I have a polaris scrambler 400 (1999). I went on a ride recently and the bike operated fine for the first 5 hours but started to run like crap after a while of riding. It is back firing when you rev. it and let off the gas. It acted like there was dirt in the carb holding open the needle and loading up the carb. I cleaned the carb. and put it back on. I started it for the first time and it it idled up then down to a stall. I started it again and it idled up and then idled down and almost stalled until I gave it some throttle. As long as I keep giving it some throttle it will stay running but it back fires after I let off the throttle. It seems like to much gas. Could the reeds be bad causing the bike to run like this or even time to rebuild the top end. I am lost on this one.

 

Hows the air filter? 2 strokes are very sensitive to dirty filters.

 

The filter is clean. I even took it out and ran it but still the same. I am going on another ride down at Hatfeild and McCoy next month and need to get this rascle fixed. Don't want to take the trailblazer. Need the 4 wheel drive on the scrammy.

 

You can check your compression to determine if it needs a rebuild. Needs to be better than 115psi. Check your reeds and fuel filter. You need to make sure it is getting enough gas. It could be that you drain the float bowl everytime you start it and it is starving for fuel. I would start with compression test.

 

Would it be back firing if it is starving for fuel. I thought it only back fires when it is loading up with fuel. I will start with a compression test. Then move to the fuel filter and reeds.

Thanks for all the help GE4x4 and 2manytoys

 

You might want to check the flywheel,make sure the key didnt shear.It will have these same symptoms.

 

Yeah, I had problems like that when my flywheel got trashed. The keyway was widened out to 3 times normal, the flywheel was spinning part way on the shaft, and throwing the timing way off.

I had to get a new flywheel, sucks because that one was race cut, then i had to get a new flywheel and have that one cut. Its on its way back from Rick now, along with a chain tensioner.

 

could the flywheel also cause my electric start to not work. Not lining up with the bendiex on th starter. My electric start will click but not engage. I might have to check the flywheel then.

 

Hey, Troyer23J
Did this mess up the shaft that the key fit in or is the flywheel softer than the shaft.

 

You may also want to pop the throttle cover off and check the throttle "cutout" system ETC