Timing hole plug finally blew out

Bottom End (crankcases and crankshaft)
Post Reply
King
Inactive member
Member
Posts: 400
Joined: Mon Jan 27, 2003 1:25 pm
Bikes: *
Been thanked: 4 times

Timing hole plug finally blew out

#1

Post by King »

Well my timing hole plug finally blew out. The threads were iffy when I got the bike 30 odd years ago and slowly got worse. I managed to get by wrapping the plug with Teflon but last week it blew out and that was that. I know the proper fix is to get the over-sized plug/tap and install it but most folks I have talked to said that was chancing getting filings in the engine --not good. I'll save that for the next bottom end job.

So I got an expandable rubber plug at the auto parts place. Problem was the smallest diameter they had was 3/4" and the hole is 5/8". But i was able to turn down the end that goes into the motor on the poor man lathe (3/8" drill) and shave the rubber of the plug to fit. I slid it in until it touched the fly wheel then tightened it up pulling the bolt base away from the wheel and expanding the plug to fit the hole.

It works, and yes it is ugly, but I'd rather be Riding Ugly than Sitting Pretty.

This solution is not new with me but I thought I would mention it in case anyone has a similiar problem.

King
caschnd1
Senior Member
Posts: 614
Joined: Tue Jul 13, 2004 7:04 pm
Bikes: 1949 FL Chopper
Has thanked: 5 times
Been thanked: 37 times

Re: Timing hole plug

#2

Post by caschnd1 »

King,

Thanks for posting that info. I'm in exactly the same situation that you are. When it happened to me, I cleaned up the hole and the plug real well. I then ran a bead of high-temp (copper colored) RTV Silicon around the timing plug and "threaded" it into the hole. I let it sit for a couple days and cure before starting it up. It's been completely sound for 8 months now. Not even a wisp of oil. I was thinking about using your trick with the expandable plug if this starts giving me trouble before my next bottom end work. Glad to know it works.

In my case I can't use the oversized tap. The last time I removed the timing plug, in addition to the threads coming out with it, a chunk of the flat shoulder that the plug seals against came with them. I think to properly fix my timing hole it will have to be welded back up, machined flat, then drilled and tapped.

-Craig
FlatHeadSix
Senior Member
Posts: 2677
Joined: Sat May 29, 2004 8:21 am
Bikes: '31 VL, '34 VD, '45 WLA, '47 WL, '49 FL, '51 WL, '58 ST (Hummer), '71 GE (Servi)
Location: Lonoke, Arkansas
Has thanked: 5 times
Been thanked: 49 times

Re: Timing hole plug

#3

Post by FlatHeadSix »

the plug on my '49 FL did the same thing and I also did not want to risk aluminum filings in the bottom end after an on-board re-tap. Here's what I did and it has actually held up well.

I started with a brand new plug and wrapped ONE layer of teflon tape around it, pulled it real tight so it bottomed in the threads. Then I cleaned up the old stripped out hole, degreased it with a little laquer thinner and mixed up some JB Weld. I put a thin layer of JB around the inside of the hole and carefully inserted the plug. I let it cure overnight before riding the bike.

Plug stayed in, never leaked and looks completely stock. Here's the good part, after about a year I put some new points in and decided to pull the plug to time it, I figured I could always JB it back in again. When I turned the plug out it was just like new, the teflon tape and JB stayed in the hole and looked as good as new threads. I timed the bike and threaded the plug right back in, its still there!

worked for me
King
Inactive member
Member
Posts: 400
Joined: Mon Jan 27, 2003 1:25 pm
Bikes: *
Been thanked: 4 times

Re: Timing hole plug

#4

Post by King »

Thanks guys. It's good to know that there are more ways than one to skin that cat.

King
PanPal
Senior Member
Posts: 1500
Joined: Wed May 09, 2001 11:02 pm
Bikes: 50 EL chopper
44 U that looks like a 37.
60 FLH (Sold)
59 FLH (Sold)
58 FL (Sold)
08 CVO Road King
Location: Maryland
Has thanked: 241 times
Been thanked: 137 times

Re: Timing hole plug

#5

Post by PanPal »

One of my pan motors may have the same issue. What the guy before me did was installed a pipe plug. I have not checked the threads per inch comparison between the original and the plug but it isn't leaking, so I'm not fooling with it now.

Loctite offered a thread repair compound as I recall also.
caschnd1
Senior Member
Posts: 614
Joined: Tue Jul 13, 2004 7:04 pm
Bikes: 1949 FL Chopper
Has thanked: 5 times
Been thanked: 37 times

Re: Timing hole plug

#6

Post by caschnd1 »

PanPal,

I've seen the pipe plug trick too. One word of caution... pipe plugs are tapered. The more you tighten the more pressure they put on the hole. The cases are pretty delicate (compared to a typical pipe fitting). You don't want to end up cracking a case.

-Craig
PanPal
Senior Member
Posts: 1500
Joined: Wed May 09, 2001 11:02 pm
Bikes: 50 EL chopper
44 U that looks like a 37.
60 FLH (Sold)
59 FLH (Sold)
58 FL (Sold)
08 CVO Road King
Location: Maryland
Has thanked: 241 times
Been thanked: 137 times

Re: Timing hole plug

#7

Post by PanPal »

Good point! I would also watch that the hole does not enlarge slightly with each inspection and eventually interfere with your flywheels.
Post Reply

Return to “Bottom End / Crankcases / Flywheels”