update, I had the horizontal head off to address a small oil leak between the head and cylinder. Clean up, new O rings appears jobs a good un. as a result of the head coming off, i completely removed the exhaust system to see what was going on inside. Nothing of note in terms of oil etc, all nice and dry. Gave it a good swill through with some meths and dried it. Nice and clean now. rebuilt her checking belt tension, cylinder head bolt torque, reseated the exhaust and new gaskets then moment of truth. she started first time off the button, settled after a short time into a nice tickover with a nice crisp throttle action and apparently no oil leak. when i dismantled the exhaust, I found a tell tale that gasses had been blowing out between the joint of the rear downpipe and the main system. The only thing i can think off in relation to the "oil" spattering i mentioned, was in fact condensation being blown out of the joint in the exhaust. She really needs a good run out for me to see if this is still an issue. Crank breather is also bone dry. On that note, the airbox breather hose, Ive found has a split in it. Anyone know where I can get one from as a replacement? thanks in anticipation.
Heat shrink large diameter.....the type with adhesive in it. IIRC the hose is about 25mm diameter, so 30mm heat shrink should do it.....might even get it in red.....
I'm back again.... You know when i said i got her running all nice and right, it now appears I have quite an issue... I wont go into the history of this bike here suffice to say there has been an issue with an intermittent oil leak concerning the rear cylinder. It has reared its ugly head again.... SO the symptoms are when running oil is entering the rear exhaust producing blue smoke as would be expected, but it is also blowing up from the joint between the rear downpipe and main exhaust so quite a bit of oil involved. I've taken the exhaust off and there is a slight pool of wet oil in the mouth of the rear cylinder. Plug is slightly wet. Now then, Obviously oil appears to be getting into combustion chamber although I would have to confirm this on taking apart. The head has had replacement guides and valve stem oil seals a couple of years ago when it was last apart. There are no such issues with the front cylinder. The only thing that hasn't been checked is the piston /ring and bore measurements. My feeling is from the amount of oil involved, its blowing past the rings. The crankcase breather is blowing fine and clear. which brings me on to the next question. What the best way to proceed? I am looking at tearing the bike down (again!) and taking the rear cylinder to get it honed and possibly a new set of rings if required. Does anybody know if there is anything else I may have missed or should consider before going all out for this path? I don't know the condition of the bore the bike has covered 33000 miles. That now said, anyone got any recommendations as to the best place to get this work done.... I'm Midlands based.
First thing is to do a compression test comparing the front and rear cylinders. In good order you should see better than 140psi although 125 + is probably just acceptable. Importantly, both cylinders should be approximately the same. Say within +/- 5 psi.
as above as it's a mystery that breather not puffing - even when good and hot and blipped? it could be that oil ring alone is failing of course - apart from this, makes me wonder about valve guides/seals again, despite them being done recently.
Thanks guys, I've invested in a comp tester so that will be my first port of call. It is obviously an assumption that the seals are ok, either way its looking more likely that a teardown will result. Im now going to throw a little built more history into the mix.... Back in 2001 I was riding the bike on a holiday in scotland when a ringland on one of the then Arias HC pistons gave way with the associated engine failureand the bike shitting itself. At the point of rebuild the engine was stripped and rebuilt completely with new shell bearings and shaft bearings throughout. new pistons, honed bores valves re set and even a new rear cylinder head as there was a hairline fracture in the casting which ironically caused an oil leak into the chamber. All was well except an intermittent misting of oil on the white frame . because of airflow I couldnt track this down to anywhere specific. It now appears that whatever the issue was has now let go in a big stylee. Im wondering if there is any undetected bore damage bearing in mind the Arias pistons were Aluminium. This is now personal between me and the 900 I will conquer this!
Just a thought, was there an issue once with an oilway bleeding into exhaust port, poor casting or something, was it on an Elepant or Pantah detevative?
Interesting. A previous head on the rear cylinder had issues due to a hairline crack that enlarged as the engine warmed so on startup, no smoke as the bike ran it was like a steam train. that head was replaced. I cant be unlucky enough to have a second one surely? Comp test first then go from there....
Hi again folks, yep I have the old head but its buried in the garage perhaps a project for these testing times, Talking about testing, the compression tester arrived today so I went straight on with the test. Bearing in mind the measurements are taken cold , Vertical 130 psi horizontal 110 psi SO I now ask this, the figures suggest that the horizontal cylinder is the one with the problem. Could it be that oil is being forced into the cylinder into the exhaust and up to the rear cylinder? It just doesn't seem right to me as there was an amount of wet oil in the exhaust port of the vertical cylinder which is I always thought the vertical cylinder was the problem. If there was such a scenario surely the exhaust port of the horizontal cylinder would be wet with oil ? im now getting a little confused not to add pissed off. so next up, horizontal cylinder is coming off.
Before anything else, have you got a good churning speed? was this carried out with both plugs removed? were these results "wet" or "dry"? I would do this a few times with a healthy battery both wet and dry for starters. Also, you are connecting up a couple of slave spark plugs resting on an earth i'm guessing?
I did the head swap. I sourced a replacement empty head from a bike with a lot fewer miles. I swapped the valve gear components over having had the valve guides replaced and valves lapped in. valve stem oil seals and all correctly shimmed. (This bit was done elsewhere.) throughout all of this, no regard has been paid to the horizontal cylinder which was probably the issue.
Hi Chris, yep Turnover speed is really good both plugs out. I turned her over until I got oil pressure then took the readings. I repeated the exercise several times. in addition I disconnected the ignition circuit ( ignitech ) whilst I was doing all this.... I think i'm going to pop the front cylinder off and see whats what. Horizontal is consistently lower by a good margin.
just to answer your early question, a lower comp reading in your horizontal cylinder won't cause an over-oiling problem in your vertical cylinder combustion chamber. Just a long shot but are you happy with your valve clearances on horizontal cylinder? Sometimes the first attention that's needed on an otherwise well-looked after 2V 900/750 engine is to restore valve clearance on (typically) the exhaust valves due to seat recession.
You could try them both with a couple of squirts of thin oil just out of interest as it can help to shed more light.
just had a good firkle around the exhaust port of the vertical cylinder and i'm convinced that is the source of the oil leak as there are what looks like damp oil tracks coming from within the exhaust port and the exhaust itself is wetter than an otters pocket. looks like too much oil for the valve stem seals so its out with the motor....
