Exhaust Valve Guide over oiled...

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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GrayKay
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Exhaust Valve Guide over oiled...

Post by GrayKay »

I've owned this Ajay since 1971 and done lots of work re-painting and mechanicals over the years...
She sat unused from 1985 to 2008, then restored to today, regularly used ion my retirement.

But... a couple of years ago, started having exhaust pipe problems.. oil coming out of the joint at the head after a longish run.
So I checked the book, and the yellow circled area is a void to catch oil from the rockers, allowing the oil to drain into the valve guide.

I plugged this opening but still had oily exhaust area.. maybe its simply the valve guide is worn too much.

Could someone please measure the diameter of the opening to see if mine is wrong..(I can get a 1/8" drill shank into my head).

Any other ideas gratefully listened too, bike in bits now so time to fix these issues.

Cheers from Oz.
GK.
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clive
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Re: Exhaust Valve Guide over oiled...

Post by clive »

What about the oil supply to the inlet valve? The metering screw only needs to be just off fully closed. Too much oil coming in there may then be finding its way out via the exhaust pipe joint to the head due to a very slight leak at that point especially after a long run. Try reducing it and see if that helps. Not sure cutting the oil supply to the exhaust valve is a good move.
clive
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clive
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Re: Exhaust Valve Guide over oiled...

Post by clive »

As to wear on the guide your best info comes from the Army

http://archives.jampot.dk/book/Workshop ... ndards.pdf

This suggests internal diameter of the guide on overhaul is acceptable at 0.3775 and condemn at 0.380 so I suppose it depends how well your 3/8 (0.375) drill bit shank fits. Sounds ok. There is a wealth of info for you to check in these inspection manuals but it included a warning to check that the hole in the valve guide lines up. Plugging the hole would be a no no then.

My other thought was did you have the rings off or fit a new piston before the over oiling problem started? On some Pistons if the oil ring is upside down instead of acting as a scraper it pulls oil up into the compression chamber. Good luck.
clive
if it ain't broke don't fix
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Rob Harknett
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Re: Exhaust Valve Guide over oiled...

Post by Rob Harknett »

After some 65 years of riding, from using the bike for every day transport & touring that's never bothered me. In the last 30 odd year's just using the bike for pleasure, it happens more often. Probably no fault with the bike, only due to the way it has been used and maintained. Oil is not changed for a longer period of time. it will sump oil, so this level has to return to normal. At that time excess oil in the engine wants to get out. Deposits in the engine will hardened. Drain the sump if the bike has stood for a few weeks, leave it to drip to empty out as much as possible. Start the bike and wait for the sump to refill to its correct level and oil is returning OK. This could take a few minutes. Give the bike a good run to clear its throat. While the bike is still hot, drain the sump again. Drain the oil tank, clean filter and give the old bike some fresh oil. Now the bike has more chance for it's oil to circulate back to the oil tank without trying to get out else where. I would still not worry if a little oil came out. If a lot, then something is wrong. When was the last time piston rings were checked & ring grooves cleaned ? ( rings broken or stuck in grooves ) I notice Clive's reply has beaten mine with some useful advice.
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clive
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Re: Exhaust Valve Guide over oiled...

Post by clive »

Having reread your post i am not sure where the 1/8 hole is. Presumably the one you plugged as its too narrow to be the valve guide. Well the hole in the head size for the hole you plugged does not really matter as there is a coresponding hole in the valve guide which will control any flow. But 1/8 sounds about right.
clive
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GrayKay
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Re: Exhaust Valve Guide over oiled...

Post by GrayKay »

clive wrote:What about the oil supply to the inlet valve? The metering screw only needs to be just off fully closed. Too much oil coming in there may then be finding its way out via the exhaust pipe joint to the head due to a very slight leak at that point especially after a long run. Try reducing it and see if that helps. Not sure cutting the oil supply to the exhaust valve is a good move.
Thanks Clive
the oil to the inlet valve is ok, new valve and nut, set 1/6th way out from just sealed.
Look for the Sun through the rain... Hint - it's in Queensland DownUnder!
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GrayKay
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Re: Exhaust Valve Guide over oiled...

Post by GrayKay »

clive wrote:As to wear on the guide your best info comes from the Army

http://archives.jampot.dk/book/Workshop ... ndards.pdf

This suggests internal diameter of the guide on overhaul is acceptable at 0.3775 and condemn at 0.380 so I suppose it depends how well your 3/8 (0.375) drill bit shank fits. Sounds ok. There is a wealth of info for you to check in these inspection manuals but it included a warning to check that the hole in the valve guide lines up. Plugging the hole would be a no no then.

My other thought was did you have the rings off or fit a new piston before the over oiling problem started? On some Pistons if the oil ring is upside down instead of acting as a scraper it pulls oil up into the compression chamber. Good luck.
I have decided to go all the way...
New piston and rings on the way..
Will have new guides made to suit my head and newish valves.. the old guides were different diameters and lengths.. so back to new bits.
Look for the Sun through the rain... Hint - it's in Queensland DownUnder!
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GrayKay
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Re: Exhaust Valve Guide over oiled...

Post by GrayKay »

clive wrote:Having reread your post i am not sure where the 1/8 hole is. Presumably the one you plugged as its too narrow to be the valve guide. Well the hole in the head size for the hole you plugged does not really matter as there is a coresponding hole in the valve guide which will control any flow. But 1/8 sounds about right.
The hole in question is the one inside the yellow circle.. drains the oil down into the exhaust valve guide.
The guide oil hole lines up ok.. but now decided to renew most bits...
Look for the Sun through the rain... Hint - it's in Queensland DownUnder!
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GrayKay
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Re: Exhaust Valve Guide over oiled...

Post by GrayKay »

Rob Harknett wrote:After some 65 years of riding, from using the bike for every day transport & touring that's never bothered me. In the last 30 odd year's just using the bike for pleasure, it happens more often. Probably no fault with the bike, only due to the way it has been used and maintained. Oil is not changed for a longer period of time. it will sump oil, so this level has to return to normal. At that time excess oil in the engine wants to get out. Deposits in the engine will hardened. Drain the sump if the bike has stood for a few weeks, leave it to drip to empty out as much as possible. Start the bike and wait for the sump to refill to its correct level and oil is returning OK. This could take a few minutes. Give the bike a good run to clear its throat. While the bike is still hot, drain the sump again. Drain the oil tank, clean filter and give the old bike some fresh oil. Now the bike has more chance for it's oil to circulate back to the oil tank without trying to get out else where. I would still not worry if a little oil came out. If a lot, then something is wrong. When was the last time piston rings were checked & ring grooves cleaned ? ( rings broken or stuck in grooves ) I notice Clive's reply has beaten mine with some useful advice.
Thanks Rob
The bike certainly gets plenty of workout time.. used weekly or at least, two weekly, no problem with wet sumping, one of the things I tried.. drain plug out and left for two weeks.. minimal oil in the cup.
Oil changed every 1000 miles, filter every second change, use straight SAE50. She's a good un, now getting some NEW love with new bits.
Look for the Sun through the rain... Hint - it's in Queensland DownUnder!
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clive
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Re: Exhaust Valve Guide over oiled...

Post by clive »

With all those new bits don't leave the oil hole supply to the exhaust blocked. You said you had blocked it although it does not look it in the photo. With the temperature in Queensland I think you are going to need oil for the exhaust valve, especially with a new guide.
clive
if it ain't broke don't fix
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