I have a 400 2006 Auto I just raplased my stock tire to mudzilas. 25x8x12 front back25x10x12. I went riding and had no top end speed the most it will go was about 25 mph. has any body had this problem or it might be that my carb is clog. And has any body came with any idea of how to put a fuel shut off valve.

 

I am not too sure what the weight of the mudzilla tires are but did you put them onthe stock steel rims or get aluminum rims with the tires? The Alum rims will make the overall weight of the tire a little lighter. You might check around on some web sites like, highlifter.com, or here in other posts to see what the weight of a stock tire is complared to your new tires. Since you went with 25 inch tires I am not sure your problem is with the tires?

How many miles does you 400 auto have on it? My 400 engine really woke up around 1000 miles. It may be that your engine needs to break in more.

I was also unaware that the 06 models do not have a fuel shut off valve. An inexpensive inline shut-off as well as a filter can be picked up at any auto parts store. Install them between the carb and the fuel tank on the fuel line.

Also, these days it is a good idea to always run some sort of fuel additive/fuel dryer/fuel stabilizer in the tank on your ATV. As most do not get driven much and can sit for a week or two between rides and that is all the longer the fuel needs to get water in it or get old. Especially the longer you let it sit. I use some stuff called seafoam great stuff.

Hope this helps

SJ