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zama carb rebuild question

Started by bushhog920, June 22, 2012, 01:41:07 PM

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bushhog920

what are the tricks to removing the metal plugs on the carb to access the ports, and how to install the new ones and what type of glue do they use on them. or are they really worth removing to clean the carb.

Al_Smith

As a general rule few people remove the plugs .Most times a carb failure is a result of the soft components becoming stiff .

T Welsh

bushhog920, As a rule when I rebuild a carb I do not usually take the welch plug out, I spray it down with carb cleaner blown through the passages with the compression in the can and then blow it dry with the air gun,making sure that everything is clean and all orifices are free of contamination. As Al_Smith said,generally its the soft components that harden up over time. Tim

nmurph

I use PINK nail polish to seal the edges. Be careful when punching through the welch plug. It is a good idea to change them. I have put many carbs together only to need to go back in and clean out behind the plugs.

Al_Smith

Nail polish was indeed the standard sealant used as thread locker ,sealant etc on carbs for years back when gasoline was gasoline .It never worked well on for example methanol burning  engines such as sprint cars .

Now exactly how it would hold up to ethanol blend I haven't a clue .I do know that red loctite will .

joe_indi

You need to look at an unused welch plug  to understand how it is held in place. The new plug drops easily into its seat because it has a diameter a wee bit less than the diameter of its seat. This decreased diameter is achieved by shaping the plug like a dome. Once it is in its seat decreasing the dome by tapping the dome with a flat punch causes it to increase in diameter and thus become tight in its seat.
You tap it too much it becomes concave at the top and the diameter decreases again and it becomes loose in its seat.
So, When you tap it to a slight concave shape it becomes loose. Okay you do that to loosen the plug.To refit it tightly, just invert it and tap it again. You might be able to use it a couple of times if you are really careful.
A sealant is usually applied before the plug is installed.This sealant is applied only on the edge of the plug.
A solvent such as thinner used for lacquer paints will soften the sealant.
When you refit the plug you will need a sealant, Al's sealant (nail polish) is, I think universal, because we use it here too.Nail polish was what was also recommended by a Stihl engineer from Germany when he showed us how to service the carburetor.
Now, there is always the chance "disaster' might strike by way of a unusable plug.
That is not a big problem. Its happened often to me.
I use a suitable hole punch to cut me a new plug out of  a beer can top or bottom. The diameter should be more than the seat and you will need to shape it into a dome to make it go down into the seat.I use the hammer end of a punch to do that job.

Removing the plugs , the H and L screws, and the jets assure that all the passages are free of any muck or dirt.

Joe

sawguy21

Just be careful not to push the dome in too far, the wells are shallow. Go too deep the carb is junk.
old age and treachery will always overcome youth and enthusiasm

bushhog920

thank you all for the good info that was what i was looking for.

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