Oversize Valves

[tdsongster]

Anyone running oversize valves on their 400ex?

[Chef]

Yes sir.:D

[tdsongster]

Are they a significant perf enhancement? What kind of cost is this mod?

[panteramatt]

Man chef, you got some nice toys!

[Chef]

Originally posted by tdsongster
Are they a significant perf enhancement? What kind of cost is this mod?

It depends on the rest of your setup. With the right cam, compression, valve type, valve job, and size, yes they can make a big difference. If they are just thrown in there, chances are they wont be a jaw dropping hp maker.

[TC426EX]

I have oversize valves too (+1mm) and noticed a difference from before I did it. You need to have a pretty heavily modified engine for it to be worthwhile though like Chef said...

[Chef]

To answer your question TD, it probably isnt going to do alot on your motor...Give it some more compression and, depending on how big it is already, maybe go bigger bore and they will do something. My valves in my 400 head are almost 3mm over on intake and 2mm over on exhaust. On the 450 They are about 3mm bigger than stock on both sides and 5mm bigger I think than the TRX valves.

[cals400ex]

i have been considering oversided valves but i don't know. i am only running a 11:1 426 and i don't know if they will help. i am thinking about running a 440 or a stroker but i haven't got really any great news with either of these.

[hondamxerd]

hey chef, hows that husaberg run compared to your other off road toys?

[Chef]

Dont know...don't have a motor.:scary:

[400exrider707]

Not to change the subject but I was curious about your husaberg too? Whats up with the motor man? You have any sweet pics of it?

[dirtmomma]

Is it a MUST to put bigger valves in a big bore 440?

[EXDUNER127]

A 440 is not a 440 without the oversized valves and other goodies; porting, 3-angle valve job, etc. Otherwise it just a bigger bore than a 426, with 440 there is more potential to the motor meaning you can open up the valves ports, intake-exh. ports more than you can to a 416 or 426!

[Chef]

Originally posted by 400exrider707
Not to change the subject but I was curious about your husaberg too? Whats up with the motor man? You have any sweet pics of it?

Just take a look in that 1999 dirtwheels of whatever month...its in there. Its the same one. The motor is just waiting on money...big bore, big Ti valves, big cam, etc.

[cals400ex]

who did you all have do the headwork for the installation of larger valves? i don't want to wait a year but quality is important too.

[tdsongster]

I am having C&D Racing do my motor, porting, piston, cam, etc and expecting to get it back in about 1 1/2 weeks. REALLY anxious to see how it performs with all the new mods...