A forum for owners of Yamaha TTR250 trail and enduro bikes!

I am not sure why but the bottom of the three oil filter cover bolts seems susceptible to stripping the thread. 

Unfortunately this has just happened to my project TTR as I was changing the oil and filter. Disappointing as I was using a torque wrench but not unexpected as the bolt came out "funny" - not sure how to explain but it didn't undo as per normal!

This is how I did the repair.

There is quite a lot of preparation to do before removing the clutch cover. 

Remove header pipe, kickstart, rear brake pedal, and loosen the engine guard and the footrest mounting bolts so that the footrest can be swung down out the way. This is what it looks like at this stage.

Remove the oil feed banjo bolt and copper washers from the top of the cover and then, working in a criss cross fashion, loosen and then remove the Allen-headed bolts. There are quite a few different sizes so, to prevent muddling them up, I punch some holes in a piece of cardboard and store them in that. 

The inside of my cover looks fine and the gasket remained intact.

The repair will involve drilling out the damaged thread, tapping the resulting hole and then screwing in an insert (M6 x 1.0) that will take the 6mm bolt. I used a Recoil kit but other kits are available.

I drilled out the damaged thread from the outside of the casing to help keep the hole in line with the bolt hole.

Strangely the tap wouldn't fit in the hole so I had to cut the thread from the inside of the cover.

I then used the special tool provided in the kit to wind the insert into place.

I wound the insert in until it was flush with the inside boss. The pic below shows what I mean. Note the insert's "tang" is still present.

I then used the punch from the kit to knock off the tang working from the outside of the cover.

This is what the tang looks like. Make sure you don't lose it as it could cause a bit of damage if it got into an oilway.

This is what the fitted insert looks like from the inside of the cover.

All that remained then was to refit everything in reverse order making sure that all the Allen bolts were carefully torqued up to 10Nm. I annealed the copper washers on the oil union banjo bolt before fitting.

The new insert will be stronger than the original thread in the casing so should easily outlast the engine.

Job done!

Brian