What Spark Plugs for 1977 750 SEI?
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Thread: What Spark Plugs for 1977 750 SEI?

  1. #1
    Member
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    John DeMaria
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    What Spark Plugs for 1977 750 SEI?

    Today I decided to “winterized” my 1977 750SEI. Wanted to warm it up and change the oil. I’ve fitted the Sachse Elektronic Ignition and it always starts INSTANTLY. Not today....... been a few months, so I drained the tank and pulled it off. Drained the float bowls, cleaned out the bowls and removed, blew out jets. All back together, on the the remote bottle, fresh fuel. Same thing, trying but not catching. Installed 6 new plugs, FIRES instantly, ran beautifully. Too bad about all the snow around here.

    So here is my question: what spark plugs are others using? Resistor plugs? I’m using NGK DR8EA right now. I seem to remember Sachse recommended a heat range hotter than standard? Do they suggest resistor plugs or non? Any input appreciated.
    Last edited by leleven25#; 12-10-2019 at 06:56 PM.

  2. #2
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    John DeMaria
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    No one knows what plugs they have in their 750 SEI? Merry Christmas and Happy New Year to all!

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    Tony Sangwine-Gould
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    Hi I saw no one had answered your question about plugs. I have a 500 quattro and my factory maintenance manual says the 750 and 500 use the same plugs. Marelli CX8L or Bosch X260T2. I use the NGK D8EA.

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    Senior Member
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    Cam Douglas
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    I have a 900 Sei, but I dunno whether the recommended plugs are the same as for the 750. I've got NGK D8EA in it at present. Seem to work OK.

  6. #5
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    Thank you both, that seems to be the general consensus. I will stick to it.

  7. #6
    Senior Member RichardJ's Avatar
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    Richard
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    Hi John,
    I think you are using the correct plugs. Your problem may have been caused by trying to start your bike with old fuel, and this fuel contaminated your plugs. You don’t say whether they were wet when you took them out. I sometimes had a similar problem after I first rebuilt my engine. Until I got the carbs balanced correctly it would sometimes refuse to start. I found that simply changing the plugs fixed the problem. And these would have been new plugs. This is similar to flooding the engine, but as these plugs are so small it is difficult to get the plugs dry without removing them.
    If you still have your old spark plugs you could try putting them back in ( assuming that they are now fully dried out ). However, I expect that is a bit of a fiddly job on your six, and may not be worth it, just to test a theory.

    Richard.

  8. #7
    Senior Member
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    Cam Douglas
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    Quote Originally Posted by RichardJ View Post
    Hi John,
    Your problem may have been caused by trying to start your bike with old fuel, and this fuel contaminated your plugs.
    Yes, The Benelli mutis seem to be sensitive to old fuel. I've had similar issues if the bike hasn't been running for a while (typically a couple of months or more).

    Best way to get the old fuel and carbon crap off plugs is to pull them out and heat business end of them with a gas flame (propane torch is plenty hot enough). There will be a yellow flame initially as the oily carbon rich residue burns off. But when the yellow flame disappears the plug will be clean and dry.

  9. #8
    Member
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    John DeMaria
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    RichardJ and Sprocket....... I believe you are both correct. Plugs were wet and slightly dark when removed. New plugs fired instantly! I’ll clean the used ones up and have them at the “ready”. May be a bit distracted for a while. I’m a Honda CB750 Collector, and finally got myself a RICKMAN Honda (1974 CR750). Happy New Year!

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