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Rebuild Intervals for 250 2t

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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?

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

Yikes!

I change once a year

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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.

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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.

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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.

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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.

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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!

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Yikes!

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

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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.

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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

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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.

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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
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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.

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

I run mine 1year at a time.

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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

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Yikes!

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.

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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?

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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

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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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