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The Ultimate 400EX

41K views 129 replies 15 participants last post by  Josh 
#1 · (Edited)
Well here I am again with a dilimma. I just sold my other 400EX and now its time to sink some money in my baby.

I just bought some new tires and a case of Amsoil 0w-40 for quads.

The up coming things I have on my list that are:

JE piston standard bore 12:1 compression
Hot Cams stage II cam
Full Flight Racing A-arms +2+1
XR250R cdi box

I will also be posting up a video of my recent practice once I get it complete.
I will keep updates up with photos and this will be a running story of my quad and how I advance it to the next level to for racing and later up to a 450R.
 
#5 ·
i think so i think you have to have high compression gaskets. put a web cam instead of hot cam and oversized valves.
 
#7 ·
only problem with web cam is you have to have hardened rockers and heavier cam journal and harder springs for your valves

where can i find high compression gaskets because i was just going to order oem since i can get them cheaper and honda seems to always be the best
 
#6 ·
I have 12.5:1 compression 416 kit which is about as high as you can go and I have stock head studs and haven't had a problem. I bought the kit so it came with the gaskets so I'm not sure about a high compression gasket. I like the power my stage 2 hotcam gives me but it has a slight tick that's hard to get to go away. Overall its a nice setup
 
#12 ·
You shouldnt need a cam cover gasket as it should be metal and they are reusable. As for head studs, just be safe and get a heilicoil kit. This wat you are threading into a steal insert with much deeper threads into the aluminum. Im running 12:1 on a 406 and i run the piss out of it on pump gas and havent blown it yet :icon_ rasta:
 
#14 ·
i know that i was trying to decide if i should stay wiht oem or go with cometic

and valve cover gasket is paper atleast the oem one is and i need a new one cause mine is leaking

so. . . which should i go with cometic or oem. I can get oem cheaper but cometic is metal so its reusable for the most part
 
#17 ·
I have cometic on everything i have ever rebuilt. even on my truck lol. The factory honda gaskets are alot like cometic they are a multi layer steel design with is the best you can get for the application and usually dont need to be re-torqued. Theres my .02:)
 
#19 · (Edited)
If i remember correctly mine did come with a valve cover gasket but i am still using the stock one because they are metal already and i never needed it. Im pretty sure i gave it to my brother for his 416 he was building that was jenk and someone did the old build a gasket on everything but the headgasket lol. Cometic is quality stuff tho. I got mine off ebay and i looked at there pictures and made sure they had all the gaskets i needed in the kit. The valve cover gasket is a very easy gasket to spot in the pics. and i dont know what your talking about me saying i bought the whole engine gasket kit? I never split the cases....on this quad lol. I have only bought topend rebuild kits for my 400ex and yes i say kits because mine blew out a brand new namura hg instantly lol
 
#20 ·
I said I got the full motor gasket kit because I found out my crank was bad. U could always use a xr400 gasket. That would eliminate the base gasket and increase the compression closer to real 12:1
 
#21 ·
Alright well, I am leaving for vacation today so I'll be back next wednesday and that is when I am going to order all of my parts and get her ready for the first race this year.

I will post pics of everything that I do to her. I'm so excited finally getting to beef up the quad I have had since 2008.
 
#23 · (Edited)
Hey everyone, its been a few days since I have been on. . . Just got back from vacation and look at what was waiting on me :)

The next thing to do is order my motor parts which I am going to do Friday from a new local shop if he will cut me a deal and keep me from having to deal with feebay. By the way if I get the CRF450R timing chain what year do I need to get. . . I forgot and can't remember lol. I can't wait to ride with these new beauties on the there should stick to the dirt like white on rice. . .



I also got this hat air brushed and I thought maybe you guys would like it. . . I will have to post a pic of my bros shirt this guy did. He is very talented and air brushed an actual picture of our quad on his shirt.

 
#24 ·
Looking good! and maybe you can shed some light, im looking for some a arms, ful flights or american star, and was wondering how the measurements they say worked. is it +2+1 on each side or +1 on each side so its +2 wider overall? seems these go by all different measurements haha.
 
#26 ·
I am actually fixing to buy some full flight a arms and to shed light on your question. . .

+2+1 stands for plus two on each side and an inch forward which is what you want for mx racing because moves the center of gravity and turning radius forward which makes it handle, jump, and ride better.
 
#25 ·
OMG SOMEONE RIPPED ME OFF!!!!!!!!!!!

JK just took them off to get the new tires put on and that it looked funny sitting the way it did.



Here is a picture of my lady with the new tires on there and they look sweet. I can't wait to try them out on a track.

 
#27 ·
Well here I am again with a dilimma. I just sold my other 400EX and now its time to since some money in my baby.

I just bought some new tires and a case of Amsoil 0w-40 for quads.

The up coming things I have on my list that are:

JE piston standard bore 12:1 compression
Hot Cams stage II cam
Full Flight Racing A-arms +2+1
XR250R cdi box

I will also be posting up a video of my recent practice once I get it complete.
I will keep updates up with photos and this will be a running story of my quad and how I advance it to the next level to for racing and later up to a 450R.
Just build s 250R and get it over with.
 
#28 ·
Ok Thanks Josh thats exactly what i was looking for, The should be perfect for the woods riding i do and the tracks i ride on. And BTW, instead of buying and building a 250r, then just drop a 250 2 smoker in it, thats my future plans for this winter :icon_ rasta:
 
#30 ·
Yup, but (this is sacrilegious i know) but i will more then likely end up using a kx250 motor. So not only do you end up with a motor that cranks 50+ horse stock, but you cut over 50 pounds with the 2 smoker:icon_ rasta: Scary thing is, it is NOT a complicated task either. Hardest part is the pipe and even that is just a few little cuts and welds. So for the cost of head work and top end kit you can feasibly buy the motor and slam it in.
 
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