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In a previous post i had thought I found my issue with a cracked flywheel magnet however it turns out it wasn't the flywheel with the cracked magnet causing the problem. It idles fine and if I can get the revs up it runs good up top but in the mid it pops ad backfires. Fuel vapor can be seen coming back out the carb as well as the odd flame. I have in all replaced the flywheel, a cracked carb boot, bad wires and caps, plugs, went through the carb 3X, Checked valve timing as well as lift, Comp is 150psi, checked trigger and coil resistance. The only thing I'm left with is the CDI. When I checked the timing at an idle it was correct. at 5000RPM it was good, at 3000 it should be 25 deg. but it was only 15. Could too little advance be causing the backfiring? Want to make sure before I buy a new CDI. Would be great if I could send my CDI to someone to try out on their bike.
Thanks
 

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Hi ... X2guy
Cactus Pep here ,,,,,,, I have no spark at all and have been doing some tests.
See below.............
If you have spark and it runs, it's most likely not the CDI ?
The reverse speed limiter runs through the Speedometer and could be causing the problem.
From all the tests you have run it looks like you have a Service Manual ? If you do read and run all the Speedometer tests. Your may find your problem there. Just because the Speedometer lights up and gives you the proper speed dose not mean that it's working right. Speedometer tests are on page 10.8 of the manual.

I have run all these tests (below) so far and I'm still working on it ? But I have no spark at all.
So my problem is a little different. I think you have already run these tests, but this is what I have done so far. I will be running the Speedometer tests next, just to make sure before I buy a CDI Coil.

I have a problem with a 2003 Sportsman 600. Have been working on it off and on for a week now. Yours and mine are wired almost the same. Yes it could be the CDI. But not likely if you have spark and it runs ? First and easiest test ... Check the ETC switch, it's in the box above the throttle on the right handlebar, top just pops off. Those points should be open (not touching each other) If they are, adjust the throttle cable till they stay open. Next test is to unplug the BLACK WIRE on the three wire plug (with black, yellow, and brown wires) that is connected to the CDI. Don't unplug it from the CDI, follow it up toward the handlebars about 6 inches. There is a single wire connector there, unplug that. It goes on to the red kill switch on the left handlebar. Unplug it and crank and check for spark or see if it runs right. That will eliminate a possible kill switch malfunction. That wire also goes through the Speedometer so it will eliminate a problem with the reverse speed limiter also. If you have spark then ? Test the Ignition Switch, Engine Stop/Kill Switch, and Speed Limiter for shorts to ground. Also there is a plug at the Stator/Alternator, right side of engine, make sure it's connected tight. Next would be to test the signal coming up from the Exciter Coil and the Pulse Coil to the CDI. This gets tricky, you will need a Peak Reading Volt Meter. Exciter Plug (Brown and Yellow wires should read 34 DCV). Pulse Trigger Plug(Black and Red wires) should read 3.3 DCV. This Info is on page 10.15 in the Service Manual. There are also other tests in the Manual, but I have given you the best ones I think. If you could get your hands on a Service Manual it would be a big help to you. Also the Dealer price for my CDI is $229.31 + Tax. So make sure you need it before you buy it. Usually Dealers won't take back electrical parts. Shame, because it would be easy to just get one and try it. If you have a good buddy ? With close to the same Scooter ? Check the part numbers to make sure if you do this. My part number is # 4010785 1. It's printed on the CDI, yours may be also. Good Luck, I'll check back soon to see if you post again. Hope this helps.
 

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Discussion Starter #5
Thanks Cactus...
ETC switch is OK
Unplugged the black kill wire from the CDI and still the problem is there. I don't feel this is related to any speed limiter trouble as When the speed limiter is engaged it does not cause to engine to backfire. It just cuts spark intermitantly. The bike idles fine and if I can get it tor rev up to higher RPMs it goes fine as well.
Just in the mid range where you do 90% of your riding it backfires and will barely run. Timing at 3000RPM should be 25deg BTDC and This one is showing only 15%.
I always thought that CDI's either work or they dont but my opinioon has changed and have seen CDI's that will spark and allow the engine to run but not well.
My price for the CDI is 290. I can get aftermarket ones for $100 for all models 500cc's and under. Cant find anything for this year 700.
 

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From, Cactus Pep.
Got your post and e_mail X2guy ....
Did you try pushing in the Speed Limiter Override button wile riding froward at mid speed ? Speed Limiter Override works through the Speedometer ? I know it's only suppose to work in reverse but ???????
Also you could look for parts here ... http://www.polarispartshouse.com/
Good Luck, I'll keep a watch here when I can.
"PEP" :>)
 
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