SOHC.co.uk Forums > CB350/400

400/4 no spark

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hairygit:
You'd be amazed how often it happens, you are not the first, and certainly wont be the last! As I said, the grease/gunk they put on at the manufacturing stage stops corrosion in storage/transit, but nowhere does it tell on the packaging (or in most manuals!) that it needs to be wiped off before using. Glad it was something so simple and it's up and running now. ;D

ogri211:
Always good when you find it and it's an easy fix that's part of the fun nice one.

2 for the soul:
Hi all,

this is probably the most relevant thread for my issue! Funny but I had exactly the same issue and solved by cleaning the points - felt like a numpty but it's always the simple things - well said!

So... (1976 cb400f) I checked my spark plugs and I've got two NGK DR8ES-L - which I've recently found out are not what I need, but are the one's I got sent by davidsilverspares (the original NGK D8ES-L are not easily available anymore). I've also got two NGK D8EA - which I've read are the best replacements for the D8ES-L.

My problem is the threads in the engine case only accept one of the plugs, not the other. I.e. I can thread in a DR8ES-L into cylinder 3 but not 4, but I can also thread a D8EA into cylinder 4 but not 3.

Question 1 - WTF!?

Question 2 - is this normal or do I need to re-tap the case to allow the D8EA plugs to go in?

Thanks for any help or advice!

Nurse Julie:
Sounds like something not quite right there as all threads are the same on all the plugs you have mentioned 🤔D8EA should fit in all 4 ports no problem......has someone re tapped incorrectly in the past ?. Also, have you started them off with your fingers first so you can actually feel the threads catching correctly?

2 for the soul:
Thanks for a speedy reply!

Yes, very odd! I don't know that the ports have been re-tapped in the past, but this may be the case.

I looked at the threads on the plugs and they appeared identical (by eye). But yes, it's like the ports are threaded only for the specific plug, but that's odd if the threads on the plugs are the same.  :-\

I've started them all off by hand to make sure they're settled before starting with the socket-set. When in the 'wrong' port they start fine and then slow right down as if they're tapered.

I've seen some stuff online and on forums about thread 'chasers' and re-tapping etc. Just don't want to have to take the engine out if I don't need to - it's so close to running!  ::)

thanks

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