Hello

I have a Polaris Sportsman 500 1996 model. Overall very tidy condition for its age. I was told by the previous owner that it did run but needed a new carb because he had snapped the float holder whilst giving it a clean.

Bought a new aftermarket carb and come to start it.. no spark.

I have been through the service manual and came to conclusion that the CDI was bad... New aftermarket CDI and still no spark.

Igntion coil is correct to spec
CDI Trigger coils resistance is correct to spec
CDI & Charging coils are to spec
I have removed the black lead from safety circuit to eliminate this but still does'nt fire up.

Using a peak voltage adaptor on the blue white wire to the igntion coil I am getting 1.4V with electric and pull start. From previous experience I believe this should be in the 10's-100's volts to generate a spark?

I am getting around 3V when measuring across the trigger coil. Good volts from the CDI Charging coil (Can't remember exactly what from memory). 120V from the charging coil and around 2-3V whilst cranking out of the regulator.

Kill switch operates correctly, throttle control switch is damaged but wires are open circuit as they should be.

I have read that the overide switch assembly can cause issies so will give this a clean tommorrow however taking the black wire from the CDI should pick this up?

I am really at a loss as to what might be causing this!

Any help would be geatly apprecaited, Thank you.

 

Pull the black wire from the reverse limiter module also and see if you have spark. If it shorts out it can retard or stop spark also.By pulling this wire you bypass the over ride button. Pulling the black wire from the cdi just eliminates it from the kill circuit. Make sure the contacts in the etc switch in the throttle housing aren't touching either as it can cut spark if they are. Really no good test on the cdi module. Stator resistance checks,coil checks along with other trouble shooting steps in the manual are given first and if a cdi itself is found suspect after the staor and coil have been eliminated as problems, then replacement of the cdi with a "known good one" as most manuals say is the next step.

 

Thank you for the reply.

Tried this but with no success however I believe I have found the problem. I triple triple checked everything again and found that although I had checked the ignition coil secondary through the lead I never checked it with the spark plug cap reconnected.

Low and behold the spark plug cap is knackered! Shoved a nail in the end and I've got a nice blue spark!!

Thank for the help.

 

Had to google the word "knackered" to find out what the devil it meant.. Anyway glad you have spark..

 

OK this bike is driving me round the bend now.

Replaced spark plug cap and thought happy days away we go..... but no!! Have a lovely spark when using the electric and pull start but cannot get the bike to run.

It will fire randomly when using the electric but once it fires it will not run. Dies as soon as you let off the start button. If you hold the start button on it will run.

When using the pull start it will fire and run but I have to have the carb set at 5 1/4 turn to start and bogs as soon as you touch the throttle.

Have read other posts talking about the coil / flywheel distance so I popped this off to have a look. The inside was absolutely clean apart from a little bit of grease here and there. Gave it a good clean and the coil gap was around 0.02 so well within spec.

Also seen other post talking about battery volts whilst cranking. I am getting between 10.5-11.5 which does seem a little low. Have tried using a jumper battery but this still gets dragged down. What might be causing this and will this cause it not to run on the electric?

I really don't understand how it will run on the pull but not electric ??

Any help is greatly appreciated.

 

As long as you have spark it should run. The battery is there only for the starter and the lights. This ignition system is magneto triggered on this old model and actually doesn't need the battery. Pull starting should crank it up and run right if everything else is ok. You can check the resistance on the pick up coil wires(white and white/red) leading to the cdi if you wish. Should be around 97 ohms +/- 20%. If this checks out then I'd pull the valve cover and check the cam. 1996-2000 models 500s were bad on soft cam lobes.Some would crank up and idle ok,but pop back and die when throttle was given. Here's an example of what to look for.Bad Cam Pic - ATVConnection.com ATV Enthusiast Community You can also try softly tapping the pick up bracket inward a tad to decrease the distance between it and the flywheel tab. Many have done that. Could be some like this guy that had a rope break,plus I really think over time the pick up becomes weak and needs to be closer than what the manual calls for. http://forums.atvconnection.com/pola...ml#post3155476

 

This is it! I can't understand why it won't run on the electric but will on the pulleft

It is a brand new carb but I'm going to pick through it tomorrow and mAke sure there is nothing odd going on.

I will pop the top back off tomorrow then and look at the cam lobes. Valves seemed to be functioning well when I checked the clearances but will confirm for sure.

It was that thread that I have read hence why I decided to pop the flywheel off and have a look. Some build up of grease on the stator that wiped off but other than that it was surprising clean. The overall bike is very tidy which also adds to the confusion as to why I can't get it to go!!

I have measured across pick up coil whilst cranking and have around 3.1V. Does this sound good to you?

Thanks for the help.

 

2.5 dcv average on the pick up coil with a peak reading volt meter. Normal volt meter may not be that accurate.I always just went after resistance as it was a pretty good over all test. Sounds like what many would do over time.Would pull start but wouldn't electric start.That's why many people move the bracket inward a tad. Not taking throttle is another issue though.

 

Thank you for all of the help.

Been away and only got chance to look today but it is indeed a bad cam!

Thanks again been a great help

 

Plenty of aftermarket cams one ebay now. Be sure to replace the exhaust rocker arm also."NEW" CAMSHAFT CAM SHAFT Exhaust Rocker Arms for SPORTSMAN 500 2X4 4X4 96~12 | eBay