Rebuild Intervals for 250 2t

I've heard it vary pretty greatly on rebuild intervals from 30 hrs to 100. For a beginner rider who doesn't race but rides a mix of small home made mx tracks, some fast fire roads and some tighter trails. And rides a few hours each weekend in the spring/summer maybe a little in early fall. With all that how many times a year would a 250 2t need a top end?

I also hear alot of people around here say that a 2 stroke requires more routine maintenance than a 4t but its just cheaper. Is that true?

with less than 6 harescrambles a year and trail riding every weekend. i do them every 200-300 hours.

with less than 6 harescrambles a year and trail riding every weekend. i do them every 200-300 hours.


I change once a year

Depends. Some run till the compression is so low, the bike will not start. Some pros re-ring between motos. I suspect your intervals may be somewhaere inbetween.

In reality, if you do regular compression tests (keep good notes), keep the air filter clean, avoid submerssions, do not rev the snot out of it needlessly on the stand, you will know when it needs attention. More or less the same for a 4S. There is no set interval. Really depends on you.

I've never understood the once a year thing. What if you ride 1/2 as much as the previous year? Put an hour meter on and get precise with your intervals that way you have more documentation to come to meaningful conclusions about changes in mix ratio/jetting/compression, etc.

If it were me, I might not go quite as high as schrode, but I would easily put 125-150 hrs on mine.

I do every 50-60 hours regardless if compression is good. Top end is cheap to rebuild. The bottom end I will go until 200 hours or when it starts to lean towards being out of spec. But, I always replace things before they break.

I would suggest buying and hour meter and start keeping a log of everything that you do to the bike and at what hour. I do a mix of hare scramble racing, motocross, endure, trail riding. I just changed my YZ250 top end at 42.7 hours. It needed to be changed but I was still in that safe range. It cost basicly a few hundred dollars a year to keep a 250 2 stroke up and running for an average rider. If you race a lot or do a lot of riding throughout the year then the cost goes up.

once a year. and thats probably about 150 hours or so. bottom end, just check everytime i do a top end and take a good look at bearings and replace what is needed then button it all back up for the next season!


I change once a year

1 1/2 to 2 years here.

edit: i just finished tearing down. now i'm doing 3rd rebuild on my 08 husky wr 250. she's getting a replate now. there's wear marks w/ missing spots of cross-hatching on the cylinder.

Edited by schrode

A beginner could go 200 hours on a 250T top end, as long as he never sucks dirt, runs lean, or with too low octane fuel.

I have lots of people around me trying to convince me to go 4 stroke. They claim that 2ts may be cheaper but 4ts last alot longer between having to rebuild and that 2ts are really finicky and you will spend more more time working on jetting and tuning/working on stuff than riding. Is there any truth to these claims?

Edited by tw191

I have lots of people around me trying to convince me to go 4 stroke. They claim that 2ts may be cheaper but 4ts last alot longer between having to rebuild and that 2ts are really finicky and you will spend more more time working on jetting and tuning/working on stuff than riding. Is there any truth to these claims?

No. These people are, at best, ignorant.

I have lots of people around me trying to convince me to go 4 stroke. They claim that 2ts may be cheaper but 4ts last alot longer between having to rebuild and that 2ts are really finicky and you will spend more more time working on jetting and tuning/working on stuff than riding. Is there any truth to these claims?

This forum is biased towards 2 strokes and especially the 250 2 strokes. I dont think many have experience with 4 stroke race bikes. Ill start off to say if you stay on top of maintenance, you should not have a problem with either. Both will need changed at about the same rates and if anything I would imagine the 2 stroke would last a bit longer considering its reline is much lower, that is considering we are talking 250f vs 2502t. I blew up my 250 2t a while ago and it was $400 in bottom end work plus a top end so $600. Beats me how that compares to a 4 stroke going as i have never blew one up but i had a 250f and it lasted for a long time and only had top ends put in it, with a clutch. My topends last <40 hours but im racing at an expert level and that will vary for you. Ride both bikes and pick for your self, dont let someone else pick for you.

Edited by Ringo25

Basing a 2 stroke rebuild on hours is a rough guide at best. How you ride, how much you ride, what oil ratio, filter upkeep. forged vs cast. I measure pistons, cylinder, ring gaps, visually inspect pistons etc.

Good rule of thumb, once you have a fresh motor break it in, check compression, write it down, once you drop 10% of you broken in compression psi take it apart and have a look.

Run it till it blows then buy a different one. Lol

I run mine 1year at a time.

I have lots of people around me trying to convince me to go 4 stroke. They claim that 2ts may be cheaper but 4ts last alot longer between having to rebuild and that 2ts are really finicky and you will spend more more time working on jetting and tuning/working on stuff than riding. Is there any truth to these claims?

There is some truth to that. I own both 4T's and 2T's. The 4T's are less work because they can tolerate wider temperature swings without re-jetting and the pistons are constantly lubed by engine oil. The 2T's require more jetting to keep them running crisp, and pitons/rings only get a small amount of oil.

The kicker comes with the price of rebuilds. The 4T's require more parts and money, especially if there is a catastrophic engine failure like a crank coming apart or piston breaking. My pro buddies also have to replace their 250F crankshafts at 50 hours to keep them from grenading and taking out the engine cases. That isn't the case with the 2T's. Even the fastest guys can run their 2T cranks for 100's of hours without replacement, as long as the engine never sucks dirt.

Edited by CamP


I change once a year

I change every 200-ish hours, which is more frequently than once a year for me. I'm not a big-time-revver, but I do ride hard, and sometimes race, at the expert/A level, and sometimes podium.

My wife rides faster and harder, and has won some national level races, and we have been doing the same 200-hr schedule for her for years without issues. Not all our riding is flat out tho. Quite a bit of it is extreme technical mountain terrain, where the revs are pretty low.

The more hours your are riding on mx tracks, the more frequently you should change pistons.

There is some truth to that. I own both 4T's and 2T's. The 4T's are less work because they can tolerate wider temperature swings without re-jetting and the pistons are constantly lubed by engine oil. The 2T's require more jetting to keep them running crisp, and pitons/rings only get a small amount of oil.

So the 2ts are more work then?

So the 2ts are more work then?

If you consider swapping a main jet 2x per year and small adjustments of the air screw for smaller temperature swings more work... then yes. I used to be terrified of jetting my bikes but it takes a few minutes at most and is extremely simple. I guarantee if you buy a bike, post in that section of this website the modifications it has, people will give you an answer within minutes of what jetting will get you very close to ideal for your local conditions. Modern 2 strokes don't "foul plugs" and all of the horror stories you hear unless your jetting is waaay off.

The hours in between top ends might be less with a 2 stroke (depends on how you ride) however any monkey with a toolkit and $120.00 can do a top end in an hour or 2. For the type of riding you are describing doing I would say you will probably need to do a top end every 2-3 years(based on 26 or so rides at 2 hours a piece). You will probably need to change the trans fluid 2-3x per year and depending on how dusty your local conditions are, you might have to clean your air filter once a month (up to once a weak if really dusty).

Edited by c-slak

Race bikes are more work than trail bikes.

There are very few trail 2 strokes anymore.

In my experience I work on my 2 stroke more often but it's very simple and easy to work on.

I have not owned a "race" 4 stroke for more than a year so I've not worked on any of mine often but when I do work on a four stroke it takes a lot of time and patience and special tools.

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      Let’s put the needle in. These are how the needle numbers go:

      The top clip position is #1, the lowest one, closest to the bottom, is #5. (The picture says six but it is five in this case) For reference #1 is the leanest position, while 5 is the richest. I put the clip in the 4th position. Read at the bottom of the page and you can know what conditions I ride in, and you can adjust them to your preference.
      Put the clip in the new needle, slip it in. Take the vise grips off your grips and start guiding the plunger holder down to the bottom. Remember not to let that assembly come apart because it is a pain in the ass to get it back together! Once you get it to the bottom, put the two screws on, and then put the cover on.
      Now that you have done the carburetor mods, there is still one thing you want to do to complete the process. Don’t worry, this takes less than a minute! On the top of the air box there is a snorkel:

      As you can see, you can slip your fingers in and pull it out. Do that. This lets more air in to the air box. Don’t worry about water getting in. There is a lip that is about 1/8” high that doesn’t let water in. When you wash, don’t spray a lot under the seat, but don’t worry about it too much.
      The next thing you must do is remove the exhaust baffle. The screw is a torx type, or you can carefully use an allen wrench and take care not to strip it:

      The screw is at the 5 o’clock position and all you do is unscrew it, reach in, and yank it out. This setup still passes the dB test. The bike runs 92 dB per AMA standards, which is acceptable. Just carry this baffle in your gear bag if the ranger is a jerk off. I’ve never had a problem, but don’t take chances.
      That’s it! Start putting your tank on, seat, and covers. After you put the seat on, pull up on the front, and the middle of the seat to make sure the hooks set in place.
      Turn on the bike, and take a can of WD-40. Spray the WD-40 around the boot where it meets the carburetor. If the RPM rises, you know you have a leak, and the leak must be stopped. You must do this to make sure there are no leaks!
      Here is my configuration:
      04’ 230F
      Uni Air filter
      132 Main Jet
      45 Pilot Jet
      Power up needle, 4th clip position
      Fuel screw 1.75 turns out
      Riding elevation: 2000ft - Sea level
      Temperature – Around 60-90 degrees
      Spark Plug Tips
      When you jet your carb, a spark plug is a best friend. Make sure your spark plug is gapped correctly, (.035) but that’s not all that matters. You want to make sure the electrode is over the center, and you want the electrode to be parallel, not like a wave of a sea. Put in the plug, and run the bike for 15 mins, ride it around too then turn it off. Then take off the spark plug after letting the bike cool. The ceramic insulator should be tan, like a paper bag. If it is black, it is running rich, if it is white, it is running lean. The fuel screw should be turned out if it is running lean, and turned in if it is running rich. Go ¼ turns at a time until your plug is a nice tan color.
      Making sure your bike is jetted correctly
      While you are running the bike for those 15 mins to check the plug color, you want to make sure it’s jetted correctly now. Here is what the jets/needle/screw control:
      0- 3/8 throttle – Pilot jet
      ¼ to ¾ throttle – Needle
      5/8 – full throttle – Main jet
      0-Full – Fuel screw
      Pin the gas, does it bog much? Just put around, is it responsive? When you’re coming down a hill, the rpm’s are high and you have no hand on the throttle, does it pop? If it pops, it is lean and the pilot jet should be bigger. If it’s responsive your needle is set perfectly. You shouldn’t have to go any leaner than the 3rd position, but I put mine in the 4th position to get the most response. Your bike shouldn’t bog much when you have it pinned. If it does it is too rich of a main jet.
      Determining the plug color, you will have to mess with the fuel screw.
      That’s it, have fun jetting, and any questions, post on the forum, but remember to do a search first.
      Also, if your bike requires different jets due to alititude, humidity, or temperature, please post the following so we can better assist you:
      Average temperature
      Altitude (If you do not know this, there is a link in the Jetting forum that you can look up your alititude)
      Average Humidity
      What jets you are currently running
      What the problem is (If there is one)
      Just do that and we'll help you out the best we can.
      EDIT: The girl using this login name is my girlfriend. You can reach me on my new login name at 250Thumpher
      Then again, you're more than welcome to say hi to her!
      -Phill Vieira
    • By kashlak
      JUst curious of how many bikes,quads,trikes people owned over the years and what they were?
      78 honda atc 70
      85 honda atc 110
      ?? handa trail 70
      78 yamaha mx 80
      85 yamaha yz 60
      82 yamaha it 125
      85 kawasaki kxt 250 tecate
      79 yamaha yz 400
      86 yamaha yz 125
      85 yamaha yz 80 (playbike)
      92 kawasaki kx 250
      93 yamaha xt 350
      and last but not least a 99 kawasaki kx 250
    • By Bosch232
      Were the XL's the predecessor to the XR's?
      I have a friend who's looking at an old XL350, and I don't know anything about these bikes.