I have a 97 scrambler 500, that is having issues with timing. I had to common issue of the motor not revving up, but would idle fine.
so far I’ve replaced the Cam and Rockers, new Carburetor, CDI Box, Stator and pulse, as well as the main coil. Same issue will not rev up. Checked timing and no matter how much I move the stator plate, timing won’t advance to hit the timing mark. It’s retatrded. FYI, the old Cam was only worn down less than a thousand of an inch, so old Cam was within specs. I’ve pulled the ETC wire with no change. I’ve pulled the Rev limit wire and no change. I am at a loss and need help please !!!!

 

May not be timing related if you're sure on the cam chain,cam sprocket and crank sprocket alignment are correct.Air box and filter ok? Has to be sealed right or the engine will bog. Plus if it's a Chinese carb have you gone into it,cleaned all passage ways and checked the jetting against the stock Mikuni carb? A lot of them had dirt and trash,some had metal shavings in the bowl according to some that posted on these.Plus have you pulled the fuel line from the carb and cranked the engine over to see if the pump is working ok? Should be a steady stream of fuel if it is.

 

I Pulled the fuel line going to the carb and the flow was a spit and sputtering, I bypassed the fuel pump and Ran it gravity fed straight to the carb. I have acceleration now, but there’s definitely a flat spot in the throttle. Once you get past that flat spot, it will Rev all the way up.
as it comes back down from high RPMs, it spits and sputters and stalls. I’ll pull Carb and go thru it next. Thanks a bunch for the advise. I assumed because it would idol it was getting fuel.

 

Get a cheap fuel pump on ebay or amazon for 12 bucks or so and hopefully that'll solve your problems. Plus don't chunk that $350+ Mikuni carb if it's not damaged beyond repair. Just get a carb kit and rebuild it if the Chinese carb doesn't do that well.

 

Thanks for the fast reply, just ordered fuel pump and new choke cable, the old carb is just fine, it just needs a new float needle. I was having difficulty finding the correct Needle seat rebuild kit for the original Mikuni Carb?
97 is a tough year to Nail down parts

 

97-98 Sportsman 500 kit(Shindy 03-428) is basically the same for the Scrambler 500. Main jet might be different size but still a pretty good deal for all that you get.https://www.ebay.com/p/Shindy-03-428...-Kit/745752913
By the way this is the introduction area.. Welcome to the forum.. Future questions or posts you can go to the Polaris general section or the expert section.