Topic: Replacing spark plug caps '74 CB750

[jembers]

Hi all,

I bought my bike from someone who had installed an electric starter on the bike (it's a Dynacoil). They said they did a bit of research on it and it was recommended that the spark plug caps be changed out from the OEM caps and he recommended the following caps:

https://fortnine.ca/en/ngk-spark-resistor-cover-sd05f

https://fortnine.ca/en/ngk-spark-resistor-cover-xd05f

I was close to cutting the OEM off yesterday but got caught up doing some other things and have not realized I should maybe ask some opinions about these caps on this site before going ahead with hit. Has anyone installed these on their CB750? One thing that crossed my mind this morning is that the threading may not be the same size, which I need to double check.

Looking forward to anyone's opinion. TIA.

[jlh3rd]

they unscrew, don't cut them off.

[ekpent]

 It sounds like you maybe have replacement coils and wires ? Are the wires yellow or a different color then black ? Rather then going with a new resistor cap you could use a resistor spark plug. More info on what you actually have and a picture or two would be helpful.

[1976cb750f836]

Not to highjack, but, why would you need to change plugs to resistor, or caps, with a starter install???

[jembers]

Not to highjack, but, why would you need to change plugs to resistor, or caps, with a starter install???

The guy I bought the bike from said he did some research on the starter and it was recommended that these caps be installed as well.

I pulled the one OEM plug off and I'll be honest, I'm pretty green at this stuff and don't fully understand how I'm supposed to screw these new NGK plugs into the wires. Pics below of my situation. Any suggestions?

https://imgur.com/gallery/hu0uBob

[Henning]

Correct NGK plug caps are SD05F and VD05F, used with non-resistor spark plugs. Dunno what the XD05F is. They're correct if you're using plain copper-cored spark plugs leads. Like Ekpent said, it would be helpful if you posted a pic of your setup.

[Scott S]

 You're saying "starter" and "Dynacoil"..... the starter is what turns the engine over when you push the button on the RH control.  The "Dynacoil".... do you mean a Dyna points replacement system?

[ekpent]

 In his one lone picture he has what looks like a non stock plug wire that has been stripped back like he is ready to rewire a lamp. If the plug cap was permanently attached as in aftermarket and had no resistor in it that is why I suggested a resistor plug. To the poster you must trim off that twisted wire sticking out so the insulation and wire are flush and then simply screw the new plug cap into the wire. Don't forget to slip the rubber cap on the wire first. As for the 'starter' not sure what that is all about.