Stripped spark plug hole
Retired Super Moderator - At large E=MC2
Joined: Feb 2011
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From: Tulsa,OK
Start by threading the special Helicoil tap into the remaining threads in the head. This is to ensure the new threads are concentric and parallel with the originals. Continue threading the tap in to cut the new, oversize threads. To avoid getting aluminum chips in the cylinder when retapping the threads, you should coat the tap with grease. The chips will stick to the grease and come back out with the tap. Back out the chip-laden tap, and clean up any remaining chips.
I've also filled the cylinder (before tapping the hole) with oil-soaked clothesline to catch any chips -- but that was in a racing engine with a squish band only a few thousandths of an inch deep. Street engines with a more normal compression ratio should be fine if you are careful, and blow the chips out with compressed air. Mostly, you don't want any chips to find their way out the exhaust port and wind up in the catalytic converter.
Read more: How to Repair Stripped Spark Plug Threads: Auto Clinic - Popular Mechanics
I've also filled the cylinder (before tapping the hole) with oil-soaked clothesline to catch any chips -- but that was in a racing engine with a squish band only a few thousandths of an inch deep. Street engines with a more normal compression ratio should be fine if you are careful, and blow the chips out with compressed air. Mostly, you don't want any chips to find their way out the exhaust port and wind up in the catalytic converter.
Read more: How to Repair Stripped Spark Plug Threads: Auto Clinic - Popular Mechanics
Registered Users
Joined: Apr 2016
Posts: 16
Likes: 3
2005 600f41 syripped spark plug.
Has anyone ever had success putting a time sert in a stripped spark plug on a 2005 CBR600F4I.
I have my head off and the clearance between the plug and the 4 valves seems very little. Looking at the time inserts i believe i need approx 2mm on either side of the plug hole. The OD of the time sert is 14mm and the OD of the spark plug is 10mm.
Is this impossible or has some actually installed a time sert successfully.
What are the other options. A helicoil doesn't look as strong for long term service.
Should i just find nf a used head.
I have my head off and the clearance between the plug and the 4 valves seems very little. Looking at the time inserts i believe i need approx 2mm on either side of the plug hole. The OD of the time sert is 14mm and the OD of the spark plug is 10mm.
Is this impossible or has some actually installed a time sert successfully.
What are the other options. A helicoil doesn't look as strong for long term service.
Should i just find nf a used head.
Junior Member
Joined: Mar 2021
Posts: 1
Likes: 0
Have you considered taking it to the service? Westminster Motors is pretty good, maybe they could help?
Registered Users
Joined: Apr 2016
Posts: 16
Likes: 3
Stripped plug.
Have you considered taking it to the service? Westminster Motors is pretty good, maybe they could help?
Time sert never knew this to be a problem as no one mentioned this issue before.
They sent me an extension handle for the tap and cut 6mm off of it so the tap could cut new threads right to the bottom of the head and then the insert would thread in witb 8 threads to grab onto.
They're guessing repairs in the past were done without removing the head and no one was awsre that the tap was not cutting new threads all the way through. So when i was talking with the guys making the tools they said they are already cutting all extension handles 6mm shorter to eliminate this issue.
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