WOT and engine dies -- vacuum leak?

[bradmeehan]

My 85 Aero 50 dies at wide open throttle or when under a lot of load like a steep hill from a stop. Of course i've cleaned the carb a billion times. I'm thinking vacuum leak in the fuel lines?

Any other ideas?

[Bear45-70]

What set up and what main jet?

[bradmeehan]

Not sure Bear. It's the jet that was in it when I bought it and I don't know how to tell the size if I remove it. Is it stamped?

[Bear45-70]

Not sure Bear. It's the jet that was in it when I bought it and I don't know how to tell the size if I remove it. Is it stamped?

All jets are stamped with their size. Another reason why drilling jets is a bad thing, the number is then useless. However the '85 Aero 50 comes with and 80 main jet, but it has been found they run better with an 85 main. Beside gas is crap anymore.

Does it shut off like the key is turned off or slow up then die?

[bradmeehan]

More of a 'key off'. Runs strong to around 30 then cuts off. I back off and its good; I open it up, it dies.

[Bear45-70]

If it was me I would throw a new plug in there first, then check the fuel supply.

[bradmeehan]

Ok. I'll do it in the AM and report back. Thanks Bear.

[deuce217]

I am having very similar issues. I have a 85 spree, it has been doing this off and on. Sometimes it will not start at all, no spark, but I will always have pulse to the ignition switch. Enough to shock my finger if I use myself for a ground. lol and typically it will produce spark back at the spark plug. So I then install the plug and ride it, it will cut out at about 25mph just like the kill switch was activated and as soon as I let off the throttle it regains spark and will continue to run. Sometimes it will run perfect for a week with no issues, then I tear it back down again and test everything. I have a coil on order, I will let you guys know if it solves the issue. My generator seems great I never have any charging issues, new battery. When this thing is running well I hit 38 mph on flat road, I have only installed a washer on the rear pulley to achieve this.