250x maintenance/Rebuild Schedule.
  • HeWhoAteTheCaviar
    Posts: 15
    Joined: Tue May 29, 2018 4:46 pm

    250x maintenance/Rebuild Schedule.

    by HeWhoAteTheCaviar » Tue May 29, 2018 5:14 pm

    So I recently purchased a new 17' 250x brand new. Ive heard from numerous different people both in person and via online forums regarding the top/bottom end rebuild schedule for the Unicam 250cc 4- stroke. With this being my first high compression liquid cooled bike, I'am looking for guidance regarding the maintenance/rebuild process. I'am a broke college student and can't really afford a $1200 dollar bill for a rebuild ever 1 to 2 years, something people have recommended i should have done. I ride my bike aggressively, but i don't abuse it unnecessarily by any means. Any preventative maintenance advise would be GREATLY appreciated. Honda for life!!
    20. Pocatello Idaho. 17' CRF450RX
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    JimDirt
    Posts: 4406
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: 250x maintenance/Rebuild Schedule.

    by JimDirt » Tue May 29, 2018 10:32 pm

    Welcome to the site !! \:D/

    As long as you keep the oil clean , and don't bounce off the rev limiter , then you should be able to get several seasons off it , just keep check on the valves , if they start moving (getting tighter gaps) , then its time for a valve job , but that will not run you $1200 , if you are mechanically inclined , you can remove and replace the head yourself saving lots of labor costs , then all you need is the price of the valves , and someone to cut the seats (Ken can do that here) , unless your racing it , I would say go to Stainless Intakes , that way it will double or triple the life of the valves

    On a side note , my 06 450X is on the original piston , rings , clutch , the only thing i have had to redo/replace , is the Intake Valves with Stainless , back in 06 , i have not had to adjust them since ... (your mileage may vary) 8-[ , i did put a HotCams Stage 1 in it back in 06 , which makes it really work well for single track , as it almost eliminated stalling and its got torque for days now , i did re-valve the suspension and re-spring it for my weight and riding needs , i was thinking of putting in a new piston this winter , just because its been on the original one for 12 years , i mainly single track and desert ride it , if i want to rip around , i ride my 02 450R (pictured below) , its still competitive (in the 50+ Intermediate/B class) , and only mods to it is a 12.5-1 piston 2 seasons ago , along with Stainless Intakes and stiffer valve springs (and re-valved suspension as well which i do myself)

    Basically , if you don't beat these things into the ground , they will last as long as any other brand , just keep the oil and especially the air filter clean and oiled , and you will be happy , dirt getting past the air filter , is a death sentence for valves , don't ask me how i know :-~
    2020 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho
  • HeWhoAteTheCaviar
    Posts: 15
    Joined: Tue May 29, 2018 4:46 pm

    Re: 250x maintenance/Rebuild Schedule.

    by HeWhoAteTheCaviar » Wed May 30, 2018 3:25 pm

    Welcome to the site !! \:D/

    As long as you keep the oil clean , and don't bounce off the rev limiter , then you should be able to get several seasons off it , just keep check on the valves , if they start moving (getting tighter gaps) , then its time for a valve job , but that will not run you $1200 , if you are mechanically inclined , you can remove and replace the head yourself saving lots of labor costs , then all you need is the price of the valves , and someone to cut the seats (Ken can do that here) , unless your racing it , I would say go to Stainless Intakes , that way it will double or triple the life of the valves

    On a side note , my 06 450X is on the original piston , rings , clutch , the only thing i have had to redo/replace , is the Intake Valves with Stainless , back in 06 , i have not had to adjust them since ... (your mileage may vary) 8-[ , i did put a HotCams Stage 1 in it back in 06 , which makes it really work well for single track , as it almost eliminated stalling and its got torque for days now , i did re-valve the suspension and re-spring it for my weight and riding needs , i was thinking of putting in a new piston this winter , just because its been on the original one for 12 years , i mainly single track and desert ride it , if i want to rip around , i ride my 02 450R (pictured below) , its still competitive (in the 50+ Intermediate/B class) , and only mods to it is a 12.5-1 piston 2 seasons ago , along with Stainless Intakes and stiffer valve springs (and re-valved suspension as well which i do myself)

    Basically , if you don't beat these things into the ground , they will last as long as any other brand , just keep the oil and especially the air filter clean and oiled , and you will be happy , dirt getting past the air filter , is a death sentence for valves , don't ask me how i know :-~
    Thats a huge relief. I normally change my air filter every 2 to 3 rides but I will start doing it every ride from now on for sure. I'am pretty content with the engine's performance other than some mild jetting issues giving me slow throttle response at low RPM. Someone told me it's because the carburetor is tuned to meet California Emissions so it runs super rich from the factory. Understandable, but a disappointment non the less. Any advise to help combat this sluggish throttle response? Also, what is the best fuel to run in the 250x? I've stuck to ethanol free 91 octane, thats the highest grade of fuel available in Southeast Idaho where I'am located.
    20. Pocatello Idaho. 17' CRF450RX
  • User avatar
    JimDirt
    Posts: 4406
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: 250x maintenance/Rebuild Schedule.

    by JimDirt » Wed May 30, 2018 8:55 pm

    Yea , every ride is a must on the air filter unless your riding in wet conditions where there is no dust , as for the jetting , generally from the factory , the bikes are Lean , not Rich , so you might be getting a lean bog , not a rich bog ,

    As a example of jetting from the factory , the 450X comes with a 142 main and a 42 pilot , i live (in Southwest Idaho/Weiser) around 2100 ft and ride from 2000 to 8000 ft , i am jetted at 162/45 , with the fuel screw at about 1-3/4 turns out

    What i would recommend is checking what jets you have and go up accordingly , the bike from the factory is jetted for Sea Level and then even leaner to pass Ca. emissions , so you will need to go up like the example i gave for mine (not as large because its a 250 , but in the same gap range) , and get a Adjustable Fuel Screw (one that actually has a knob that sticks out so you can adjust it without removing or twisting the carb to get at it) , i use the R&D Flex Jet , you can be riding , and reach down and adjust it for dialing in elevation changes , its worth every penny you pay for it https://www.crfsonly.com/catalog/produc ... ts_id/2792 , Also opening up the top of the airbox , helps the engine breath more , basically you cut the snorkle off the top , or some people cut the entire top off so its more like a R opening , the bike is choked up , so breathing will increase performance as well as help with bogging , etc .

    There is a member here named Leardriver , he usually hangs out in the Jetting part of the forum , you might PM (Private Message) him to see what jetting he recommends for the elevation your riding https://www.crfsonly.com/forum/memberli ... le&u=14707 , or just brows thru the 250X forum at the top there are Stickys , with Jetting Specs that people are using , try to find 2 or 3 that are within your elevation , and generalize what the average jetting use works out to and go from there https://www.crfsonly.com/forum/viewtopi ... =8&t=13472

    As for fuel , what your running is fine , if you want , go to the local airport (small private plane airport) , they usually have a pump near the runway , just bring a gas can and use a credit card to pay at the pump , it will ask for a Tail number , just look around at the planes and pick a number or one close to it and enter it (usually starts with N and has 4 numbers and another letter at the end) , and fill a 5 gallon can , what i do (its 110 octane) is mix 1 gallon of Av gas to 1 -0 1/2 gallons of Non Ethanol Premium , and it will help even more with the sluggishness or any stalling issues , it wakes the bike right up , and won't hurt anything , and it will help the engine run cooler , as its burning more efficiently
    2020 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho

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