Back on the 13th July I posted a thread regarding my 47 UL which didn't seem to be running right. There was a lack of performance and the plugs were coming out different colours
The diagnosis was a manifold leak. It took me a while to build a manifold leak tester and get access to some compressed air
Sure enough when tested the rear cylinder was leaking quite badly around the manifold. When I stripped it down the rear nut was very tough to remove. The bike was fitted with an OEM brass manifold I guess from an earlier model.
In any event I decided to have peek seals fitted and sent the manifold and nut off to have the new seal fitted properly.
When I came to fit the new set up I realised the rear nipple was moving in the cylinder. I guessed when I pressure tested in that I would have a leak from the nipple. I was correct in fact it was much worse than than the original leak I had started out with. I guess I must have disturbed the nipple in trying to get the manifold off originally.
Having taken the carb. off and put on an old nut I can move the nipple in the threads without applying any real force. Looking inside I can see the bottom of the locating pin just rocking as the nipple moves
The nipple is going to have to be replaced for sure
Sorry that's a long lead up to the questions
Where can I get new nipple? Are aftermarket ones any good or should I try to find a NoS one from somewhere?
As the nipple is already moving in the cylinder my feeling is that it may just unscrew once the pin has been ground off but I have read that that may damage the threads in the cylinder and it is better to carefully cut through it and crush it inwards. Any advice on the best way to go would be helpful
Finally as and when I get the new nipple do I need to use some kind of sealant to make sure the threads seal air out - if so any suggestions on what is best to use?
Grateful for any pointers on getting the old girl up and running sweetly again
Thanks
Martin - from the UK
The diagnosis was a manifold leak. It took me a while to build a manifold leak tester and get access to some compressed air
Sure enough when tested the rear cylinder was leaking quite badly around the manifold. When I stripped it down the rear nut was very tough to remove. The bike was fitted with an OEM brass manifold I guess from an earlier model.
In any event I decided to have peek seals fitted and sent the manifold and nut off to have the new seal fitted properly.
When I came to fit the new set up I realised the rear nipple was moving in the cylinder. I guessed when I pressure tested in that I would have a leak from the nipple. I was correct in fact it was much worse than than the original leak I had started out with. I guess I must have disturbed the nipple in trying to get the manifold off originally.
Having taken the carb. off and put on an old nut I can move the nipple in the threads without applying any real force. Looking inside I can see the bottom of the locating pin just rocking as the nipple moves
The nipple is going to have to be replaced for sure
Sorry that's a long lead up to the questions
Where can I get new nipple? Are aftermarket ones any good or should I try to find a NoS one from somewhere?
As the nipple is already moving in the cylinder my feeling is that it may just unscrew once the pin has been ground off but I have read that that may damage the threads in the cylinder and it is better to carefully cut through it and crush it inwards. Any advice on the best way to go would be helpful
Finally as and when I get the new nipple do I need to use some kind of sealant to make sure the threads seal air out - if so any suggestions on what is best to use?
Grateful for any pointers on getting the old girl up and running sweetly again
Thanks
Martin - from the UK
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