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Domi 88 cylinder head oil return

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Domi 88 cylinder head oil return

Posted by Graham Martin at August 16. 2017

On checking the cylinder head on my 1958 domi I noticed the oil return hole under the right hand inlet valve spring assembly has a small steel plug in it. A gentle tap showed that it would move and I think I can remove it with an air line to the other end.

My question is should it be there? I can find no mention of this in the literature.

Much appreciate some advice.

Re: Domi 88 cylinder head oil return

Posted by robert_tuck at August 17. 2017

Should not be there. Can only assume that this is a mod to encourage more oil to flow down to cam followers. If the inlet valves have seals may be a good idea, perhaps in your motor hardly any oil gets up there anyway?, like mine used to be.

Re: Domi 88 cylinder head oil return

Posted by Graham Martin at August 17. 2017

Previously robert_tuck wrote:

Should not be there. Can only assume that this is a mod to encourage more oil to flow down to cam followers. If the inlet valves have seals may be a good idea, perhaps in your motor hardly any oil gets up there anyway?, like mine used to be.

Thanks Robert those are my thoughts too. My problem has been oil forcing it's way through the exhaust ports and this might be the reason. If I remove the plug and I've checked the chamfer on the tappets are facing forward, I just might have solved it. Fingers crossed.

Re: Domi 88 cylinder head oil return

Posted by roger_wilson at August 17. 2017

Previously Graham Martin wrote:

Previously robert_tuck wrote:

Should not be there. Can only assume that this is a mod to encourage more oil to flow down to cam followers. If the inlet valves have seals may be a good idea, perhaps in your motor hardly any oil gets up there anyway?, like mine used to be.

Thanks Robert those are my thoughts too. My problem has been oil forcing it's way through the exhaust ports and this might be the reason. If I remove the plug and I've checked the chamfer on the tappets are facing forward, I just might have solved it. Fingers crossed.

My 1957 88 cylinder head has this hole which I understood to be the drain for those valves the other valves drain thru the hole in barrel to crankcase? I have excess oiling to the valve gear even with the hole clear.

Re: Domi 88 cylinder head oil return

Posted by robert_tuck at August 17. 2017

Oil in the exhaust ports is likely to come from guides not sealed to head  . I would tap them part out ,seal round with RTV and tap back in. Should be able to see oil track from guide in the ex port.

Re: Domi 88 cylinder head oil return

Posted by anna jeannette Dixon at August 18. 2017

Hello,  This oil way is NOT a mod has you so call it is a drain hole and should never be blocked up!!! ,   and you should NEVER EVER KNOCK OUT VALVE GUIDES  COLD   HAS they are An INERFERANCE FIT   and a good Gas or electric oven  should get them hot  and they should fall out  please use suitable gloves to handle the hot cylinder head and a good size wooden chopping block  or make one from a 9 inch by 3 planks of wood   and good peace of planed pine or hard wood are both good for this  job  also you can make a nice wooden engine stand has well most useful when rebuilding a Norton engine  singles or twins  and you can make a wooden engine fork  this goes over the mouth of the crankcases and is marked out to fit over the barrel studs this stop the movement of connecting rods and pistons and most useful when fitting the barrels  use a nice peace of ply for this sanded down and primed  with MDF sealer so no splinters come off 

 to save you arms and money plan ahead  before any engine rebuild or strip downs  and get your information right for your model do your home work  

     have a lot of nice rides out and fun in the sun   yours  anna j 

Re: Domi 88 cylinder head oil return

Posted by robert_tuck at August 18. 2017

Anna, you really must think before posting. I never suggested valves guides should be removed COLD.  I never said the oilway was a mod. The plug is. I know you have good information to impart but it does not help if you ramble on.

Re: Domi 88 cylinder head oil return

Posted by anna jeannette Dixon at August 18. 2017
Previously robert_tuck wrote:

Anna, you really must think before posting. I never suggested valves guides should be removed COLD.  I never said the oilway was a mod. The plug is. I know you have good information to impart but it does not help if you ramble on.

Hello  right you are  Robert  this BIT of info was for all, not just  one,  When we were young we argue over most things and some time fall out with each other but we soon got back together  and just have a laugh so do not take thing too seriously  life to short  where all in this has a hobby let have some fun  happy days  yes   yours  anna j 

Re: Domi 88 cylinder head oil return

Posted by Graham Martin at August 21. 2017

Just to round this off:

The obstruction would not move with air so I filled the hole with oil, used the shank of a drill as a piston and it flew out no trouble. The obstruction was of a similar size to a roller from a bearing but not as hard. There is no way that such an object could have got there without being carefully inserted so either the previous owner had upset a mechanic or someone had a very odd theory on oil supply!

When I acquired the bike the engine was encrusted with oil & muck and this little plug probably explained why and suggests the previous owner was riding it in this condition. As they say there's nothing stranger than folk!

Re: Domi 88 cylinder head oil return

Posted by anna jeannette Dixon at August 22. 2017
Previously Graham Martin wrote:

Just to round this off:

The obstruction would not move with air so I filled the hole with oil, used the shank of a drill as a piston and it flew out no trouble. The obstruction was of a similar size to a roller from a bearing but not as hard. There is no way that such an object could have got there without being carefully inserted so either the previous owner had upset a mechanic or someone had a very odd theory on oil supply!

When I acquired the bike the engine was encrusted with oil & muck and this little plug probably explained why and suggests the previous owner was riding it in this condition. As they say there's nothing stranger than folk!

Hello  Grahan AS you say there is nothing stranger than folk and the Members of the Norton owners club are the exception  to the rule  being the most weird and wonderful lot they are  I just wish they would communicate more with each other, as this website was made for this reason  but is under-used by members 
   now do have a nice time sorting your nice Norton out  and do be careful out there where in dangerous times,               yours   anna j 
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