Damaged piston (VFR400)

If thats right then I suppose alpine star has the dibs on the idea, he sounded like he was asking about the sprag in a round about way...

Its and easy test, press the starter, if the starter turns and the engine dont then its the sprag.

Originally Posted by yorkie_chris

One way clutch, it allows the starter to drive the engine over when the starter is spinning faster, but releases when the engine spins faster.

Full name is a sprag clutch. If they go pop then when you press the button the starter motor will whir without cranking the engine. Some bikes can have issues with them if you let the battery get low and they kick back.

Why would a low battery cause kick back. I know on odd occasions I get kick back, not nice!

[fastdruid]

Originally Posted by ThEGr33k

Why would a low battery cause kick back. I know on odd occasions I get kick back, not nice!

Because it doesn't quite have enough 'go' to spin the engine past TDC and bounces back again, the sprag doesn't disengage in time and it tries to force back against the starter motor. Early triumphs were legendary for shagging sprags if the battery was low.

Druid

Ah, so the first attempt at failing a bump start, and the second successful attempt at the bump start, then attempting to start my bike a few days later = shagged sprag?

Druid do you know what part I need for an NC30?

[yorkie_chris]

Bump starting won't bother the sprag clutch at all. Starting on the button (or failing to) might knacker it though.

Ah ****e hope mine aint on the way out... Sigh. I sometimes get kick back as I mention.

Will keep an ear out for this.

[fastdruid]

Originally Posted by EssexDave

Ah, so the first attempt at failing a bump start, and the second successful attempt at the bump start, then attempting to start my bike a few days later = shagged sprag?

Druid do you know what part I need for an NC30?

Depends on what's gone, my CD200 broke the pins, in which case you'd need 3 of 28126-323-000 http://www.davidsilverspares.co.uk/p...tnumber_11691/ or £2.95 each

If you need a new gear thats 28110-MJ8-000 http://www.davidsilverspares.co.uk/p...tnumber_16324/ or £20

If you need the body then thats 28120-MR8-000, superceded by 28120-MR8-610 http://www.davidsilverspares.co.uk/p...t_28120MR8610/ 93.60

Rollers are 91101-337-000, springs are 28125-426-000

Anyway, PM me with an email address and I'll send you the microfiche.

Bump starting shouldn't affect the sprag, only the starter motor affects the sprag.

Druid

[Spanner Man]

Good morning all.


If the engine wont turn over on the starter how did the garage manage to do a compression test? I doubt that they ran up the road with it in gear, with someone holding the compression tester running alongside!
Sounds like their talking Beelocks! I would suggest that you get your bike out of there sharpish.

NC30's charging systems are pretty poor, & suffer regular failures or the rectifier/regulator, & the generator. So get it checked out, as a low battery could cause the starter clutch to mis-function.

NC30's have pretty tough engines. However, as the valve shimming procedure is pretty fiddly most garages don't bother doing it. So it is possible to burn a valve.


Cheers.

Originally Posted by Spanner Man

Good morning all.


If the engine wont turn over on the starter how did the garage manage to do a compression test? I doubt that they ran up the road with it in gear, with someone holding the compression tester running alongside!
Sounds like thier talking Beelocks! I would suggest that you get your bike out of there sharpish.

NC30's charging systems are pretty poor, & suffer regular failures or the rectifier/regulator, & the generator. So get it checked out, as a low battery could cause the starter clutch to mis-function.

NC30's have pretty tough engines. However, as the valve shimming procedure is pretty fiddly most garages don't bother doing it. So it is possible to burn a valve.


Cheers.

Turn it off of the crank? I have no idea how you do a compression test though to be fair

[ophic]

Originally Posted by ThEGr33k

Turn it off of the crank? I have no idea how you do a compression test though to be fair

This could explain the reported lack of compression