Beta Riders Club Discussion Forum

I recently found a snapped off engine bolt when I pulled the skid plate for something else.

The bolt cost £16 from Beta UK so I decided to measure the thread pitch and length for next time so that I can buy a cheaper alternative.

For some reason, it is thin in the middle, but the thickest part is m10 in diameter.

Using a leaf thread pitch gauge, I measured the thread pitch, which is 1.25mm

I also measured the length at 12cm

IMG_20211010_122827_914 by a a, on Flickr

I don't see why a generic bolt matching those measurements wouldn't fit and it would probably do a better job as it won't have a thin part in the middle.

I believe the reason for the smaller diameter in the middle is due to dissimilar metals so the bolt does not seize to the aluminum of the engine.

mtdirtbag wrote:I believe the reason for the smaller diameter in the middle is due to dissimilar metals so the bolt does not seize to the aluminum of the engine.

Wow, I never thought of that! Surely some copper grease would do the job just as well, though!? As long as grease provides a barrier between the two metals.

One issue is that those bolts normally are a high tensile strength, say 10.9 grade for example, and those are normally only available in pavonated black finish, that in a dirt bike starts to rust soon and is not pretty. I find it hard to impossible to find higher grade bolts in a good finish.

Another thing with most motorcycle bolts is that they have smaller hex heads than the industry standard, for example an motorcycle M8 bolt can be a 10mm hex head, but the industry standard available bolts are using 13mm hex heads...

Regards.

How often are you expecting this to happen? Especially for only 16 squid for the proper bolt.

Make sure they are all tight and it is unlikely to happen again.