416 kit

[tide2085]

I am going to do the 416 kit on my 400ex and i wanted to know if you have to get the cylinder bored or if you just put a different sleeve in???

[honda400ex2003]

i dont think you can get a 416 sleeve so it would be bore. it is much easier and cheaper to just bore it to 87mm anyway. steve

[tide2085]

i can just get it bored at a local machine shop right?? nothing special needs to be done to the cylinder??

[honda400ex2003]

anyone with a bore machine or a vertical mill should be able to do it with the right equipment. i would suggest taking it somewhere that does alot of dirtbike and atv ones at least but a local guy should be able to. steve

[CJM]

You will need the piston to bore it, at least the 3 places I called and the one I chose all told me they needed it.

Boring is cheap, less than 100 bucks.

[honda400ex2003]

that is correct, they need the info for the piston to make sure they get the gaps and tolerances right so take the piston with it to bore it and you will be set. steve

[tide2085]

thanks a lot guys one more question can the cylinder be honed???

[honda400ex2003]

yeah but that is different. it is only a clean up and would not take off much material. it would require a 85.5 ring or something. that would be dependent on how much they want to take off with the hone i suppose but it can be done. steve

[tide2085]

alright thanks for the info

[honda400ex2003]

no problem glad to help steve

[a4guy]

I have been thinking about doing this. There is nothing wrong with my quad the way it is but I do need to replace the base gasket because I can see it leaking a little bit after a hard ride.

I have done a little reading on the 416 mod and as I understand it all you need is the piston kit/gasket kit and to bore the cylinder. Is there any jetting that needs to be changed? Can you still use the sparks +6 or is the +3 recommended?

[CJM]

It will probably need to be rejetted. I just finished mine the other day and did I already had a lexx slip on that it was jetted for.

Mine runs but is to lean as it pops on decel.

[a4guy]

Good to know. Thanks.