OK I've noticed that power in these motors are all at high RPM. My old 98 Quadrunner 500 had the same motor as my new 500i and they behave exactly the same. You need RPM to keep those tires turning, the bottom end is ok but not great like you would think it should be. I have some questions. My spark plug is jet black but dry. I take it this means my fuel mixture is to high, if I decrease the Jet and get my spark plug to the point where its a nice golden brown will this increase bottom end? If not then I'm going to need something that will increase my bottom end, any suggestions?

 

Rejetting will not increase your bottom end but it will tweak your fuel efficeincy and gas mileage.

To increase bottom end there are several methods.

Method 1

Replce air filter with a high flow job, replace the factory muffler with a pipe, and rejet to match the new flow. This should give you about 5 HP maybe more.

Method 2

Big Bore kit, i.e. replace your piston and sleeve with a larger one and install a thinner head gasket to increase compression.

Method 3

Do both of the above and you may end up in about 10 HP or more increase (Signifigant but costly).


Or you can simply live with it. [img]i/expressions/face-icon-small-wink.gif[/img]

I rejetted, I moved down from a 150 main to a 147.5 which took care of it. I had a black spark plug as well, before I rejetted. Stick your finger in your muffler when it is cool and see if black carbon comes off on you. If so, you're running too rich.


EtherNut

 

Switching to a higher compression piston is a cheap and easy way to gain power right across the rpm range. If Wiseco offers a 10.25:1 piston for this model try that, it will make a big difference.
The piston itself is cheap, $135CAN, which I guess would be about $75US, and it comes with the rings and wrist pin. Other than that you'll need a head and base gasket, and a few hours to do the job.

 

Well I took off those damn big tires and what a difference in power. I have 2 sets of tires and rims so I can do this easily. I'll see how the outlaws suck up my power in the summer time, in the wet soft snow they soak up all the power. I'm happy with my stockers for now.