Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Mikep328 on June 03, 2026, 11:12:16 AM
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I'm wanting to install a Stahlbus brake bleeder valve but don't know what thread size the OEM bleeder is. Anybody know - M7x1x16, M8 x 1.25 x 16, etc? Thanks!
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Never heard of Stalbus Valve, reads as a good idea though.
I'm surprised the sellers dont have an application chart.
I bought a set of these, very handy, don't know how I managed without them.
https://www.ebay.co.uk/itm/387257447219
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I use them on other bikes. It more convenient/faster than futzing around with vacuum or pressure bleeders on such small systems. I have both and use the pressure bleeder for cars but I can bleed motorcycle brakes faster using the bleeder valve when you factor in the time it takes to get the vac or pressure bleeder out, set it up and then put it back away.
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I use them on other bikes. It more convenient/faster than futzing around with vacuum or pressure bleeders on such small systems. I have both and use the pressure bleeder for cars but I can bleed motorcycle brakes faster using the bleeder valve when you factor in the time it takes to get the vac or pressure bleeder out, set it up and then put it back away.
When you have used the bleeder valve to get a good air free lever feel, do you then swap back to the standard one or do you leave it in place?
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"When you have used the bleeder valve to get a good air free lever feel, do you then swap back to the standard one or do you leave it in place?"
It replaces the standard bleed screw permanently.
Attach a tube from the bleeder valve to a cup/plastic bottle, whatever; open the top section of the bleeder 1/2 turn; pump the brake lever until no bubbles (ensuring master cylinder doesn't run out of fluid); tighten top section; remove tube. There is no need to open/close the bleeder as you pump the brake lever.
As I said, on a motorcycle it's much faster than pressure/vacuum bleeders simply because there is no time involved in getting the equipment out/putting it away. This would NOT be the case with a car; pressure bleeder is much better!!!!
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Have you identified the thread size you need on your 400F ?
I am not sure if this is correct, internet search says M8 x 1.25 ??
Update looks like M7
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A search for Honda part number '45224-579-013 Brake Caliper Bleed Screw' shows thread size to be M7 (7mm) in diameter.
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So it's either M7 or M8... ?
My measuring of the outside diameter of the 400F bleeder screw thread comes up with 8mm though I'm doing this by eye with a ruler, NOT with a caliper. I have no way to accurately measure the thread pitch. Stahlbus has M7 valves in 1mm thread pitch and M8 in either 1 or 1.25 thread pitch. So, at the moment I have no idea which of the three to order!!! ;) I'll check if the local hardware store has a bolt/nut thread gauge to measure the threads..
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If I recall correctly, you can try counting the number of threads over 10 mm. IE 10mm/8 threads = 1.25 pitch
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As above, can be quantified or could be checked against a "gauge" with the spark plugs being 1.25mm pitch, take the bleed nipple and drop threads into each other to get confirmation if it matches or differs by plus or minus to indicate which pitch you have.
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I've checked my 400, it measures more like a M7 as McMaz says,
I checked the nipple thread o/d against my M7 thread gauge tool certainly not M8.
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I think the M8 refers to to spanner size of the nipple, not the thread size
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I think the M8 refers to to spanner size of the nipple, not the thread size
Yes mine are M8 for a ring spanner, thread definitely looks like M7.
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I use them on other bikes. It more convenient/faster than futzing around with vacuum or pressure bleeders on such small systems. I have both and use the pressure bleeder for cars but I can bleed motorcycle brakes faster using the bleeder valve when you factor in the time it takes to get the vac or pressure bleeder out, set it up and then put it back away.
Never found a need for this on my 750, I normally just loosen the bleed nipple and let it gravity bleed without pumping the brake lever.
Tighten the bleed nipple when bubbles stop appearing and Bob's yer uncle.
Brake fluid change every 2 years is enough to keep any corrosion at bay.
Good luck
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Seem to recall Mike it's a M7 x 1.00.