Hi email me any questions vryder64@optonline.net

 

Trevor check your post messages people call them PM

 

If you post your questions and answers here instead of emailing or PMing each other, more than one person can benefit from it, now and in the future.

 

 

Progress finally! I didnt see any PM.

I pulled the muffler, and she runs much better. The muffler isnt clogged, I can blow through it freely. This to me says exhaust valve/cam. I checked clearance, its right at .006 intake and exhaust. Strongly suspecting worn cam/rockers. I have 2700 miles, leaning towards new head assembly if I can find one. Anyone know how I can get the cam specs to check the exhaust lobe?

 

Leak down test would be first thing to do before you tore anything down. It can tell you if valves,rings or both are a problem area. Cam lobe heights are listed in this cheap manual with other things you can check.2000 Polaris Sportsman 335 Service Manual PDF Download

 

leak down less than 5%, so really good. I am feeling pretty strongly that removing exhaust added enough vacuum to intake for carb to function. I dont understand why vacuum is low...

 

Just go through the cheap 5 buck manual I listed. Shows a lot of trouble shooting checks for mechanical,electrical,etc. Plus shows the cam lobe height, compression range and other things to check before you start throwing parts at it. Simple things such as leaking vacuum hose or a worn diaphragm in the fuel pump can cause problems. You can generally rule out a fuel pump if you pull the fuel line from the carb and crank the engine over. Should be a steady or pulsing stream of fuel. If you find it to be weak,pumps are cheap on ebay or amazon.Plus the fuel section in the manual may be helpful also.

 

Checked all vac lines for leaks
checked tank vent
new fuel pump and all lines, pumps great
new carb
adjusted air screw and float
good compression
good leakdown, 5% or less
new battery
new coil
new plug
new cdi and voltage reg
all new fluids for fun
Valve lift is good
only revs plugging intake, or no muffler. Both increase vacuum.
I have plenty of manuals, and know basic troubleshooting.
Im stuck at timing chain/sprocket wear, split woodruff key, or cylinder wear on bottom half of cylinder. Any one else have thoughts before I do surgery?

 

Aftermarket carb can be the weak point as many are hit or miss. Some may have machining bits in the bowls along with trash. Some people have noted that some orifices weren't drilled all the way through. Unless the oem Mikuni is trash,better to rebuild them with a good Shindy carb kit. If the carb is eliminated,then check the flywheel key next. Easy to see if it's split and if the flywheel has moved when you remove the nut. Same thing for the crank sprocket key. If split it can throw cam timing off. Don't know if I mentioned it,but most Polaris atvs won't run right unless the air box and filter are installed also.