400ex valves!!! stock or aftermarket need help

[Wired]

what do you guys that have built alot of EX engines recommend? stock valves from service honda, or aftermarket valves from like vesrah or kibblewhite? any suggestions are welcome!! need help asap! thanks

jon

[Wired]

i just read something on oversized valves just now, whats up with them? pro's con's? might as well do it right right away :D

[trx400ex]

get the oversized valves, thats what i did and there not anymore $$$....call an engine builder like LRD maybe and talk to them about them...i certainly dont know enough to educate anyone...just dont call Tom;)

[JD400exrider]

I am not a engine builder but have done some research on replacement valves. From what i have heard the intake valves on the 400 are a little soft. I am going to replace them when i do my 416 kit with a black or white diamond valve. Colby at C& D can get them or xr's only has them Over size valves i don't know a whole lot about.

[K_Fulk]

Go with the stainless valves al the way around. The stock ones wear out kinda fast and with the stainless valves you can just keep getting them reground. The bigger valves help more in the upper rpm's.

Valves huh :)

I went thru this decision process and decided that there is allways the one little extra thing we want on the quad :D and I was thinking real hard about the oversize valves but in the end decided against them.

Deff dont waste your time and money on the stk OEM ones and go with the Diamond valves from Kibble white and its not just the material that makes the diff but the amount of pieces that the stocker has that can go bad. I think the stk valve is a 3 piece and I have seen more than one where the "head" came off.

Now the oversize thing is more complicated because there are diff opinions on this even between the pro engine builders. I had heard from some to deff get the oversize (most all wanted to sell me a complete exhaust and other stuff too) and just a couple others that they arent worth the expense and the head and chamber design wouldnt flow more with them anyhow etc.

You have to also consider the extra machine work required to fit the larger valves and the potential cost of that also.

I would think that unless you intend on spending a good amount on porting and polish etc and a higher flowing carb and some other mods then you most likely wount be needing the oversize valves on the 416.

Just some thoughts anyhow.

[Martin Blair]

get some oversized valves and ti springs from white brothers, they dotn make them but its in there catoluge i forgot who makes em but you can get them from WB

[Wired]

well will the oversize valves hurt my engine in any way?? or de-perform as some would call it? their the same price as standard size valves and the engine work shouldnt cost me too much where i get it done at. i can get the Kibble-white precision machining - black diamond valves for under 30 bucks a piece, same price for the oversized intakes. what you guys think. plus i can get these within 24 hours so thats always a good thing so i can get my engine back together as quick as possible!

[Taco]

Well remember if you get the oversized valves your gonna need your head reground to accept em and then ya might as well get a lil port &polish work done:D Oh and no i dont forsee any negative effects except more power. From what I have read I would only do the Intake valves oversized.

[YZROOSTINYA]

the only time I would add valves or springs is to gain the benefits
of a lighter valvetrain. But the cost of a TI set up is extradordinary and the rest of the motor would have to have some serious work to reap the benfits.

I think you would see more gains from porting and a larger carb versus larger valves. If you had a stoker or 440 and greater bore than maybe

[trx400ex]

I think everyone would agree that if your going to get new valves (1) and you can get OS valves at the same cost (2) then you should go for it.....maybe the gains will be minimal, but so is the cost

[K_Fulk]

I would just get the o/s valves and when you get a full race port done and put a bigger carb on it. The 400 will get a good kick in the pants.