Carbie Question

Jim

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BS-34's off an 80SG.
So... I ordered a pair of 135 mains from Partzilla...

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.... received these....

MVIMG_20180730_141447.jpg


They are identical to the 135 air jet and smaller than the mains.......

MVIMG_20180730_141425.jpg

They will in fact.... fit into the hole for the main......

MVIMG_20180730_142452.jpg


So, my question is, will they work as mains or did Partzilla send me the wrong jets?
I really don't know if a #135 air hole is equivalent to a #135 fuel hole...... anybody?
 
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They are Mikuni main jets, just not the style used in the BS34s. Yes, they are what's used as the air jet. It's a main jet but in this case, it flows air. That 135 is the main jet used in the '78-'79 BS38s as well, and as an actual fuel flowing main jet. The parts diagram you ordered off of is also screwed up, or at least the parts listing section is. Notice that the corresponding diagram number for the jet you ordered is zero. Many of those "zero" parts listed aren't for the BS34s, they're for the '78-'79 BS38s. No, Partzilla didn't send the wrong part, it's what you ordered. So, it's all quite confusing, isn't it, lol.

If you reference some of the parts diagrams for 650s using the BS34s, ones with more correct parts lists next to them, you'll find that the stock main (#132.5) is N.L.A. But that's not a big deal really because these are very common Mikuni main jets and available from many places. You want the Mikuni main jet type N100/604, what's commonly called their "large round main".

M98LIeO.png


Those small round mains you got may work but there's a possibility they won't stay tight as well as the larger headed version would. Also remember that they are what holds your needle jet in place. I think Yamaha (or Mikuni) switched to the larger headed jet in these carbs for those 2 reasons I mentioned.
 
No, Partzilla didn't send the wrong part, it's what you ordered.
So Partzilla's 80SG carb. parts page is wrong....
I need 100/604's Got it. Thanks.
Hey.... at least I got some new air jets....:rolleyes:
 
The small round mains flow just the same as the 100/604s; I used them in my 36 mm. pumpers for awhile and never had issues with them coming loose, but as 5twins wrote, the 100/604s would be a better choice. Niche Cycle Supply has become my preferred source for carb parts; good prices and selection. They sell both genuine Mikuni brass and cheap repops, and indicate clearly which is which.
 
Jim
Do you have the black rubber plugs that go in the pilot? Mine were missing from PO and all the jets were so lean and screwed up i was suprised mine started at all and ran like a bag of shit.
Cheers.
 
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