Gearbox drain hole

[bikerbob]

Swinging arm gearbox. The treads in the drain hole are stripped Iam looking for a fix that does not include removing the gearbox, have tried using PTFE tape on the bolt but no good someone must have had this problem before so is there a solution without removing the gearbox, Thanks

[muskrat]

G'day Bob.
Run a tap the next size up through the hole and use a bigger bolt. Put grease in the flutes of the tap to catch the swarf.
Cheers

[bikerbob]

Well Musky that is what I have had to do but it is by know means an easy job. First of al you need the bike up on a bike lft I doubt if you could do this wth the bike on the ground.  You also need to remove both the outer and inner gear box cases this is essential as you need to remove  large gear on the end of the latyshaft. This gear is directly above the drain hole and only has about 3mm clearance from the inside of the case. I needed to open the hole up to 8.5mm to tap out 10mm if you tried to drill out without removing that gear the tip of the drill would hit it before you could get the drill through not to mention the 10mm tap.  I did not use a drilling machine as there is not much room the stand gets in the way as the hole is at an angle. I ground a hexagon on the end of the 8.5mm drill and used a suitable socket with a ratchet  also had to put a pointier tip on the drill to get it started.  What is also important is the new 10mm bolt has to be no longer than 12mm because even with a flat washer and fibre washer it just clears that layshaft gear. All I have to do now is make some new gaskets and put it all back together that will have to wait till the weekend.

[Black Sheep]

For a proper bodge? Cut a strip from a coke can, insert it into the drain hole as a crude liner, screw the bolt back in. Ah, back to the old ways...

[muskrat]

G'day Bob.
Sorry I'd forgotten about the gear above the hole. Good you got it done.
Bl@@dy drain plug holes. Last week I stripped the sump plug on the plunger. Tapped out the hole to 1/2" whit. Skimmed the head down off a bolt to 1/8" thick then drilled and tapped it for an 8mm bolt.
Cheers