Author Topic: CB400F2 - Petrol tap  (Read 723 times)

Offline Aye Gee 1977

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CB400F2 - Petrol tap
« on: January 04, 2024, 04:02:47 PM »
After a mere 40 years on non-use, I thought now was the time to restore my beloved 400 - bought new when 1 was 17 years of age and then ridden to death before being retired at 65,000 miles

I have had a few problems - the rear hub housing was worn due to the bearing turning within; this was a recurring issue when in regular use.  Not noted previously, the sleeve between bearing and axle on the drive side has worn - presumably it was turning on the axle rather than the bearing; fortunately the spindle is unscathed.  Anyway, all stripped down including splitting the crankcases (for the second time in my ownership) and now being reassembled.  The chrome plating seems to be taking an age - it won't be long before it is holding things up.  I just hope they haven't lost anything.

Parts are not too hard - but I can't find a rear mudguard (so had to patch the holes with fibreglass(!).  I managed to dismantle the horn such that it now makes a noise of sort - and only broke the plastic a little when reassembling.




Anyway, I did a silly thing and applied some heat to the petrol tap to loosen its screws - which was successful!  I now know there is a tapered nylon bush inside - with a low melting point.  Does anyone have a spare bush or bustd tap, please?  If it matters, it has a 20mm thread.

If not, can anyone speculate whether (and which ideally which) of the cheapo petrol taps on ebay  might yield a suitable innard

Thanks

 

Offline Aye Gee 1977

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Re: CB400F2 - Petrol tap
« Reply #1 on: January 04, 2024, 04:19:11 PM »
After a mere 40 years on non-use, I thought now was the time to restore my beloved 400 - bought new when 1 was 17 years of age and then ridden to death before being retired at 65,000 miles

I have had a few problems - the rear hub housing was worn due to the bearing turning within; this was a recurring issue when in regular use.  Not noted previously, the sleeve between bearing and axle on the drive side has worn - presumably it was turning on the axle rather than the bearing; fortunately the spindle is unscathed.  Anyway, all stripped down including splitting the crankcases (for the second time in my ownership) and now being reassembled.  The chrome plating seems to be taking an age - it won't be long before it is holding things up.  I just hope they haven't lost anything.

Parts are not too hard - but I can't find a rear mudguard (so had to patch the holes with fibreglass(!).  I managed to dismantle the horn such that it now makes a noise of sort - and only broke the plastic a little when reassembling.




Anyway, I did a silly thing and applied some heat to the petrol tap to loosen its screws - which was successful!  I now know there is a tapered nylon bush inside - with a low melting point.  Does anyone have a spare bush or bustd tap, please?  If it matters, it has a 20mm thread.

If not, can anyone speculate whether (and which ideally which) of the cheapo petrol taps on ebay  might yield a suitable innard

Thanks

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Offline McCabe-Thiele (Ted)

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Re: CB400F2 - Petrol tap
« Reply #2 on: January 04, 2024, 04:31:51 PM »
I suspect it's unlikely that innards from a new aftermarket tap will be interchangeable.
Many now have rivets holding them together.
I would try & source an original used one I'd start with Steve at 400 bits.

I bought one off e-bay but the thread was wrong so had a refund, it also differed from the photo that showed screws, there are a couple of different sized threads iirc where it fits the petrol tank.

What confused me was there is only one part number listed in the parts book 16951-377-005 like this one below.
.https://www.ebay.co.uk/itm/115828691611

I have a dented early 400 petrol tank & the tap is a different size fitting to my later 400.
« Last Edit: January 04, 2024, 05:11:00 PM by McCabe-Thiele (Ted) »
Honda CB500 K1 (new pit dug out ready)
Honda CB400 four super sport (first money pit)
http://www.sohc.co.uk/index.php/topic,23291.0.html

Offline taysidedragon

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Re: CB400F2 - Petrol tap
« Reply #3 on: January 04, 2024, 05:36:54 PM »
I bought a tap repair kit from David Silver a few years ago and I'm sure that it included the nylon bush thingy.

I just had a look at DS and the repair kit doesn't include the nylon Bush. ☹
« Last Edit: January 04, 2024, 06:08:32 PM by taysidedragon »
Gareth

1977 CB400F
1965 T100SS

Offline Aye Gee 1977

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Re: CB400F2 - Petrol tap
« Reply #4 on: January 04, 2024, 06:54:06 PM »
I suspect it's unlikely that innards from a new aftermarket tap will be interchangeable.
Many now have rivets holding them together.
I would try & source an original used one I'd start with Steve at 400 bits.

I bought one off e-bay but the thread was wrong so had a refund, it also differed from the photo that showed screws, there are a couple of different sized threads iirc where it fits the petrol tank.

What confused me was there is only one part number listed in the parts book 16951-377-005 like this one below.
.https://www.ebay.co.uk/itm/115828691611


I have a dented early 400 petrol tank & the tap is a different size fitting to my later 400.
Thank you.  I will ask if 400bits has anything to help.  It does seem that there is more than one fitting size

Offline Aye Gee 1977

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Re: CB400F2 - Petrol tap
« Reply #5 on: January 04, 2024, 07:00:31 PM »
I bought a tap repair kit from David Silver a few years ago and I'm sure that it included the nylon bush thingy.

I just had a look at DS and the repair kit doesn't include the nylon Bush. ☹

I kept an old note of some problems with the bike that included need for a new filter etc.  And joy of joys, I recently found a brand new refurb kit that I must have bought 40 years ago and had quite forgotten.  It all went downhill when I put the blowlamp on the tap.

For those that like details, the large nut on the kit is plated whereas the one on the bike is plain brass

Offline McCabe-Thiele (Ted)

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Re: CB400F2 - Petrol tap
« Reply #6 on: February 08, 2024, 10:38:29 AM »
Have you sourced a suitable replacement tap?

I'm interested in the outcome/solution.
Honda CB500 K1 (new pit dug out ready)
Honda CB400 four super sport (first money pit)
http://www.sohc.co.uk/index.php/topic,23291.0.html

Offline Aye Gee 1977

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Re: CB400F2 - Petrol tap
« Reply #7 on: February 10, 2024, 11:41:18 AM »
My solution, and only time will prove its worth, has been to cast a new nylon taper cock.

I tried reusing the old nylon, but it resulted in bubbles and voids as it boiled soon above its melting point.  I have had more success using a petrol resistant 3d printer filament.  It was cast in the ally tap casing with bungs to prevent leaks to unwanted ports.  Some work with a sharp knife and files required when cast.

It seems to work but it will be tried for real later today.

The best advice is not to melt the one you have!

Offline Matt_Harrington

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Re: CB400F2 - Petrol tap
« Reply #8 on: February 12, 2024, 08:37:35 AM »
I like the idea of using 3D printer filament. Keep us posted on the results...
Matt
___________________________________
CB400F 1976 -  Almost finished
CB400F 1977 - On the road!
Moto Guzzi T4 - 1981 - My tourer (plus a loft full of spares)
Moto Guzzi Le Mans 2 - 1981
Triumph 3T - 1947 (somewhat dismantled!)
CD175 - To be restored

Offline Johnny4428

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Re: CB400F2 - Petrol tap
« Reply #9 on: February 12, 2024, 11:25:40 AM »
Great solution if it works! Here’s hoping. I’ll put my order in now for one! 😜
1952 Cymoto on Triumph bicycle.
1961 Matchless G3
1974 Honda CB550K1. Running resto,
1978 Honda CB550K3.
1999 ST1100 Pan European 50th Anniversary.
1975,1980,1984,1986 Honda C90’s
1973 Honda CB750K3

Offline Aye Gee 1977

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Re: CB400F2 - Petrol tap
« Reply #10 on: February 12, 2024, 07:57:28 PM »
Ahem! The DIY moulded tapered cock works a bit, but passes a little fuel even when closed.  It seems an odd arrangement to me, insofar as the spring presses the cone out of its house, which can't help. Maybe I have misunderstood how it is meant to work - my cone was a strange shape following its relationship with the blowlamp.

The DIY method works sufficiently well to persuade me it could be done - given sufficient patience and skill.  But in the meantime I have found someone that seems to sell the innards of the fuel tap https://nrp-carbs.co.uk/shop/index.php?route=product/product&product_id=5802

I have ordered a kit.  It's said to be for a a 1975-76 model whereas mine is a 1977 CB400F2.  I'll post an update when it arrives.

Offline Johnny4428

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Re: CB400F2 - Petrol tap
« Reply #11 on: February 12, 2024, 08:54:45 PM »
That’s a pity but good you found a supplier. I’m sure the spring goes between tap and cone to push cone inwards thus tightening a seal.
Of course it will push it away from the seal behind the front plate.
« Last Edit: February 12, 2024, 09:01:36 PM by Johnny4428 »
1952 Cymoto on Triumph bicycle.
1961 Matchless G3
1974 Honda CB550K1. Running resto,
1978 Honda CB550K3.
1999 ST1100 Pan European 50th Anniversary.
1975,1980,1984,1986 Honda C90’s
1973 Honda CB750K3

Offline davidcumbria

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Re: CB400F2 - Petrol tap
« Reply #12 on: February 13, 2024, 07:11:20 AM »
Please will you post dimensions of the cone when received. Be great if it also worked in my 550k1 tap .
500/4 in 79. No bikes for 30 years. 750/4 in 2013, 550/4 in 2023. Also own  R1100GS, RD350LC YPVS , Triumph Street Triple, Yamaha XT250

Offline Johnny4428

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Re: CB400F2 - Petrol tap
« Reply #13 on: February 21, 2024, 11:25:47 AM »
Ahem! The DIY moulded tapered cock works a bit, but passes a little fuel even when closed.  It seems an odd arrangement to me, insofar as the spring presses the cone out of its house, which can't help. Maybe I have misunderstood how it is meant to work - my cone was a strange shape following its relationship with the blowlamp.

The DIY method works sufficiently well to persuade me it could be done - given sufficient patience and skill.  But in the meantime I have found someone that seems to sell the innards of the fuel tap https://nrp-carbs.co.uk/shop/index.php?route=product/product&product_id=5802

I have ordered a kit.  It's said to be for a a 1975-76 model whereas mine is a 1977 CB400F2.  I'll post an update when it arrives.
Just a thought was your refurb kit for a single outlet tap or a double outlet. Don’t even know if there is a difference in the cone configuration?
1952 Cymoto on Triumph bicycle.
1961 Matchless G3
1974 Honda CB550K1. Running resto,
1978 Honda CB550K3.
1999 ST1100 Pan European 50th Anniversary.
1975,1980,1984,1986 Honda C90’s
1973 Honda CB750K3

 

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