hey guys.. i dont understand these stroker kits.. what do they do? what are pros and cons? please help.. are there certain mods that you need to have to get one? are they worth the money? help me out!

 

no one knows either??

 

ya i don't quite understand them either whats the difference between them and a regular big bore kits or are they the same???

 

i thoguth they wre totally differnt? well i wass juss wondering because ive seen a 285 stroker kit.. and thought about that.. until i saw the price. lol cuz the only way you can get it is if you rebuild the bottom end so its 500$ for the bottom and then 200$ for extra long stroker lol

 

Stroker kits change the length of the stroke, normally longer to increase displacement. Most of them have a different piston with a different pin location and also bigger piston diameter. A stroker kit takes the big bore kit to the next level. Since displacement is a function of bore and stroke, making either or both bigger or longer will increase displacement. A stroker kit requires you to change or modify the crankshaft. A big bore kit only increases the bore or cylinder diameter. So you don't have to split the case and do crank work. They definately work. Other mods will add power like pipes etc. A stroker kit alone with just carb rejetting will increase power on it's own. I would not be able to say if they are worth it to you but they are to me. They are expensive though.

 

Ya. ok thank you i get it now.. the only thing i dont get is this. lets say i have a lot of mony annd i wanna get a stroker kit.. what all has to dbe done? juss bottom end work? or is ther eboring involved also?does this make the bike more reliable or less? is there any cons to it? o and im looking at a yz250 motor with a long rod.. what does that mean?

 

A stroker kit normally involves tearing the motor down and changing the crankshaft. Normally a stroker kit also has a new, bigger piston with it. So, the cylinder will have to be bored. With the right balancing etc. you can change the stroke without boring the cylinder. You won't get all the cc's that you can without boring the cylinder as far as you can but, it's not mandatory.

The overall power output will be higher so It will run hotter. There may be some changes that will need to be made to keep it from running hot.

Overall reliability should be pretty good with a well designed kit, maybe a little less than stock, maybe not.

I haven't been dealing with many yz250 motors but i will guess that a long rod yz250 motor is a motor that has an aftermarket connecting rod that is longer than stock and the piston has a higher pin location to accomodate the longer rod. This will improve power by increasing piston dwell time at top dead center allowing longer/higher combustion pressure. This last long rod part is speculation based on my experience drag racing cars and building v8's but i may be wrong.

Mike

 

Long rod is used in a stroker kit but you can also use one without one and use the shorter piston like he said. Only major problem with them is they increase piston speed at any given RPM so your red line is lowered. You have to try to get enough power into your new powerband to make up for the lost power on the very top that your new red line cuts off. The main advantage to them is that you get power all over the rev range.