Spark Plugz

[brettxlch]

Guys do you know what the orig brand of plug and part number came in my 73 XLCH ? Just Curious...thanx

[Chris Haynes]

Guys do you know what the orig brand of plug and part number came in my 73 XLCH ? Just Curious...thanx

Originals were Harley-Davidson brand. Actually made by Champion. The main difference on H-D plugs is that there is no pre gap inside the porcelain. Back in the dasy I would use Champion J 12. I don't believe these are available today.

[brettxlch]

Thanx Chris, thats very interesting, maybe one of the club members have some pix. Gee had no idea harley did this.....but im fairly new to the hobby..brett

[pan620]

H-D 4-5, i believe that is what they came with.

[kitabel]

4-5 is the heat range (not the plug type) and is used for all models regardless of plug type.
The iron Sportster used the Champion 14mm thread, letter code "H" plug with 7/16" reach (depth in the head).
The Champion "J" code is 14mm × 3/8" reach, it fits the Sportster but it's too short and carbon will form on the unused exposed threads inside the head. It was used in panhead engines.
I have some more comments on my site here: http://victorylibrary.com/tech/plug.htm

[Rubone]

The old Champion crossover was an H-10 for Sportster, the equivalent of an old H-D #4.

[duffeycycles]

H8C or H10C Champion in todays numbers

[ihrescue]

Just to add a little more detail from the MoCo side of things the Harley Davidson XLH, XLCH Parts Catalog offers all the following part numbers for both XLCH and XLH for 1971 - 1978. Indications are that they are exchangeable to XLH and XLCH for those years and no explanation on what is the difference between the plugs associated with the part numbers.

Spark Plug No. 2 ( 2) 71 to 78 - XLH, XLCH 32305-48A
Spark Plug No. 3 (2) 71* - XLH, XLCH 32303-47A
Spark Plug No. 4 (2) 71* - XLH, XLCH 32301-47A
Spark Plug No. 4R (2) 71* - XLH, XLCH 31629-78 (radio static suppression)
Spark Plug No. 5 (2) 71* - XLH, XLCH 32307-58

Not sure if this is useful if you already have the Champion number.

Mike Love

[duffeycycles]

The R plug is resistor for radio or electronic ignition
the others are heat range

[TomL]

H8C/HD 4 32301-47a 14mm tpi/.440" reach(11.2mm) 1972-1978 Sportster 1000cc