57 Fastwin 18hp carbuerator question

[fm elliott]

I have just replaced magnita, and have good spark.....have just rebuilt carb....but motor wont fire. How do i know if carb is working properly? I have removed carb while still connected to pressurized tank but can't see gas spray coming from rear port. When I tilt the carb to one side gas drips from one or both holes on the port side. I am very familiar with atv and other small engine carbs.... where when throddled, they spray gas into the intake. How does this carb work? Thanks in advance.

FM Elliott

 

[bob1340]

Re: 57 Fastwin 18hp carbuerator question

I have just replaced magnita, and have good spark.....have just rebuilt carb....but motor wont fire. How do i know if carb is working properly? I have removed carb while still connected to pressurized tank but can't see gas spray coming from rear port. When I tilt the carb to one side gas drips from one or both holes on the port side. I am very familiar with atv and other small engine carbs.... where when throddled, they spray gas into the intake. How does this carb work? Thanks in advance.

FM Elliott

Gotta have air going through it for it to work. It's a venturi type carb I am guessing. I don't think they have a accelerator pump on them. I am guessing the jet or passage ways are plugged. Get a carb kit and tear it apart. Make sure and remove those aluminum soft plugs and spray out all the passage ways. My carb appeared pretty clean when I took it off, but once I removed the soft plugs I found all sorts of crud.

Also, before you pull the carb spray a little fuel/oil mix in it and see it it fires.

 

[fm elliott]

Re: 57 Fastwin 18hp carbuerator question

I appreciate that and you may just have hit the nail on the head. I ordered a carb kit and new float. As I re-built the carb, I noticed the soft plugs and other various parts that didn't seem to go with my carb. I'll go back and peplace those. Any tips on removing and replacing those would be appreciated. Also do you know the settings for the needle valves? (Seems like it was 1.25 out to start).

 

[lindy46]

Re: 57 Fastwin 18hp carbuerator question

I remove them by drilling a small hole in them, and pry them out with a small screwdriver. Be careful when drilling to just go through the plug. I use a thin wire to clean out the passages inside. A twist tie wire works great.

 

[fm elliott]

Re: 57 Fastwin 18hp carbuerator question

thanks. if anyone has the jet adjustments....i would appreciate it

 

[bob1340]

Re: 57 Fastwin 18hp carbuerator question

thanks. if anyone has the jet adjustments....i would appreciate it

Not sure. On my '71 model it is 1 turn out to start. Try it there and adjust it so it runs the fastest/smoothest at about 750 rpm and still idles at 550-600 rpm.

BTW I think you are talking about the adjustment at the top of the carb throat? The jet should be fixed, but I am still thinking of the '71 model carb. Back in '57 the jet may have been adjustable.

 

[lindy46]

Re: 57 Fastwin 18hp carbuerator question

1957 has a high speed (lower) and slow speed (upper) adjustment. Set the low speed to 1.5 turns out to start, and the high speed to 3/4 turn out to start. Get her to idle halfway decent, then take her out on the water and run WOT. Adjust the high speed to optimum. Then idle down and adjust the low speed.

 

[fm elliott]

Re: 57 Fastwin 18hp carbuerator question

i appreciate both of your input. i should be up and running tomorrow, Thanks again.