SDC74 rebuild

[stillsawing]

While taking note of the contents in the rebuild kit, I noticed that there is two gaskets for the pump side of the carb. Both have the same cuts and openings, however one is much thicker than the other. Why the difference? I plan on using the black/neoprene pump. Trying to get my S1050 to run better.  

[edju1958]

I've never seen 2 identical pump diaphragms in a carb kit.I have seen the 2 different pump diaphragms that are used in some applications in a kit however.I'm wondering if there was some mistake made when packaging the kit?Like you,I'd use the same diaphragm as was in the carb originally.I'm assuming this was a K10-SDC?

[fossil]

Jun 7, 2022 17:00:14 GMT -5 stillsawing said:

While taking note of the contents in the rebuild kit, I noticed that there is two gaskets for the pump side of the carb. Both have the same cuts and openings, however one is much thicker than the other. Why the difference? I plan on using the black/neoprene pump. Trying to get my S1050 to run better.  

For the SDC-74 you want to use gasket 92-108 which is the thick gasket. Should be 0.064" thick

[edju1958]

Sorry,I misread the post.I thought you wrote diaphragms instead of gaskets.

[stillsawing]

Am I to assume that the thicker of the two gaskets allows for more fuel pumped for a 100cc saw? 
Thanks for the response 

[5terrysupersaws]

  The fuel pump cover on a SDC-74 is a flat steel plate, use of the thick gasket is necessary to provide 
 clearance for the check valve flaps to open. Other models of SDC carbs with aluminium covers have the pockets
 cast into the cover.


  More info in this thread:  houseofhomelite.proboards.com/thread/9496/walbro-carb-help

[stillsawing]

Thanks again for directing me to the proper gasket in SDC74. The carb works great, no spit back. Want to throw a couple of crank seals at the saw to reassure of no lean situation.