Is it true a 300ex really only gets 60 mph??? A 660 grizzly gets more than that!!!! The best thing to put on to get more speed is.....?????please help!!!!!

 

more like 55

 

Try a pipe and filter. If you want to get more you will need to do some head work, buy a cam, and maybe bore it and put a nice high compression piston.

Even with a lot of work you are still starting with a 282 cc. A grizzly has a true 660 cc engine and a 5 valve head if I'm not mistaken. Even with the massive 4x4 frame it only outweighs the ex by around 230lbs. and sports twice the motor.

Top speed is not everything and a ex is really a fun bike.

Enjoy it!

"No matter how fast you are, there was, is, or will be someone faster."

 

60 mph on a trailer, 52-55 on a good day.

 

58 stock

 

thanks for the info. also I was wondering where would be a good place to but all the stuff at a reasonable price? (in canada if possible) Also how does this boring work? does it really make a big difference? (not really fimiliar with it) thanks.

 

about 56 mph stock, but depends on the riders weight also. u can increase top speed by getting a new complete pipe and a filter would help, but dont worry about the top speed it will make acceleration better and thats really what u should want.

 

Increasing the bore diameter or "boring it out" increases the displacement of the engine. In other words it makes it a bigger engine. Another way to increase the displacement is to "stroke it" or give it a longer stroke by using a different crankshaft and/or connecting rod. For maximum increase in displacement you can bore and stroke it.

I think the stock bore on a 300ex is 282 cc so you really don't have a 300 cc engine. It is in fact a 282 cc engine. I'm not sure of the maximum bore size for a 300 ex jug but you can probably get it over 300 cc's.

When you increase the displacement the engine can burn more fuel on each stroke thereby producing more power. This is why a 400 ex has more power than a 300 ex.

Another factor is the compression ratio. A higher compression engine produces more horsepower per cc. To get higher compression you can "shave the head" and/or install a "pop up" piston. The reason that higher compression makes more horsepower is simple. Just think of a coke can. The more you shake it up the more it will spew when you open it.

Before you look into all this try the exhaust upgrade. Make sure to add a K&N filter and re-jet the carb. You can also toy with your sprocket sizes to get more top speed if thats what you want.


If you are going to do some engine work you should start with the intake and exhast anyway.

Remember this: The key to increasing power is increasing the amount of fuel and air that goes in and out of the engine.

 

thanks again!!! yeah exhaust system will be the first thing to be done. putting a smaller sprocket on the back wouldn't hurt anything???? if not it's and easy way to increase speed!!! What kind of jets would u suggest or should be done????? thanks

 

Check with the company that you purchase the pipe from about re-jetting.
Putting a smaller rear sprocket or larger front will increase the top speed a bit but you will lose some bottom end. It will not hurt anything at all. I never changed the sprocket sizes on my ex so I can't tell you from experience how much gain you will get with a certain combination but I have had good results on other past bikes. Maybe some other guys can respond about their results of changing sprocket sizes on the ex. If not just use the forum search engine.