which engine is the better choice?

[mini chopper]

okay so im building a small buggy, i have to engine options, the first being a yz250f, the second a kx250. which do you think would suite me better for off roading? or if i was to build a shifter kart, with a race chassis and everything, which would be better?

 

[DCProductions]

The kx250 has 42 hp? (http://www.supermotojunkie.com/showthread.php?30465-Any1-know-stock-HP-ON-2001-KX250-or-RWHP)

and the yz250f has 34 (http://en.wikipedia.org/wiki/Yamaha_YZ250F)

So I would say the kx250. In both applications it would be more hp, but are you asking this for other reasons than just hp?

 

[CaptCanadia]

I think he wants the engine to be easily modified as well. From Bing searches I think the yz is easier to modify. You'd have to look more into yourself though.

 

[mini chopper]

not really the HP, but how will it perform? will the 4 stroke have more low end than the 2 stroke? i mean a 10 Hp difference is pretty big and i would take that. plus a 2 stroke is lighter. so i think im going to take the kx, i was just looking for your opinion as to what engine you would use if it was your kart

 

[CaptCanadia]

Well ya that's true. For a shifter you have to go with a 2 stroke. It just wouldn't be a racer without it.

 

[DCProductions]

You can gear a 2 stroke to perform reasonably well at low end, but I see your issue. I didn't even see that those two engines were different strokes! I still think that 8 more hp can compensate for any advantages the 4 stroke has.

 

[anderkart]

or if i was to build a shifter kart, with a race chassis and everything, which would be better?

With a race chassis, I'd suggest using a honda CR125. Hardly any racekart tracks in the USA allow engines over 125cc. to compete (and this model engine is by far the most commonly used so its easy to find all the special parts you'd need like motor mounts, pipes etcetera).

So using any 250cc would eliminate any chance of racing at a track and also lower your karts potential resale value. A CR125 shifter racekart would be so fast you wouldnt believe it.

 

[CaptCanadia]

Sorry to ask this, but anderkart what would the minimal be to compete and have fun? what would that cost me?

 

[Homemadgokarts1221]

I like the KX250 better

 

[anderkart]

Sorry to ask this, but anderkart what would the minimal be to compete and have fun? what would that cost me?

You might get lucky and find someone selling a used one for $500, but shifters are usually the most exspencive racekarts of all the different race classes and could easily cost $5000 new. You could research some used prices at this search link: http://www.google.com/search?source...AZ_enUS369US369&q=for+sale+125cc+shifter+kart

 

[CaptCanadia]

Okay I'll defiantly research this stuff. Thanks.

 

[Doc Sprocket]

okay so im building a small buggy, i have to engine options, the first being a yz250f, the second a kx250. which do you think would suite me better for off roading? or if i was to build a shifter kart, with a race chassis and everything, which would be better?

I'd go with the 4-stroke on the buggy for grunt, and the 2-stroke on the race chassis for light weight and speed.

 

[B man]

I'd go with the 4-stroke on the buggy for grunt, and the 2-stroke on the race chassis for light weight and speed.

i thought 2-strokes had more grunt?

 

[DCProductions]

2 strokes consistently have less torque but higher rpm, if I'm not mistaken.

 

[CaptCanadia]

Ya you'd get more speed with the 2-stroke.

 

[B man]

how do they have less torque? they fire every time opposed to every other time? shouldnt that equal more torque?

 

[machinist@large]

how do they have less torque? they fire every time opposed to every other time? shouldnt that equal more torque?

You are confusing torque with horsepower; they are related, but different. Torque is what actually moves the load; horsepower is the rate at which the work is getting done.

In your question you asked if firing on every turn of the crank = more torque. Somewhat. what it really makes is more HP (rate at which work is being done).

 

[DCProductions]

The gas does not produce as much "oomph" because it is mixed with oil. Also compressions are different, but because it fires every stroke, it can achieve higher rpm and in most cases, higher hp than a comparable displacement 4 stroke.