ok i have a 400ex and im really thinkin about puttin a 416 kit in it. I just wanna know straight up what I other mods i would need to such as cam, polish porting etc. in order for it to run good and be reliable any help would be greatly appreciated

 

Cheaper to buy the 450R.

Put $3K to $4K in your engine and a new 450R will probably still out run you.

Just put the 416 bore and a cam and exhaust. Any more than that, do the above.

My Neighbor has over $12K in his '89 250R, and my $2700.00 Polaris Sport 416cc with out run, out handle, out wheelie, etc.

Point is when you do the engine, everything else has to be upgraded too in order to make the perfect combination....................buy a 450R and save money in the long haul......


good luck............

 

I recently bored my 400 out to a 416 at the beginning of the summer and I have had no trouble with it. I also put a hotcams stage 2 cam and I am running an open airbox,and I have an aftermarket exhaust. I had to do some major jetting but other than that is was fairly easy. I don't race I just ride the local trails and so far It has run great.

 

I have a 416 EX(.080 over 12.5:1) with portwork,1mm bigger intake valves,Edelbrock carb,Web track cam(all-around)rev-box,Sparks exhaust,and it hangs neck in neck with the 06 450r's.(stock)It will carry the front wheels in 3rd gear as long as you want,all kinds of torque.If you buy a little at a time,and keep an eye out you can get by pretty cheap buying (new)parts off of ebay.You could run pretty well with 11:1 or 12.5:1 piston,good exhaust and rev-box,k and n filter with proper jetting. Something to think aboutg,your not to far from Abernathys in Union City,Tn. where they advertised 06 YFZ 450's for $4999.00 on their website.Just a thought.