Finally purchased my performance kit for the new foreman 450s. It consists of a jet kit, k&n air filter and sock kit , and last a hmf exhaust slip on muffler. I followed jetting instructions with the kit designed for the foreman which stated to us the 126 main jet for elevations below 3000 feet. There is also a website you can go to for jetting and it says to use the 136 main jet! So far I have installed the 126 as per the set up sheet with the kit. The atv definately shows more torque throughout the entire rpm range. Its not explosive by no means, but the grunt is definately improved. Fuel mileage seems to be about the same..Hill climbing in second and third was improved. Large mud holes did not bog the machine in second gear as much as it did before. I may try rejetting to the 136 main jet next week and test ride again. If there is any more improvement I will post the results for you. The kit is advertised to increase horse power as much as 25%. I dont feel like i gained that much in my machine. A dyno report of the same machine showed 16hp stock, and 20.5 after the kit was installed. I believe that would be enough to really feel in the seat of the pants! I feel like the most hp I gained has been in the upper rpm range at this point. Still dont feel like it was worth the 300plus dollars expense. The kit did not come with a silencer, it had to be purchased for an extra 20 bucks. with the silencer it is slightly louder and deeper toned than the stock. without the silencer installed its way too loud. I did test with the silencer installed.

 

Link to jetting website please?

 

The website with jetting info is as follows: http://hmfengineering.com/jetpg.html

 

Kewl! Thanx, but I think they have the 400 ex and the 450R backwards! LOL

 

When jetting, you want to start too rich (large), then work your way down until it begins to run bad (lean). Then back off one jet size, so you are sure you are not lean, which can ruin your engine.

 

Rode the Foreman pretty hard for about an hour. Seems to be getting stronger by the minute. Now has 20 and one half hours on the machine. The last four hours with the performance kit. Pulled the plug for a reading after the hours ride..Plug shows to be just a little rich. Looks about identical to the spark plug out of the box stock sportrax 250 of my godsons. I am curious to see if the performance increases. My godsons sportrax now has around 35 hours on it and gets stronger with every ride. I really dont know what the length of time is to completely break in the four stroke honda engines, but they do seem to get better and better. When i first purchcased the 450 Foreman after owning the 2wd rancher 350, I was very disappointed in the power of the Foreman. It was extremely slow and weak feeling campared to the 2wd Rancher..Now after riding both machines again today, I dont think the Rancher has a chance to keep up with the Foreman torque or speed wise. Still a heavy machine to ride, but I am learning to love it more and more!