WR250f

[Rockey5000]

Ok I got my dad into riding and convinced him to buy a WR250f. To me it seemed like a solid choice, good for trails, good power (or so I thought). So we got one at the local Yamaha dealer for a good price. Got it home and gassed it up, I started it and let my dad take it for the first spin. He rode for five mins. and came back and said "Is the choke still on?" I looked and said no and I took it for a ride. Wow! My friends XR100 could give this bike a good run for its money. So what is wrong, why is my WR so slow? Should I bring it back to the dealer? All Iv'e noticed so far is the very small exhaust opening. This bike looks very choked up. The engine from what Ive heard is the same as a
YZ250f engine, which is very fast. I hope this can be fixed, because my dad just spent $5500 on a bike that I assured him was a best bet!

 

[JWW]

Do a search for 250f mods. Some people wont like the link but try www.thumpertalk.com . Do a search there also. You will find tons of info to open the bike up.

 

[dell30rb]

mabye since it aint broken in it dosent have good power

 

[kciH]

I would complete the break in requirements and then perform all of the modifications that you find. I'm not sure about the 250 but for the WR426 the list is relatively short and mostly can be accomplished at home with simple mechanical knowledge and tools.

Is your dad a big guy? The yzf250 is just like a 125 with a little more power and a somewhat easier to use powerband. You will have to uncork the motor and rev it to get the power needed.

 

[Danman]

Some things to search for Grey wire (the mod in envolves removing form the wiring harnes, yz timing (changing the exhaust valve timing slighty to the same as the YZ, Re-jetting, BK mod (changing the duration of the squirt on the accelerator pump of the carb), Grinding the throttle stop off. I sure there is one for the exhaust. From what I have read the above mods (most are free or realy cheap) put the bike in good shape and make a big difference.

Good luck.

 

[kciH]

I would focus on the throttle stop, grey wire, and timing issues in addition to the exhaust. The BK mod was uneeded on my 01 426 and most of the other guys I talk to with 01 and newer bikes don't need it. The only one of the mods that requires any real work is the valve timing so you might as well do it when you have the valve cover off to check the clearance after break in.

 

[Rich Rohrich]

It's important to keep in mind that it's reall unwise to change the engine over to YZF cam timing unless you uncork the exhaust at the same time. Regardless what people have said in various places about Yamaha modifying the cam timing on the WR to reduce the hit, the real reason they have different cam timing specs to to compensate for the exhaust restriction and to reduce pumping losses. In short free flowing exhaust requires the YZF cam timing restricted exhaust use WRF cam timing.

 

[Rockey5000]

Thanks for all the help guys, I went to Thumper Talk and found all the info. So far I removed the exhause baffle and did the throttle stop. The difference was unbeliveable. You have a very good post Rich, I didn't know that about the cams. I wasn't going to change the timing, but now I have changed my mind. Thanks for all the help!

 

[1999RM125]

ha a bike takes over 5 minutes to break in... and when its being broken in, you shouldent pin it or come anywhere close to pinning it... mabye the bike just started to break in, then you "modded" it and then it finished after...