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[Daiwiskers]

Sorry 14mm on drain plug

[stinkwheel]

So not this drain plug then?
https://accessories.hitchcocksmotorcycl ... ges%2F4048

My bad. I found a second, larger drain plug on a different bit of the parts diagram.

https://accessories.hitchcocksmotorcycl ... ges%2F4054

M14 repair plugs:
https://www.ebay.co.uk/itm/OIL-SUMP-GEA ... SwlupdEMJb

Definately M13? because most motorcycle drain plugs are M12...

[PeteF]

If you have a friend with a lathe you could get something made up.
You can always go smaller of course with a suitable adapter. Just take longer to drain the oil.
If there are any threads left at all you might bond the adapter in.
If the adapter was made with a hex on you could then take the drain plug out without stressing the bonded in adapter.
Just an idea.

[JohnStones]

Thanks for all the advise.
I removed spark plug & heyho its same dia as sump plug - 14mm metric fine 1.25
I have ordered 14mm taper/plug tap & bought new sump plug & Loctite 243
If this holds I can use smaller drain at front of engine for future oil changes
If this does not work Hitchcocks sell sump repair kit - Tap/Helicoil .

[PeteF]

If the plug won't tighten the threads are mostly gone. Running a tap down will not bring them back but MIGHT just re-form them enough to get a grip. If it does seal you'll be lucky but don't disturb it again.

[stinkwheel]

If it's a taper tap and taper plug, than might do it, depending on how oversize the taper goes.

For an iffy but holding drain plug thread you probably don't want to be repeatedly undoing, I have seem people drill and tap the centre of a sump plug for a smaller flanged bolt, loctite it into the crankcase with an agressive locking compound (green bearing fit) then use the smaller bolt as the drain.

[Boxerman]

If this holds I can use smaller drain at front of engine for future oil changes

I think the small drain is just to drain the the oil from below the crank, I don't think it will drain all the oil out.
Early engines like mine did not have the front drain plug and always left a bit of oil in the 'crankcase'.

Frank

[Rushour]

The main drain plug on the GT 535 is 14 x 1.25 which is the same as spark plug thread. there must be short reach helicoil kits around - I know our hosts do them.

[Rushour]

And just for the record - the spanner size of a bolt bears no resembelence whatsoever of the thread size .

[Rattlebattle]

If this holds I can use smaller drain at front of engine for future oil changes

I think the small drain is just to drain the the oil from below the crank, I don't think it will drain all the oil out.
Early engines like mine did not have the front drain plug and always left a bit of oil in the 'crankcase'.

Frank

I agree; you’ll need to fix it so that there is a usable drain plug.