Helicoil loose (stripped thread)?

[Gareth Jones]

The top forward cylinder stud on my R80GS (91) is not doing up to required torque. The feeling is like when a nut or bolt is about to strip (although I thought to hell with it and turned some more, I didn't get the 'give as it stripped feeling'). The stud head also sticks out from the rocker assembly by about another 5-10mm than the rest. The Haynes manual mentions the helicoil, but doesn't give a fix. Assume my best option is to remove the head and cylinder, to retap and fit a new helicoil. Any suggestions before I rush in?

-----
Old Yakka

 

[Paul Young]

Hi Gareth,

Just one point to be aware of is that there is an oilway on the stud you mention, and this comesout at an angle relative to the face of the cylinder base. This means that, if you cut a larger bore to helicoil, the oilway moves back down the hole & away from the cylinder base. It is then blocked by the helicoil and you lose the lubrication to that front rocker post.

They way I got round this on a previous engine was to use a Timecert (better than a helicoil) and cut a channel down the threads on the stud to allow oil through from the base of the hole where the oilway is fed from. I had several studs made up with varying thread sizes at the base end, by a local engineering workshop. You are welcome to these as I no longer need them - they may also work with helicoils if you decide to use them.

Cheers for now,

-----
Paul
'00 R1150GS - "Paddy"

 

[Gareth Jones]

I have had an insert fitted this morning. I think it has blocked the hole, even though it was 'countersunk'. I intend to drill down between the thread and the crank case until I hit the feed. A bit dodge, but all I can think of at the moment.

-----
Old Yakka