I have a 97 Scrambler 500, that is having issues with timing. I had the common issue of the motor not reving 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. And now after good help from “Old Polaris Tech”, I’ve replaced the Fuel pump, 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 removed the exhaust and completely cleaned it, it wasn’t clogged. Does anyone know what actually Advances the timing? I am at a loss and need help please.

 

Advancement is electrically through the cdi module. Hook the etc wire back up but leave the black wire from the limiter off. Mechanical timing needs to be spot on,hopefully you've got that right if I remember correctly from your other posts.If in doubt look at this.https://atvconnection.com/forums/pol...ml#post3305250 Plus have you made sure the cam decompression lever spring hasn't moved from the lever? This can stop one from revving up also.Plus check compression. Should be between 55-90 psi on average because of the decompression device.

 

Sorry for the late thanks, but I don’t get to work on this ATV until I get off work and have time. I followed your instructiosn and went ahead and pulled stator plate. Doubled checked the timing chain in relation to the single plated link and the Dot on the crank Cam drive spocket tooth. Then I made sure the same goes for the two plated links on top Cam sprocket teeth dots. Everything was spot on lined up. I pulled the side plate cover to double check the Compression release spring and actuator ball, it was up and visible. I will get back to you on compression, but I can tell ya it’s difficult to rotate engine with plug in. But I’ll get you a good number shortly. What else could it be if compression hits. Good number? CDI?

 

One thing you can try if you haven't already is to use a timing light to see if it flashes in unison with the limiting. If it does,I'd go through the stator and electrical checks in the manual.1997 Polaris Scrambler 500 Service Manual PDF Download If the light stays continuous,the problem may be carb or other fuel related problem that's causing the limiting.Plus just a reminder that air boxes and filters have to be installed or they'll run crappy also.

 

One question I have unanswered is concerning the stator plate position. Shouldn’t the timing change when the Stator plate is moved from one end of the adjustment slot to the other end? My flywheel mark does not ever reach the timing point on the access hole. The timing mark is 1/2 inch behind the timing pointer even when I was able to get the engine to Rev up with assistance of starting fluid, I believe that’s retarded timing? That’s why I went with a new Carb in hopes to fix the fuel issue, didn’t change. New fuel pump as you know.

 

If moving the plate doesn't help then it's possible a cdi could be at fault since it controls ignition advance.I'd go through the electrical checks and trouble shooting steps before you tried a new one.

 

Finally have full power! Amen. The new CDI box i First bought to fix the problem didn’t, so that’s what led me on a expensive wild goose chase of replacing and adjusting just about everything on the ATV. I’ve made a full circle back to the CDI Box and the first CDI box was bad from the get go and I didn’t know it. So, I bought another box, a “Rick’s” brand CDI box and that fixed the problem. My first diagnoses was right, I just didn’t anticipate getting a BAD part that was brand new in a box. Thanks for your Help.

 

Been there done that...I've learnt to ohms test anything "new"...not 100%, but catches most DOAs...

 

Chinese Parts.. You sometimes get more than what you paid for in trouble. Prices are cheap and people jump at them offered on Ebay and Amazon. Yes stators,cdis,etc from Ricks or Ricky Stators cost more but you don't usually have to worry about whether a brand new part is good or bad.. Glad you finally found the problem..