Hi everyone, just a question re my 907, it has suddenly started intermittently blowing smoke on start up, sometimes it seemed to choke on oil, other times it starts cleans as a whistle, found a split oil seal and replaced it but no real change, I'm guessing it's seals and guides, perhaps rings as well, just wondered if anyone has had a similar experience, it's done just on 80,000 kms.

Cheers

I think the likely problem is the exhaust valve guide showing wear. When the motor is stopped and cooled down this allows oil to seep past the seal and coat the valve. Hence, smoke on start-up.

Where you hiding ? . How long has your oil been in there for and what sort are you using . And what Km's does your bike have . My 906 has done nearly 80,000km's and doesn't smoke at all but I did note that there was a bit of wear in the valve stems / guides. If you really want to put rings in it there are 2 types ( one is almost a dykes type ) AND there is a after market Subaru ring set that ( last I looked ) is only about 80 bucks and has the same dimensions as stock ( which are closer to 400 bucks )
Hamish

Hi Hamish, I'm in Morrinsville, use Motul semi syn 10w40, bike done 80,000km, where are you.

Thornbury , which is about 30 km's west of Invercargill . Oil sounds ok , the reason I ask is that sometimes when the oil is getting a bit old it can smoke more , and I get the feeling ( no real proof ) that higher quality oils are likely to do this when left in a bit long . I have a friend ( sort of ...... he has a Harley ) who was about to change the motor in his Hi lux ( diesel ) due to excessive smoke and a death rattle upon cold starting but he changed from some flash Harry synth oil to some bulk buy fleet ( 20 litres ) oil and the bloody thing is like a new motor ..... #uck me it even has oil pressure now .............still leaks all over my driveway tho

Hi Hamish, I keep the oil fresh, change it and filters every 5k. Funny thing is that smoking started overnight rather than a slow increase.
I also note that the seals rotate easily by hand, is that normal, I thought they would be tighter.

Cheers

No they shouldn't rotate, they should grip the top of the guides quite tightly. It sounds like the seals have become hard and aren't doing their job.

sometimes they ( the seals ) can go up and down with the valve if they aint tight on the guide , and if you have an intake one doing that when cold ........ I once had a XR500re and when I took the baffle thing out ( to make it sound like a mans bike ) it smoked upon start up , took a while for that penny to drop and when I fitted the baffle thing back in ( girls bike again ) it stopped smoking on start .... go figure , coulda had a loose seal .... never looked If its only on start it might be livable with ..... just tell any ( derisive ) spectators that the cam has so much lift there aint no room for stem seals