Well I have a 2007 Polaris Trail Boss 330 ,that I'm working on for a friend
he bought this quad new and never had an issue with it, however this strange issue came up

"symptoms"
engine will crank over fine (engine cool, not cold, because here it;s in the 70* range at night), it will take forever to start up (run) that's if I can get started, usually the plug is wet with fuel within the first few attempts of it not starting( I think I have a spark issue, even though I got spark)*****************unless I hook up my 12v car battery to the 12v quad battery then it will start up quick without any problems*****************...now once started the engine runs perfect and will start up immediately after killed off, however after it sits for a few hours, it's back to hard starting again unless I jump it from my 12v car battery, then it starts right up

troubleshooting I have done within the last few weeks after work and some on weekends

compression excellent. valve clearance per FSM, cylinder leak down test returned good, so no valve problem in my opinion
a new battery is installed and is fully charged, new spark plug with proper gap, good coil, I tested it under compression and out side of the head grounded, fresh fuel, new fuel filter,no vapor lock, tested fuel pump with vacuum gauge, checked all grounds for good connection, check charging system and checked out good,carburetor cleaned and checked needle and seat for proper seating, float has no holes and still in factory setting

I'm thinking an electrical problem at this point?

thanks for any advice on this issue

 

Could be a weak starter that needs the extra amps to turn it over enough to crank,plus I would check out the stator resistance since you have the manual. Stator could be starting to get weak and can only start with added ump from a jumper battery(which isn't a good idea either). Check this out first, plus you can pull the recoil cover and clean up the stator area. Could be it just needs to be cleaned from any accumulated dirt,water,etc. Plus check for any voltage drop in the battery after sitting for a few hours. If you have the fsm should show you all the checks needed. OPT

 

thanks for the advice
I will check those things today and get back to the post
I did test the battery for voltage drop the other day, with engine running I get 14.5 v at terminal on my DDM, however when I kill the engine the volts drop like a rock down to 12.8 v and after sitting for a while the battery volts will even go lower like 12.5 v
what is your opinion on the battery voltage?
now talking about the starter, I will check into that also, maybe do a load test on it, however the starter doesn't sound like it's faster with battery jumped
what about the CDI box I hear so much about? could the capacitor in the cdi box cause this issue?
thanks!

 

12.5 to 12.8 is normal battery voltage after shutting off the engine.Make sure all connections are tight. Check the battery voltage after it sits for a couple hours and see if it drops lower than this. If it does could have a draw on the battery from somewhere in the wiring harness or even a brand new battery can be bad straight out of the box and not be able to hold a charge. Have had this happen several times,especially on maintenance free batteries. Plus a resistance check out on the stator and coil can help you narrow down the problem. Don't replace a cdi unless all other things check out. OPT

 

question
would a 12v battery jumped from another 12v battery, give the starter, more amps dor starting?
I'm no electrical expert

 

just went out to the polaris, with engine cold (sitting all night and afternoon) used my suv 12v battery hooked up to the atv 12v battery, just for seconds only, and the darn thing started right up within the second crank revolution
would not have started this quick, just using the fully charged atv battery

I;m like a blood hound on the trail of a good scent

 

Did you check the battery voltage before you jump started it? Could be the battery(if in doubt have it load tested),starter or bendix could be dragging, could have a weak weak electrical system, etc! The 330 trail Boss usually has no problem starting when everything is right! Use your manual to trace it down instead of jump starting! Jump starting is not a good idea even with the auto engine off,even worse if the vehicle is running,can burn up the electronics! OPT

 

yes, just did another test, before the rain
Battery voltage for atv before jump is 12.51
Battery voltage for car before jump is 12.68 (not running)

Now atv battery to car battery jump (car not running), the atv will not start cold 12.51 jumped from 12.68 = no start

I start the car engine and get a battery voltage of 14.2 v normal charging voltage
put jumper cable from car to atv (car 14.2v engine running) to the atv 12.51 = a starting engine without hesitation and no time to wet the pug with fuel
I feel like were getting closer to evidence of the problem
I did replace the starter drive (bendix) Friday, and I know about burning up an electrical system, I only jump off just a few seconds so the engine starts and I can continue troubleshooting
thanks for your continuing help, just to say that when I received this polaris to work on it had a broken pull starter rope, I replaced it, however there were ***** of shredded rope that I pulled out from the recoil area, maybe the pick up coil got moved from it factory position? causing this problem