WT. Here’s a bunch of stuff culled from postings during from my sprag episode. I’m also mid-way through writing up some tips I picked up – I’ll post them for you when I get back tonight (at work today:angry).
I know you’re a tech so please excuse if I’m teaching you to suck eggs in any of this.
First off all – check this out:
http://www.apriliaforum.com/forums/showthread.php?t=155882
It’s most likely that the sprag and the housing are the damaged bits – the housing may look OK (just a few wear marks on mine) but it’s worth changing – unfortunately no one has yet found an alternative to the Aprilia part.
The sprag itself you can use the BM part –
http://www.motorworks.co.uk/bmw/products/product.php?f=b&bke=bmw&q=ENA57177
Part No. ENA57177
But you have to either fit it the ‘wrong way’ or rebuild it (simple but delicate job) so that the ‘balls’ lock the other way. You might find it a bit cheaper than from motorworks but they are reliable blokes and got it to me next day.
It’s about £58 quid plus postage – you can also use the Ducati sprag but it’s about £100 – don’t know whether the Ducati sprag runs the same way.
Aprilia Sprag - UK183
Ducati Sprag - UK100
BMW Sprag - UK55
Says Kiwi.
Notes:
Royton at REPS (
http://www.repsmotorcycles.co.uk/) gave me the low-down on the BMW sprag.
If you assemble the sprag the way the Aprilia one comes out (with the flange trapped between the flywheel and outer housing) it will lock the wrong way (which I might have seen if I’d taken notice of the direction arrow on it!).
The BM part (and, Royston reckons, the Ducati part as well) has a smaller, tabbed flange which looks like it should fit in the milled recess on the back of the sprag housing.
Royston reckons he fits them the other way, with the tabbed flange between the large drive gear and the housing. He says he’s done several this way and at least one local bike he knows of is still starting strong three years later (the others he hasn't had back so ...).
To my relief, he also says that when he first used the BM part, he rebuilt the sprag to run the other way – just as I did – and it was fine.
The other query I had was the spring clip. The Aprilia part has small slots for the castellations on the clip to fit into: The BM part (and, according to Royston, the Ducati part also) just has gaps in the bearing cage, so gives no positive lateral location (you’ll understand what I’m on about if you see one). Royston says ‘it’s not going anywhere so don’t worry’ and he’s done enough of them to know.
I’m assuming that is a BMW part number (anyone confirm?) as opposed to a Motorworks one but anyway, it’s just a sprag clutch for a BMW F650 (circa 98, 99, Royston said, if you want to be specific).
You may find it even cheaper than this but I’ve dealt with Motorworks before (er, 1989 actually) and they’re top blokes – had this in stock and got it to me next day (think it was about 65 quid with postage).
For the housing and gasket, I tried the usual suspects who were very nice but quoted around 5-7 days from Aprilia – and we all know about Aprilia parts delivery times. So I phoned Speedaway Motorcycles
www.speedaway.co.uk and they had both housing and gasket to me next day.
For the locking tool I used an M8 x 100mm plain bolt from my local engineering supplies place. The hole is in the r/h (as you sit on the bike) side just behind the oil pressure (?) switch at the bottom of the engine. The blanking bolt on mine was a gold allen headed bolt.
Get a socket on the flywheel then lay under the bike and ‘feel’ the bolt into the recess on the crankshaft.
You’ll need plenty of heat – about ten minutes with a blow torch on the centre boss until I saw the loctite start to drip out, then it should crack off with a breaker bar without too much trouble.
You’ll need Loctite 648 for the flywheel taper when you rebuild it – I bought a big bottle and it ain’t cheap so I might be able to decant enough into a smaller one if you want me to send you the tools. Let me know.
If you’re worried about using a non-Aprilia part, I did mine just before I went to Spain for four days of track abuse and it is fine (touchwood!).
Hope this helps.
irate
