Reyals Bemus

I plan on getting a 250x or r for a supermoto build. I'm leaning towards the X, cause its more offroad oriented and the 250r is for race. I don't race but I occasionally like to smack up the trails.

I've got a few questions:

People tell me that there's a huge difference between the R and X. For example, they say if I got the R, I'd be burning valves and eating sprockets between every few tanks of gas. Yet when I look at the specs between the R and X, they seem to have the same motor, different tranny. So wouldn't I be doing all the same amount of maintenance on the X? Or is there a difference in the motor that makes it lower maintenance and less-peaky?

Thx in advance.

Reyals Bemus

Basically what I'm asking I guess is:

Is the 250r really that race-oriented that its not suitable for offroad and normal use?

atf8611

will this be for road use, or just track? if for the road, go with the x. it should have a stator that can handle lights and everything. the gears on the x are probably more highway speed friendly as well. I think that the engines may have different heads, or at least different cams. either way, you should check the valves often to avoid problems. if this is going to be a track bike, the r will be better. are you still going to ride off road (with the dirt tires)? i think if that is the case, either one should be fine. I would go for the "R" unless you plan to make it street legal. but if you are going to be street legal, you might want a 450. sorry if this doesnt help any.

Reyals Bemus

I don't race. I thought the X might be better for a combination of offroading and stunting.

I was just wondering if the X is less maintenance than the R. From what I've read on the internet, I think so.

The X has a wide-ratio trans while the R has a close-ratio for track. The R will obviously jump off the line faster, but the X has higher top-speed.

Which tranny is better for stunting?

mike1984

i just bought the R last week.... already swapped bodywork and swapped to sm wheels.... here are the differences

stator
cams
i dont know why they would change the whole tranny when they could just change sprocketing.... but who knows.... am having a blast on the R... a valve adjustment is actually really easy just read the owners manual.... but i do plan on putting better valves in on my first topend rebuild when its due (also easy) i cant remember which ones they are but there are some valves out there that require ALOT less adjusting.
heres a pic for ya!

E-Loc540

X model tranny has a shorter 1st gear and taller 4th and 5th gears than the R model. the motors are nearly identical minus the porting and the camshaft as someone said earlier. X-will be better for slow stunting because its made to run more in the lower RPM range...its got more torque and is less prone to stalling in the lower revs that the R model....

-BYRON

nice:YEAH

Reyals Bemus

Yeah that's really nice. How often do you need to rebuild top end/adjust valves? People say once a year...

mike1984

book says for "racing" valves need to be checked every 6 hours or 3 races... not necessarely adjusted just checked.... and a top end every 15 hours..... but usually it really only needs to be done once a year.... its not expensive to have done either

TimsKFX400

and thats if youre constantly on and off the throttle hard like you would be if you were on a track.

Schooler

you dont need ot check your valves every six hours thats bullshit.....i check mine on my yzf250 every six months and it runs like a champ..also a good freind of mine has a 250 f....has raced it for a year straight and the only thing hes ever done to it was change the oil and clean the air filter....250s ar bullet proof..its the 450s that suck *****

Reyals Bemus

Sweet, this is what I want to hear!

So I shouldn't lean heavily towards the 250x just because its more for the trail than race.

E-Loc540

The YZ250F is damn near bullet proof I know alot of people that go with-out adjusting the valves because the clearance never changes. The CRF250 stock valves suck...mine went 1 good strong year and that was it before the intake valves were toast...and when they wear out they beat up the seat real bad too so you have to either get a new head or get your seats re-cut. Alot of people switch over to steel valves for valve train reliability. Its like everything else.....the harder you ride it the sooner it breaks. I know alot of people whos CRF valves didnt last a couple months from being new. There is a post somewhere in here about the Honda valves thats pretty interesting.....I did hear that the 06' YZ250Fs are common for snapping the valve stem. All bikes have they're flaws, you just have to stay on top of the maintenance and take no shortcuts when servicing them.

E-Loc540

im not sure about the 450s but again I know the Honda has the less reliable valve train system than the other bikes...

E-Loc540

Its all in what you want....if you want a 250X but want the power of the R, put a flowing exhaust on it and a r-model camshaft...best of both worlds....used stock R- cams are cheap....hell I have an extra 05 R model cam from when I put an aftermarket Webb cam in mine.

Reyals Bemus

The 250X has plenty of power, considering I'm moving up from the 150 fun bike.

Maybe checking the valves every oil change would be a good habit?

So I'm hearing that I should buy steel valves off the bat for reliability, bulletproof-ness and less adjusting over time.

E-Loc540

Not really the valves on the X shoudnt be an issue as the cam is far less aggressive than the R model...I would run the stock motor just keep your oil and air filter changed and take a peek at your valve clearance every so often...The people that race they're R models and beat the hell out of them are the ones that usually have the valve problems. I almost promise you very little problems from your X model if you maintain it correctly and dont ride it around on the rev limiter.

E-Loc540

and ive found out that once its time to adjust the valves the valve wear has already started to occur...you can keep adjusting them but your just beating your seats to death.

Reyals Bemus

So at that point, just replace them?

What are the stock valves made of? Lower-quality steel or something?

E-Loc540

stock intake valves on both the R & X models are made of titanium....exhaust valves are steel. The problem isnt really the valve its a combination between the valve spring and the valve seat. The spring cannot control the valve during high revs. The valve actually floats (looses its contact with the lobe of the cam) believe it or not a stiffer spring will keep the valve in contact with the lobe so it doesnt smack into the seat. The valve seats are also super hard so they dont cushion the valve when it seats, plus it doesnt wear with the valve. Titanium is strong as steel but not as hard...you dig? Titanium is also very brittle once it passes its flex point. Again its not in the valves its the spring/seat.