My girlfriend's 2001 400ex quad is finally smoking enough under acceleration to warrant rebuilding. I was thinking of moving to a 416 but want to work within the following requirements:
stock exhaustpremium pump gas

Anyone running a similar setup? I need advice for a piston manufacture, compression, and cam.

Thanks.

Jon

 

I'd go with a 10.8:1 JE Piston, and a Hotcam Stage 1 or Stage 3.
Stage 1 would work best with the 416, but it also ticks very loud. Stage 3 is designed for bigger bore motors and more powerful ones, but it'll still give you a nice gain. Both are the same price. BTW, The old Stage 2 Hotcams are the New Stage 3's. The New Stage 2s havent been released yet.

Heck, you could run a 11:1 440 big bore with a Webcam, 3 Angle Valve Job, Race Port and Polish, FCR Carb, and all the goodies and still run a stock exhaust and 93 octane. The Exhaust will just restrict it a lot and it won't have its full potentional.

I think the first setup I listed will be perfect for your situation though. Definatly go with JE or Ross though.

 

I am pretty comfortable tearing down the top end and putting back together. I still have a few questions.
Do I use the standard Honda top end gasket kit?
Do I tell the machine shop what size to bore it or do I take them the piston too and they will know?
Will it work okay with the stock cam?

We are seriously considering replacing the quads this fall so I am not sure I want to dump any extra money on performance. Mostly, I want to fix the burning oil problem. In fact, I considered keeping everything stock. I even noticed Honda sells an oversized piston.

Thanks for the help.

/jon

 

come on guys, don't make me post in the Yamaha forum. [img]i/expressions/face-icon-small-wink.gif[/img]

 

I would take in the piston when you go to bore so they have exact specs to work off of. There are always variances no matter how exact things may be.
As for the cam, it is necessary to really take advantage of the additional CC's and it isn't a huge investment for a solid gain. Consider this, a 440 kit does very little till you add a cam to fully take advantage of the additional volume created by the larger piston.
I would also eventually look to invest in one of the new generation quiet exhaust systems to take better advantage of your setup.

Good luck,

TPR

 

i wouldn't really expect the bike to perform much better with just a higher compression piston. the stock cam stinks so if you want more power, i would definately get one of those. i would probably get a ross or je 406 (around 10.6:1 compression) and use the THIN cosmetic flexsteel gaskets. you will need the head and base gasket for sure. you will need to bring the piston to the shop with you. give them the piston, tell them to bore it AND gap the rings to match the cylinder. give them the spec sheets that come with the piston too so they know what to gap the rings too. the stock cam will work, just don't expect more power if you use it.