b275 spitting gas vapour out of carburetor under load

dmcleod · Oct 6, 2013

Hello Everyone,

My b275 gas tractor is having a problem when its under load, it is spitting gas vapor out the carb, I've taken a video of it which is in the link below but I can't post it as a link i will try and post below. We did fix some exhaust leaks so I thought it was some sort of back pressure issue but i loosened up the exhaust again and created some leaks and the same issue occurs, other than that there have been no issues. Spark plugs are perfect, no fowling etc. It also doesn't have as much power during this. I've also tried adjusting the timing with no success. Anybody seen something like this and have any ideas?

youtu_dot_be/cZv9XbzS3WI

remove the "_dot_" and put a period and paste in your web browser.

Thanks!
Dave

Bob · Oct 6, 2013

Ignition base timing, ignition timing advance, valve adjustment, camshaft timing, camshaft wear.

JDemaris · Oct 7, 2013

My first suspicion would be a leaking intake valve. It will show up more on a B275 then on many other gas tractors due to the downdraft automotive carb (British Zenith VN or VNN). A bad cam lobe can also do it, or a bent pushrod, or broken rocker-arm.

dmcleod · Oct 7, 2013

Thanks jdemaris and Bob, if its an intake valve would I hear a backfire out the carb?

b275 spitting gas vapour out of carburetor under load

dmcleod

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Bob

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JDemaris

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dmcleod

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