G'day Fellas.
For a long while she has been leaking from the lowest point of the primary but only when hot. On inspection the previous owner must have either broke off the screw or stripped the thread. The hole was drilled off square in both the inner and outer cover. I filled the holes with JB Weld and drilled & tapped square. It still leaks.
My question is which is the best gasket & sealer to use?
I also assume there is supposed to be a locating dowel in the inner but there isn't a corresponding hole in the outer. It must be an after market. Your thoughts.






Cheers

 

Helicoil or timesert the hole if you have enough metal to tap a larger hole for the thread insert. That should give you a good solid starting point. I have always had good luck with the foamette style gasket but before installing the foamette style gasket, make sure the "wrong holes" are filled with JB weld and sanded flat/flush with the gasket surface.

Don't know what to tell you about the hole for the dowel other than it's a good idea to have the locating dowel.

 

+1 on the Helicoil/thread repair

 

JB Weld is highly overrated as a repair and sealant.Has no strength. I use black Permatex gasket maker for any leaks. Petroleum, ,gas , and high heat resistant. Never let's you down. Ken

 

G'day Fellas.
Thanks for the reply's.
YD- Not enough room for a "timesert", maybe just enough for a helicoil.
As you can see by pic #4 it looks like there should be a dowel but the hole is very dis formed. As the position of the dowel is critical it will take a bit of calculation (and luck) to get it right. Certainly looks lie an "after market" cover.
SD- As the owner off two 1950's BSA's I'm no stranger to helicoils or oil leaks LOL
evot- yes I know JBW isn't as strong as the parent metal. I was just trying to fill the gaps. Mightn't look good in the pics but the repairs are level with the mating surfaces.
I've just ordered a new gasket https://www.ebay.com.au/itm/174232336549 plus a bit of

JB Weld 31314 Hi-Temp Red Silicone Gasket Maker & Sealant

. Hope it holds for next months 5 day 2200 mile ride.
Thanks again.
Musky

 

From the looks of the pictures, that inner primary was monkeyed with. Looks like someone did some filing on it and who knows what else. It's going to be spendy but I would replace both the inner and outer primarys. Do it right and do it once then you won't have to worry with leaks. If all the oil leaks out, the primary chain will get hot as hell. Then it will start slapping the top of the chain case. Eventually, the slider on the tensioner will wear down and catch the chain. The chain then will pretty much be a grenade in the chaincase.

Do some poking around and find some used OEM parts. There was a guy in St. Louis who used to sell used HD parts. He had a warehouse full. I wouldn't buy anything aftermarket. The covers are likely to be warped.

carl

 

Muskrat21, I have had good luck just filling holes, gaps or dings in gasket surfaces with JB weld also. Especially if surrounded by the parent metal. Surface just needs to be clean and dry, maybe rough it up for better adhesion of the JB weld. Can use painters tape as a dam or wall to help hold the jb weld so you can build up the area if needed.

Good choice on the gasket but 70.00 ?? Wow...

Don't use any type of sealant or dressing on that new gasket or you will ruin it. If you check all of the gasket surfaces to make sure it is smooth and you took care of any defects, you should be good. i agree that cover is not the best but what else can you do at this point. Parts are hard to come by and pricey right now. Not sure why. Ever since covid things have gone nuts.

Lastly, you could file or grind down a spare dowel so it is just proud of the inner primary gasket surface, then color the area of the outer primary gasket surface with a sharpee or marking pen (machinists blue, dykem, layout blue etc) and carefully install the outer primary without the gasket using 4 or 5 bolts. Even better, use 3 or 4 studs (cut heads off some bolts) so you can just slide the cover on in the proper location. The slightly proud dowel will mark the layout blue so you can determine exactly where to drill the hole in the outer for the dowel.

If your modified dowel is hard to remove, use a spiral style easy out to grab it and pull it off.

Good luck with the project and let us know how it works out.

EDIT: one more thing, put a small flashlight (torch is what I think you aussies call it) inside the primary, put the primary cover on without the gasket, snug the bolts down. Then turn off the shop lights and look around the entire gasket surfaces of the outer primary for light shining thru any larger gaps or nicks. Reposition light and repeat. This will help you find any larger defects in the gasket surfaces that may be the source of your leak. Sounds crazy but it works.

 

Yankee Dog said:
"Even better, use 3 or 4 studs (cut heads off some bolts) so you can just slide the cover on in the proper location."
That's what I made to keep everything properly located. Put'em in place, slip the gasket over them, then the outer primary cover. Pull the "Studs" after getting the rest of the primary bolts started.

 

G'day Fellas.
Thanks again for your replies.
Carl- I do intend to one day replace both inner and outer covers but not until she needs major surgery (only got 30,000Kms on her). On the last 1000km ride she only leaked about a cup of oil.
YD- That's AU $ = about 40 greenbacks. Your method of doing the dowel is exactly the way I thought of (just made two dowels for the 51 BSA). Good idea about the torch inside the case. I made the last gasket with 0.032" gasket paper and used Permatex Aviation #3 non hardening. On removal it looked like it was getting full and even compression. The only spot it leaks is from that pesky bottom screw. The gasket is over a week away so time to ponder.
guido- I'll be using that method.
Cheers

 

Muskrat,
I’m wondering if that leak might be working out around that bottom screw. Have you tried putting silicone on the screw itself before running it in the hole..??
That non-hardening aviation sealant is good stuff. That might work as well, maybe better.
Just a thought.