Hi, hope you can help me. I have a 2009 yz 250 I race here in Hawaii and we do alot of tight trail riding.My problem is when my bike heats up to the point of it boiling over it just dies out but when I kick start it, it fires right up. I'm not sure what to do.Please help mahalo, Eric

1985 YZ250N, With the Fork off, Cap off, Spring out, take a clear school plastic ruler pore in 5W synthetic fork oil till it's 135mm from the top with the fork tube all the way down, till it just touches the ruler and the 135mm mark. Reinstall the spring, pacer, washer, Damping rod to cap, and install back in the clamps. I raced this bike for 18months in 1985/1986. Change the seals when they leak and toss the 38Kg Fork springs for 41Kg + springs to your riding weight. Over all was a good fork for it's time and Race tech can rebuild the fork and shock to your riding style and you're riding weight. I Miss the Fork flex on hard landings to my other New bikes. I still ride and Race the 85,YZ490 with the same fork.

The factory recommends 15PSI. I usually run 12PSI.

Depends a lot on what tires you have and what kind of "track" you are riding. You typically want a firm tire (more pressure) for a soft surface and a softer tire (less pressure) for a hard track but there are always exceptions depending on the details of the track and what tire you have mounted up. If you are riding a track with a lot of hard braking bumps or firm ruts or even tree roots (if you ride trails) you should run more pressure - like maybe 13-15PSI. If you run less than about 10PSI you risk pinching the tube and getting the rim damaged from sand intrusion between the bead and the tire which can cause a lot of problems unless you change your tires frequently and run multiple bead locks. To run really low pressures usually means you don't have the best tire on your bike for the conditions in my opinion.

To simplify:
Soft track, hard tire - run 12-15PSI
Hard track, soft tire - run no less than 10PSI

I would suggest a 250 2-stroke or a 4-stroke. Lots of power, lots of pull and the motor would likely last you for years. I've raced both the 125 and the 250 2-stroke at the pro-am level (A-class) and the difference in engine life is tremendous. I would re-ring a 125 every week (running 26:1), while with a 250 I could go for 2-3 months or more without doing the top end while running 32:1.

A YZ 125 will definately be a bit of maintenance - primarily because it has a single ring and the ring doesn't last long. A pro or semi-pro racer would re-ring every race (when the 2-stroke was popular) - some races I would re-ring in between motos. I know you won't be racing, but I would still imagine you would want to freshen up the top end at least every other month at the most. Granted - you can re-ring a 125 in about 45 minutes for a cost of about $18 if you know how and it costs a LOT more for a 4-stroke and is more of a job.

Other than the ring, the rest of the maintenance will be about the same between a 2-stroke and a 4-stroke. You'll still have to do your air filter every ride and your engine oil (tranny oil in a 2-stroke) every other ride. Tires, spokes, sprockets, clutches, chains, brakes - all pretty equal maintenance between the two. Lots of variables, of course.

The difference will be keeping the motor fresh and for that, the 4-stroke will beat the 125 2-stroke. Not the 250 2-stroke, though - these motors last as long or longer than the 4-stroke and are a LOT cheaper to maintain/rebuild.

This is MY experience and my opinion. Your mileage may vary.

Scott

Sounds like you are fouling your plug.Some possible causes make sure you air filter is clean. Correct gas oil mixture.How the bike is being use Trail riding/freestyle.This bike in stock form will foul plugs if it is being used as a trail bike.If everything is good air filter/gas-oil. Then you need to do a spark plug reading. This will determine if you need to rejet the carb. Hope this helps
D.

First of all if the bike sat for years the plates may just be stuck together. Disassemble and inspect the clutch. For racing some clutches are all aluminum plates. To last longer two or three plates may be metal. Some people put in all metal because they do not race and that set up will last longer. Aluminum plates are soft for better clutch grab. Aluminum plates tend to wear out faster than the the friction plates. So when you inspect the plates figure on replacing all the aluminum's , your friction's and metal's are probably fine.

I race mine (it's a 2009), but I also trail ride with it. It's good either way.

This is not good. Heat builds up without oil in the engine. The bike probably seized up due to the heat. That means new piston and rings and possibly a new cylinder. Crank bearings could also be severly damaged. Gears can weaken and loose temper, ( become softer). You had best go to a dealer or other bike mechanic and let them look at it. The repair will probably be $1000 or more, and an exact cost is only a guess because without tearing the engine down you don't know how bad the damage is. If you are really lucky, only the top end has been damaged.

hot it up? you mean make it go faster ? wow it's a realy quick bike right out of the box if the bike seems to be lacking power easy check is the air filter ...pristeen like so clean you would eat off it? 2005 ...when was the last time the top end was done ? about every 30 hrs for a two stroke half of that if you are racing it by racing I mean getting on a motocross track and riding with other guys about your skill level till you have arm pump that makes you wish you had stayed home. if the above conditions have been met then a pipe is probably your most logical choice don't wast time and money on the engine making it high compression and needing race fuel 100++ octane is a total waste for all but the elite riders and it makes the bike unreliable and fussy "like a hot blonde pretty to look at but high maintence" Good Luck & Ride safe

depends alot on your, riding style, final gearing, terrain, and to an extent even jetting/temperature/humidity/etc.

I have figured 2.5-3 hours of average riding based on 2.1 gallon tank for trail type riding. If your really aggressive/heavy on the throttle, you may get closer to 2.

if you ride with quads, get them to bring a small container of premix for you. try not to run out tho.........no gas=no oil.