Author Topic: CB750 round tops; bowl drain screw thread?  (Read 981 times)

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Offline Garage_guy_chris

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CB750 round tops; bowl drain screw thread?
« on: May 11, 2016, 09:27:38 AM »
Hey guys im sitting at work and need to know what the thread size is on CB750 round top bowl drain screws? I imagine its either M5x0.8 or M6x1.0

I want to do the clear tube test and had a thought about how to make some fittings using the drain screw holes to hook the clear tube too
1971 Cb450 Cafe  (on the road)
1974 Cb750 Restomod (on the road)

Offline harisuluv

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Re: CB750 round tops; bowl drain screw thread?
« Reply #1 on: May 11, 2016, 10:26:52 AM »
i think it's an m6.

Offline dusterdude

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Re: CB750 round tops; bowl drain screw thread?
« Reply #2 on: May 11, 2016, 11:07:27 AM »
Its a bastard 6mm but i dont recall the pitch at the moment

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mark
1972 k1 750
1949 fl panhead
1 1/2 gl1100 goldwings
1998 cbr600 f3

Offline dusterdude

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Re: CB750 round tops; bowl drain screw thread?
« Reply #3 on: May 11, 2016, 11:10:10 AM »
I think its 6x.07

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mark
1972 k1 750
1949 fl panhead
1 1/2 gl1100 goldwings
1998 cbr600 f3

Offline evanphi

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Re: CB750 round tops; bowl drain screw thread?
« Reply #4 on: May 11, 2016, 11:39:04 AM »
Get a spare drain screw and cut off the big part. Then press it into the end of some 1/8" clear tube.
--Evan

1975 CB750K "Rhonda"
Delkevic Stainless 4-1 Header, Cone Engineering 18" Quiet Core Reverse Cone, K&N Filter in Drilled Airbox
K5 Crankcase/Frame, K4 Head and Cylinders, K1 Carbs (42;120;1 Turn)

She's a mix-matched (former) basket case, but she's mine.

CB750 Shop Manual (all years), searchable text PDF
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Offline dusterdude

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Re: CB750 round tops; bowl drain screw thread?
« Reply #5 on: May 11, 2016, 03:52:49 PM »
Check with cal on the hose size,when we checked mine we stuck the hose in the hole,worked out good

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mark
1972 k1 750
1949 fl panhead
1 1/2 gl1100 goldwings
1998 cbr600 f3

Offline Garage_guy_chris

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Re: CB750 round tops; bowl drain screw thread?
« Reply #6 on: May 11, 2016, 08:21:48 PM »
When i got home from work i took a look at some loose ones the thread is a metric fine M6x0.75 it is a dead thread pitch from what i can tell i checked on McMasterCarr and nothing, called my local bolt and hardware supply shop and they had nothing chain wide...

I was planning on getting some bolts drilling them out running a nut down to the shank and bingo have some spigot tap things to check fuel level but its a no-go
1971 Cb450 Cafe  (on the road)
1974 Cb750 Restomod (on the road)