I am a proud owner of a 250ex and i have found a few tricks to get maximum power out of them without internal engine modification. The very first thing you will want to do is remove the airbox lid and get a new filter, prefrably a K&N....next, to help all that air thats comming in get out, get you come pipes, i got FMF Megamax pipes and a coustom header made by a buddie...that setup is good enough but just get whatever you want. Next, on the back of the airbox right above the bottom, drill a hole that is 1 inch or larger across...i dont know if this helps but it cant hurt at all unless you are a trail rider that likes to go through water then i wouldent realy modify the air box at all. I would also switch to some diffrent tires because if you like to race yours like i do, the stock ones bicycle realy bad when theres traction... i got a slightly smaller diameter than stock hoosier racing tire that fits the stock rim with slight sidewall hangover to get them digging but not too much. For the sake of your engines health now that its breathing better, rejet your carb. wrong carb settings can sometimes hurt your engine so get a guide on wich jet to use. also, throw a few safety features onto it such as new, larger, front and rear bumpers and some nearf bars. If you are hardly ever goign to need it to be utility or a rock climber bike and just a play around racer, go ahead and get a trained profesional to lower it for you, it will also add to the safety and stability of the bike. one last modification i would like to give you that is most useful and the cheapest/easiest is unpluging the rectifier.... when you do so it disengages the magnets and lets the engine run MUCH free and gets it revving faster, i'v heard it can increase power up to a whopping 10% depending on your other modifications. with all this and a bit of experience you will be able to beat 300s easily and possibly a 400 with a untrained rider. I hope this is helpful to all of those 250 riders out there looking for more power.

 

I have an older 250 (the first one my dealer got in), and a brand new 06. The older one is moded and the 06 is stock, and wow, is the 06 ever underpowered!

I did a UNI air filter (don' t trust a K&N!), vented the airbox lid, and a MegaMax muffler. I found that it would not jet properly with the airbox lid off completely (good thing too, because it keeps the airbox cleaner). The little 250 can only handle so much air and run properly, so I ended up with four UNI filtered vents in the lid.

Stock tires are lame! Replaced them with Holeshot XC's, on ITP T-9 rims. Makes the quad +3" wider, for a lot of added stability.

 

in my opinion i think the 250ex is looked at as too much of an underdog to the larger modles. It is so hard to find modifications for them, you just have to make your own.

 

why do u hate K&N's so much? i've been running one for a year now with no problems, just keep an outerwear on it and change oil regularly and there are no problems...

 

Ah. See, you're an okay dude. You have an outerwear. Lots of people don't, and boast a really high dirt/air flow. I'm just too cheap to get an outerwear every 6 months and I like cleaning my UNI and SEEING that it's perfectly clean. I can't tell on pleated elements as well.

 

I ran K&N's with Outerwears for one year. Every time I pulled the filter off, I would wipe the inside of the intake boot with a white cloth to see if it passed anything. There was ALWAYS a dirty film.

Why take a chance with your engine, for a little bit of added performance???? Seems like a no brainer to me!

 

If you would clean my uni for me I would jet down and use it instead of the K&N [img]i/expressions/face-icon-small-smile.gif[/img]

I do agree with the outerwear though, and especially for those not running an air box lid like myself, or when riding in wet or dusty terrain.

I am serious too becaues the K&N is just soooooooo damn easy to clean and oil that I cant see messin with messy foam filters, and also will never know why riders dont keep up on maintaining them because there so easy to do. If you dont oil them there is nothing to stop the fine dust from getting past the filter (how they all work btw) and then its on the way to messing with the valves and then the piston and cylinder wall, and that is why they get a bad rap.



And 250rider that was an excelent post on modding the 250ex!!!!!

 

haha, thanks, im just a 13 year old race car driver that has to have everything to the max on performance and i saw on alot of 250 fourms where no one knew what to do to them so i thought i would get on here and post what i did

 

Thanks for the post!

I decided to cheap out and buy a 250EX instead of one of the 400s from Kawi or Honda. I just need it to ride around with the boy and his Desert Cat 90 until he outgrows that machine. Then I can hand off the 250EX to him and get a faster ride for me later on. Figure it would make a good machine for him to learn how to use a clutch on when he is old enough.

For now I'll use the extra cash to buy a trailer to haul them around on. Throwing a few mods on it would be an idea. I plan on getting rid of the balloons that the 250EX has for tires first!!




Darrin

 

Suspension is where the little 250 really needs help! I haven't gone there yet, because I'm always spending so much on my bigger bikes.