HS40 diaphragm carburetor -Welch Plugs

B

bed9fc

New Member
#1
#1
I am wanting to know the importance of removing and replacing the welch plugs on the 631588 diaphragm carburetor during a rebuild. The engine went through a flood and I did a complete tear down of the entire engine to clean, dry old and fresh lube approximately 1 week after the flood to salvage the engine/minibike. This includes all electrical and a minor carburetor rebuild (not removing the welch plugs, but replacing everything else). The engine ran, but was never 100% and was told that the carburetor needed to be replaced. I was unsure at the time, but kept the carb because I want all original equipment. Due to this fact, I removed the engine and used a new engine for my neighborhood riding needs.

Fast forward 17 years (went to college and stuff), I am ready to put the old engine back on and do a restoration. Do the welch plugs on the 631588 seal off potions in the carb not used or are they remnants of the casting procedure? I am going to do a complete rebuild of the carb again and start over, but I want to know the effects of the welch plugs not being replaced from when I was 14 years old. Lastly, I will be replacing the welch plugs anyway!! Any help would be greatly appreciated.
 
markus

markus

Well-Known Member
#2
#2
Very important, Those are finicky carbs to begin with and they need a very thorough cleaning. your fuel tank and fuel needs to be a spotless too, those carbs have no where to hold debris like a bowl does so even the smallest speck of whatever will give it issues as it tries to pass through the carb. The smaller welch on the bottom exposes the tiny reservoir for that needle and a good place to get cleaned out. I recommend getting a welding wire cleanout tool or carb jet cleaning tool (they are the same thing) to poke through wherever you can on them. You also need to try and check the throttle and choke shaft for wear, The throttle shaft can be replaced easy and usually available and you can add the felt seal too. Be easy on that carb, its a very hard one to find, They are not the same as a typical diaphragm carb body and went out of use long ago.
 
You must log in or register to reply here.
Top