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[mcdonaldroadcapt]

I have changed spark plugs in my bikes for 50 years and have never had this happen. Plug cross threaded coming out on rear cylinder and ruined the cylinder head. I put a Snap-on camera probe down in the spark plug hole and can see metal particles on the top of the piston. I guess I have a bill coming as I would not attempt the fix myself. With 45,000 miles on the bike, would you have them do a valve job on the rear cylinder head while it is removed? Pardon me but I hate myself today!

[MrSurly]

I would absolutely have the top end freshened up if you have to have a head pulled.


Of course, you run the risk of "while you're in there" and other work that could be justified since you have it that far down, but rings and other bits would be seen (my opinion) as optional, but if you are replacing or rebuilding one head, you should do both.

You have the option of not rebuilding it of course, you could just helicoil it and move on.

[mcdonaldroadcapt]

Thanks for reply. Will decide once they get into the project. I will go over and survey once head is off.

[Dr.D]

Use this excuse for HC pistons and cams and turn this accident into an upgrade.

[mcdonaldroadcapt]

Good point! Thanks.

[East Coast]

Use this excuse for HC pistons and cams and turn this accident into an upgrade.

Exactly!

[Ridgerunr]

Anti-seize on the plug threads is your friend.

[CVODON]

Pretty common occurance in the automotive industry these days. Plugs lasting 100,000 miles in allum head motors = thread failure when they are finally removed. So Heli-coil has become common practice, I saw a local Ford dealer do a  Expediton 5.4 recently and they put heavy grease on the bit, then on the tap and finally cleaned threads with brake cleaner and installed the insert. Then they used a homemade air driven vacuum tube inserted into cylinder to suck out the residue, inspected with snap-on camera, installed plug and, in there opinion, all was good. This same deal is possible on a bike. Not suggesting, just saying.... Complete procedure only took about 45 minutes as he could get to that cylinder easily.

[smkymtnboy]

Pretty common occurance in the automotive industry these days. Plugs lasting 100,000 miles in allum head motors = thread failure when they are finally removed. So Heli-coil has become common practice, I saw a local Ford dealer do a  Expediton 5.4 recently and they put heavy grease on the bit, then on the tap and finally cleaned threads with brake cleaner and installed the insert. Then they used a homemade air driven vacuum tube inserted into cylinder to suck out the residue, inspected with snap-on camera, installed plug and, in there opinion, all was good. This same deal is possible on a bike. Not suggesting, just saying.... Complete procedure only took about 45 minutes as he could get to that cylinder easily.

to easy not to try?! what you got to lose!?

[Twolanerider]

The inserts hold up well if done right to begin with.  Unless one is just itching to pull the heads (then the cylinders and pistons and god knows what else before the itch subsides) to do more there's really not a good reason not to repair as described above.  I keep insert kits in my supplies tool box just in case I'm screwing around in the shop of an evening after the parts store is closed.  Every size kit is missing at least a couple of inserts, and some several more, because chit always happens when you're working late.  It is so much less stressful when you can walk across the shop, grap some parts and know you're good to go.

[DanG]

Anti-seize is your friend? Tell that to the factory. I just pulled the plugs out of mine for the first time since new and had problems getting the front cylinder plug out. It came 3/4 the way out and then started binding. Put penetrating oil on and got it out, but ruined the first couple of threads. The plugs were obviously put in bone dry.

[mcdonaldroadcapt]

Yes I always use anti-seize on plugs. However, this time bad luck. I had thought about a small high vacuum hose to suck out metal shavings but I'll just have to see after the boys take a look.  Thanks to all you guys for the good input.

[chicoman]

Thread the plug in and out as you are removing it and lots of these stripping problems go away

[Afdharley]

Pretty common occurance in the automotive industry these days. Plugs lasting 100,000 miles in allum head motors = thread failure when they are finally removed. So Heli-coil has become common practice, I saw a local Ford dealer do a  Expediton 5.4 recently and they put heavy grease on the bit, then on the tap and finally cleaned threads with brake cleaner and installed the insert. Then they used a homemade air driven vacuum tube inserted into cylinder to suck out the residue, inspected with snap-on camera, installed plug and, in there opinion, all was good. This same deal is possible on a bike. Not suggesting, just saying.... Complete procedure only took about 45 minutes as he could get to that cylinder easily.

Exactly what I was going to suggest. Definitely worth a shot unless you have been talked into that big upgrade. Lol

[JKM]

If I was you I would use this opportunity to have the heads done.  The early 110s have been know to have weak valve guides.  Also the valve springs are too stiff and should be replaced with behive springs.  You could shave a little off the heads to bump up your compression while you're in there.  This should be done to optimize the cam you're using.

Now, depending on budget you could consider doing a 113" kit from GMR.  This would give you new piston and rings.  Actually I think I heard that oem 110 rings are very hard to come by and expensive so the upgrade may not be that much extra.  Before spending the money you should measure you're crank runout.  Not sense spending money on the top end if you're bottom end is not solid.

You should have a discussion with some of the builders on here like GMR and Scott at Hillside in terms of options and cost.