426 build!

[trx400exrider14]

alright,i was originally gonna get the 440 kit but decided now to.I need help first. Tell me everything i need to buy to make my 400 a 426 safely and tell me what to get so it dont over heat. What compression piston is best,cam,timing chain,etc.

[CJM]

Bore size isnt where power is, compression is. Do a 406 or 416 with an 10:1 or 11:1 piston, stage 2 hotcam, heavy duty head studs from GT Thunder, 2002 crf450 timing chain. That along with an 04-05 450r carb and a good exhaust will make your quad quite powerful. Add in a 3 inch spal puller fan and a larger oil tank and it will run cooler too. I have the same exact setup I mentioned and Im quite happy. Its not 450R but its got plenty of power.

The good thing is too if the piston/bore ever wears out you can then bore it to 426 if you want. You do 426 and something happens your buying a new cylinder.

[426kidz]

my bike is a very solid 426 fast and no probs at all...is going too cost you though start off by ordering a wisco 11:1 high comp piston,stage2 hotcam and a 89mm cometic gasket kit. than send your top end to get bored and polished also get HD studs put in my GT thunder there great! than you can do a HD timing chain.also run a full system, there is some more just pm me with any questions. make sure to stick with the right companies and do not take the easy way ou! if you have to debate wether or not you want to spend the extra on somehting than you def need it. for example HD studs many will say dont need it many will say it extra insurance on the motor I say do it right one time and there will be no second time! just take the time to do it right thats all!you will not be disapointed with the 26 at all:D :D ... I also have many pics from my build to guid you just ASK!

[426kidz]

would not worrie about fans and a carb...jet the stock one right and it will be fine! want speed re-gear also. I put some air shrouds on mine and no problem over heating even in 98degree weather ridding very hard!

[trx400exrider14]

how long does it usually take to get everything sent off and put on?like the boring and hd studs?

[CJM]

Ford the record, a 426 (actually 423cc) and a 416 (413) is not gonna make a huge pile of difference in power. Your talking 1mm larger than the other. now if you had say 50 more cc then youd notice power. But like I said before: compressions power not bore size. Thats why so many with 440s are saddened the bike they spent $$$ aint that much faster-lower compression. Stock is like 9:1, but with the thick gasket honda uses its closer to 8:1. Using thinner gaskets like the cometic multi-layered "MLS" steel or an xr400 head gasket achieves correct comp ratio.

Like I said, stick with 416-if you blow it then you can then bore to 426 if you want. Blow it with the 426 and your going 440 or new sleeve, $$$$

The 450r carbs worth it, larger carb means more power overall. You will be surprised at how much over the stock one. And the fans worth it, should you ever find its hot out and your running hot 1 flip of a switch and your down at least 20F in temp.

Please understand: Ive built quite and advised people on how to build up an EX and no one has ever been unhappy with my advice :D

The below will run on 93 octane if jetted properly all day with no issues:
-JE or wiseco piston, 10:1 or 11:1

-Hotcams stage 2 (midrange to topend power)

-Full exhaust or slip on, your choice. Full exhaust is like 500 but a slip on is cheaper. Grinding the welds at the header flange fixes the only restriction the EX header-cause otherwise its actually really good.

-CRF450 2002 timing chain: this is a HD timing chain and will outlast a stockone. Its thicker with more links, fits fine and is cheaper too boot. if you have alot of hours inspect the chain guides and buy a new auto tensioner as they wear out.

-Heavy Duty head studs from GT Thunder: Well worth it, heat is the killer of these aircooled machines. The exhaust studs will pull out and you will have headgasket issues if it gets to hot. Well worth the 100 bucks from GT Thunder (turn aorund time is about 2 weeks) for them to do it. I had them bore my cyl too and everything was 200 including shipping.

-Spal 3 inch puller fan, put it on the oil cooler and when you turn it on it cools everything down quite well.

-Open airbox lid: Its worth it unless you ride in mud and water alot. Allows the engine to breath much better. Use a UNI brand air filter and either an EHS outwears box lid or a cover for the filter to make sure dirt dont get in.

-Larger oil tank. its not needed really for most, but more oil means more cooling capacity, means lower temps, means better running engine. Why do you think many cars have transmission cooler-cooler trans lasts longer and shifts better-same principle.

-04-05 450R carb. The carbs larger, allowing more fuel and air into the mix. Thus more overall power. With a few simple parts like a hotstart block off and a 450r throttle cable you can mount one up. Check the Popular threads link in my signature-its well worth the coin spent on the carb

-As noted before-only use cometic brand MLS steel viton coated gaskets. They are thinner than the stock gaskets, seal SUPER well (I had to chisel mine off last time! and they arent to costly. Just make sure you use the MLS ones, they look like rubber coated steel-not paper.

Stick with the stock carb and you need a 165-175 main jet (it depends on your elevation and such), 42 pilot, 2nd or 3rd clip on needle and 2.25-3 turns out the air/fuel screw. 450r carb would be about the same jets but a 48-52 pilot.

[trx400exrider14]

About how much would all of this cost saying i got the 416? retail prices,not ebay or nothing

[426kidz]

understood...that being said i would still stick with my advise. this is not to argue take our advice and run with it... but it took about a week i believe GT is great!

[426kidz]

I also went straight thru ebay...your gonna have too just look and price things out. I did mine over the whole winter so i bought things here and there so i did not keep a price list. but i did keep all my packaging,lol i could find out, also it wont be any less going with a 416 or 426 not a noticable dif atleast.

[trx400exrider14]

well i mean,i might as well stick with the 416,and if i dont like it i can always upgrade to the 426

[trx400exrider14]

would either of you guys think i could manage a 500 dollar budget?

[426kidz]

if you have that kind of cash go for it...you will want to go bigger i believe but your call...are you looking for speed or what? race or drag?? if your not racing or anything just get a full system stage2 cam and re gear and right tire size. there is alot you can do to improve your bike without going this far!

[426kidz]

NOOOOO 500.00 will not cut it unless you have a full system already. its expensive! post a pic and we will see what you should do to improve it...also let us know what kind of ridding you do

[trx400exrider14]

yea,im racing,i race woods,so i want alot of bottom end for hills and mud and stuff,i heard stage 1 cam for that,is that true?

[426kidz]

1=bottom end, 2=mid-high, 3=topend

[trx400exrider14]

i already have a slip on,ill go a full system after everything is rebuilt

[426kidz]

yeah i say curtis sparks or hmf my personal favs. but once again it will cost you do some price checks you will be surprised

[trx400exrider14]

i might wait till after the season,i dont think i can get stuff done in 4 weeks time

[426kidz]

its possible with the right funds. alot of time you call them they canhave things done pretty fast. just depends on how much time and money you have... you have the knowledge for sure..just come ask one of us!!!:D ;)

[CJM]

my buddy has a stage 1, 406 and 11:1 We race woods, trails, pits, dunes, etc. he dislikes it and wishes he had a stage 2 b/c he lacks a bit of upper end power.. I have stage 2 and have all around good power period.

If you have 500 it can be done, buy alot of the parts on ebay. Pistons, cams, gaskets. I specially like the store apex racing-jeff has always done me good:
-Piston wiseco $120, JE is $150
-Stage 1 or 2 hot cam is about $130
-Gaskets are about 30 bucks
-Bore is usually between 50-100, depends on the place
-GT sells the studs for $50 and installs for $50 = $100
-You already have a decent exhaust live with it for awhile, a full system does make slightly more power-but a slip on is pretty ok till later
-450R carb is about $100-200, depends on seller. Parts to block off hotstart and throttle cable are about $40
-CRF Timing chain is $50, but make sure while everythings apart you check both chain guides for wear (they arent cheap) and the tensioner (it springs back if you insert a screwdriver-it dont its bad and replace-its $60)

It can be done for 500 bucks, maybe closer to $650 but it can be done. Best advice I can give is you will save BIG TIME if you can do the work yourself or find someone reliable for cheap. Dealer or a custom shop is gonna be $$$$$

[426kidz]

yeah got to find cheap but reliable ways...500 is really not close if you ask me but if you can pull it off i would love to know how.I payed 350 for my hmf alone. your looking at a bore gaskets and a pipe for 500.00. id wait

[trx400exrider14]

yea,ill keep all the advice you guys offered,my most concern is keeping my quad reliable and safe,thanks for taking the time out to tell me about all of this,i will deff pm either of you guys on questions,thanks!

[426kidz]

no prob either way you will be happy its a honda!;)

[supertrooper90]

I race harecrambles and ride some mx. I did a 416 JE 10.8:1 with a sparks x1 cam port and polished head and 450r carb. I left the base gasket out and used hi temp silicone to get the piston near zero deck height. I am very happy with it for an all around package. If you have 500 to spend, I would do the piston, studs, and cam. That ll basicly kill your budget. And add the carb later, It makes a really nice increase in power.

My wifes 400 has a hotcams stage 2, with a weisco 11:1 piston I like my package much more. Has more power throughout the entire powerband.