I'm fixing up a 2007 polaris 330 for my neighbour's. Story is they couldn't get it running last year and then it sat for a year. I brought it home drained the gas and cleaned the carb. Fresh gas and a battery charge and I got it going. Runs good at half throttle, at idle it dies, at full throttle it bogs. Runs a bit better with the choke on but not much. Some back firing, gonna check the compression tomorrow.

 

Don't just try to clean a carb. At least replace the needle and seat,but actually cheaper to get the aftermarket kits than to but an oem needle and seat. Adjust the throttle cable slack to where you only have 1/8" slack at the thumb lever. If slack is more than that the etc contacts in the throttle housing can touch and kill the engine. http://www.ebay.com/itm/CARB-REBUILD-REPAIR-KIT-POLARIS-TRAILBOSS-330-2X4-2003-2004-2005-2006-2007-2WD-/270462316796?hash=item3ef8cf70fc&vxp=mtrPlus Here's the fuel/carb section from the service manual that can help on float settings,etc. https://www.google.com/url?sa=t&rct=...U2gGlaHJWSIlbA

 

Alright thanks for the reply, but I did a compression test and the gauge read about 90-100psi. I know what that means! Top end time. Cause a normal engine should have around 120psi right?

 

Nope compression sounds about right as there is a decompression device on the end of the cam that slightly opens the exhaust valve to make it crank over easier. Valves set at .006 intake and exhaust.

 

Oh ok, I guess I'll either rebuild the carb or replace the needle. Could it possibly be a timing issue?

 

Sitting for a year I'd say rebuild the carb as cleaning doesn't always help. Plus don't overlook simple things like a new plug,air filter also.

 

Yup ok I'll rebuild the carb and yes I put a new plug in it.

 

So I rebuilt the carb and set the valves. Still no improvement, at least it idles now. But it still bogs above 1/2 throttle. It seems when i'm driving it if i reach my hand inside the carb and push the needle up it gains the power. So is it running lean? and how do i adjust that?

 

Recheck that you have the diaphragm and spring correct along with the slide needle parts set correctly. If you can manually lift the vacuum slide and the engine revs up,some things wrong some where.Plus if you have the air box off it will be lean! It has to have the box,filter on and sealed up to run right.The carb jetting on the 330 is on the lean side even with the air box on. Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse

 

I put the air box on and it ran like new, Thanks.