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Can I give my two cents worth of Vapor Lock as I perceive it? It's not uncommon during the summer months for many contractors to report fuel around the carb and tank when a machine has stood in the heat unused for a few hours.
As I see it most tanks have a vent to allow air in as the fuel is used, this is a one-way valve so as not to have fuel escape from the valve. When left standing the fuel vapor will expand in the heat, often causing the tank to have a 'bulged' look. When you undo the tank cap you can hear a rush of air/vapor. I've seen this pressure build up to the extent it can force fuel past the needle valve and flood the engine making for difficult starting.
I advise using a richer mix of oil/petrol during the summer months if the weather is exceptionally hot, ie from 50 to 1 to 40 to one. The slight increase in oil content will help maintain compression and aid heat/friction without excessive smoking from the exhaust.

As said in a previous post, leaving the tank cap loose to vent can, in most cases, help eliminate this problem

atb Phil :usflag:
 

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Hi Phil,

I go past the limits of my knowledge much too often.
Hey, I do that every day :dizzy: must be an age thing with me.
You say it's running lean, have you got an adjustable carb? maybe just a tweak more fuel?. When I tune a two stroke engine I do my best to balance the carb so the engine (when warm) will start in any throttle position. Are you in one of the 'heatwave' states? if it is extra hot do try a tad more oil in your mix, it really can help to keep the engine temperature down to an acceptable level.

Here's a pic of a Stihl I had in on Saturday, they guy figured he could run it lean on the oil :hammerhead:



Over here the cylinder/barrel is half the cost of a new machine.
Another one bits the dust
atb Phil :)
 
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