Official 250x/300ex thread

[blasterman87]

ok a few of us have these and i figured id make a thread for them to keep from stopping up others... ill add a few known mods, 400ex carb/a-arms/plastic fits,with some mods a 350x motor mounts up, ive also heard a xr600 motor is an easy swap?? some stock problems are, the exhaust is very resrictive esp the header its very small, the carrer bearings are weak, and rear brake caliper freezes up if not taken care of somewhat.

now some questions.. are the 400ex arms longer? does a 400ex axle/swingarm fit? what bout shocks?

 

[4cfed]

i know the 400ex arms bolt on, stock rev box sucks!! i think mine is a/m but i gotta look into it, i know my coil says TEC on it and online shows them as beeing agreat company for honda coils.

300ex plastics fit on the 250x yamaha hubs fit the 250x axle, just needd a washer to make up for the lenght of the yammy one being alil shorter than the honda,

there known to have valve problems from sh*t maintanace... if you bought aused one spend the lil bit and change out the valve spring retainers as they wear and fail which drops valves and bends them,

 

[blasterman87]

good post on the valves ill have to look into that with mine, im also looking into the xr600 swap

 

[4cfed]

only reason i say that is cuz they are prone to fail if not maintained, friend bent valves twice this winter,... also make sure the compression relive valve works properly... should be 'down' when not kicking ( down as in look at the cable running to it and make sure the compression relive valve/ cabe are to the right)

 

[blasterman87]

mine doesnt have a cable running to it anywhare

 

[4cfed]

no cable coming off the kicker housing, runing it a lever type thing on the right side of the head????.... its not needed.. but its nice to have.. it releases some compression when you kick start it to make it easyer to start.... granted i dont need it as im fully capable of kicking over a high comp motor, but its nice for them long days of riding, and your tired makes startin easyer.. except mine takes like 5-8 kicks to start, i gotta tweek the carb yet

 

[blasterman87]

yeah no cable, my older x didnt have it either... heres the link to the carb chart

Carbs

 

[4cfed]

hmm.. prev owners removed them???

thansk il check it out later or tommrow.. so i should just be able to messure the air intake tube side

 

[blasterman87]

yup im guessing they would have had to be removed, if i remember right i could flip the switch by hand at the top of the head

 

[98blaster+4]

if anybody is interested i have a set of rear rims and 22 inch mud tires from an 88 250 x

 

[4cfed]

messured... i have a keihin pe 34 mm carb.....

thats a good carb and size for a mild 250x???

 

[blasterman87]

Convert inches to mm - Conversion of Measurement Units

here ya go

 

[blasterman87]

its 57.15 mm .

 

[4cfed]

yeah... there so it might have been a lil more than 2 1/4 so it would be a pe 34 mm for sure... not sure what stock is but it seems to work good with the set up

 

[blasterman87]

stock is a 28mm, and stock on a 400ex is 35.5mm

 

[4cfed]

ok.. so the 34mm is fine than??.. i went and re messured and its actually a lil over 2 1/4 inches.. so 34-35??? ether way its 34-35 so thats a good jump from stock

 

[blasterman87]

idk, sounds like a good set up to me, atleast with a 4poke you dont have to worrie about jetting as much because it gets lubed with regular oil

 

[4cfed]

yeah... it seems to perform quite well the way it sits,

 

[blasterman87]

yeah, i need a grab bar for mine and a rear caliper

 

[blasterman87]

whats a good compression for these motors?