Are those lights from Walmart? If so drill a hole in them and put a short screw in it to stop the lens from falling off, I found out the hard way on a set a had.
exhaust gasket GASKET,EXHAUST PIPE
3GD-14613-00-00 (replaces 90430-38054-00)
it is #17 on the parts finche here is a link to the page
http://www.motorsportmonster.com/fiche_section_detail.asp?section=18290&category=ATVs&make=YAMAHA&year=1992&fveh=470
http://www.ebay.com/itm/JE-PISTONS-222085-YAMAHA-1987-2009-YFM-350-Warrior-85mm-/290552628676?hash=item43a64945c4&item=290552628676&pt=Race_Car_Parts&vxp=mtr
10.5 to 1 compression $150.42
and here is a link to a 85mm gasket set
http://www.cometic.com/powersports.aspx
until the dipstick reads full lol, here is the link to the manual (it's a sticky) has all the info on amount of oil and how to change it http://www.yfm350.com/forums/showthread.php?t=20507