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Post by dusty350 on Jan 21, 2018 13:33:02 GMT 1
Mark was over at mine yesterday and pointed out something I had never really noticed before on a set of carbs;  20180121_112100 by David Miller, on Flickr Seems obvious but both carbs are marked 31k 00 and are identical apart from that ally boss under the inlet on the carb on the right in the pic. I looked at the 31k's on my white Lc and both have the boss, so mine are obviously a mismatched pair. Anyone know what it does ? There doesn't seem to be any drillings or passageways in it that I can see anyway. Dusty  |
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tommo
Drag-strip hero
Posts: 279
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Post by tommo on Jan 21, 2018 15:35:21 GMT 1
does the air inlet stick out further ?
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Post by earthman on Jan 21, 2018 15:42:59 GMT 1
Would it have anything to do with the fitment of the float bowls? To make sure the choke one goes on the correct side??
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Post by Tobyjugs on Jan 21, 2018 15:46:47 GMT 1
Hi Dusty i have never seen that either and i have a few pairs. I thought i would show you a picture of how i blank the vacuum spigot off. An M4 tap fits easily into the hole and you can tap the spigot and blind off the hole with a bolt and a little Loctite pipe sealant  |
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Post by yamark on Jan 21, 2018 19:40:54 GMT 1
I pointed this carb difference out to Dusty, as I bought a pair of 31k carbs a while back off Ebay. I looked through the stock of my 31k carbs and 3 have this boss on, 1 does not. I hope someone on here knows why there is a difference and if you can mix and match. |
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Post by earthman on Jan 21, 2018 20:06:42 GMT 1
Sorry guys, are we talking about this bit of the carb??  |
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Post by yamark on Jan 21, 2018 20:09:50 GMT 1
Yes, that's the boss, some 31k carbs have it, some don't.  |
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Post by liffy16 on Jan 21, 2018 20:55:37 GMT 1
Could be part of the manufacturing process as the body's are 'handed'this cast boss could stop you misloading that 'hand' carb in fixture?
deffo something to do with manufacture ,different casting supplier even?
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Post by 4l04ever on Jan 21, 2018 23:09:41 GMT 1
Could possibly be drilled for a water heating circuit for cold weather bikes....or for fitting brackets for bolting carbs together or for fitting emissions extra parts on...
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Post by JonW on Jan 21, 2018 23:28:15 GMT 1
I also noticed this on a set I have, one of each like you have. I couldnt fathom it either :/
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Post by LC_BOTT on Jan 22, 2018 11:13:55 GMT 1
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Post by JonW on Jan 22, 2018 11:56:52 GMT 1
both mine say 31k
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Post by Norbo on Jan 22, 2018 12:51:20 GMT 1
seen it loads of times
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Post by dusty350 on Jan 22, 2018 17:58:41 GMT 1
Mine have 31k 00 embossed on the little blank on the side of each carb. Dusty |
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Post by jon on Jan 22, 2018 18:28:39 GMT 1
If these carbs are in fact NOS then they both have the boss, meaning for whatever they were made that way for Yamaha saw fit to do it to both carbs. Dusty, If it’s got the same code stamped on both carbs though I wouldn’t worry about the mismatch. Jon |
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Post by dusty350 on Jan 22, 2018 20:57:06 GMT 1
Both Mark and myself were more intrigued than anything, as to why they are different. The extra "bit" doesn't seem to do anything that we can see. I hadn't even registered it until Mark pointed it out, and both the 31k carbs that are fitted to my Lc have it. If one carb was 00 and the other 01 than it would make more sense, but both mine are definitely 00. One of life's little mysteries !!  Dusty |
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