We my wife a used 01 Scrammy 2x4 this summer. It was bought in an area of 0-500' elevation.

Our area is pushing 3,000 ft. elevation. Very low humidity. In the summer it was hard starting but once you got it warm and out on the trail it would start OK. Not great but OK. Still plenty of power. I can lift the front wheels no problem.

I tried starting it yesterday at the 3k elevation 45 degrees temp and would not start. Would cough and sputter and backfire bad like a m-80 firecracker going off when cranking over, you could feel the concussion on the right calf /leg. I have never tuned a carb but I assumed it is way rich because of elevation change so I took the k&n off and left air box wide open ( I was in my garage). Finally got it to start and had to sit there and babysit it feathering the throttle for about 10 min then it leveled out. I let it idle for another 10 then shut it off. 30 min later I tried to start and absolutely would not start. Had to push back into garage.

All stock except k&n-no outerwears. Came with bike will be switching to foam filter soon.

Also, it knocks a lot more than I am used to on other bikes I have had . You can hear knock when idling but when you give it a bit of gas the knock goes way down and it sounds pretty much like any big single. I think the idle may be too low. Maybe a valve adjustment is needed? Is that normal with a big single?

 

I have had the same problem with my scrambler and predator. I completely disassamble the carb a clean every passage way, assamble and its as good as new. The knocking is most likely the clutch and that is normal at idle.

 

Is it a 400 2 stroke or a 500 4 stroke?

 

If it is a 500 you could need to adjust the valves.My 500 was getting that way and it had tight intake valves.

 

Big Blue, Sorry, 4stroke 500....Thanks

 

I agree with ftwflh , check your valves for adjustment . Just checked mine and the intakes were way to tight (not allowing the intake valves to completely close). If it's a jetting issue i recomend a dial a jet ... http://www.thunderproducts.com/dial_a_jet.htm

 

I also agree with the replies above mentioning the valve adjustment. Mine was extremely hard to start cold. The intake valves weren't closing they were so tight. Just be sure the machine's tune is good as well. I'd also check the spark plug and see if it looks like the engine's running rich/lean, too. Good luck to you and sorry you're having problems.

 

CHECK THE PLUG? Heck you have the tank off to set the valves change the dang thing if it is bad or not[img]i/expressions/face-icon-small-wink.gif[/img]

 

He didnt mean check if the plugs bad, he meant to see if its rich or lean or just right, but yeah change it[img]i/expressions/face-icon-small-cool.gif[/img]

 

What I was saying is that it is such a pain to get to the plug you need to chamge it any time you have the gas tank off.