Front sprocket fell off whilest riding!!!

[Stowelly]

Ok I have a honda NSR 125, when it came to changing the chain and sprockets, id noticed that the previous owner had left the front sprocket on there, with no screws and no retainer clip (i had done over 2000 miles at this point) quite worrying, so put some fresh screws and new retainer clip in (done as tight as possible).

now im riding along today and all of a sudden lose all transmission, have to get the bike recovered, just got the fairing off and had a check, both the screws and the retainer clip where again missing, and the sprocket caught in a part of the frame.

any idea how this could happen?

in the gunk covering the sprocket cover it does look like there are a hell of a lot of bits of metal that looks identical to that of the screws, surely they couldnt just disintigrate though?

nightmare!!!!

[Kickstart]

Hi

Those clips can come off easily. Had it happen a few times in the past (Honda seem to be the main ones using them, but not the only ones). Best to put loctite on the bolts between the clip and the sprocket.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Damon]

It's quite possible the bolt got caught inbetween the chain and sprocket both destroying the bolt and moving the sprocket off the shaft. Did it have a lock tab washer behind it or was it just a clip? I really can't see how it happened unless you only fingertightened the bolt

Can you get a pic of your front sprocket. It would be interesting to see the setup.

Damon

[Frost]

The sprocket and clip will easily get covered in chain lube, which is designed to stop stuff gripping. Clean it all with some petrol and a tooth brush before putting it back together.

Check your chain tension. A loose chain whipping about could help shake the sprocket and bolts loose.

As said above loctite helps.

[Stowelly]

thanks Keith, will keep that in mind!

Damon: cant get to the bike right this second, but could get a pic later if it is that important.

but basically it has the sprocket itself

this clip goes over it

https://images.wemoto.com/full/SPROCKET_FRONT_RETAINER/10004275.jpg

and then twists to the side behind some teeth to lock it in place, then this is screwed to the procket itself


https://www.kazumaracing.com/images/imagecache/375-283-FRONT%20SPROCKET02%28530-12T%29PANTHER200MD.jpg

[Damon]

Ahh I see...

As above I would recommend a strong threadlock. Is the thread on the sprocket ok? If it was chewed up and not a close fit it could cause the bolts to vibrate out.

[Stowelly]

[Damon]

[Pete.]

Be warned that the red loctite in the photo is designed as 'permanent' threadlock. If you intend to ever remove bolts with threadlock on them you should use the blue one.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[ms51ves3]

[neil.]

Very lucky indeed...

Looks like the same mechanism as the YBR. Never had these bolts loosen or drop out though, but last time I changed the C&S (2nd time overall), I used 243 on the threads as I read about tgis happening and was paranoid. Are you torque-ing them up properly as well? Also, I had the opposite problem to you last time I took the front sprocket off - a stuck screw which I rounded off the head of...
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CBT February 2008 | A2 June 2008 | Yamaha YBR125 (written off) | Honda CBF125 (current)

[ZRX61]

[Stowelly]

this is red but is 243. is it ok to use?

thanks

https://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_199465_langId_-1_categoryId_165691

[neil.]

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