talking of alternatives for Rotax 912, what about starter motors and stators?

[zerogravitas]

Hi Danny & Co, thanks for your hard work with this, have sent you a PM. This has been my day 🤣 Stumbled across this forum and your thread in my desperation. I'll have to take the X-Air up again (super fun, but not the same, not great for getting anywhere! But at least i'd be up in the sky!)

 

Edited May 5 by zerogravitas

[zerogravitas]

I have bit the bullet and gone for one.

My only concern is this is the longer 0.9kW (mentions 914 in Illustrated parts catalogue) variant so whilst front interface the same the positive terminal at the rear may impinge on white chassis shown below. But for cost of this i can buy both short (to be found) and long variants way withing the cost of £400-500 of getting one from America.

 

I can either strip for more info or sell on. when i get the old one out i will do controlled disassembly.

 

This is non-certified.

Starter Motor Fits BMW F650GS Dakota 652cc 00-07 228000-6900 228000-8050 18820 | eBay

[danny_galaga]

I can't remember if I ever noticed there were two power ratings! Going by that illustration, I have the 0.9kw version. Keep us informed! 

[zerogravitas]

They've sent me a clockwise rotation one i think rather than Counter-Clockwise. Does anyone know the rotation for certain. I've just assumed CCW from seeing it somewhere! Though it makes sense with connected gears turning opposite directions - Anti-clockwise sprag clutch into clockwise engine.

 

I actually have a straight up replacement that i managed to find for £200 rather than £500-700. But i will try add what i can to this thread.

Edited May 11 by zerogravitas

[danny_galaga]

Your ebay listing says CCW. If you are careful you can put some jumper leads on it and see which way it spins. Be careful though as it will jump when it spins. Unless you carefully mount the lugs in a vice. But don't clamp the carcass (body) in a vice since I think it is permanent magnet, you don't want to crack them. Does your old starter work at all? You can do the same with that and see if they both spin in the same direction.

[zerogravitas]

Sorry for radio silence. So in the end I found a replacement rotax starter of the same size. I have some photos of the old and new. I will dissect the after market one i bought and take pics.  i think one of the most important parts is the presence of an oil seal at the front (for a Rotax 912).

 

 

[danny_galaga]

Before you pull apart the aftermarket starter, can you check to see it's spinning the same direction as the Rotax one? 

 

I would be surprised if the aftermarket one isn't pretty much exactly the same, other than the possible direction of rotation. So it should have an oil seal, since the engines these starters go on have the same set up as the 912. That is, sprag clutch in the crankcase or gearbox, running in oil.

 

Looking forward to more news 🙂

Edited May 27 by danny_galaga

[Red]

Looking at workshop drawings for the F650 engine and noting the gear arrangement between starter and sprag clutch the starter motor will have clockwise rotation

 

[danny_galaga]

13 hours ago, Red said:

Looking at workshop drawings for the F650 engine and noting the gear arrangement between starter and sprag clutch the starter motor will have clockwise rotation

 

Don't forget the Rotax 912 starter sticks out of the crankcase, and the f650 nestles above the crank case, effectively changing which way it turns the sprag clutch. Does that come into it? I get dyslexic looking at gears 😄

 

What's disappointing, if it spins the wrong way is that the f650 starters are listed as ccw. Do we know which way the Rotax starter spins?

 

Is there no one here with a loose Rotax 912 starter they can test? 

Edited May 28 by danny_galaga

[Red]

 

8 hours ago, danny_galaga said:

Don't forget the Rotax 912 starter sticks out of the crankcase, and the f650 nestles above the crank case, effectively changing which way it turns the sprag clutch. Does that come into it? I get dyslexic looking at gears 😄

 

What's disappointing, if it spins the wrong way is that the f650 starters are listed as ccw. Do we know which way the Rotax starter spins?

 

Is there no one here with a loose Rotax 912 starter they can test? 

There are a few factors, firstly the f650 starter is actually 180 degrees different in orientation to the 912 and there are 2 gears between it and the sprag.

who actually lists the starter as ccw?

 

http://faq.f650.com/FAQs/Photos/TransmissionPhotos/269-Alternator.jpg

Edited May 28 by Red

[Red]

I must be wrong about the F650 rotation as the rotax starter is ccw so if the same starter fits an f650 then it too must be ccw, apologies for wrong reading of the F650 setup, though I still cant see it, must be something hidden in the gear train

[danny_galaga]

11 hours ago, Red said:

I must be wrong about the F650 rotation as the rotax starter is ccw so if the same starter fits an f650 then it too must be ccw, apologies for wrong reading of the F650 setup, though I still cant see it, must be something hidden in the gear train

We don't know who's right yet 😄

 

But in the world of starters it's unusual to have basically the same starter built for two directions. Definitely can occur, most obvious example I remember is the Bosch car starter motor. They built a version that ran the other way for air cooled VW's. Every other one spun the same way as virtually any other car starter. But we are talking hundreds of thousands, and then millions of VW's versus a few thousand 912s. With something niche, normally you work around what's readily available. We've seen that with other peripheral parts of that engine, including the fuel pump. 

 

I wish I'd thought of all this before I put my engine in, I would have tested the starter on the bench. Now the engine is in, it's a real pain to get to. Maybe the mount was designed by someone from Alfa Romeo 😄