found out why my 400ex runs bad

[mineralgrey01gt]

Decided to tear it down today and check it out why it was running so bad and started blowing oil out the exhaust. Found the cylinder to be seriously scarred, piston rings are shot, piston isnt too healthy either, a valve is chipped and such, and a few other little things. So now its going to sit until i can afford to do the 440 on it now with a full valve job and such

[honda400ex2003]

bummer man that really sucks bad. steve

[mineralgrey01gt]

its no big deal, what could i expect for $550? What valves are good to put in for a 440? Im considering doing a 416 instead though. Who is the best at porting these heads?

[Ntensweapon]

C&D does good work.
My local engine builder does good work also. He did a top end on mine and cleaned up the porting that jannsen left behind.
Lenny Mumm
Mumms the Word Racing
319.390.0281

[lester985]

how much does c&d charge for port polish and 3 angle valve job

[bigbad400]

i have a head ported at cnp motorsports in ft wayne indiana, that they installed +1mm kibblewhite titanium valves in. perfect condition, lost the crank parting the rest of motor. shoot me a pm if interested.

[lester985]

pm sent

[hypersnyper6947]

better you find it like that than keep on riding it and grenade the whole thing,

have fun on the rebuild :D

[mineralgrey01gt]

Im definitely happy I tore it down now and not went on the ride this weekend. I also needed to know if I go with a 416 can I just get a stock top end gasket kit? I think that's what I'm going with and a stage 2 cam with ported head. That should make some nice power.

[mineralgrey01gt]

Scratch the last question, I found the piston kit on eBay with the gasket kit. With an 11:1 compression ratio do I need to run any octane higher than 93?

[ds268]

You would be much happier going with a basic overbore of 416 or 426. The first thing I did with mine a month new was 440 and all the bells and whistles and it never did make power like I thougt. It's no where near what my current 426 is, and nothing else has changed.

If you decide to go for the 440, I have a like new cylinder sitting here.

[mineralgrey01gt]

Thanks but I'm going 416/426 since it'll be a little cheaper. If I knew the 440 would make really good power I'd do it but I'm not to worried about making huge power out of this engine. I plan someday to make it a hybrid so I don't want to drop tons of coin into this engine

[ds268]

Awesome, you'll be much happier trust me. Seems like the 440 is a hit or miss, plus they make so much more heat with that bigger bore. My 426 would kill my 440 no question and I can ride my 426 all day long at the dunes without heat soak.

[mineralgrey01gt]

Which compression piston do you have? I might go with the 11:1 but I want to stay with 93 octane. Also I see JE makes a piston kit with the piston an such and the gasket kit for $275 shipped. Anyone know of anyone cheaper? I'm having trouble finding the gaskets

[ds268]

I run an 11:1 weisco piston and it runs on premium pump but at the dunes, because it takes more power to move and runs hotter I will mix in a gallon of race to prevent detonation. Trail riding its happy all day with 91 octane. You can get a cheap gasket kit from rockymountainatv.com, $17 for the Tusk gaskets that work fine. My piston cost $120 with wrist pin and rings.

Tusk Gasket kit (http://www.rockymountainatvmc.com/productDetail.do?&navType=type&webTypeId=202&navTitle=Engine&webCatId=17&prodFamilyId=3146#vehicleSelect)
Wiseco Piston for 86mm (http://www.rockymountainatvmc.com/productDetail.do?navTitle=Engine&webCatId=17&navType=type&webTypeId=201&prodFamilyId=3784&listingId=&sizeAttr=3329#vehicleSelect)

[mineralgrey01gt]

Awesome man thanks a ton. Looks like I'll have it going sooner than I thought

[ds268]

Good luck to ya! You may wanna look into a cam for that and really wake it up. I've always run a white brother's cam but they are hard to find even though there isn't much special about it. Hotcam stage one or two, I recommend the stg 2.

[mineralgrey01gt]

Originally posted by ds268
I run an 11:1 weisco piston and it runs on premium pump but at the dunes, because it takes more power to move and runs hotter I will mix in a gallon of race to prevent detonation. Trail riding its happy all day with 91 octane. You can get a cheap gasket kit from rockymountainatv.com, $17 for the Tusk gaskets that work fine. My piston cost $120 with wrist pin and rings.

Tusk Gasket kit (http://www.rockymountainatvmc.com/productDetail.do?&navType=type&webTypeId=202&navTitle=Engine&webCatId=17&prodFamilyId=3146#vehicleSelect)
Wiseco Piston for 86mm (http://www.rockymountainatvmc.com/productDetail.do?navTitle=Engine&webCatId=17&navType=type&webTypeId=201&prodFamilyId=3784&listingId=&sizeAttr=3329#vehicleSelect)

im double checking but that gasket kit will work right? Im about to order one. I already have a honda OEM head gasket ill be using

[ds268]

Just make sure you order it for your year of 400ex. I clicked the link and it came up with it as being for an 05 450r but make sure you tell them. No idea why it did that or changed.