Hello I have a 03 400ex with a WhiteBrothers revbox a WhiteBrothers R4 muffler and a K&N filter and soon a WhiteBrothers stage1 cam. I prefer bottom end power I like to hill climb at the dunes in Oregon were I live. But any ways I've been debating on what bore to move up to I hear the 416 is good but there is so many options i'm not sure. oh and should I do the bigger bore now or just wait till The quad is in need of some engine work the quad only has about 40 hours on it and runs really strong . I'am also having some trouble with my with my rev box it doesn't like to start sometimes if it has sat for a while I end up killing plugs and draining my battery I was told by this guy at sandlake to cut a 1" hole in the top of my air box it will help with that problem and get the full performance out of the revbox. I want to get 35+ ponies out of my baby but with out sacrificing bottom end power and tourqe. and advice would be helpful thanks. and I'll be running sandskate 2 paddles.

 

call powroll they have a few things to offer

 

SANDRIDER503-I am not sure how far you live from eugene but i use a shop here (CASCADE MOTORCYCLE)that did a great job on my 686 raptor and built a very good 440 ex for my wife so if you want more information on this let me know.Both the raptor and the 440 perform very well compared to your average build up so i would recommend at least talking to these guys.As sandman said you may also try powroll as i have had good luck with them and they did build a good runner for his son so either way i think it would be worth your time to at least check them out.Your probably going to get the most out of your honda by getting rid of the air box lid rather than just drill a hole in it and of course you will want to re jet your main to compensate for the introduction of more air.As far as your rev box is concerned i think that the white brothers is superior to the big gun so you are on the right track there and i say this after trying both on my wifes 440.You will probably be happiest with a 440 as opposed to a 416 for low end grunt but with the right cam the 416 would do well also.A properly set up 440 can really surprise some people in a drag race so if you take your time to dial yours in you will have a great time outrunning some larger bore quads.Good luck on your project and let me know if i can help with any more questions..

 

Hey thanks alot the 416 is probably what I'll go with because it seems to be the one I'am interested in I have heard the 440 is alot of work and you have to keep it dialed in constantly I'am looking for good reliable power. I'am about 2 hours from Eugene do you go riding down at Florence alot I'am thinking about going as soon as I get my new motor put back in my toy hauler. I'am guessing some time after Christmas is there any good riding for New Years at Sandlake or Florence I'am looking to have some fun with the family so if you hear of anything let me know.

 

Sandman..... looks like you've found the inherent rich spot in a cold 400ex!! I've messed with my buddies bike and can't seem to get that rich spot out when it's cold. The only thing I have to say about this is that you don't need the choke on very long and keep the bike revved a little while you're letting it warm up. Also something that helps with this is to crack the throttle open a little when you're starting it.

Good luck with the bike!

 

oh mine starts fine but again it is stock carb and cam, the engine runs good but it is tame,dunes 440 screams i have seen it take it to several larger machines, but to get there is a lot of work he has done a lot of tuning, if your white bros cdi is older i've heard they are hard to start when cold. if you have your old cdi switch and see if this is true.

 

SANDRIDER503-Yes i ride in florence most of the time and for most of the year except for the next couple of months when i am busy waterfowl hunting.You may have got some misinformation on the reliability and up keep of a well built 440 because ours is as reliable and easy to maintain as a stock motor. A 416 would be a good choice also but you will be able to get more torque out of a 440 simply because of the extra bore size.

 

Sorry about that Sandman...... I meant Sandrider!!

 

Hey no problem thanks for all the help