How to use a "Keensert"

If you can remove the cylinder head then life is easy.

However, not all 2 stroke cylinder heads are removable. Here's an example.

----- Original Message -----
Sent: 02 Jun 2012 16:55:06 -0500
Subject: Ask_A-Tech

Enginetype: Outboardgas
motormodel: Mecury 115 4 cyl
Serialnumber: OC216*** 1989
Configured: single
boatmodel: Larson
Boatlocation: Fresh
typeofneed: Tune-up
Username: Jim
Permission: Yes
confirm_submit_form: boat
TechQuestion: Submit Question




Seems i have stripped 3 out of 4 of the spark plug holes. I used a back tap and tried to clean them up, but no good. I'm actually picking spirals of metal out of the holes. what is the better option.
1) - remove head and use a heli-coil
2) - remove and replace the head /gasket.

Either way, I'll need to know the torque for the head bolts , tightening sequence, should i use thread locker, etc, etc.



Hi Jim:
The serial number indicates that this engine has a water-jacket cover and not a cylinder head. So, removing the cover will not expose the top of the piston. However, you will need to remove the water-jacket cover to make the repair to the spark plug threads.
You will need to get a "Keensert" thread repair kit. They make a kit specifically for spark plug thread repair.
Heli-coils do not work for spark plug thread repair.
Here's a video on how "Keenserts" work.

You could remove the powerhead/crankshaft and pistons to make the repair or...
Rotate the crankshaft so that the piston is half way down before drilling and tapping. Since the cylinder top is not removable; to remove the drilling and tapping material from the inside of the cylinder; make an attachment hose for your shop-vac to get inside the spark plug hole before you insert the new "Keensert".
You can use a combination of rubber hose and copper pipe to get to the edges of the inside cylinder. Also, a tac-cloth can be pushed in thru the spark plug hole and used to wipe the top of the cylinder and cylinder wall to verify filling removal. A coat hanger bent double-over and with a right angle at the end can be used to swab the tac-cloth around in the cylinder.
A small flash light and mirror or bore scope can be used to look inside the cylinder to confirm that all the fillings have been removed.

Hope this helps. Let me know if you need more.


     "Keensert" Kit for spark plug thread repair.

Directory  |  Diesel Engine  |  Tools  |  Mailbag  |
Home Page   |   Odds n Ends    |  Boat Builders  |  Engine Page  |  Electric Page  |  News Page  |  Safety page  |  Trailering  |  More About Us   |   Related Sites   |   Special offers   |   Event Calendar   |   Opportunities