Top End Noob

Take it to a professional...this can be done with the engine together. Nothing with repairs is about luck it's good tools and the skills to use them. If you don't have the skills then it's all luck with poor odds.....If you have the skills go for it!



Graham not meaning to pick on you but those actually do work well, I prefer helicoil inserts but they are much harder to install (higher level of skills needed). If you had plugs melting onto an insert you've got other problems...more likely corrosion stuck them together use an antiseize compound on plug threads (SPARINGLY)

Sparkplugs require some cooling; inserts and Helicoils do not transfer heat well to an aluminum air-cooled (high temp) head. They are fine for other bolts and studs but not sparkplugs. Inserts can be used on liquid cooled heads with little trouble. You will never buy a remanufactured head with a insert or Helicoil in any sparkplug hole. The professional way would be to weld the sparkplug hole up and re-drill then tap.

If the head and the repair is short term than do it. But I doubt you will get 50000 miles out of an air-cooled head with a sparkplug insert. If your going to do a top end then why waist money on a good valve job for a jacked-up head that you could get used for the price of the rings and/or gaskets? Why be cheap and do it half a$$. But you get what you pay for.

BTW, I am a professional motorcycle mechanic and shabby work does not leave my shop like using inserts on sparkplugs.

Take it to a professional...this can be done with the engine together. Nothing with repairs is about luck it's good tools and the skills to use them. If you don't have the skills then it's all luck with poor odds.....If you have the skills go for it!



Graham not meaning to pick on you but those actually do work well, I prefer helicoil inserts but they are much harder to install (higher level of skills needed). If you had plugs melting onto an insert you've got other problems...more likely corrosion stuck them together use an antiseize compound on plug threads (SPARINGLY)

I have to agree, I've never had a problem using helicoil even with an LS7 engine. You shouldnt have a problem with metal at all and like was said using grease on the tap will catch most of it and using compressed air helps to blow most of it out.

[headsbikesmopars]

Mr. Cinders,
I believe that some material from the head has already fallen into the cylinder and scored / taken out the rings in #3. That expains the oil in #3. Yes pull it down but don't buy anything untill you KNOW. Freshen it up with new rings, don't forget to hone first,.. AFTER you check the tapper in the bores. Good idea to pick up another head it will cost as much to have the plug threads repaired by a pro. You will need to freshen the seats and lap the valves anyway even with the 'old' head so no additional real expense there. Have the deck cleaned up with a .005 clean-up mill. Good luck and keep us informed as to your progress..we are all still learning.

Terry

[Nessism]

Thanks for the info on the rust/carbon.

As to the damage on my head, it does not need rewelding. The retapping would be merely chasing the threads on the insert hole and installing (properly) a new insert. I have the kit for that already. Indeed, the insert that is stuck on the old plug and that threads into the cylinder now matches the insert in the Sav-A-Thread kit. So I think that repair could be pretty straight forward.

I may still spring for a "new" head in case I screw up the plug hole job.

Why not just install the new insert now? A few aluminum chips in the cylinder won't hurt anything, plus if you grease up the tap before chasing, there shouldn't be much if any chips at all.

Never had any good luck fixxing sparkplug threads, waist of time. If your going to just replace the rings and not bore it then get one size over bore rings and gap the rings to spec (grind end of the rings to get the right end gap). Always hone cylinders when you rering. Have the valves and seats cut with new guides done by a pro.
If you shortcut on the top end now, you could get a chance to redo it agian soon.

Take it to a professional...this can be done with the engine together. Nothing with repairs is about luck it's good tools and the skills to use them. If you don't have the skills then it's all luck with poor odds.....If you have the skills go for it!

Steel plug inserts and an air cooled head don't work well together. The threads on the plug tend to melt to the insert (plug overheating). Been there and done that. You will need a new insert everytime you change the plug.

Graham not meaning to pick on you but those actually do work well, I prefer helicoil inserts but they are much harder to install (higher level of skills needed). If you had plugs melting onto an insert you've got other problems...more likely corrosion stuck them together use an antiseize compound on plug threads (SPARINGLY)

Thanks for the info on the rust/carbon.

As to the damage on my head, it does not need rewelding. The retapping would be merely chasing the threads on the insert hole and installing (properly) a new insert. I have the kit for that already. Indeed, the insert that is stuck on the old plug and that threads into the cylinder now matches the insert in the Sav-A-Thread kit. So I think that repair could be pretty straight forward.

I may still spring for a "new" head in case I screw up the plug hole job.

Steel plug inserts and an air cooled head don't work well together. The threads on the plug tend to melt to the insert (plug overheating). Been there and done that. You will need a new insert everytime you change the plug.

The dark carbon is normal and will wire brush or blast right off

The rusty stuff is no problem

Where it becomes a problem is at the valve seats - if they're pitted, machining is required. You can't see this in the photos

I would ask the sellers if all the bolt holes are clear, broken fins, plug holes intact and go for it.

You couldn't get your damaged head rewelded and retapped for the $100 cost of the "new" head

Thanks for the info on the rust/carbon.

As to the damage on my head, it does not need rewelding. The retapping would be merely chasing the threads on the insert hole and installing (properly) a new insert. I have the kit for that already. Indeed, the insert that is stuck on the old plug and that threads into the cylinder now matches the insert in the Sav-A-Thread kit. So I think that repair could be pretty straight forward.

I may still spring for a "new" head in case I screw up the plug hole job.

[Big T]

The dark carbon is normal and will wire brush or blast right off

The rusty stuff is no problem

Where it becomes a problem is at the valve seats - if they're pitted, machining is required. You can't see this in the photos

I would ask the sellers if all the bolt holes are clear, broken fins, plug holes intact and go for it.

You couldn't get your damaged head rewelded and retapped for the $100 cost of the "new" head

You might consider getting a used head instead of fixing that one. They are dirt cheap, why take a chance with a bogus repair?

Define "dirt cheap." eBay shows a bunch of cylinder heads with prices (including the stealth premium for "shipping") from $75-100.

That might be worthwhile, but help me read the tea leaves on condition.

For instance, the photos of the bottoms (top of the chamber) sometimes show rust, others show black carbon. Which is easier to deal with for clean-up?

Compare this:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=370458320619&viewitem=&sspagename=STRK%3AMESINDXX%3AIT

to this:

http://cgi.ebay.com/ebaymotors/HEAD-CYLINDER-NO-SHIMS-GS750-SUZUKI-GS-750-1978-_W0QQcmdZViewItemQQhashZitem19b88af59aQQitemZ110470296986QQptZMotorcyclesQ5fPartsQ5fAccessories

and this:

http://cgi.ebay.com/ebaymotors/77-SUZUKI-GS750-GS-750-ENGINE-CYLINDER-HEAD-_W0QQcmdZViewItemQQhashZitem5d29bc9be5QQitemZ400132185061QQptZMotorcyclesQ5fPartsQ5fAccessories

Any clues to educate this consumer?

[Big T]

Replacing the cam chain guides is a must if you're tearing down the top end. They're old, they're plastic, they keep your valve train intact

Also, service the cam chain tensioner per Brians site

Are we up to $1,000 yet?

As for what needs replacing, follow Nessism's mantra

And yeah, a new head would be cheaper and faster. You can get it blasted, replace the valve stem seals and check the guides and valve sealing. Plus, you won't have any snapped off exhaust bolts to get machined out.

Never had any good luck fixxing sparkplug threads, waist of time. If your going to just replace the rings and not bore it then get one size over bore rings and gap the rings to spec (grind end of the rings to get the right end gap). Always hone cylinders when you rering. Have the valves and seats cut with new guides done by a pro.
If you shortcut on the top end now, you could get a chance to redo it agian soon.

You might consider getting a used head instead of fixing that one. They are dirt cheap, why take a chance with a bogus repair?

Thought about it. Might snap one up on eBay to avoid the repair (or if the repair goes pear-shaped).

[tkent02]

You might consider getting a used head instead of fixing that one. They are dirt cheap, why take a chance with a bogus repair?

Don't forget valve stem seals and a big bucket o cash. Have you priced oem valves and components yet?

Actually, valve stem seals (i.e., the ones that don't survive valve removal) are what I meant for the must-have list.

Don't forget valve stem seals and a big bucket o cash. Have you priced oem valves and components yet?