Hi all sorry I haven’t updated recently. Been doing RHS studies.
I eventually ruled out a problem with the barrels and pistons by replacing them. Which left the heads being the suspects. (recap) The motor smoked a bit but not excessively, the heads had new guides fitted and then smokes badly and spits oil out the exhausts.
I spoke to Len Patterson at the Cylinderhead Shop about them and his theory is that, when the old guides were pressed out carbon debris could have scored the guide tunnels and after refitting the new guides oil has been running down the back of the guides. He uses certain methods that counteract this and Im hopping he’s going to finish mine soon.
While all thats been going on I’ve had the tank re-lined and re-sprayed. I’m also hoping to get the big bore frankies I bought last summer carbon coated as after 6 months in my garage they look terrible.
Hopefully the next update should be about me riding off into the sunset. Cheers AV
that therory is hard to believe for the amount of oil to cause it to smoke as bad as it was the guides would near enogh have to be a throw fit in the head i think they are also pressed in to a step on the guide that regardless of the scores on the holes where they fit should seal it
on one of mine i wound engine over till both pistons about half up the bores and filled with oil next morning 25 mm of oil had leaked to sump i took them off glased bust them (cast ones ) rebuilt and it was fine
I spoke to Len Patterson at the Cylinderhead Shop today, he’s had a look at them and he’s saying that the step or ridge in the guides are gone, there’s no vacume on the exhaust valve and its very low on the inlet.'m pretty sure the old barrels and pistons were ok, I wanted to change the rings but I had no luck finding them. As i’m interested in reliability i decided to replace the barrels and pistons for a brand new kit which after fitting made no difference to the smoke or oil spitting out of the exhausts.
I made a mistake in my choice of Engineering firm. I was under the impression that fitting valve guides was fairly straight forward and one of the first questions Len asked me today was “is it a firm that just does cars”. yes.
I’m open to any suggestions from anyone on this forum who could draw light on this problem. I think maybe a thread on good engineering firms that know Moto Guzzi would be useful, most of the good sites on google seem to be in the US.
Not sure what he means by no vacuum? It sounds a bit like they are not sealing?
After fitting new guides, were the seats recut to the new guide and ground in? Not that that would cause an oil consumption issue.
Being a LeMans 2 There is no source of oil from the inlet tract via the breather system.
I assume you haven’t used a synthetic oil in it have you?
I think lack of vacume might have something to do with the lack of ledge, (do correct me if this is wrong) where it allows some oil for valve stem lubrication but seals enough to stop oil getting where it shouldn’t.
What’s very annoying is that it did smoke a touch before I took it apart and I’m fairly certain I took it apart correctly. I was hoping to get to a Courier meet at the Ace cafe last October and was hoping to get it done by then (next year maybe).
If I look at all the possibilities, then I always have to come back to the heads. if it was rings then surely the new cylinder kit cured that? If it was coming in through the head gasket, then why is there oil in the inlet tract and oil coming out the exhaust port? Also to be considered, is that it’s a lot worse on the right hand side. the left smokes but there’s less oil coming out. The only other thing it could be is if the heads are cracked?
I used 20/50 mineral oil ‘Halfords classic oil’ (which is rumoured to be Duckhams).
Halfords 20/50 minreal should be fine.
Synthetic oils are too slippery and sticky to new surfaces to be used for bedding in the rings on an old low tech engine.
A mate had this on a freshly rebuilt Aerial 650 twin, used a synthetic oil and it smoked badly as the oil scraper rings couldn’t wipe the oil off the barrel. But that wouldn’t be visible in the inlet tract, It would stay in the combustion chamber
Oil in the inlet tract is suspicious. I assume you are still on the open bell mouth carbset up standard to the LeMans.
Assuming the tank is petrol tank is clean, with no oil contamination then there is no way oil can get into thesystem. I have heard of poor crank case breathers pushing oil into the air filter system in other Guzzi models.
If you’re brave or foolish, you could try the Italian method https://en.wikipedia.org/wiki/Italian_tuneup
Could it be leaking from the head gasket?
Where is the oil flow within the barrels? Could that be sucked into the combustion chamber?
It,s been ages since I had the barrels off one of these, I know there are O rings somewhere that seal an oilway. Missing those out could cause a leak.
Not sure this is any help, but looking at this from a different angle, is the bike breathing OK? if not, the crankcase gets over pressurised and forces out oil all over the place, the only reason i ask is i had this problem with a le mans 2, i fitted a sump spacer and cleaned out the breather box and pipes which were full of crud and it cured the problem. cheers, Chris.
Good call, definitely worth a check. It is fitted with a sump spacer, also got the long dipstick, and I carefully measured 3 litres of oil which measured up perfectly with the high mark on the dipstick. I have heard it said that the dipstick should be re-calibrated when fitting a sump spacer.
I should get the heads back next week and in the mean time I’ll check the breather.
Indeed a mystery, now what did Sherlock say, “When you’ve exhausted all the possibilities everything else, however improbable should be considered”.
The heads come back from the Cylinder Head Shop next week and basically they’re going to remove and refit the valve guides, fit K line inserts and recut the seats, so I’m going to have to work out shim sizes for the valve springs. Hopefully this is going to sort it.
I did think of this, the problem is the oil is in the inlet tract and its in the combustion chamber. If it was just the combustion chamber then you could say head gaskets or o rings, but with oil in the inlet tract then you have to think guides or cracks in the heads. Also worth thinking about is that the right hand side is pissing out oil, on the left hand side its burning off, nearly all the oil thats getting in. Now if the theres a defect in the machinery used to make the repair then the defect would show up as uniform, but in my case it doesn’t so I’m thinking material breakdown worse on one side than the other? I’m also thinking human error, either my own or those that were paid to do the job?
Anyway I’m going to check the breather system for any failures there. Should get the heads back next week so hopefully bring this thread to a close and start the next one, I’m riding to Coventry from Cirencester up the Fossway every Saturday morning (term time only) at 7am(ish) who’s coming?
Doh that’s making some sense, there’s vacuum in the inlets, which could suck in oil from loose valve inlet guides or whatever.
Anyway I’m going to check the breather system for any failures there.
If you have a tyre pump with an air bed nozzle attachment, can insert that into the small diameter metal tube coming out the top of the bell housing, this is the return to sump drain for any oil that gets in the crankcase breather box; with the dipstick taken out, blowing air into here should cause an audible bubbling noise from inside the sump if the tube is clear. (Normal quantity of oil in sump.) Can’t poke wire down it cos there’s a banjo union where the end of the straight lower sump tube comes up in front of the flywheel. The banjo union is on the end of it.
Could it be fuel contamination?
You haven’t filled the tank up with a container previously used for diesel or 2 stroke? Or done something to the tank that be causing it?
Not sure if the LeMans have the ball valve in the top of the crank breather or not? They can get worn and stick so the engine can’t vent pressure.
I presume it’s open bell mouths so there is no link to the breather system via an air filter system like in other models.
Just a quick heads up, dare i say it, there is a good le mans breather write up on the GUZZI RIDER forum titled "LM breather box valve ‘fix’ " which details the breather mods i made to my own le mans (and pictures of my home made stainless breather box), well worth a look if you would like to know more about the breather system. all the best, Chris.
pressurisation is easy to discount run it without the dipstick in it that way the case cannot pressurise might splash a bit of oil out buut will prove a point
Good news, I’ve cured the problem I spotted a pair of second hand heads on Ebay from Gutsibits, I checked out the valves that came with them and they seem like new, well I’ve just been round the block on it and very little smoke, came out the exhausts (some of that smoke is probably the oil that is still in the exhausts). I couldn’t feel much pressure coming out the breather so I took out the dipstick and felt a massive difference in pressure coming out. next task will be to check the breather box, hopefully be on the road soon.
I can only assume that some dodgy engineering coupled with a breather problem was the cause of the problem. I’m still waiting for my original heads to come back from the Cylinderhead shop so I can’t be sure. I’ll put them aside as spares when they do eventually turn up.
Just need to say a big thank you to everybody who posted or viewed this thread and hopefully catch up with some of you when the weather warms up.
