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2 stroke vs. 4 stroke gas MPG

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I had a Yamaha DT400 2 stroke long ago. Great power but only 40 MPG at best. WR250F now, dualsported, I get 60 MPG. I built a Yamaha RD350 2 stroke long ago, lots of power but only 36 MPG. My Honda 360 got 57 MPG. YZF600R got 54 MPG. TT225 got 60+ MPG. 50cc 2 stroke moped got 57MPG.

On a 2 stroke, when the piston gets to the bottom of the stroke, the exhaust is rushing out at the same time the air fuel mix is rushing in, having been compressed in the crankcase. Some of that air fuel mix rushes out the exhaust port without getting burned and is wasted. When the piston is at the bottom of the stroke both the intake and exhaust ports are wide open. On a 4 stroke, depending on the valve timing there may be some overlap between intake and exhaust but nothing like a 2 stroke.

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yea 2 strokes arent that great on gas mileage. thats one of there downfalls

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by definition you should use more fuel in a 2 stroke.

For the same distance traveled, at the same RPM, you'll use double the fuel in theory. Because it makes power twice as often as a 4 stroke.

Duh

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Why does it matter??

+1

Well it doesn't to most including me. But if you are trying to figure out the cost benefit of one over the other the amount of fuel could be a factor.

We have one of each at the moment, yz250 and yz450f. We also had a yz250f and a RM125/144, yz125. Among others.

The two strokes take what seems almost double the fuel of the 4 strokes. That may be a bit of an exaggeration but I have never really tried to figure it out.

We love them both for different reasons. But the

Braaap is hard to beat.

:cheers:

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My 450 sucks gas, i can just about run it out in a 20 min practice moto at the local sx style track.

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My 440 2t is still on same 5 gallon can at 35hrs ride time.

3.5 gallon tank.

You will burn more on MX track than trail riding... more wot.

I was told it would drink fuel but hasn't been any worse than my 300exc or the 250exc.

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+1

Well it doesn't to most including me. But if you are trying to figure out the cost benefit of one over the other the amount of fuel could be a factor.

We have one of each at the moment, yz250 and yz450f. We also had a yz250f and a RM125/144, yz125. Among others.

The two strokes take what seems almost double the fuel of the 4 strokes. That may be a bit of an exaggeration but I have never really tried to figure it out.

We love them both for different reasons. But the

Braaap is hard to beat.

:cheers:

I only ride my YZ and RM and have yet to think of the MPG. I'm out to have fun and ride. WHY limit myself because of the MPG of a bike? Yah know?

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If you were running fast gas, torco, av-gas it would be higher.

Remember its vacation time.. prices go up. Then they will blame it on a natural disaster or refinery issue etc. Check prices in other countries and then you will be happy paying that much.

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I used my '07 YZ450 for some dual sporting back a few years ago, and the loop trails I was on were milage marked. Pegging "MPG" numbers is almost impossible as there are SO many variables that dictate actuall "MPG" and also the fact there is no way to acurately measure miles traveled (unless your bike is modified with a digital speedometer). I do remember I was riding logging roads, averaging 35 mph, with light engine loading and I was able to travel about 44 miles on a tank of fuel. So that is about 22 mpg. (this data per my Garmin GPS). I also recently did some riding on my YZ144 and I again gathered GPS data and I was able to get about 17 mpg in similar conditions.

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