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Preparing a Used Bike for Riding

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Hello everyone, I'm new here at thumpertalk and completely new to dirt-biking as well. I recently bought my first bike, a 2004 wr250f. A bike purchase that has been long overdue since I rode my first dirt-bike (80's honda xl80) many years ago. I would consider myself mechanically inclined as I do any of the work on my SUV and have picked at/got in the way during various repairs to dirt bikes, snowmobiles, atvs, etc over the years.


The history of the bike is completely unknown to me, although the bike does not seem to have had too hard of a life. The bike seems to start, idle, drive well all through the gears, steer and stop without issue.  I have also browsed the service manual the past few nights to familiarize myself with the bike. I must say I was surprised at the service intervals, but I'm sure the manual may over exaggerate the frequency of some maintenance.


The bike has been striped of a few factory pieces: Lights, electric start switch (motor is still there), kill switch (only the on/off button is there), kickstand and the exhaust has been replaced with a 'fmf powercore 4' (i think anyway). I'm still unsure if/and what 'free mods' have been done but expect some have been due to the other modifications.


I have ridden the bike probably about 5 minutes in total since i bought it a week ago because i want to make sure it is 100% reliable before i do so (despite the pressure from friends :cool: ). There are two things that concern me so far. When I quickly twist the throttle from an idle it bogs down for about a second. (I'll upload a video soon). The other thing which concerned me much more was oil pouring out of the dipstick hole when I went to check the oil. (let it warm up, waited, then checked). Based on my reading on here this could be due to too oil much or possibly a dirty/clogged frame oil strainer.


From browsing the forum i have put together a list of things I should do before I ride, considering the bike has an unknown history.

-Change oil, replace filter and clean oil strainer in frame.

-Replace air filter. (I have a k&n recharge kit, would this do rather than replace/)

-Change coolant.

-Grease suspension linkages, axles, and steering head. (What type of grease is best?)

-Lubricate cables and chain.

-Change spark plug.

-Check the valve clearances

-Replace the old gasoline in tank.


Anything here that I don't need to do before my first ride, or anything to add? Any quick tricks on checking the valves or just follow the manual to a t? Should I do anything with the carb? (fairly intimidated by it, have no former experience)


I also have some seafoam left over from cleaning the throttle body in my SUV, is it okay to run things like that through the bike, if so where is the best place to run it through?


Sorry for the long read but I wanted to be in depth as possible, and also introduce myself.


Will post pics asap!!

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I'm all for changing the engine oil (and pouring in the correct amount shown in the 2004 Yamaha WR-250FS Service Manual - you DO have that book...right?), oil filter, and checking the oil tank strainer.


I would throw the current air filter away and only keep it if you knew with 100% certainty the previous owner literally installed it 5 minutes before you came and bought the bike.

I wouldn't trust it, and I'd buy a new FOAM air filter of a quality brand like Twin Air, Maxima Premium, or Uni Filter.

Also, use a BONA-FIDE foam filter oil when oiling the filter (I always use Maxima FFT foam filter oil).

Service the air filter (clean, dry, and re-oil) after every ride, no matter what your buddies say (Example: I have a very intelligent riding buddy who is a "precision machinist" who can make itty-bitty parts by hand, but yet completely neglects his dirt bike air filter and chassis bearings. Go figure.).


General-purpose lithium-based grease if fine for the chassis bearings.

This is also another biggie you need to do not only now upon first getting a used bike, but also periodically once you start regularly riding the bike.

I ride my 2002 WR-250F every Sunday and grease my suspension and steering head bearings once every three months.

Don't forget about the top shock absorber bearing while you're at it.

You can decide on your own frequency schedule based on how often you ride and how much gunk you tend to ride through, but be certain not to be like my machinist buddy - don't kid yourself and be realistic.  :)


I'd lube the cables, throw away any that are suspect, and not just lube but REPLACE the drive chain for safety, unless, as with the air filter, you know for sure it was replaced just 5 minutes before you bought the bike.

Using an unknown drive chain is risky.


I would check the valve clearances (write down the measurements) and do it again shortly after you start to ride the bike regularly (and writing these measurements down, too).

If they are at the same measurement positions, I'd then decide to check them on occasion. 


The WR-250FS service intervals shown in the Yamaha Owner's Service Manual are really no different than any other dirt bike sold by Yamaha over the decades:


The recommendations shown in the manual are realistic if you are racing the bike and earning points are more important than showing any kind of mechanical sympathy for the machine you just bought (AKA not giving a sh*t about beating the piss out of it for whatever reason).


If you are a for-fun rider who rides for recreation (even if you can ride fast) and will stop short of plowing through the muckiest bogs and swamps and isn't at peak revs all the time, the service intervals can be extended, with the exception being the air filter which is serviced after every ride.

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So I changed the oil, coolant and checked the valves so far. I think the valves are ok because I fit the feelers what were within spec under the cam. But here is where I have a question. How hard should you have to push before it goes in. I'm worried I may have got a false reading by pushing too hard (if that is possible).

I also confirmed that the grey wire has been done, it has a yzf throttle stop installed and there is a few holes in the side of the air box.

And finally I have a video of the bike running. I hear what seems to be excessive cable noise coming from the top of the engine, I could be normal but I'm going from cars to bikes so it seemed loud to me. Also I have a pretty bad backfire/bog as you can see in the video, I'm guessing it might be lean but I'm not sure because it started easily today with no choke at about 18 degree celsius. Feel free to point me in the right direction. :)

(not sure how to embed a video since I am doing this from a mobile device)

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Engine sounds normal to me.


If the bog is still there while actually riding the bike (not in the garage), make sure the carburetor is properly clean and the accelerator pump works correctly.

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