. There's little doubt, that with some added tuning, our race bikes are going to be pushing well past the 20 hp mark. Check back with us for race updates and new developments. For more information please e-mail service@moto-scoot.net.

Moto-Scoot Stage IMoto-Scoot Stage I
MotoScoot Stage2Moto-Scoot Stage II
Motoscootstage3Moto-Scoot Stage III
Lifan 150
Skirtless PistonSkirtless Piston

4v72ccHead Kit

172cc, 4 Valve