Re: NU50 problems help

Adam Kollipara /

NO, the auto choke SHOULD have fuel in the fuel lines, but only in 2 of them. The vacuum sucks the gas through them.

Here's the "1982 Honda Urban Express Shop Manual": if you need it.

Tube 3 has only air. Tube 2 has the gas/oil mixture coming from the carb. Tube 1 has gas/oil mixture coming from tube 2 going into the engine to be used.

When starting cold, the bimetal strip should be bent so that the valve inside the black plastic connector (you can't see this) is blocking tube 3 from letting air in. This will create the rich mixture to start it cold. When it warms up, the bimetal bends so that it will let more air to keep in running (it doesn't need the rich mixture). Once the engine reaches about 150 degrees F, the auto choke shouldn't have to do anything. The bimetal strip will be bent to let air go through the valve only, blocking tube 2 from letting any gas/oil in, and the engine will use the gas/oil directly mixed from the carb.

Here's some pages from the "'77 - '81 Honda Express Shop Manual": showing how the auto choke works.



To see if the auto choke isn't working (the air is usually the problem, and I'm having this same problem), put you finger over the inlet to tube 3 in the bystarter. Start the engine and see if it keeps running. I had to do this and it worked. Th problem is that the bimetal strip isn't working to block the inlet to tube 3 when starting cold. Try putting a little plastic inline fuel shut off valve in tube 3 to see if this solves the problem. When starting cold, turn the valve to OFF and when it warms up, turn it to ON.


I hope this all helps.


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