Hey guys i bought my scrambler about a month ago and its been great up until today. i just changed rear brakes last night on it, and got ready to go riding today, pulled out, and the bike wouldnt go. it acted as if it had an emergency parking break stuck or something but it wasnt stuck. it just felt like the power dropped off and wouldnt rev and go. the bike will start up and idle fine, it'll run fairly good at low rpm but once you get into the midrange and top end, it will either flatten right out or backfire and pop. Here's what i did so far. i checked the air filter, good and clean. i changed the spark plug put a brand new one in (the plug was a bit rich so just changed it to be on the safe side). I took off the carb the main jet was a 170, everything inside looked pretty clean, the float height looked ok, etc. The choke seems tight but i push and pulled on it to loosen it up a little, "seems" ok to me. I checked the fuel tank, its flowing fine. I checked the fuel lines, now here's the trick...the impulse line (by the clymer manual) says its not supposed to have any wetness to it at all, i pulled the line off and it was wet. They say if its wet then you have a bad diaphragm but i need a mighty vac to check for sure. A diagraphm is around 35 bucks so i really want to make sure but i cant take off the pump because then ill definetely need a diaphragm. Im very frustrated with this, by the way its a 2001. Everything on this bike is super clean, i just dont know why it up and did this to me. Anyone have a similar experience?

 

it sounds like you got your rear brake adjusted too tight. do you have the brake on the axle or output shaft. if it's on the output shaft the bolt that runs in the center of the caliper needs to be backed out. there's a 7/16 nut that locks down to hold the bolt from backing off. loosen it and back that bolt out till your rear tires turn freely then lock the nut back down. if your caliper is on your rear axle i can't help you there. i've never messed with that style.

 

Does sound like you did something to the brakes but the backfire and pop sounds like a lean condition or the brakes are bogging down the motor. Try loosening the fuel cap then try it. The vent might be restricted.

 

thanks for the replies so far. what i did was went ahead and took a look at the rear brakes, i loosened them up, and in fact i even took them off and drove the bike and still did the same thing. i took one of my buddies fuel pumps and switched it just to see, but his fuel pump wasnt the right one unfortunately. so i went ahead and switched the lines back onto my fuel pump, and for some reason, it started running fine again. the reason why i know its not a lean condition is because the plug looked very rich, plus it has over 100 hours on that bike and its never popped or sputtered at all. At any rate, im happy that it "seems" to be working correctly now however im baffled at why it did that to me. Every indication was pointing either electrical or fuel obviously, but why it up and started working fine is weird.