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While we're talking about valve guide seals: I find it interesting that an old time machinist, who does lots of valve jobs on every kind of engine seems to think the seals aren't that necessary. He did a valve job on one of my bikes, no valve guide seals, it doesn't smoke and it doesn't use oil. I personally don't like chancing it so from now on I will bring him valve guide seals. He works mainly on car engines but has hundreds of tractor pull trophies, maybe 1000 trophies. It would be interesting to see what he could modify a TW head to do.
 

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I bow to Ken's experience and expertise. That dude's got some serious TW mileage built up. :cool:
 

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Ref reply #14

".......it only had 45 miles on it, it had sat in a garage for about 2 years. Carb was all gunned up but after cleaning that out it ran great for 750 miles......."

It's not just the rings bedding in is it?

I bought a new car a while ago and that used oil until the engine was run in??
😲 good call ,and if you have used fully synthetic oil before the engine has bedded itself in this can cause the piston rings to not seal properly against cyl wall and burn oil
This is a reason why mineral oil is sometimes used by engine tuners after a rebuild , then dumped after specified mileage and then correct spec synthetic oil and new filter carried out again
But to be honest with you do as the members have said either a leak down test if you have equipment, or if not a simple compression test dry/wet .
You poss may be able to see valve stem oil seals through springs , in case a seal has come off valve guide or broken up due to it standing a while or gone hard
Failing that it looks poss like the cyl head needs to come off for a look inside
 

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While we're talking about valve guide seals: I find it interesting that an old time machinist, who does lots of valve jobs on every kind of engine seems to think the seals aren't that necessary. He did a valve job on one of my bikes, no valve guide seals, it doesn't smoke and it doesn't use oil. I personally don't like chancing it so from now on I will bring him valve guide seals. He works mainly on car engines but has hundreds of tractor pull trophies, maybe 1000 trophies. It would be interesting to see what he could modify a TW head to do.
That’s true , but the tolerances have to be spot on, so when you put new guides in head , normally you measure new valve stems then ream the new valve guide to fit after it’s been pressed into head, the triumph 650-750 twins had this set up, the seals are for generic multi purpose machining where tolerances are within spec or near enough and also to make maintenance less frequent. Believe you me phosphor bronze valve guides don’t last that long without it smoking a bit from leaky valve guides especially on old British triumph bonnies , been there , got the t- shirt
 

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I bow to Ken's experience and expertise. That dude's got some serious TW mileage built up. :cool:
Mine are mostly street miles though. I wonder how the hour versus mileage would actually come out. It seems the off road is much harsher on the engines. Or maybe running them wide open sometimes is really good for them. 46,491 on my mileage now.
 

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Is that oil in the intake tract? It looks like it might be from the pictures. If it is it’s being dumped in from the crankcase breather.
 

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Discussion Starter #47
I checked the breather and air box before tearing the engine apart, did not see any evidence of oil getting pulled through, and carb shows no sign of oil going through it. Also took another look at intake valve on head, it looks pretty clean.
The first oil change I did was right around 650 miles, where I went with a Mobil 1 synthetic. This included at least 15-20 hours of off road riding. I would think that would be plenty of time with the Dino oil to break engine in?

Anyhow, I appreciate all the help, I’ll let you know how it goes when engine is back together
 

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Odd that such a low mileage bike would have this as yet un-resolved problem.
Since the cylinder head is already off with the noted damaged oil seal needing replacement I would go ahead and pull the cylinder too while adding new set of rings to the shopping cart.
This can make de-carbonizing the piston a bit easier too.
Hopefully for peace of mind and to achieve long term engine reliability the burning oil source can be clearly identified and corrected.
Best wishes.
 

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Discussion Starter #49
Well, parts finally came after ordering from 3 different places and waiting for 6 weeks. Was able to get the bike back together after replacing the head stud seal and head gasket. Took it out for A ride and it’s still burning and spitting oil out of the tail pipe, there were a few drips on the swing arm. Went through about 1/3 quart in 30 miles. At this point think I’m just going to do the entire top end and be done with it. Kinda Strange that a low performance/maintenance engine is having issues 850 miles in. I’ve been pretty carful with all maintenance. I don’t know what the PO did in the 45 miles he rode it, sheesh.
 

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after all you have done, i am willing to put money on that exhaust guide seal, or maybe a cracked guide. maybe that is some of the noises you were heading. since the exhaust guide is at the low side, it basically lays in oil all the time, so any problem there will show in oil burning. i would doubt if the o ring that looked damaged, was the problem. with your compression i would think that the head gasket is in good shape, which would make it very hard to have oil pass throught. also if the oil ring is bad, you will get oil seeping on the outside of the head. as far as your worry about oil in the oil filter and running down when you openned it, well that cavaty is full of oil, it has to be. no worries there
 

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Discussion Starter #51
Yeah, I don’t pretend to understand these engines well, but it seems that there are a limited number of places that oil can get into the combustion chamber, and the valve seals/guides and piston rings are the last major culprits. As you said, that oil seal was a red herring. Should go faster pulling it apart this time. I am going to move the piston down from TDC and check the cylinder for any damage, should have looked last time, but it didn’t occur to me. Worst come to worst there is a good mom and pop shop not far away who can lend a hand.
 
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