KX 450 or KTM 450 or 500

[DynojetResearch]

ok , now that you guys have made the decision process a little easier I am leaning towards the KTM just one more question a 300 2 stroke or the 450 pros and cons cost to rebuild I have had a couple people tell me that the 300 makes good power and there is nothing like the sound of a 2 stroke.

thanks again

A little easier to make the decision for what to pull the trigger on is what we're here for!!!....300 2 stroke versus 450 4 stroke is a difficult decision even between those 2. If you're looking for sound - yes the 300cc is nifty making people wonder who is cutting wood with a chainsaw in the forest in February?! If you're looking for the utmost in "easy" performance, the 450 bikes take the win in that category. I can attest that I have yet to see a 300 2T out-torque a 450 MX bike from a low 2000RPM through redline - the 450 4 stroke always runs a higher torque value to the wheel than any XC/XCW version of a 300...back to back on the same dyno. This is crucial in the snow....

While you're aggressive on the snow, would you plan to ride this bike in the summer? If so, are you an easy, flowy ATV trail rider, hard core MX-er, or tight tech single-tracker? 300's excel in the tight trails feeling light, swift, and easy to pick up, whereas a 450 has a long powerband for fast trails or accelerating hard into kickers on a track.

Along with some of the things mentioned, the best part about the 450 4T is the EFI and how it compensates for every environmental condition such as air temp, engine temp, and PRESSSURE (courtesy of this nifty MAP sensor part number 75041085044 specific to the KTM bikes also found on each OEM EFI bike) --- if the elevation increases or a low pressure weather trough blows in thus lowering the Atmospheric pressure, the MAP sensor picks up on this. Same engine, same suction at sea level versus a high elevation produces a different sensed air pressure entering the engine which shifts the resultant fuel output to the cylinder to a different trimmed amount. A carbureted 2 stroke will take some creative engine shrouding, carb heating, and pipe wrapping to create a consistent machine for operation during the winter months, but will keep up with your buddies just fine....
But Don't get me wrong - the first OEM to fuel inject a 2 stroke making it available in the states - I will buy it or build my own whichever comes first. But to get you rolling this season, a 450 MX bike sounds right up your alley. The KX pulls hard with a powerband identical to the KTM, but doesn't have E-start - so if you want E-start, go for it - but be prepared to pay Extra for the Orange color.

 

[Rush44]

Along with some of the things mentioned, the best part about the 450 4T is the EFI and how it compensates for every environmental condition such as air temp, engine temp, and PRESSSURE (courtesy of this nifty MAP sensor part number 75041085044 specific to the KTM bikes also found on each OEM EFI bike) --- if the elevation increases or a low pressure weather trough blows in thus lowering the Atmospheric pressure, the MAP sensor picks up on this. Same engine, same suction at sea level versus a high elevation produces a different sensed air pressure entering the engine which shifts the resultant fuel output to the cylinder to a different trimmed amount.

Thank you Dyno for the clarification on this. The last time I was looking into altitude compensation I was riding a KX450F which only has the temp sensor as part of it's simple FI system. This is great news about the KTM since it does a better job of explaining why this particular bike does not overfuel as bad as many of the Jap bikes. My reasoning behind this was because the fuel map is already leaner than most other FI bikes so I assumed that the starting leaner map was the cause of this. Great news and thank you for your knowledge. Much appreciated!

Looks like the 12.5 Dungey was the first this sensor was available on the 450sxf line?

 

[SnoFro]

As for altitude compensation, KTM, Husaberg, and Huskys all use a map senser atmospheric pressure.

 

[350scott]

Where did you get the 610 kit from and how much is it including what is needed?

//Rob

It's a Thumper Racing kit that I got through Brewster West in Turner Valley AB. All in with the Thumper Racing kit (cylinder, piston, gaskets), Dobeck AFR+ fuel controller and exhaust O2 sensor bung welded in was around $1500 CDN (I think) all in. Note, this was with the US-CAN exchange rate about a year ago. Note 2, if you want to be able to convert it back to stock you need to figure in the cost of a new cylinder. I had a spare cylinder from a bit of an oopsy so I didn't need to buy one. Note 3, I did the install myself so there was no install labour.

 

[JeffreyG67]

thanks for all the great information this has made things a lot easier

 

[Jaynelson]

450 xc-f is tough to beat. Get all the good stuff from a race bike (sx motor, light weight, close ratio tranny, stiffer forks). With all the good stuff from a woods bike (e-start, larger fuel tank, electric power). No reason, IMO, to buy the SX over the xc with regards to snow bike application. Kawi is a great bike but with more compromises....less money tho, which is nice.

If you want to primarily ride mx in summer - kx or sx. If you want to primarily ride woods in the summer - 500xc-w (or 500exc if you want street legal)....or a 300 obviously. If primarily a snow bike, 450 xc-f all the way. It is a hybrid woods/race bike....which is basically what everyone is trying to build at home for a snowbike anyways. Only downside IMO...as a woods bike for an average rider...its a bit much in the aggressive singletrack But that only applies if you ride that stuff.