CMB .67 HR Specs

[JimWalters]

I’m wondering what size the hex key sizes are for this motor. Nothing I have seems to fit in. Either to big or to small. Thanks!

 

[ALLAN YUEN]

I like my “ Bondhus” metric simple tools match to CMB size engines

 

[Buckshot]

Not sure why but my fractional hex keys fit the screws in my CMB .67/.80 motors better than my metric hex keys do. I’ve not tried to measure the screws to see if it is a metric fastener or not.

 

[John Beardslee]

It been awhile since I worked on these but if I remember the early version with cast drum housings we’re all Metric fasteners. Then when they did the billet drum housing they switched the housing fasteners to SAE but left the head bolts Metric.

 

[Danny King]

I believe some of the screws are 6/32 and use 7/64 hex.

 

[RaceMechaniX]

The 67/80 head and induction screws are 6/32 as Danny mentioned.

 

[JimWalters]

Thank you!... Yes i confirm that a 7/64" hex works... Luckily I happened to have one from my old RC Truck days....