Well, I promised a report, so here it is. I bought all the parts to convert my 02 650 airbox to 03. I was tired of greasing the K&N filter edges to prevent dust leaking past it. The 03 twin air filter appears to have a reasonably good fit to keep dust from getting past the edges.

What about power? I got either nothing or a very small increase in power. Not enough to shake a stick at.
-The 02 airbox had a K&N and a custom "Nyroc" snorkle that hasn't caught on yet with the Prairie 650 community. It has a slightly larger diameter than the diamond G snorkle, but no radiused inlet.
-The 03 airbox I installed with a twin air and a Diamond G snorkle.

However, I am not 100% sure my 650 is tuned right. It appears to be running a little rich. Adding the 03 filter for some unexplained reason has caused me to only be able to turn the air screws out 1.5 turns. I washed and re oiled my filter since the first ride when it was idling extremely rich and I had to turn the air screws in all the way. My filter had too much filter spray in it the first time. I don't believe it has too much now.

I ran it full throttle down the road and only got 61mph out of it. I have never gone over 59mph with these 26" mudrunners on it, but I never ran it on asphault with these tires until today. I do not know where my speed went. My 650 used to go 59mph with 28" mudzillas.

I just thought I would let everybody know what has happened so far with my 03 airbox conversion. To summarize:

1. It runs great. The airbox fits perfectly.
2. The filter fits better and is a lot nicer to remove and clean. I am born again with faith in Twin Air filters.
3. Although I didn't gain anything in power, I think people with an 02 twin air would notice a little teeny power increase going to an 03 twin air.
4. Until I figure out what has made it idle so rich, I wouldn't exactly recommend everyone with an 02 airbox go get parts to convert to the 03 airbox.

 

Thanks for the feedback nyroc, be sure and let us know when you find the reason for the rich condition, I thought it would be lean if anything with a better flowing airbox. Your knowledge base is very helpful thanks for posting it.

 

nyroc i have checked the air screws on the 03 models at a local shop and they was all set at 1.5 out rear and1.75front

 

Thanks for all the info Mr. Nyroc, I know if it wasn't for you and people like you I would have never got my Prairie. With all your very helpful hints and instructions on your knowledge base you have made owning a 650 alot more pleasurable. Thanks again and keep the rubber side down...........