A thread about a thread

[brxpb]

My l.h. Spark plug has become compromised, has anyone managed to do a repair with the head still on the bike? I've done a sump plug retap in situ plenty of grease and whatnot, can I do something similar in this case?
Any advice on the best type of repair kit, I like the look of the solid threaded inserts but is there enough space between the plug hole and the valve seats in the combustion chamber (all standard size, but new seats fitted previously).

Paul.

 

[Andy_B]

My l.h. Spark plug has become compromised, has anyone managed to do a repair with the head still on the bike? I've done a sump plug retap in situ plenty of grease and whatnot, can I do something similar in this case?
Any advice on the best type of repair kit, I like the look of the solid threaded inserts but is there enough space between the plug hole and the valve seats in the combustion chamber (all standard size, but new seats fitted previously).

Paul.

If it's only light damage then sometimes you can get away with just running a standard tap down there to clean the threads but use cutting paste on the tap to catch any crap. Do it in steps so you're always bringing out any debris and you'd be ok.

If it needs inserting I'd remove the head and do it properly. It's not a massive job to remove the head and getting even small bits of swarf jammed between the bore and the rings is going to make a serious mess of things. I don't know if one of those solid insets will fit but that'd be a much bigger job needing the head to go to a machine shop to be repaired.

 

[BrianK]

Depending on how bad the threads are, you may be able to use a "backtap" (google it) to repair them in situ. Worked for me. Pretty amazing, really, IF it works for you. Mine was more of a cross-threading issue . It's worth looking into.

 

[kerinorton]

Its not that hard to do, you just have to be accurate. First make sure the cylinder is at TDC on compression stroke. Use plenty of grease to catch the swarf when you tap out for the new "helicoil" or "recoil". Make sure the new "helicoil" is long enough that the plug threads don't go past, and short enough to not stick into the head. Screw in new "helicoil". Use narrow nosed pliers to break of the tang. Get an air gun and blast the cylinder till you are sure there is no swarf inside cylinder. Refit plug and ride. Have fun. Dereck

 

[Nater_Potater]

We had another thread from some months ago where I wrote "...there's a couple of extra steps you need to take; one, turn the engine until the exhaust valve is beginning to open. Make darn sure it's not anywhere near the spark plug hole, as you'll catch it with the tap! Two, connect a continuous air supply (your air compressor) to that exhaust pipe's exit. I usually wrap the nozzle with a shop rag, then duct tape the whole mess to the back of the muffler. Once you're to this point, you should notice a fair amount of air exiting the damaged spark plug hole. Third, pack the flutes of the tap with a heavy-bodied grease (chassis grease works great). Tap, clean, and install Helicoil or Timesert as you normally would.
It's not as sure as pulling the head, but I figure that if it doesn't work, I'd have to pull the head anyway, so it's worth the gamble to me. I have done this successfully on both two- and four-stroke engines, with no dire consequences (yet). And, if you weren't before, using anti-seize on the plug threads will go a long way in avoiding this in the future. That, and a torque wrench... Redundant, I'm sure; but I have to say it.
As far as the Helicoil inserts, the only caveat I have for them is that sinking feeling when you break off the tab from the bottom of your freshly re-thrreaded hole, and you realize a magnet will not pull that same tab from out of your cylinder, due to the fact that it's stainless! Get a good grip with your best needle-nose pliers."

The entire thread can be found at sick-feeling-t16628.html and a number of poster add suggestions for other inserts; KeenSerts, in particular, are a good alternative.

btw, would it be considered narcissistic/egotistical to quote oneself? It's almost like looking in a mirror and exclaiming "There's a handsome man!" Creepy!

Nathan

 

[dennisgb]

I found a technique that works when I fixed the threads on the spark plug of my ATV. Fill the cylinder with shaving cream. Grease the tap to hold chips. Tape a hose small enough to get into the plug hole on your shop vac and vacuum the shaving cream out when your done. Any chips that would have fallen in the cylinder stick to the top of the shaving cream and get sucked out with the vacuum.

 

[brxpb]

I've got a helicoil kit on it's way, it will be with me early next week, I'll let you know how it goes!

 

[Dkt26]

Edit

 

[auldblue]

Bps

Sorry buddy just butting in , is it so badly damaged that the usual plug thread chasers haven't cured it ,cos them there helicoils are a pain.

 

[concours]

Heli-Coils are a high quality, permanent repair for damaged threads, resulting in a thread stronger than the original. They have been included in engineering designs in aluminum parts for years.
My 1974 Hardley Ableson FXEF had them in the spark plug holes in the aluminum head from new. :idea:

 

[auldblue]

Sorry ,I don't know why I said that!

 

[auldblue]

Wait, I remember now,

 

[phillyskip]

I typically install helicoils in my Brit bike heads' spark plug hole whether they need them or not. This is done the very first time I remove the head. I've never had a problem using them........Skip

 

[auldblue]

SORRY troops, NO idea why I said that. Hog tie me, then throw me in a barrel of of wild cats!

Over 250,000 helicoils used to build the space shuttle etc....

 

[auldblue]

Just had another memory flashback.

I don't know who does the helicoil shagging on my bikes but they are very good at it. Helicoils are a deal with the devil in my book ,a mans got to do 'n all that.

 

[Hobot]

Timeserts and similar are considered by some an upgrade to spiral helicoils good as they can be in our cases over plain alloy treads. Solid insets spread load over whole area not just some hi spots in the spiral windings, if that matters.

 

[auldblue]

Timeserts and similar are considered by some an upgrade to spiral helicoils good as they can be in our cases over plain alloy treads. Solid insets spread load over whole area not just some hi spots in the spiral windings, if that matters.

Thanks Steve. Got two plugs in 69 head when I did top end in 12, starts easy no smoke or rattles and no packing material round the gasket area.but still put 5/16 coil in hopper barrel 2 weeks ago.

May the tang be with you!

 

[Hobot]

Thanks Steve. Got two plugs in 69 head when I did top end in 12, starts easy no smoke or rattles and no packing material round the gasket area.but still put 5/16 coil in hopper barrel 2 weeks ago.
May the tang be with you!

Arightty a-blue love to hear such bragging rights for me to look forward too. Almost anyone can get pu-tang enough but its rather harder rarer to be getting off on a fully fettered Commando road orgasms much as ya want.

I'm thinking of rigging up a fixture to stretch head and barrel bolts to really calibrate a torque wrench value on Peel's beefed up threads.

 

[Adrian1]

I found a technique that works when I fixed the threads on the spark plug of my ATV. Fill the cylinder with shaving cream. Grease the tap to hold chips. Tape a hose small enough to get into the plug hole on your shop vac and vacuum the shaving cream out when your done. Any chips that would have fallen in the cylinder stick to the top of the shaving cream and get sucked out with the vacuum.

That's clever! :idea:

 

[Bernhard]

I found a technique that works when I fixed the threads on the spark plug of my ATV. Fill the cylinder with shaving cream. Grease the tap to hold chips. Tape a hose small enough to get into the plug hole on your shop vac and vacuum the shaving cream out when your done. Any chips that would have fallen in the cylinder stick to the top of the shaving cream and get sucked out with the vacuum.

That's clever! :idea:

And how do you explain to your wife/mother girlfriend/other the white or blue cream in the vacuum cleaner bag :?: :shock: :roll: :lol: