I just started here, so I'll share a little before demanding advice of you. I've been riding honda motorcycles, dirtbikes, and quads since the early 90's when I got the fourtax I'm speaking of in this topic.
This quad has been sitting under a tarp in a shed for over 10 years, when the motor basically died. I want to replace it with another honda motor, but something with more power. My first choice would be a 250R, or maybe a 300 EX motor if it would fit in the frame. I spent the majority of time on this bike on dune trips to Glamis, and hope to do the same this time around.
This will be the first time I have replaced a motor, and I'm really excited and a bit nervous. Luckily I'll have my old man to oversee some (alot) of the wrenchin. I'll attach some pics of the bike for you all to check out. All opinions will be noted...

<a href="http://s100.photobucket.com/albums/m35/bridgeeowen/?action=view&current=IMG_0885.jpg" target="_blank"><img src="http://i100.photobucket.com/al...dgeeowen/IMG_0885.jpg" border="0" alt="Photobucket"></a>
<a href="http://s100.photobucket.com/al...&current=IMG_0889.jpg" target="_blank"><img src="http://i100.photobucket.com/al...dgeeowen/IMG_0889.jpg" border="0" alt="Photobucket"></a>

 

a 300ex engine will fit, its almost the same engine with a longer stroke and elec start. imo if you want more power i would do a big bore and stroker crank, you'll get more power without the extra wieght of the elec start.

 

I would love to find a 250x to use as a back up.

 

I love my 87 250X but may be willing to part with it soon. It is in near perfect shape but I am concerned about the availability of parts dwindling. I don't want the hassle of hunting for parts so I'm looking for a newer model 300ex. If interested, let me know and I can send you some pics.

 

I agree with the 300 ex replacement. I'll definitely go with the stroker option as well, if I can do it for a somewhat reasonable price. I'll update here when I find a motor.

 

im putting a 300ex motor in my 86 250x youll need the wiring harness, starter ,battery box,and of course a battery..( unless u do the kicker).as far as parts not being avalible...all the frame berrings,a arms ,swinger ,axle berring carrier,shocks,plastics ,are compatable with the 300ex ...along with most of the enjine parts...ie the top end is interchangeable and has the same stock bore...you could rebuild the 250x motor into a monster....it has a shorter stroke than the 300 and revs higher ... it has more top end ..the 300 has more low end torque ...a 330 big bore kit ..on the 250 would be awsome ,and prob eat any 300ex it came across...

 

Y2dat, you seem to know alot about the 250 & 300. I know stock HP on the 87 250X is 21.1 but do you know what stock HP is on a 96 300EX?

 

If you do switch it over to a 300ex, you are going to need the wiring harness, coil, cdi, on off switch.. all that from the 300.. If you go big on the 300 motor.. the stroker cranks and high compression pistons sometimes throw the starter clutches.. But the good news is.. 300ex is a direct fit into that frame.

 

Can you put a 250x kick starter on a 300ex engine?