My husband and I bought and installed a FMF pipe & silencer, a K&N and prefilter on our daughters 06' Predator 90 two stroke last week. We were given a (main jet) starting at 150 from our dealer. After installing the 150 the bike at and idle sounded sweet, but only rode 25ft before it bogged down and wouldn't move. Figured that was too rich, so tried a 140 next, it didn't seem quite rippy enough for us ; ) figured what the hay and went with a 135. Bike ran fine in the yard for two days at like 20 min intervals with our kiddo riding. Def major improvement with the upgrades. We took it out to the sand dunes where we live here on the Southern Oregon Coast. Bike ran great where we unloaded, but the closer we got to the beach almost rt at sea level, the bike started running crappy. We turned around and went back to our staging area. Not wanting to melt a piston or someting dramatic, just wondering where we should go with jetting from here. Does the pilot jet need to be chaged as well? Any help would be greatly appreciated. Thanx FYI: (we live directly on the Oregon coast at about 30 to 100ft above sea level)

 

First off did you check what the plug looked like?? Oily? Dry? light colored electrode? OPT