I took my left crank cover off my CRF450 for the first time, and it looks like the PO left me with two stripped bolts. Well, three actually, if you count my boo-boo the first time I changed the oil and stripped the filter cover bolt hole. All three bolts are M6x1.0, and the crank cover bolts (obviously) screw into the case, and the oil filter bolt screws into the case cover, which is magnesium.


Is this the Helicoil product I need? Will it work in both the magnesium and aluminum?


Yep.  Just use red Loctite when threading in the insert, let it dry for a couple hours before torquing your bolts.  

No need for Loctite on a Helicoil.  The spring tension holds them in place.  If you do not Loctite them and they ever become damaged they are easily removed with a pick and pair of pliers.  A new one can simply be installed in its place.  There are a plethora of other inserts out there but Heilcoil and Timesert require the smallest hole size which is a big plus in the thin castings seen in dirt bikes and they are all stronger than just a bolt in aluminum.

A little trick I learned from an old mechanic buddy of mine. When you drill the hole out for the Helicoil, put some grease on the drill bit and the shavings will stick to the bit. You will still need to flush the case but there won't be near as much junk in there.

Thanks fellas.


I was just reading a how-to and it said be sure to use the EXACT size drill bit required. Using the chart in the following link, it looks like I need a #26 for the aluminum case and a number #25 for the magnesium cover, correct? I'm pretty sure that's right...just want to make sure I am reading it correctly. http://www.noblefix.com/helicoil/HeliCoil-Drill-Chart.html

You're looking at aerospace stuff.  You don't need to be that specific.  The Helicoil package will have a recommended drill size on it.  Just use that for all materials, whatever 6.3mm is.  Helicoils aren't that specific because they come with a custom tap that fully forms the thread.  If you use a Keensert they use a standard tap which significantly cuts down on the cost (most of the cost of the Helicoil kit is the tap) but you have to drill the hole oversized because the standard tap does not fully form the shape of the hole required as Keenserts require a flat peak on the female thread..

Edited by 1987CR250R

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now