My past atv experiences have all been with basic hunting and working situations. I just purchased a new AC 500 manual 4x4 that has been snorkled, extended exhaust, new ITp wheels and 27.5" Swamp Lites. It only had 24 miles on it and the guy I bought it from had all this done but new very little about riding an ATV much less what all the features were for. I took it mudding yesterday and it had trouble pulling in the mud. It went where none of my buddies could go. It even crossed a low tank that was about 3 foot deep and very muddy. But in normal mud around the tank I was blown away by smaller and older atv's. Hill climbing was much worse. It felt as the the bike did not have enough power to turn the big Swamp Lites. It really bogged down in the mud. I had to leave it in first and crawl through. The bike is super fast but seems to lack pulling power in the mud.

Also, had to pull or push a few bikes out of mud, but when I pulled them out, even in 1st gear and low, my 500 would bog down and didn't seem to want to pull.

 

The tall tires have changed your gearing considerably. Basically your first gear is like what 2nd was. It is the price you pay for having tall tires. They look cool but as you have found out. Looks don't make you go, and sometimes make things worse.
Yes it will still be fast once it gets going but you now have lost the gearing that you need for hard going and pulling.
The 27" only give the AC 1" more clearance, from 12 to 13 (what is the point), A set of HighLifter springs would have done the same or more for a lot less money. About $150 for springs on all four corners.
Unfortunately the only way you will get back your gearing is to go back to the origional 25" tire size.
You are right about the origional owner not knowing too much, he probably did what people told him to do, not realizing.

 

buckaroo50
I have been reading into the k&n filtering and jetting is this hp mods and do you think it will help. What other torque and hp mods are out there?

 

K&N will help. I don't use one, I use the stock filter with Marvel Mystery Oil on the foam. Gives about same results.
Read my post in the Arctic Cat forum about 'Air-jetting', I gained a bunch of HP and boosted my MPG from around 20 (22 if I took it really easy) to 24+ and I was not babying it. The whole rpm range got stronger. I used to have a slight problem getting the last few hundred rpms out before the limiter was hit (sort of a flat spot), now it pulls really strong right up to the limiter, and if I didn't have a limiter it would pull stong right past that point. In addition of helping on the top end it has a lot more low end punch too. How I came about it was an accident but it works great. Actually I started to do some rejetting went from 150, 147, 145, 142 and that took care of the flat spot but I lost hp... knowing that I was makeing the engine leaner I figured with the larger jet (150) all I needed to do was to figure a way to get more air into the air box. A K&N will allow what air in the box to get to the motor easier but if you can't supply more air there is little to be of bennefit. 'Air-jetting' gives you that extra air that you need. The engine determines how much air you need not the filter, the filter only determines the rate of delivery (a dirty filter slows the dilevery down, no filter speeds it up). The key is to supply what the engine wants. I even thought of rigging up a funnel and having ram-air, the rubber duck-bill (at the bottom of the air box) for draining off water would also bleed off any excess boost in air from the ram.

 

the 500 can make a lot of power.i build a lot of power products for the 500 pm me for more info