I have a weird orfice...on my MRS stove

11:03 a.m. on April 3, 2010 (EDT)
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I got a great deal and a MRS wisperlite stove at a yard sale for $10. So I purchased the expadition repair kit and gave it a tune up. However when I went to replace the jet and shaker, they are completly different than what is in my stove. My jet has smaller threads and the shaker needle wont fit inside. ( see attached photo) I did install new o-rings and hoses and I also installed the wick that came with the repair kit, and pulled the cable out of the hose and cleaned and lubed it. After the tune up, the stove works great. Do I need the smaller orfice (jet) as a spare? What purpose dose the shaker needle serve? The jet cleaning tool ( small wire on a stick ) seems to fit into my smaller orfice just fine. Mike.

11:04 a.m. on April 3, 2010 (EDT)
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OOPs...I should have posted this under Gear repair, not gear selection. sorry. Mike

2:25 p.m. on April 3, 2010 (EDT)
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You have an old style whisperlite as indicated by the cloth wrapped fuel hose(and obviously non shaker jet). The newer style have brass wrapped hoses. Many prefer the performance of the older type, and it's not really a huge imposition to use a pricker to clean the jet.

2:39 p.m. on April 3, 2010 (EDT)
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There are two orifice diameters for the Whisperlite International. One is marked with a "G", the other with a "K". I can not tell from your photos if you have the basic Whisperlite or the International. Interestingly enough, the orifice diameter of the kerosene jet is smaller than the white gas one, even though (or maybe because of) kerosene being higher molecular weight.

As abman indicates, there was a change from the original Whisperlites to the "shaker" series sometime in the 1980s or 90s. The "pricker" as it was called was a carryover from the days when we all used Sveas (or the Optimus and Primus versions - which goes back to when they were 3 completely separate companies. But that's a tale for another thread, all the merging, spinning off, changing emphasis, etc). The shaker was an improvement over the pricker in that the wire on the pricker often got bent or broken off. So you usually carried 2 or 3 of them on an expedition of any length. The wire on the shaker to clean the orifice almost never broke, except when you disassembled the stove and got careless. It has the big advantage that it didn't cause as much wear on the orifice. I went through several jets in my Primus 71L over the years, because the hole would wear asymetrically when using the pricker (there is a tendency to insert it from the same direction all the time, hence uneven wear).

9:04 p.m. on April 4, 2010 (EDT)
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Bill S

Do you mean I can get rid of my prickers?

Jim S

May 20, 2018
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