Unless you are planning to put a 416, 426 or a 440 kit in your 400 keep it stock. I've installed a WB r-series, dynojet kit and a K&N on my 400 and stock 400's that I used to beat (when I was stock) are now kicking my butt. Stock 400's are getting me off the line and pulling away in the end. This makes no sense to me with everything I've read here in the connection and dyno test results that WB sends with their pipes. Maybe it just sounds like you're going faster. I'm not attacking any mod manufacturer, but I do believe that Honda's R&D deserves credit. In 3 weeks I'm adding a IMS 440 kit, CT/Web drop in cam, a port job and maybe a carb. Hopefully then I will be able to dust those stockers.

 

Something must be wrong because, when I first started building my 400, I put on a rev box, fmf pipe, and k&n w/dyno jet kit. I would kill any stock 400 from start to finish. Are you sure they are stockers you are racing. With your mods you should be puting out like 29-30 horses, the stockers only put out 26-27. It could be a jetting problem, or something?

 

dude, you gotta adjust your jetting perfectly...

heres what i found out through my experience...

jetting changes include:
adding, decreasing disks
chaing main, pilot and jet needles in carb
different air filters, plus airbox lid design..


just because you have alot of discks dosen't mean that you will go faster. Each engine has it's sweet spot. However with proper jetting you should be able to adjust disks.

i am only running 7 disks right now with a uni and a 170 DJ main, and mine flies over a stock bike.

 

It is because of that white bros. pipe...J/K

 

What makes the White Bros. pipe junk. Not trying to uphold WB pipes just because I have one, but could you expand on what makes a good pipe from a junk one. Perhaps I'll buy a different pipe.

 

I was just kidding... J/K = just kidding..

 

You need to jet your machine correctly. Dynojet jet kits are way overhyped, from my experience they offer nothing but a way to lighten your wallet. You can get larger main jets from your dealership cheap. Further, these kits do not know what your machine wants; often, they don't even come close. Before you spend lots of money on other motor mods, jet the machine correctly and see if you are satified with the power gains. Jetting is quite simple to do; go to the tech connection, do an advanced search on carbs, with all models selected, and read. You will learn all you need to know.

Before you jet, pick the amount of disks you would like to run (like 10), then jet to that selection. Don't start swapping disks just to try to tune your carb, it never works very good that way.

ogre

 

Pudjumper I totally agree with you.4 stroke are better to be left alone unless you plan on doing the bore and cam thing.Its not like a 2 stroke where you have a huge difference when you pipe it.When I had a my DS650 I put a big gun pipe,jetted it and a air cleaner.600 bucks later you no what I felt.Jack S@#t!!!!Was not worth the money at all plus it sounded like a harley davidson.Now my raptor has plenty of sack and I learned my lesson on the DS650.Keep it stock!!!!

 

My 400EX was anemic after I added 22inch tires to increase my ground clearance, wouldn't even pull a wheelie in second gear.

After I put the Complete Big Gun System, a K&N Filter, DynoJet Ket (160Main) on it, it woke right up. Right back to wheelie in fourth gear, with taller tires, AND I smoked a stocker locally. It uses a lot more fuel now, but definately runs stronger. I shyed away from the 440 kit because I heard that the air cooled engine didn't have enough material to keep cool if you bored it out for the 440 kit. I can't remember where I heard it, but I definately liked my quad after I put the money in it.

But, my Raptor will stay stock, except for some sproket changes, and possibly different tires. It has plenty of azz.

 

Get rid of your Dynojet needle and their excuse for a mainjet setup, and put your stock needle back in with a bigger KEIHIN main jet. Make sure the main jet is a real Keihin main, and not a copy of one. Dynojet kits do work if you can get them dailed in, but they don't make it any faster then the stock carb parts(as long as you go up on the main).