cam selecion and engine mods help

[Don400EX]

Hello, I am very new to this board (today!!!)
but I would like to ask some questions. I have 03 EX that has a white bro's pipe on it and K&N filter. I bought it used and my buddies 02 ex 400 walks away in a drag. I also have soem blue smoke.. so I prolly have bad rings.. no biggie. here is my delima.

I think that I am leaning towards a 426CC kit for my ex 400. My local Honda dealer recomends againts the 440 as they claim it isnt reliable enough (pulls head studs) and runs too hot. Anyhow, he is recomending that I get the Xr400 cam over either of the hot cams. his reason is that the hot cams dont have "decompression" like the honda cams do.
anyone have any thoughts? any experiences? I would like to hear how the XR400 cam works VS a hot cam stage I and stage II.
Thank you in advance.
Don

[TC426EX]

I cant help you with the cams since I havent personally owned any of those, but I would also reccomend a 426 over a 440. As far as pulling head studs, youll be doing that with a 426 or 416 too if you go with a high compression piston. Anything over 11:1 runs the risk of pulling them. There was a point when I first had my motor built that I skimped on that, and blew a head gasket every other week for like a month and a half. I finally had to get oversize studs put in like I should have in the first place. I am running 12:1 compression though. If you have the extra 100 bucks I would really reccomend doing your head studs anyway to save a headache and increase your reliability. East Coast ATV has them if youre interested. Welcome to the site, and keep us posted on your motor work as it comes along, you should really like the power gains youll get from those mods. You might want to think about removing the choke from you carb too to get some extra fuel/air in there. There is a post in the tech section on how to do it.

[Don400EX]

remove the choke?? as cold blooded as this thing is.. it would never start!!!!

[dn1911]

as far as cam suggestion i would ask here (http://www.trx450r.org/forum/index.php?showforum=4) just label it "400ex cam selection". we have a HotCams R&D guy on there all the time. he should be able to clear that up. also don't skimp on the studs.

[RytM1]

When I installed the 416 kit in mine, I used the xr400 cam. It wasn't bad, but later came to find out that it is nothing more than a slightly tweaked stock cam. I then switched over to the HRC cam, and love it. When I had the xr400 cam, I basically had the same mods as you. I am now running the FCR39 carb, and have had the head ported and polished, which may also take advantage of the HRC cam. If you are set on the xr400 cam, I still have mine laying around the garage. It was only used for about a season and a half (which for me was no more than 8-10 rides). Make me an offer.

[Don400EX]

I just pm'd you about your cam for sale.
Thanks

[TC426EX]

Originally posted by Don400EX
remove the choke?? as cold blooded as this thing is.. it would never start!!!!

Actually youre wrong about that!! I live in cold *** OH and when I was still running the stock carb on my built motor with the choke removed it started RIGHT up even in winter. I was not using the factory CDI unit though. You will want to get a hi rev CDI box for your bike from GT THUNDER or TC Racing to compliment your motor mods... Youre right though, your bike WONT start if you go with a white brothers, big gun, sparks or ebay box. Im telling you man, remove the choke, then all it takes is 3 pumps on the throttle and push the start button and youre in business!!!

Also, I reccomend you go with a more aggressive cam than the XR400 cam your dealer is suggesting. You will outgrow that cam in a Hurry man. The Hotcam Stage 2 or the HRC are much better choices...

[eagertorace]

hello, i have a 400ex with the following mods.
1. full lrd exhaust
2. k/n filter and rejetted w/lid off.
3. curtis sparks advance key.
4. high rev box.

stock bore and piston, could i tell a big difference if I removed the choke or not? Always wanting a little more power.
someone please help!

[Rico]

You MUST go up at least 1 size on the pilot jet if you remove the choke. I actually recommend going up 2 sizes to a 42 but you need to go up at least 1.

[TC426EX]

Originally posted by Rico
You MUST go up at least 1 size on the pilot jet if you remove the choke. I actually recommend going up 2 sizes to a 42 but you need to go up at least 1.

yes, I was running a 42 when I had that setup...

[weightlifter01]

get a TC racing cam and a TC racing hi rev cdi unit jet your carb or get a good aftermarket one like edelbrock or keihin 39 fcr while youve got the motor a part go ahead and get the head ported if yo want a bigger motor thats up to you but compression is what builds horsepower so I would go up to a 11:1 J&E or Wiseco piston if you go with anymore compression than this you'll need to get the bigger stud kit for your head.Oh yeah go ahead and splurge and get the titanium valve springs (less weight)