Topic: 74' cb550 spark plug cap verify before I purchase

[Jimsun]

Hey guys,

I read these 2 posts and I checked my spark plug caps. I'd like to replace #1 and #2 and #3 because the reading is 9.95k, 5.16k, and 4.95k ohms respectively. Spark plug cap #4 reads 9.96k ohms which is within 5-10% tolerance of the stock 10k ohms.

http://forums.sohc4.net/index.php?topic=102798.0
http://forums.sohc4.net/index.php?topic=55384.25

I want to go back to stock as i'm running D7EA non-''R''. I'm wondering why there's 2 types of spark plug caps part #s. I thought it's just 1 part # for all four caps? Unless its just the different housing.


http://www.buymotorcycleparts.com/honda_parts.htm?aribrand=HON#/Honda/CB550_A__MOTORCYCLE%2c_JPN%2c_VIN%23_CB550K-1000001/FRAME_%2b_WIRE_HARNESS/CB550-JPN-A/2Y133740F13374009C

12   30700-GAR-000  !    CAP ASSY., NOISE SUPPRESSOR      
13   30700-MC8-000  !    CAP ASSY., NOISE SUPPRESSOR

[DH]

 Physical dimensional differences between inner and outer caps would be my guess as the reason for 2 different numbers. Cylc 2/3 take a shorter
cap that has a 90 degree bend. Cyls 1/4 takes a longer body cap that has a 45 degree bend. you need 2 of each. Internal resistance rating should be the same.

[TwoTired]

The different spark plugs are for the two lengths/angles used between inner and outer plug caps, 102 degrees and 120 degrees.  Also, the way the spark wires were routed changed along the CB550 model span, I think for 77.  Earlier models had leads clamped to the cylinder cover, which made routing different.

Look at the PDF found here:
http://www.ngksparkplugs.com/products/performance/resistor_covers.asp?mode=nml