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[johnmowcop]

Hello. Information please if you can help. I want to use a Harley magnetic drain plug on another bike (1960 650 Matchless actually). I will need to make an adaptor to the existing drain plug which is 3/8 bsp. Can anyone give me the thread details of the Harley drain plug. diameter and type of thread also length of thread.
Thank's for looking.
JohnT

[TN]

No, but can we see the Matchless?

please

[Sprintkid]

Machine original plug and insert magnet. Better than adapter

[hd-dude]

Machine original plug and insert magnet. Better than adapter

X2

[johnmowcop]

No, but can we see the Matchless?

please

OK, not sure how far I will be allowed to take this before the plug is pulled by the moderators.

The Matchless is one I am part way through rebuilding, I cannot show a photograph of that particular bike but one is here attached taken from the internet, it's the same as that but that does not have the correct silencers (mufflers) the correct ones are short megaphone type.
I have the engine stripped down for checking out, the frame and other brackets etc have now been powder coated black. The tinware, tank, (oil and fuel), mudguards (fenders?), toolbox are away at the painters (Maroon is the chosen colour).

When I got the crankcases apart the drain plug hole is partially stripped, I suspect this is by constantly having to drain the sump after standing, these bikes, and others of the same era are renowned for draining the oil-tank contents into the sump when left unused for even short time. Before starting the sump has to be drained. I guess this constant taking the drain plug out and putting back in eventually part stripped the threads in the aluminium case. The drain plug is currently held in by about three threads ( I will post two other posts with attached photographs of the crankcase so you will be able to see what I am trying to describe). The options for repair, as I see it are:
1) Fill the hole with weld and re-drill and tap to take the original plug. I don't want to do that, if you look at the other pictures you will see the hole is fairly large and pretty close to the joint faces, the heat from the weld would probably distort the faces. These bikes leak oil without me giving them an excuse by distorting the sump sealing face.
2) Drill the hole to the next practical thread size up, tap the hole and make a plug to fit. This would be a 3/4" Whitworth thread. I am considering doing this, then thread-locking the plug in place after drilling and tapping it to take a smaller sump plug, hence the question about Harley sump plugs, I think they would be ideal for that. The constant removal of the drain plug would then be steel on steel, less likely to fail.

Hope this clarifies why I asked the question.

JohnT

[johnmowcop]

Machine original plug and insert magnet. Better than adapter

Image of the crankcase showing closeness of the sump plug hole to the main sealing face

[johnmowcop]

X2

Image showing the part stripped thread in the sump plug hole.

[TN]

I get a woody when I get near a goofy footed classic British bike. 


Good luck with your project, I use to have a set of whitworth tools, and a few bikes to go along with them. I been looking.

[fastfreddy]

 Helicoil  ,  google is your friend, these work. my other name is crossfred… don't ask how I got that nick name

[mark]

Would this work?  I've seen Time-Sert mentioned on several bike forums as the best fix for a stripped drain plug.

https://www.timesert.com/html/drainplug.html

[johnmowcop]

Helicoil  ,  google is your friend, these work. my other name is crossfred… don't ask how I got that nick name

Thanks for all the comments. I am looking to use a Helicoil insert.

JohnT

[08glide]

another thought ,since you're constantly having to drain, is to put a drain plug in with a petcock on it. they're offering this for some autos. my BIL has them on 2 of his autos.

[Sprintkid]

Does that seal with the threads or seal on the face? It looks to me that it is the face. If you helicoil , take that into consideration .