Topic: cb350f spark plugs

[poofdog]

Hi, Just wanted to get an idea of what kind/heat range plugs you all are using.  My bike has a dyna ignition and the PO had NGK DP8EVX-9 in it.  I had some carb issues as the bike had set a while, but that is all cleared up now.  I pulled the plugs...I have about 200 miles on since I got it going, and they are very black.  The bike runs great, there is some faint smoke if you rev it to about 5k or so in neutral.

Any Thoughts?

[flybox1]

NGK D8EA.
you'll need to make a few more adjustments/tests to determine if they are just carbon fouled, oiled, or if you're simply running rich....

[Bodi]

The 350 and 400 fours don't have valvestem seals on the exhaust guides so they will puff a bit of oil smoke when revved. Not a problem, and tells you the stems are getting lubricated at least. If the smoke is black then it's too rich somewhere in the throttle range- but even that is not unusual, rvving in neutral is not a good test of much anything.
You can't tell much from old plugs. Put in new D8EA or DR8EA or D8ESL  if you can find them, that's the original spec but a discontinued type.
These engines run rich at idle to avoid stallout when gassed, since there's no accelerator pump. So the plugs will (should) be very dark after a long idle session.
Do some plug chops with new plugs and see what you get.

[robvangulik]

You said it runs great, so ride it, and don't be afraid to rev it
And when you've filled the tank a couple of times, check the plugs again, by that time you have cleaned the engine inside and 'run it in' again!

[gtmdriver]

When I got my CB350F it had resistor plugs AND resistor plug caps and there was a slight misfire at idle.

I fitted new resistor plug caps and non-resistor plugs (D8EA) and it's been no problem ever since.

They do need revving though. They are designed to run to 10,000rpm so make sure you don't chug it around too much.

If you do a lot of short runs the plugs may look black as you're running with the cold start  on for a relatively long time.

[poofdog]

Thanks for all the feedback.  I put in another set of the same plugs that came out.  The PO gave me an extra set, they seem to be just a fancier platinum pre gapped version of the original.  Anyways, it guns great and got a chance to put 50 miles on today.  Runs like a swiss watch. Thanks Bidi for the info on the valve seals and idle mixture.


Thanks all.

[cjespersen]

For cb350F

NGK D8ESL
ND X24ES
Bosch X290 T-17
Champion A8Y-MC