Help me with my build (only ppl who know what they are talking about plz)

[dr qwerty]

Ok, Please bare with me, and if you know your stuff chime on in...

SO, my bike went boom in the sense, my friend rode it with the oil out and let metal on metal occur...I freaked and reacted like a rich kid (took it str8 to the shop)since my friend who has the most know how deployed...And I was out of time since i leave in a month to deploy as well so i wanted my bike running prior to my departure as well as the friend who blew up the engine is leaving at the end of the month as well.

My friend is paying to have to put back, they quoted it 500.00 from start to finish back to stock
Then i asked how much more to make it a 416 since i've done little research n what i've found i want my reliabilty....They convinced me on the 426cc and it would be 620.00

The price is NOT the important part this is...
1. What should i ask during this...
2. What needs to complament the 426cc upgrade, i.e. i heard head studs, springs etc...?
3. They told me i can run the 426cc stock if need be, but adding jets, filter, exhaust etc...will really open it up...
4. With the 426/uni filter/exhaust/stage 2 cam/450r carb/
can i run with a 450r with the filter and exhaust
5. What sprocket set should i go with...how many teeth up front and in back since i've upgraded to the listed mods above...?

I wanted to keep my bike stock since i have a 700xx and wanted the 400xx for my girl and to keep it reliable...Help me out please!!

[DMAXX99]

Ok well the 426 is a good option i just had it put in my bike cuz the piston rings are shot, i've got an hmf pipe, k&n filer without the box lid and i had the dynojet jet kit put in and all that with the 426 is a ridiculous difference from stock im really happy wih it. As far as hangin with the 450s idk about that im running stock sprockets and i raced a yfz on a small track and straight stretch. It was fairly close race since its 400 versus 450 but i still got beat the torque and low end power you gain is very noticable after 3rd gear but i still got beat by 2 bikelengths....You have more on your bike it sounds like so idk about ur race it oughtta be closer but that depends on rider difference i guess. All in all i think you will be very happy with the 426 choice i know i was

[Wheelie]

I'd go with a 416 over a 426 personally.

At the very least, install a HC stage 2, a slip-on, and filter to compliment the piston. For some added bacon have the head ported and install a 450R carb.

IMO with the above listed setup, stock valve springs and stock gearing should work great.

Head studs would be a good idea, but aren't an absolute must. A good tune, good head gasket and proper head bolt torque go a long ways to ensuring the stock head studs survive in a modified environment.

Since the engine was run dry, replace the crank and crank bearings, oil pump and cam bearings at the very least.

[Sanddraging28]

if you are looking to run pump gas then i would go with a 11 to 1 416. if you dont mind paying for race fuel then i would suggest a 12 to 1 416 or a 13 to 1 426.
you will not see a big difference between a 426 and a 416 if you are only running 11 to 1 compression. it would be better to go to a 416 and save the overbore if you ever need it.
the down sides to higher compression is that HD head studs are a must. a stage 2 cam will work well with any of these setups. since this rebuild is coming from a lack of oil failure then i would definetlly replace the cam chain,cam bearings,and the tensioner. as far as the bottom end is concerned the 400ex is a tough SOB. depending on how bad the failure it is not always needed to split the cases and replace all the bearings. the shop should be able to advise you on how bad if at all the bottom end was hurt. one of the parts most often hurt on a 400ex that was run low on oil is the piston end of the rod. its easy to check once the piston is removed from the rod. replacing the oil pump is also a good idea.
you shouldn't need to do anything with the valve springs. a good port and polish job is a great upgrade but keep in mind its one of the most expensive upgrades you can do. and its one area that you never search for the best price. find somebody that has a proven track record and pay him his asking price.
adding the 450r carb will only better the improvement over stock. its a great upgrade and is turning into on of the most common also. a good exhaust will now be a must have. i would look into a full system to get the most out the parts you are putting in the motor

make sure that the shop you are dealing with has a good mechanic that knows what to look for when dealing an oiling problem failure. but with what you have said already they seem to be pretty knowledgeable.

[dr qwerty]

So i talked to the woman, there and she couldn't give me any solid answer, she did how ever tell me to call back tomorrow to speak with the service manager to ask all the ?'s i want. All the y show on order is weisco piston 426cc kit and new gaskets...(couldn't tell me the comprassion ratio, but i looked at weisco web site and they only make 426 in either 10.1 or 11.1 which i have researched can run on pump gas 91+)
She didn't see a new sleave on order...is this bad?
She also couldn't answer if they have taken my stock cam so i can just order a stage 2 and have them put it in at no cost since they have to put the stock one back in anyways....
What should i be asking...?

[killer400ex]

i just finished my rebuild last week with the same mods you are thinking about, i went with the 11:1 426 wiseco piston, i talked to a few mechanics and they said that heavier duty head studs arent necessary but there is no harm in putting them in, also the only time you need to have a new sleeve put in is when you bore over 440, i had mine professionally bored for like $20. i am extremely happy with it now, the power difference is huge and i just put the stage 2 in a few days ago and re jetted for it and its hard to imagine that anyone would not be satisfied by the amount of power it now makes

[dr qwerty]

Then it seems we will have the same build, but the research i've done...and what i've pieced together is that of course like any motor a properly built will run better then one that is not, and from what i understand our 426 with a 11.1 wont be much more then a hair faster then a 416 with a 11.1...also the sleave helps with heat etc...I just hope for the best...

My problem is i went to a dealership repair shop not a race shop that actually builds to win....there is a huge diff, i do not doubt they have the know how to build reliable and a little fast machine but i do bet they dont have the r/d or exp from a race shop...that has put bikes into baja etc....

I hope for the best, thank you everyone...

[jcs003]

i would go with the JE 89mm hi-compression kit(sleeve, piston, gasket). send the head out to FST to get the port/polish and get heavy duty valve train. get the GT thunder head studs. this will be a great set-up but you will need high octane gas. the motor is 435cc and very reliable if tuned correctly.

[dr qwerty]

Any links to where i get the GT heavy duty head studs?
What timing chain do i use...I know crf but what crf
I doubt i will be getting a new sleave with my 426 since the shop didn't order one and i dont want to tear it down again so i will cross my fingers by not getting a new one, but i will add a fan to help with temp...

[RaceinCircles]

Aaaha! ^^^^^

Am I really the first one to say crf450 timing chain?!

And you want any year crf450 from like 02-08..

[jcs003]

you can get the heavy duty cam chain from GT also.

[rob_990]

yea but it costs over twice as much

[DMAXX99]

the crf heavy duty chain does just fine thats wat im runnin its like 90 bucks

[Wheelie]

I got my CRF cam chain through C&D for about $35.