250 2 stroke vs 250f bottom end life

[honda424]

hey i just wanted to know on average which lasted longer, 250f or 250 2 stroke crank and bearings... let me know, thanks

[The Spanky]

Too many variables to say.

[CamP]

A 250F turns much higher rpm than a 250T, so in theory, a 250T crank will last longer. That changes quickly if you ever let dirt pass through your engine.

[i_wheelie_longer]

From my experiences, two stroke cranks seem to wear out quicker. I feel like 2 strokes are always scavenging for oil and lubrication, compared to a 4T crank. But I would much rather replace the crank in a 2T than 4T, so it doesn't really bother me.

[Mark6299]

like he said, too many variables. That said, you should mention what kind of riding you would be doing. This is an important bit of information. Basically a 125 two stroke and the 250 four stroke are in the same class. So you are kind of comparing two different class bike to begin with. For example a 250 four stroke needs to rev pretty high to make basically the same power as the 125 two smoke. So if you plan on riding the 250 Two stroke like a 125 class bike, or a 250 four stroke, then it would last a lot longer. I don't really think I am being clear with how I am describing what I mean. Lets put it this way. I do not race but I do ride fairly fast on my 250 two stroke. The guys riding 125 2T and 250 4 strokes make a lot of noise and sound really fast. Then here I am right behind them with a bip of the throttle here and a rev there, a blip here and so on. I am pretty much not on the pipe and basically taking it easy on the engine. The 250 two stroke engine can give out way more than I could ask of it. So with this in mind, the 250 two stroke will last much much longer. This is why I ride a 250 two stroke. Also, in general, I belive that the 250 four strokes are typically reved higher than a 125 two stroke to make the same amount power. That is why they were in the same class. So when you go up a class with the 250 two stroke, it revs lower making a lot of power. This is why many people use 32:1 oil ratio in a 125 2T and 40:1 or less in a 250 2T. So especially I you are trail riding, I believe that the 250 two stroke should last longer. Crank bearings and piston and rings too. My two cents.

[shrubitup]

air filter cleanliness, jetting, mix ratio, oil used, oil change frequency on the 250F, trail vs. mx, narrow gnarly trail vs. quad trail - these all will dictate which one lasts longer.

[honda424]

I ride both my bikes decently hard. I am On the pipe 80 percent of the time on my 250 and I occasionally hit the rev Limiter on my Crf250r. But I maintain both bikes very well. But if you were to guess, about how many hours could I get on a bottom end? And which would last longer?

[shrubitup]

if you haven't sealed up your airbox on the CR then it will be the one to go first.

[honda424]

I clean my airfilter and change oil after every ride and early it the rev limited an don't race on my Crf. And the cr I stay on the pipe most of the time and keep the airfilter clean and change the oil every 2 rides. But I don't race it either. And I mix it at 40:1

[honda424]

I change the oil and clean the airfilter after every ride on both bikes. And I stay on the pipe most of the time on the cr, and I rarely hit the rev limiter on the Crf. But I have a few times. And I don't race either one of them.

[honda424]

Hey sorry posted that 2 times. My computer showed it didn't post the first time so I did it again...

[honda424]

So which would pry last longer if you were to guess? And if. You just guessed then about how many hours would you say I could go on both bottom ends?

[honda424]

Anyone?

[highmarker]

Lubed with 100% oil vs. 2% oil gas mix, sealed from dust and dirt vs exposed to it. Lighter piston better crank balance vs heavier piston more vibration. In theory a 4 stroke crank should easily last longer if a top end problem doesn't take it out. But likle Chokey posted there are a lot of variables, the biggest one being the owner.

[CamP]

Dirt kills 2-stroke cranks. RPM kills 4-stroke cranks.

[honda424]

so if you were to guess.. about how many hours can somone go on a crank and bearings?

[highmarker]

what bike? racing or trails

[honda424]

i do trails... and about how many hours for both?

[CamP]

i do trails... and about how many hours for both?

A trail rider should be able to get several 100 hours out of a 250 crank, whether 4st or 2st. Just don't ever allow dirt to pass through your 2st engine or let the oil level get low or run the oil too long in your 4st.

I've been riding/racing motocross for almost 40 years and I've never lost a crank, knock on wood. Most crank failures are self inflicted.

[Sierra_rider]

so if you were to guess.. about how many hours can somone go on a crank and bearings?

I probably had ~600 hrs on my 2t crank when I replaced it. Even when I pulled it out it was still tight,but replaced it for peace of mind. Most of those hours were from trail riding with a little bit of mx.