Starter clutch rattle sfc1000

SkinnyPinny

SkinnyPinny

Full member
Location
Cambridgeshire, United Kingdom
Hi all,
Making the most of a sunny day.
so after a really good 120 mile ride I stopped for 2-3 hours. The bike started up ok but I could hear a horrible rattly sound from the starter, like a VERY loose chain, which went away after 20 secs or so.
I realise there is no chain but that’s what it sounded like.
I got back home and it continues to start ok ie no noises that shouldn’t be there.
Obviously something is amiss and before I start taking the starter and alternator cover off any idea what the likely cause is?
Does this rattly sound point to anything particular ?
Cheers all for any advice,
Stuart
 
Reading through previous posts, it seems new springs and plungers could be required? Is it possible they are sticking and causing the rattle ?
If that’s the case, Is there a preferred source for these?
I’m in Cambridgeshire if it helps,
Stuart
 
SkinnyPinny said:
went away after 20 secs or so
Click to expand...

That's a real concern - the starter and sprag should stop as soon as the engine fires. I wouldn't use the bike again until you've inspected the sprag. As you have found, it takes a pounding and at the very least new springs and rollers will be required. Plungers usually OK. I use Wolfgang or OCT - hesitate to suggest sfcpiet atm but you could message him.
The starter solenoid (or relay before Clem corrects me) is also marginal for the current it has to carry if the starter hasn't been overhauled and the bike needs a lot of cranking to fire up. With age the contacts can stick.
 
Hi,
Starting doesn’t seem to be affected, The bike starts straight away, no hesitation or long cranking time.
I have all new cables and recent battery,
It’s never don’t this before and my concern was to avoid the possibility of something braking up and leaving me stranded and worse, damage to the engine.
Years ago, I changed a sprag on an Aprilia falco I had, quite straight forward using BMW parts,
I’ll remove the starter and cover and see if it’s obvious what going on,
Thanks,
 
Could possibly be the sprag not releasing. If it doesn't and you wind the bike up to operating revs the starter motor could destintigrate due to centrifugal forces.
Ask me how I know.
 
Check if you have the 3 x m5 screws on the backplate of the sprag. If they loosen (often happens) they can catch and send your starter into warp speed, followed by disintegration. Make em tight tight tight.
 
Took the cover off and all looks fine, clean.
So nothing had disintegrated yet!
I’ll spin the starter up on a bench to make sure that’s all ok, I think it will be but I’m checking as I go.
So, I could leave it and hope it was a one off, or think it was a early warning and go ahead and replace springs/plungers & rollers,
Is there a existing thread or is it straightforward ? Been searching the forum but thanks for all and any pointers,
The bolt on the crank looks tight!!!!
Stuart
 
First things first, is this bolt normal or left hand thread? Any particular trick to undoing it? And will a puller be required?
Also, I can see the ends of 3 screws which seems tight,
I assume that removing the rotor will allow the sprag etc to come off, replace springs/rollers possibly plungers,
As always, thanks for any help,
Stuart
 

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Courtesy of a certain Mr Keith Nairn:

"1. Remove the bolt in the centre of the rotor. Should be l/h thread but it may be r/h: if there is writing on the bolt head they are r/h, if not they are l/h.

2. You then need an M16 x 1.5 bolt to pop the rotor off its taper. Use the front wheel spindle if you do not have a suitable bolt.

3. Remove the small tab from 12 o’clock on the big gear and withdraw the sprag clutch assembly. Pull it off using the big gear to stop all the springs and rollers popping out all over the floor.

4. Split the two halves on the bench clean and inspect. With a bit of luck a new set of rollers and springs will fix it."

Keith
 
Haggis said:
Check if you have the 3 x m5 screws on the backplate of the sprag. If they loosen (often happens) they can catch and send your starter into warp speed, followed by disintegration. Make em tight tight tight.
Click to expand...
Illustration ... :eek:
 

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Brilliant info-thanks,
Just found Patrick’s thread on ILOC, that also helps, noticed he used thread-lock on the crankcase bolt plus the 3 x screws,
I’m not keen on thread lock on something like this and rely on correct torque, but maybe it’s needed here,
So this makes it R/H thread?
Cheers,
Stuart
 

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Heat’s usually good, but don’t go crazy here because the magnets don’t like it. Rattle gun worked for me, as advised by Legs (as he advised me too, cheers Legs), I used it for both removing the holding bolt and driving in the M16.
Replacement is a bit different and I used a pin spanner etc so I could use a torque wrench.
Also check the little tab for wear. If it breaks off you can do damage so replace it if required (c/o Piet).
 
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