I know this is a ATV forum but asking a dirtbike question. Will a Yz 125 out run a Crf 250R on a top speed race?

 

Top speed all depends on the gearing....... it has very little to do with power......

If both machines were equally geared they would have the same top speeds regardless of power.

 

Not if one has a higher RPM at full throttle. Also one may get there quicker even if they are closely matched,... especially if one is a 4 stroke, and the other a 2 stroke. (I'm not familiar with the two bikes, configurations on motors)

On a long open straight,.... there will almost always be a faster bike, simply due to limiting and added factors such as rider weight, maintenance kept up or not, worn stuff (if one is simply used more it could either fall behind or run off on the other, from internal wear, either still close from not broken in enough, or worn out, or "just right" wear/ Just broken in good.)

Also keep in mind, rider skills.....

 

CR250 is is a bigger class, and is a faster bike, bigger engine as well. A YZ125 has some ***** though, I had an 87 brand new one and that powerband felt strong, I never beat a CR250 with it, but kept up to them to an extent.

 

its a CRF not a CR otherwise that yz 125 would get punished, alot of factors though, but both bikes are same class the thumper will put the power to the ground a little better, but the 2 stroke is a little peppier, would be a very close race but the thumper might edge out on top speed.

 

They are very equally powered. In mx racing they would be in the same class.

 

Whats the CRF, a 4 stroke?

 

Yes, the CR is the 2 stroke and the CRF is the 4 stroke.

 

Yes, the CR is the 2 stroke and the CRF is the 4 stroke.

 

True...... one will get there much quicker, and as you state RPM will vary the top speed slightly......but overall you are only talking about a couple MPH difference......

All things being 100% equal, including rider weight, skills, gearing etc...etc...... The 250cc 2-stroke would be much quicker than the 250cc 4-stroke. It would hit top speed faster....

However, the 250cc 4-stroke could equal the same top speed once both are pinned. It could not close the gap that the 2-stroke creates while getting to top speed.....

I should have been more clear but I was speaking in direct final numbers....