400ex has no power

[400exkid2]

one of my 400ex has a problem the engine doesnt seem to run right. it will start but it has no power when u get going we thought it was the carb, we cleaned it and it didnt help. if you have any idea please help

[250exkid]

change the plug...

[wilkin250r]

There is a set of systematic checks that you can perform on your quad to narrow down the problem, but every single exhaustive detail is way too much to post on here.

You're not going to get an easy answer like "It's your Kanooter Valve, just give it a quarter turn clockwise and all will be fine!!!"

First off, you need to solve the easy solutions. A clean filter, new spark plug, fresh gasoline. The next step is a clean carburetor (which you have done already), along with a complete check of all electrical connections. Also a complete check of your intake tract for any possible air leaks.

Along those same lines, you would need to do a compression check.


If you have the background knowledge already, you might be able to skip some of these steps because you would recognize certain symptoms. But I can't post years worth of experience and knowledge into a single post, so I can't pass that knowledge on to YOU that would allow you to take the same shortcuts.

It might be an easy fix, it might be a difficult fix. But either way, it's going to take some legwork from you to find and/or fix it.


So, like I just posted above. Clean filter, new sparkplug, fresh gas. Start with that, and get back to us.

[bwamos]

My first question:

What have you changed.

Did you put a new exhaust on, switch from stock to aftermarket filter, etc...?

[400exkid2]

ok ill do those
and the quad is completely stock nothing on it

[BigBore24]

if the timing chain jumps just one tooth it will still run but very sluggish. lots of other things to check first but this could possibly be it if you have never replaced the chain or maybe the tensioner

[tom416ex]

i had that same problem with my 400ex. check the carb again, one of my sliders fell apart, so only one was working. Put the slider back together and it was good to go... Let me know what happens

[400exkid2]

k it will be awhile before we start on it
has to warm up