hey guys i recently bought a used 2005 yfz450 and was wondering what type of oil to put in the bottom end, aslo the bike has a yoshimura silencer and K&N air filter, and dyno jet kit, I was wondering if anyone could tell me what my main jet, starter jet and air jetting should be at with these mods, and what it should be stock. I am not sure what the jetting is at yet i havent had a chance to open it up yet but it does have a top end bog due to too much fuel i believe because it will often backfire, any info would be greatly appreciated, thanks

 

I don't really know about the jetting, but it would help to know what elevation/area you are in. If it is an off throttle backfire it is probably to lean. As far as oil, there have been quite a few threads over the years on here about just that. As long as you stay away from the "energy conserving" types, you should be OK. I have been using the Shell Rotella labled as a diesel engine oil in my YFZ. It seems to shift a bit better with the synthetic over the conventional. The big thing is to keep it changed often, I usually do an oil change about every 5-6 hours.

 

yah i forgot to mention that i ride a 2200 above sea level and without a lid on the airbox, also when i run at full throttle i will get a bog after a second or two at full pin and when i let off the gas is when itll backfire from build up of fuel im assuming