400ex bore??

[mjh2115]

I have a '00 400, thinking about upping cc's, want to know where to start, where to get good mods, not junk, any info appreciated thx

[400exJOE]

I would highly recomend a cam. An xr400 (honda dirtbike) has the same engine but has a better cam than the 400ex. They are only about $130. There are also much better cams too. Just more money. Some are GT Thunder, Web cams, White Bros ...etc. I would get a drop-in style though like the xr400 and gt thunder. No new valve springs or hardfaced rockers. Bigger bore adds power too. There are many different sizes plus higher compression. Over 11-1 compression requires race gas though. Bore sizes--406, 416, 426, 440, then with stroking, 465, 500, and so on. Bigger bore means more money and more heat, equalling less reliaility. I think a very reliable combination with very good power gains would be a 416 10.8-1 compression piston with an xr400 cam. Marcums sells these kits for around $300. They are in the Links page. Hope that helped!

[Dave400ex]

That was Great Info 400exJoe. You could get a XR400 Cam, or you could get a little Wilder Drop-In Cam. There is a New Cam out called Hot Cam that sounds really Good and is Cheap. You could try that. You also have GT Thunder, TC, Sparks, WB, HRC, and so On. There is Tons to Choose from. For the Bore, I would go with a JE 10.8-1 416 Piston.