High comp piston?

[USAF Dirtboy]

I have a 2002 honda 400ex and was wondering if a high comp piston is really worth the $$$. Are there any noticble gains.

i would get a cam and a port and polish first, then the gains will be more noticeable

[400exrider707]

Originally posted by yzfmxer
i would get a cam and a port and polish first, then the gains will be more noticeable

I disagree. I would do the piston first actually becuase it will be a decent gain by itself. The piston and cam together would be great and then after both of those I would get it ported and polished. I dont think you would see the benefits of a port and polish until you have done other motor work first.

[400exredrider]

do piston first, start from the inside out... piston and XR gaskets, then cam maybe valves and springs, ect. youll notice it if you have a pipe and filter

[400exredrider]

your going to get the biggest gain from a cam, but remember all of these parts work together so for power, you really need it all

[450robot]

just the piston alone will give you noticable power gains, but it would perform better if it was conjuncted (is that a word) with a cam, and some head work,
to even out the flow of the new piston

just dont get to high of a compression, or you will have to use race fuel

[honda400ex2003]

So if you were going to put these 3 things in would you need an aftermarket header of would the stocker work?

[TC426EX]

piston and cam should ALWAYS be done together. You can do the piston and cam for a little over 200 bucks if you go with a hotcam. Its definitely worth the money. With just those mods you will be fine with a good slip on exhaust, although youll want to look into a full system if you plan on doing more mods over time

[honda400ex2003]

Thanks for answering my part of the question. I am going to look into both the hotcam new stage 2 and the wiseco 11:1 when I rebuild my 400ex this winter. Thanks again Steve

[bryan.young1]

since we are on the subject i think my bike stock is a 11:1 compression, and i am going to get a web all around cam and a 12:1 piston soon. i already have a WB pro-meg full system and a 2 sizes over stock main jet, i have been told that with the cam and piston i should start with a 10 size over main jet and go from there. does that sound rite? also, will i have to run race gas or do you think 93 octain out of the pump will do? thanks and sorry again for using this thread just trying to save space....

bryan

[honda400ex2003]

I'm not sure on the jetting but I would say that you will have to run at least a mix of race gas and 93 octane. I'm not sure on what you have to do with the jetting. I wouldn't think it would make that big of a difference in jetting seeing as though you aren't going to make it lean. All you are doing is leaving the vavles open longer. I would start lower than 10 bigger if it was me starting from scratch. But like I said I am not sure. Steve

[bryan.young1]

i was hoping that i could use just 93. less expensive plus a pain in the ***** to find.
thanks
bryan