Hello to all. I am new to the forum though I have been on a couple of other forums on the internet.
My problem relates directly to my 1984 FXR shovelhead - I'm stumped.
Just to give you a bit of background history, I have owned my Shovel for 21 years. I have done all sorts to it and I am confident I know the bike inside - out. In 1996 I replaced the big end, rebored and had new valve & guides fitted. I stripped the engine myself and rebuilt it, though the meticulous work like big end replacement, valves & guides, was carried out by a competent engineer.I have successfully rebuilt parts of the engine myself without any trouble.

Approx 6 weeks ago the rear pot was blowing a little smoke. I decided the valve stem seals needed replacing (stem seals were fitted to 1982-84 shovels). I replaced them but still had the smoke problem. It was not too bad, just puffed a little smoke when stood idle but seemed to disappear when riding.
I tore down the heads (again) and barrels thinking it was possibly a broken piston ring. Rings were good the barrel sides were quite smooth. Valves & guides good. I refitted new rings (+20) to both pots. I went for a short ride and the smoke had gone. Then after 14 miles I came to some traffic lights and I was lost in smoke. The bike belched smoke everywhere. I pulled over. The engine was really hot and oil sprayed from one of the rear tappet drain holes, upwards in a fine mist. Never encountered this before and thought this was crankcase pressure 'gone wrong'.
I got the bike home. Next morning with the engine cold, I started her and immediately there was smoke everywhere. I switched off.
After checking various things and keeping the story short, I had it rebored to +30, new pistons, rings, valves & guides. Started the bike and as the engine got warmer, more & more smoke chuffed out of the exhausts.
Since then I have checked the breather valve (ok), all the oil passage-ways in the gear case, the oil pump was stripped, examined (ok) and all oil lines checked. Still oil belches from the exhausts.
Now I have fitted a new oil pump (did't need one), took all oil lines off, cleaned them, checked breather pipes etc, etc - all ok. Gear case was removed again and double checked oil-ways, bushes, clearances etc.........and all was checked in the cylinders and rocker boxes at the time of re-build.
Oil returns ok in the tank.
But the bike still smokes! badly!
Started her up with the new oil pump - nothing, then as the engine gets hotter, the rear exhaust smokes. A minute later the front exhaust smokes. The smoke gets worse. There is no loss of compression. It appears that the 'top end' is getting too much oil. Or the oil is not returning quick enough. All passageways, oil lines etc are very clear. And new oil pump!
The spark plugs are oily. Oil is getting into the combustion chamber - whether it's coming up & passing the rings from crankcase pressure, or it's seriously leaking past the valve stems (with new seals)...........it's a mystery. But I've thoroughly checked everything and replaced all suspecting parts.
All I speak to, nobody has an answer!

 

seen this a few times with the late 80 inch shovels, being in england you more than likely replaced the valve seals with the tin type NOT the rubber ones

you did not say if you re did the top end as its 18 years old -- valve guides replaced - ??? -- 90s till now on the guides that were available then would have been brass and or -- i am sure they are shot - if you used OEM parts guides than they are still the steel type guides not the unleaded stuff we have today - valves also were not stainless like today --

take off the exhaust and with a good sharp light look in the ports and see if any of the wetness is around the out side of the guide as if its leaking from the alloy head location of the guide -- or is the oil at the exit of the valve at the guide and on the head of the valve is all crusty -- it could also be on both --

answer those questions -- jz

 

Hi, Thanks for replying. Yes, top end has just been fully re-fitted; pistons, rings, valves & guides. The guides are bronze and all has been fitted by a competent engineer (he did them 16 years ago and the bike has been great. It's bit wasteful but I went for a rebore & new valves & guides just as an elimination process. It's as though the 'top end' is getting too much oil or not getting away quickly enough. But it can't be.Oil returns ok and all oil pipes, breathers are clear.
Oil is definately getting into the combustion chamber and it can only get there through the valve stems or by passing the piston rings. But everything is new & fitted good. Can' t understand how oil can pass into combustion chamber.
No smoke on initial start-up but after a minute it starts and gets worse as the engine gets hotter (5 mins). This is on the rear pot. After 5 mins it starts smoking from the front pipe. Then both pipes are blowing the same amount of smoke. You can also smell the oil burning.
One or two people say 'take it for a run and let the rings bed in' but with all this smoke it seems like suicide for the bike.
As mentioned, had a rebore and new valves & guides 16 years ago and there wasn't this trouble.

 

i still dont know if its all new NOW - forget the 16 years ago - the guide seals might have come loose if they are the tin type. i have seen that many times what they make in china now is trash and not what was available 16 uears ago

 

If you don't use paper gaskets under the guides when installing them they can give you leaking issues. Have torn down a few folks didn't take the time to do correctly in the past.

Incorrect seals will do the same as stated also. My guess is it was the first and now it is both problems.

Griz

 

My Guess...Those cylinders may not have been cleaned [washed] properly after hone, and before assembly.

 

Hi folks, Thanks to all who replied and sorry for taking so long to get back.
IBDAGRIZ, you were correct - valve seals.
Stripping the top motor (again) I removed the carb and noticed plenty of oil in the 'Y' shaped inlet, from carb to cylinder heads.
I dis-assembled the top end again.....cylinder heads off then removal of rocker boxes. There was plenty of oil around the top of the cylinder heads and inlet / exhaust chambers. With the rocker boxes removed I could immediately see one of the oil seals unseated and it was as high as it could be on the valve stem. On the other rocker box, the inlet valve stem was so loose, it just 'fell off'.
I have always used the 'tin' type valve seals on my Shovel without any problems. At the Custom Chrome dealership the salesman said the Teflon type seals were much better. So I went with the Teflon ones. I don't know if there is a certain skill to fitting valve seals as you just sit them over the guide and tap them in place with the appropriate tool, obviously making sure they are "home" and that the seal is fitted "true" and straight. But two of these Teflon seals were "off" the guide.
My Harley workshop manual states that the valve seals just seat onto the guide. My buddy arrived with a Harley manual by 'Haines' which stated that Loctite 620 should be applied to the top of the guide to hold the seal in place. I have never heard of glueing the seals on before!

Anyway, the 'tin' type seals were applied and I have to say, they felt a lot tighter fit than the Teflon ones.
Top end was re-assembled and the bike is now free of smoke. Everything ok!

I think the message here is that make sure the valve seals are the correct ones!......there are different sizes, and also make sure they are fitted properly.


Thanks again to all who replied.

 

So...My '74 has No stem seals...Why don't it smoke???

Oh! My Ironhead has none Either!!!

 

Head gasket masking drain holes??
Scott

 

'74s don't have valve seals.They were only fitted to 1982-84 shovels as far as I know. '82-'84 models were also fitted with additional oil hosing from the tappet blocks to the base of the cylinders.
The rear head gasket was covering the oil hole at the top of the cylinder by about 1/3rd. It may have had played a part with the oil situation but doubtful. Oil runs away out of the rocker boxes, heads and down the hole at the top of the cylinder, but it is not under pressure so even with the hole partially blocked, oil should drain ok.
If oil is burning (blue smoke) there is only 2 ways it can enter the combustion chamber; through badly fitted rings or valves & guides (apart from a cracked cylinder head). In my case, seals!
My Harley workshop manual said valve seals should be tapped into place. In the Haynes Harley manual it says to always add Loctite 620 to the top of the guides to hold the seals.
If a valve seal becomes loose and is off the guide, that's actually worse than having no valve seal at all. With the valve opening & shutting with a loose seal on the stem, the rubber seal acts almost like a pump, pushing oil down the valve stem & inside of the guide.