Time Sert for spark plug hole?

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It's just a matter of time before my plugs strip - I can feel it getting worse each time I reinstall plugs. So I'm thinking ahead to thread repair options, which as I understand it are basically HeliCoil or Time Sert.

Anybody have any experience with this? In particular:

- Are Time Serts superior to HeliCoils?
- What size do I use for spark plug holes (if it matters, this is for a 1973 850 Mk I)?
- Time Sert says you can install their product without removing the head - great news if it's true, but I'm a little leery about metal shavings getting into my combustion chamber. Views?

Thanks as always, folks - BrianK
 
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- Are Time Serts superior to HeliCoils? YES
- What size do I use for spark plug holes (if it matters, this is for a 1973 850 Mk I)? 14mm Dia 3/4" long
- Time Sert says you can install their product without removing the head - great news if it's true, but I'm a little leery about metal shavings getting into my combustion chamber. Views? Remove the head
 
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Brian,

Helicoil makes a kit that has been designed specifically to restore spark plug threads. The kit you need is called "Sav-A-Thread" part number 5334-14. I have used this kit with great success. You don't need to remove the head if you're careful and use grease on the tap to catch the shavings.

Give it a try; I think you'll be very pleased with the results.
 
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The way I was shown, was to turn the motor till the exhaust valve was open, remove the exhaust pipe, Fit an adapted vacuum hose , grease the tap and turn on the vacuum.
 
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How 'bout this: Put that hose up the exhaust pipe, turn it on "blow," open the exhaust valve, and use it that way?

Anyway, I ordered one of those back-taps, as an initial try. If it doesn't work, I'm onto time serts. Heck, it's all good training for the next time. And you guys know my motto:

"Tighten it 'til it strips, then back off a quarter turn...."

Thanks all - BrianK
 
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I've never used a Time Sert, but they look superior to a Helicoil. Let me know how you make out. Also, would appreciate where you can buy the things with out hocking your bike and first-born. I've not found anywhere that the Time Serts kit isn't at least ten times more expensive than a Helicoil kit.

I do know the next Norton engine I build will have a thread insert in every tapped aluminum hole. I don't care how careful you are, repeated use of the aluminum threads WILL fail. My buddy put aftermarket pipes on his Harley. After he did, the front cylinder was hotter than Hadies. Eventually the bike quit running. Of course, he thought it was the pipes and/or a carb issue. After much trouble shooting and a new carb he found the rocker box on the front cylinder was loose. Valves not opening. Stripped threads. Guess it's not only the Norton cheesy aluminum that have problems.
 
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I've never fitted a helicoil nor a time sert to a Norton, but I recently removed #4 spark plug from my son's 924 and a long spring-like wire came with it. Turned out to be a helicoil. I replaced it with a time sert.

I've always used anti-seize on spark plugs, bolts and splines, especially those that thread into aluminum. Brush it thinly into the threads with a toothbrush. It seems to help a lot, if not eliminate, thread stripping.

Al
 
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I'd think that if one were using a vacuum cleaner to suck out filings it would be a really good idea to make sure there was no trace of gasoline there. Drain the carb bowls and make sure the intake valve stays closed.

Al
 
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thread inserts

Better than the helicoil is the Save-a-Thread. Solid steel insert which is swaged into place with loctite and an expanding tool. You can install them with the head on or off. I do them prophylactically during a rebuild....My Bonneville has them installed and am very happy with them for the last twelve years. Seems to be a lifetime fix.
 
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"Save-a-Thread" sounds familiar. This product is made by Helicoil specifically to repair damaged spark plug threads.
 
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Update: Well, I opted to try the quick and easy alternative, the "Back-Tap." $45 delivered, and no head removal required. Figured it was worth a try.

This thing works a treat!!! It definitely pays to heed the instructions about going over the threads multiple times, with the mandrel screwed in further (and so the circumference of the tool and its cutting threads) each time. I made about 7 or 8 passes. Greasing the tool helps cuttings to stick so you can wipe them off after each pass.

Threads look good, plug went in smooth and easy. There may still be a Time Sert in my future at some point (I think if I had the head off for other work, it'd be cheap and prudent insurance) but this cured the immediate problem.

- BrianK
 
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BTW, I totally misdescribed the problem I had and was able to cure with this tool - I did not have a stripping problem on the plug hole (I was thinking, I guess, of that problem on the caliper to fork leg - which will require traditional drilling/retapping no doubt), what I had was pure cross-threading.

The back-tap was fantastic for curing the problem I had - cross-threading. It wouldn't do anything for stripped threads. So, apologies if I confused anyone (besides myself). - BrianK
 
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