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Thread: Bosch spark plug question

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  1. #1
    DennyPink
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    Bosch spark plug question

    Fellow Airheads;

    I made a purchase ass-backwards. I bought a 4 pack box of Bosch WR7DC spark plugs, then read Snow Bums article and he recommended against using any plug with the "R" letter, meaning it is a resistor or resistance plug, not to be used in airheads. My 1992 RT owners manual recommends Bosch W7DC. Do I now own 4 paperweights? Thoughts please. Thank you!
    Denny Pink

  2. #2
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    unopened, you should be able to return them; especially if you seek an exchange for the correct item.
    Ride Safe, Ride Lots

  3. #3
    Registered User jad01's Avatar
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    I'm not sure you will be able to find Bosch W7DC plugs easily... you may want to opt for NGK plugs which are equivalent and readily available.
    Jim
    '78 R80/7 and '84 R100RS (Blues Brothers), '86 K75C (Icy Hot)
    '90 and '93 Mazda Miatas (Jelly Bean and Red Hot), '02 325ci (Blue Streak)
    '96 Giant Upland (big Kendas & freshly greased bearings!)

  4. #4
    Administrator 20774's Avatar
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    Be sure and find the right matching when going to NGK. The temperature rating scheme on the plugs are different. IIRC, Bosch W5 is a colder plug than a W6...reversed on the NGK.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
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    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  5. #5
    Registered User jad01's Avatar
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    Quote Originally Posted by 20774 View Post
    Be sure and find the right matching when going to NGK. The temperature rating scheme on the plugs are different. IIRC, Bosch W5 is a colder plug than a W6...reversed on the NGK.
    Yes- good point! The numbers do go in opposite directions for the two brands. I think the Bosch W7DC equivalent NGK part number is BP6ES. That said, I see Rick (Motorrad Elektrik) is recommending NGK BP7ES for all 1000cc twins '81 and onward:http://www.motoelekt.com/ignition.htm (scroll to the bottom).

    I recall Snowbum has a comparison table: http://bmwmotorcycletech.info/sparkplugs.htm

    Here are couple of other pages from the net that might be helpful...
    This page has a nice chart about halfway down the page showing the compatible the NGK and Bosch plugs from hotter to colder:
    http://matchlessclueless.com/mechani...n/spark-plugs/

    This has a complete compatibility chart:
    http://www.clubplug.net/bosch_ngk.html
    Jim
    '78 R80/7 and '84 R100RS (Blues Brothers), '86 K75C (Icy Hot)
    '90 and '93 Mazda Miatas (Jelly Bean and Red Hot), '02 325ci (Blue Streak)
    '96 Giant Upland (big Kendas & freshly greased bearings!)

  6. #6
    Registered User lkchris's Avatar
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    Quote Originally Posted by jad01 View Post
    I'm not sure you will be able to find Bosch W7DC plugs easily...
    It's as easy as a trip to your BMW dealer.
    Kent Christensen
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  7. #7
    Registered User jad01's Avatar
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    Quote Originally Posted by lkchris View Post
    It's as easy as a trip to your BMW dealer.
    Mmm... that maybe true for some dealers. My local dealer only carries the NGKs these days. So... your results may vary!
    I do see on the parts fiche that MAX BMW carries them (W7DC) for $6.88 each.

    Jim
    '78 R80/7 and '84 R100RS (Blues Brothers), '86 K75C (Icy Hot)
    '90 and '93 Mazda Miatas (Jelly Bean and Red Hot), '02 325ci (Blue Streak)
    '96 Giant Upland (big Kendas & freshly greased bearings!)

  8. #8
    Registered User lkchris's Avatar
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    "Carries" is a vague word here.

    Your BMW dealer has a BMW part number for the Bosch plug.

    He doesn't for any NGKs for Airheads.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  9. #9
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    Quote Originally Posted by jad01 View Post
    I do see on the parts fiche that MAX BMW carries them (W7DC) for $6.88 each.
    Thats what my dealer sent.

  10. #10
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    Quote Originally Posted by DennyPink View Post
    Fellow Airheads;

    I made a purchase ass-backwards. I bought a 4 pack box of Bosch WR7DC spark plugs, then read Snow Bums article and he recommended against using any plug with the "R" letter, meaning it is a resistor or resistance plug, not to be used in airheads. My 1992 RT owners manual recommends Bosch W7DC. Do I now own 4 paperweights? Thoughts please. Thank you!
    Denny Pink
    Try parts stores that sell VW Bug parts. JBugs lists the W7DC as being available. $3.00 each.

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