1986 70 Yamaha won't run without choke

[ohmerfam]

My 1986 Yamaha 70 won't run without the choke, and it will only run slowly (i push the control box all the way forward and i still run very slowly)

i took down the carburetors and sprayed them out well with carb cleaner and removed all the varnish.

Any ideas?

 

[99yam40]

Re: 1986 70 Yamaha won't run without choke

Make sure you have good compression and spark on all cylinders and the clean the carbs better

 

[ohmerfam]

Re: 1986 70 Yamaha won't run without choke

i have good spark, but i don't know how to check compression.

 

[ohmerfam]

Re: 1986 70 Yamaha won't run without choke

i cleaned the carbs again, and now it idles without the choke, but when i go into gear and throttle up, it bogs down and dies.

 

[ohmerfam]

Re: 1986 70 Yamaha won't run without choke

Update, replaced the fuel pump. Took her out, and when i throttle up it bogged down yet again. i then tapped the choke toggle switch on the control box a couple of times and then she roared to life. i did this several times, throttling up, bogging down, and then tapping choke a few times and taking off like a bat outta hell.

 

[parrott]

Re: 1986 70 Yamaha won't run without choke

Take the carbs apart again. Remove the high speed jets. Use a magnifying glass to check the high speed jets. Clean them thoroughly outside and inside. Crude builds up around the holes on the outside messing up the flow at high speeds. These carbs are very finicky

 

[ohmerfam]

Re: 1986 70 Yamaha won't run without choke

I tried removing those jets, is there a secret to getting them out?

 

[ohmerfam]

Re: 1986 70 Yamaha won't run without choke

Wait, i get mixed up on what the "jet" is and what the "nozzle" is. If the "jet" is the brass part with the screwdriver slot, then i know what you're talking about.

Thanks!

 

[ohmerfam]

Re: 1986 70 Yamaha won't run without choke

Removed the high speed jets, cleaned them, but still experiencing "bog" when throttling up. Tapping choke still remedies the problem.

 

[199675hpforce]

Re: 1986 70 Yamaha won't run without choke

Have you tried seafoam in gas. Did you set pilot screw to spec. Make sure your going 360 degrees with screwdriver not 180. Mark on screw. Mine is 1 1/2 yours should be same. So go 360 plus 180, then if still does it go clock wise 90 degrees.