i just bought my 03 praire about a month ago it ran perfect until about 50 miles then developed this nasty flat spot off of idle it used to yank the wheels upon full throttle now its flat on the bottom then it takes off and it doesnt have the power it had when new had it to the dealer they said the carbs was out of sinc but it stil has the nasty hesatition off of idle when you hit it wide open off of idle ??? any answers anyone???

 

When I took the red primary spring out and put the stock one back in I noticed this too on our 650. I wanted to leave the red one in but the wife didnt like it. The build up of rpms the red spring gives it eliminates the hesitation thats there. Before the red spring I didnt notice the hesitation was that bad, when you get used to the red spring power its hard to get unused to it.

 

1. Carb sync won't give the you the performance problems you have. 2. If the engine seems to run well, your belt could now be loose. That's the most likely cause. 3. Find a better mechanic - carb syncronization is a lame diagnosis. It's under warranty - make them fix it.

 

you can also notice it when free revving i have my brother n laws new 03 here also with 40 miles on it and i rode it for comparison his doesnt have the flat spot and revs our good even free revving mine was perpect till it hit 50 miles!!