2 cycle engine rebuild

Ted Urbach

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Sep 18, 2019
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Is there any secret to rebuilding carburetors on small 2-cycle engines. I have 3 that I can't get to run after cleaning and replacing parts with rebuild kits. Are any secret little fuel passages that I don't know about?
 

ILENGINE

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The issue is that most newer carbs are set up with a primer system. As part of the system the carb has internal check valves. When the carb is taken apart those valves have a tendency to either stick open or stick closed, and most carb cleaners will cause the check valve diaphragms to swell. So you run into either the carb won't prime because the valve is stuck open and sucking air, or stuck closed and fuel can't get through the main valve.

That is the main reason most repair shops don't repair those carbs any more. It isn't cost effective because the repair kit plus labor is more than the new carb. And there is a 50/50 chance that the carb will work after being disassembled, cleaned and reassembled.
 

bertsmobile1

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To further what Illengine has said.
Because of the problems with chemical reaction between common carb cleaners & the rubber parts in modern carbs,
Walbro now have formulated a safe spray carb cleaner, but a can of it down here is more expensive that a replacement carb.

Like most, I use an ultrasonic cleaner for cube carbs and a solution specifically formulated for my wholesaler for cube carbs.
Everything else get washed with dishwasher solution just not cube carbs.

The carb also gets blamed a lot when some thing else is the problem
Hook your carb up to a fuel supply then blow air through it.
If you get vapourised fuel coming out the other end, the carb is at least working.
High volume low pressure air is good.
If you have a helper or feel like making a test bed, work the throttle and see if you get more fuel when the throttle is open full.

If you live in California then doing this can earn you many years in jail because you have violated so many pollution laws it is not funny .
And of course a Californian court has determined you will be exposed to cancer causing materials. Everywhere else in the world uses science labs to do this.

Arm yourself with a pressure & vacuum gauge then hunt out the Joe Pace You tube videos.
After I found this the number of times I even touched a carb halved as most of the "carb" problems were in the fuel tank.
 
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