These kits are considered "Over the fender" meaning you do not have to remove the head.

MEASURING INSERT LENGTH  

To measure correctly for the length of insert you need for your application. Measure from
under the spark plug (Washer) or (middle of taper for tapered seat) to the last thread.
(Not to the end of the electrode).  This will give you the correct length.  TIME-SERT inserts
cannot be shortened.

(click here for Spark plug measurement and determine correct size and length insert)

Timesert Aluminum Spark Plug Inserts M14x1.25 use the same part number only add  the "A" for aluminum.

p/n 6604412

p/n 6604412E

SPARK PLUG TYPES		WASHER SEAT INSERTS			TAPER SEAT INSERTS
Installation  Instructions
KIT SIZE	PART NO.	INCHES	MM	PART NO.	INCHES	MM	PART NO.
M14x1.25 Standard	6604412 NOTES:	.270 .320 .370 .430 .530 .600 .660 .905	7.0 8.0 9.4 11.0 13.5 15.0 16.8 23.0	66144121A 66144123A 66144125A 66144127A 66144113A 66144129A 66144111A 66144112A	.270 .400 .531 .620 .660 .826 .950	7.0 10.0 13.5 15.7 16.8 21.0 24.0	66144181A  66144183A  66144184A  66144185A  66144186A  66142126A  66144187A Sealer required for all Taper Seat Inserts. p/n 6626020
M14x1.25 deep hole kit	6604412E NOTES: