Hey guys, new to the forum. Got a Grizzly 660 and just added HMF Swamp Series with K an N filter. Jetted it to 175 main jet. With the air/fuel screw out 2.5 turns and the air box lid on, I hammer the gas it bogs down. If I remove the airbox lid and hammer the throttle, it shoots off like a bat out of hell. I believe it is obviously needing better air flow. Does anyone have any suggestions. Maybe need to change the pilot jet? Thanks

 

You basically answered your own question, if more air makes it run fine, you are jetted too rich, or the needle needs to be dropped a notch. Unless you want to run without the lid, which would be safe to do if you added an Outerwears water repellent cover mesh, it would be like a lidless air box, but still keep the mud and water from landing on your filter. Either that, or drop the main a size and see how that works. What was the stock jet size, if I may ask? how many sizes did you jet up for the silencer and K&N ? Information like that will help to isolate the problem, also, did you change the needle clip setting?