Air "outake" ?

Hi all,

is it normal to have air leave the carb venturi intake? That and I often get gas spitting out of it as well.

I assuming that this has to do with my top speed problems...


Re: Air "outake" ?

Jonas Quimby /

The Honda Express commonly does this. The fault lies in a rather poorly built Reed Valve that sits between the intake and the crankcase. As the piston travels down to force fuel from the crankcase up into the cylinder, it also pushes some out the reed vavle. The problem only gets worse with age.

This is why most pictures of the Honda Express show a badly discolored air filter box. The plastic has been hit by gas for some time.

Even mine has been like this as long as I've owned it.

It most certainly means a performance loss, but I get more then acceptible power even with it.

If you're lacking top end speed I'd first clean your muffler. That's the big one.

You can improve the "output" slightly by replacing the reed valve, but any that you can buy now will eather be worn or just old, so they wont work much better.

Re: Air "outake" ?

Steamboat Aka J. R. Stevens /

I know little about the express but if it is a 4-stroke you may have a burnt intake valve. Jim.

Re: Air "outake" ?

All two strokes do this to some extent. Air has weight. When it is moving it has momentum. As the air is moving into the inlet the velocity is quite high and it has a lot of momentum. When the pison comes down and closes the inlet port the air hits the closed port and bounces back out the inlet.

It is then normally sucked back in on the next inlet stroke.

This in and out is routine and the engineers plan on it.

If the engine is modified it can get all out of whack.

Do you have a pipe on the bike? The pulses coming back into the engine can be out of tune.

Re: Air "outake" ?

No pipe to speak of, I have a badly clogged stock exhaust, I suppose that could be causing this pressure?

I've also messed with all the carb settings enough to get them totally snafu-ed.


Re: Air "outake" ?

Jonas Quimby /

The Express is a two stroke, not a four stroke.

And yes, there should be a SMALL ammount of this on any two stroke.

But the Express does it far more then others.

A clogged muffler may be causing slightly more pressure then normal (as well as a great loss of power) so it couldnt hurt to clean it out.

Also, my guide to Express repair lists the proper way to adjust the carb settings.

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