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Banjo bolt

Submitted by michael_formby1 on Fri, 09/04/2021
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Light Twins

I have just bought new oil union banjo bolts from the NOC shop (reference no 18101) and they don’t appear to fit. They go in about one and a half turns then refuse to budge. In my experience that is a sign of the wrong thread (but I could be wrong). The internal threads don’t appear to be damaged (I’d like to keep them that way). One of the heads is new.

 Is this a known problem?

Submitted by philip_hannam1 on Fri, 09/04/2021

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The number below is for the Alloy Dominator Heads. I thought that the Lightweight Twins might use a different fitting but according to Norvil 'one size fits all'.

Oil Feed Banjo Bolt      18101   -   5/16” x 22 tpi  BSF

However adding to the muddle. Norvil also list 019425 as a Banjo Bolt for the Rocker Plumbing but give no details about this item. Andover Norton also list 18101 with 067696 and D12/700 (the original p/n) alongside.

Submitted by dan_field on Sun, 11/04/2021

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I don’t trust Norvils part lists, as I recall I had this problem back in the day, unhelpfully I can’t remember how I solved it -  I’m surecAndy would know?

dan 

Submitted by andy_sochanik on Mon, 12/04/2021

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As Phil H says, they are the same as for Dominator engines 5/16" BSF thread form - P.No 18101.

Hi Michael, why are you looking for these banjo bolts?

Are you assembling your engine and they are missing? If so, the thread is the same at the front of the cylinder heads, for the head steady - you can check there. Maybe someone in the past found the same as you, has mucked about and re-tapped it?

Are you using the bike & you have an oil leak? If so, the culprit is likely to be the oil pipe itself, where its soldered into the union.

Let me know.

 

PS - I think they are the same for a Commando as well. I can find them on a 1969/70 Parts List (18101) - but cannot find them in the later (loose leaf) parts list - not listed with oil tank & pipes, nor with cylinder head?

Thanks everyone for your replies. I bought new ones because the originals were missing. I’ll try them in the holes for the head steady and see where that gets me. I’m rebuilding a bike that hasn’t run since about 1970 so, as for leaks, I haven’t got that far yet, but I’ll bear it in mind. 

Submitted by george_farenden on Wed, 14/04/2021

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Measure their diameter. Wouldn't be the first 'special' bolt to be oversized that I have come across. 

As said, try another bolt in the hole to make sure the hole is ok. If so, lay the two bolts togethrer to confirm thread pitch is correct.

Regards, George 

Submitted by michael_formby1 on Thu, 15/04/2021

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The bolts went into the CH steady holes without complaint, I took them to my local engineering supplies shop where they measured them with a thread gage, all correct. So I bought a same sized tap and cleaned out the threads with it and the bolts are in. Another learning experience. Adding the electrics next.

Submitted by andy_sochanik on Thu, 15/04/2021

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I'm pleased that cleaning the threads sorted in for you - your predecessor obviously came across the same problem & possibly tried to force a Cycle thread bolt down there - It will just turn a little, then thighten up. As the heads are soft, any force applied will damage the internal thread.

I know I'm preaching to the converted, please ensure to wash all swadf out of the oilway.

Cheers

 


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