Here's a picture of my lovely S1, except that the Crankshaft oil seal has let go.
I'm not sure how many different ways that this can happen, but for me it was simple, I'd left the petrol tap on for 3 days and it had syphoned into the crankcases.
When I left for work, the bike started ok, then blew most of it's oil / petrol mixture out of the transmssion top breather all over my rear tyre. It made for an impressive powerslide before I realised what was going on!
The following is a kind of Haynes type description of what I had to do to fix it.
It may not be the only way, or the best way,but it's the way I did it and I thought that I'd share it anyway.
It may also be of some use to anyone who wants to peek inside their trapdoor for a quick gearbox inspection.
Luckily for me, Tubers from '98 on have a small drain screw in the bottom of the cases, so that the remaining mixture could be removed, albeit you have to take the shock off to get at it. Suffice to say, in this case, a full oil change and filter was necessary.
Thanks again to Maz for encouragement and advice, as well as a speedy supply of all the parts that I needed.
It starts out easy, disconnect battery and remove silencer.
Steal one of the wife's seed trays from the greenhouse, place under bike and remove primary chaincase drain plug.
Remove gear change assembly.
Discover that the drugs that they gave you to counter the Tourettes have failed miserably as you try to loosen the four torx screws which retain the clutch cover.
Once removed, find a suitable catapult and fire them into the field.
Back off the cable adjuster,then remove the operating mechanism and clutch cable.
Slacken off the primary chain.
As per Adam's advice, make a childlike rendition of a primary case in cardboard, then remove casing screws.
Remove clutch adjuster to reveal clutch nut.
Make a locking bar from a piece of 6 x25mm aluminium and position between sprockets. Loosen crank nut anticlockwise. You need a 1 1/8" deep socket for this nut.
...Then reverse locking bar and undo Left hand thread clutch nut clockwise. A regular 1 3/16" socket will suffice for this one.
Pull the primary drive off as one unit.
Luckily for me, the old style seal is fitted with the lip or open end facing outwards, so it enabled me to use a bearing puller to extract the seal.
........Handy bit of kit if you ever see one at an autojumble. Over £200 new.
Next, I nipped to work and found a lump of plastic to make a seating tool for the new seal.
.......And there it is.
Back at home, I used a deburring tool (or a whirlygig as I call them) to make a lead for the new seal. This is because the newer seal fits with the open face inwards, so getting it started in the hole is much more difficult. Obviously, you have to make sure that any swarf is accounted for and that it cannot get anywhere near the main bearings.
While the bearing is still protected, it is a good time to ensure that the gasket face is free from any debris and congealed old gasket material. It's easier to do it now, before the primary drive goes back on.
A new spacer is fitted with the seal, so I coated both with engine oil and you have to fit them as a unit. I started it off by hand, then used the tool that I made to send it home. There should be about 1.5mm of spacer showing out of the seal.
........And there it is....
If your Tuber is jumping out of gear or hitting false neutrals, then the the detent plate in my hand is much better than the one fitted. They are only about £3.50, so you'd be a twat not to while it's apart.
While you're down there, as they say, you might as well have a peek behind your trap door and ensure that there are still teeth where they should be. It's only 5 bolts plus the pawl mechanism. You'd be daft not to.
Err, one gearbox. It's almost worth doing this at the roadside, just to piss off the XB owners.
Get the solvent cleaner in there and give it a good once over.
Check the drive dogs for excessive wear..........
.......and also the shafts that run in the needle rollers in the blind side of the case.
Inspect the needle rollers, then if OK, lube using some Sport trans.
Refit the trapdoor, having lubed the shafts. Use locktite threadlocker on the five bolts and torque up. Refit the pawl lever and new detent plate.
Use the gear lever to check that all is ok and that all gears can be selected.
Inspect magnets for any debris, then refit primary and clutch as a unit.
Fit new nut to crankshaft, after applying some threadlocker. Torque up using the locking bar. Reverse the bar and do the same with the clutch nut, making sure the washer is the right way round.
Refit the clutch adjuster.
This is what the updated tensioner looks like. If the metal part looks thinner than this one, you need to replace it.
Use a new gasket and put the cover back on.
Re-assemble the cable to the operating mech. and adjust clutch cable.
Adjust primary chain, looking at the tightest spot.
Fit drain plug back in, then throw in a litre of Sport trans fluid.
Refit the clutch cover using regular Allen screws and fit the inspection cover also.
Put the silencer and gear change assembly back on and breathe a sigh of relief.