Author Topic: 750 K3 with 657B carbs - Float needle ID question  (Read 1388 times)

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Offline Chachi

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750 K3 with 657B carbs - Float needle ID question
« on: December 17, 2013, 01:26:46 PM »
Going through my newly acquired K3 and I have a carb question. Three of the four have matching float needles and function properly and one has a different float needle and does not.

In the pic: the right is one of the three good/matching and the left is the different one.

Is the one on the right correct? If so, I just need to source one more to match my other three. It seems the needle comes in a float valve set - part number 16011-375-004. I want to confirm that my three are correct (OEM) so I can just order one set to finish me out. Any help ID'ing and confirming is much appreciated.
73 CB750 K3
72 CB500 K1 - Sold
75 MR50 Elsinore K1

Offline flybox1

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Re: 750 K3 with 657B carbs - Float needle ID question
« Reply #1 on: December 17, 2013, 01:50:25 PM »
16011-302-004 is the correct part no.  $12 ea at cb750supply.
IIWM, id purchase 4 new valves and seats and start fresh.  Get all 4 the same....

'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
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"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline Davez134

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Re: 750 K3 with 657B carbs - Float needle ID question
« Reply #2 on: December 17, 2013, 01:57:55 PM »
16011-302-004 is the correct part no.  $12 ea at cb750supply.
IIWM, id purchase 4 new valves and seats and start fresh.  Get all 4 the same....

My thoughts exactly. I have the same carbs and that's where I got my parts from. My guess is just that needle was replaced without replacing the seat?? They have to be done together so they wear the same.  Fuel can also leak from between the carb body and where seat threads in if that little gasket/washer isn't replaced as well.

Offline Chachi

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Re: 750 K3 with 657B carbs - Float needle ID question
« Reply #3 on: December 17, 2013, 02:01:00 PM »
I didn't know if OEM vs. aftermarket mattered for this. I assume the $12 set is aftermarket. I think 16011-302-004 has been replaced by 16011-375-004. I can get an OEM set for one carb for about $20. The carbs were rebuilt from a salvage yard and everything looks good in them except this one float needle that's different.
73 CB750 K3
72 CB500 K1 - Sold
75 MR50 Elsinore K1

Offline flybox1

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Re: 750 K3 with 657B carbs - Float needle ID question
« Reply #4 on: December 17, 2013, 02:12:29 PM »
 OEM for this is fine.  the valve is mated to its seat.  and if slightly leaky can be lapped to work.  but, if it closes and shuts off fuel flow, reuse it.  no worries.

just be aware that because of its difference (overall length, post height, internal spring tension, etc), you may end up needing a different float height to get it to function like the others.

but that one on the left does look like it has a nice wear ring around it.  might need a lapping or replacement.  might also not be that bad.  only you or a better pic of all 4 tips posted for us can decide/help.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline Chachi

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Re: 750 K3 with 657B carbs - Float needle ID question
« Reply #5 on: December 17, 2013, 02:55:37 PM »
I'll probably order a set of 4 and be done vs. just replacing the one. Thanks for the info.
73 CB750 K3
72 CB500 K1 - Sold
75 MR50 Elsinore K1