2000 Honda 400ex - choke problem??

honda400exrider42 · February 26, 2011

Hey, I cant think of any reasons why, but on my 400ex, when I give it alot of gas and shift through the gears(usually when I get into 3rd) my choke comes on and my wheeler bogs out and dies unless I clutch in and turn the choke off. I cant think of why this would do this. It seems like it started somewhat recently.

Last summer I put a set of rings and valve guides on the 400ex, but ended up gettings rings a bit to big, and the wheeler continued to smoke, so this spring, im going to tear it back down, anyways I wanted to know if anyone knew why the choke was kicking on? I would like to order all my parts at once and do all the work to the wheeler while im doing the topend this spring.

honda400exrider42 · February 26, 2011

Just figured Id add that its a year 2000 400ex

DirtDemon · February 26, 2011

Thanks for adding the model year, I will add it to the thread title. The only thing I can think of that might cause your choke to is loose, worn parts. I would look into replacing the components of the choke system. I would first take the carb apart and check for any signs of wear to specific parts, that way you don't buy more than you need. BTW, when you tear your machine back down, be sure to check your head for leaks, the smoking could be partly or completely caused by oil leaking past the valve guides/seals. Good luck.

honda400exrider42 · February 26, 2011

Thanks for the reply. Im guessing that the choke is due to lose parts, it felt pretty lose but I couldnt find any screws or anything to tighten, ill take a closer look when I have the wheeler apart. As for the valve guides/valve seals, I did the valves last summer, but ill take another look. My guess for the smoke is that oil is getting past my rings, because my rings were all to big. I think my cylinder is just worn, I think ill have to go up a piston size, maybe to an 86mm bore up from the stock 85. But im not sure, ill check it out. Thanks again for the reply

DirtDemon · February 28, 2011

If you did the head, then you are probably right about the rings. You should be able to get piston sets in .5mm increments, so the next size up from stock should be 85.5 if stock is 85. Make sure to have the cylinder measured before buying the piston, just to make sure you haven't worn it to the point that you have to go even bigger. Good luck, hope everything works out well.

honda400exrider42 · March 2, 2011

Hey thanks for your reply yet again. That sounds about right to me, last time all I did was rings and the end ring gap was supposed to be .014 for the first and .024 for the second, I was at .034(somewhere in there) and .040(somewhere in there as well) So im guessing/hoping it will be as simple as going up a bore size on the piston..

Just wanted to say thanks again

DirtDemon · March 2, 2011

Anytime, there is actually a thanks tab at the bottom right hand corner of each post, if you want to thank a member officially, you just click that tab and you can add a tag at the bottom of the thread that says that you are thanking said member for this post. I hit the button on your last post to show you how it displays. You are welcome, and don't hesitate to ask more questions if you got them, we are always glad to help out.