Spark plug color differences?

[jyrki]

Hi, comments on color difference in attached picture? One cylinder (cyl no 3) spark plug has darker color, others are quite brite (like milk coffee). These are new spark plugs, driven about 30 minutes, after engine rebuild (gaskets, piston rings, honing of cylinders etc) and carburator cleaning. Settings of carbureators should be the same as before rebuild/cleaning. Membranes I will change soon, as I noticed there is some small holes... and idling is not so smooth. Balancing of carburators I will do also..  I suppose relative unsmooth idling is due those membranes, but idling has not never  been so smooth ( I have owned this bike for two years only).
br Jyrki

[Pat Conlon]

Do a hot compression test (throttle open) see how #3 compares to the others.
It's hard to see in the picture if its oil or fuel.
Definitely check the vacuum readings between carbs, although if it ldles smooth, you should be close.
I can say that if Randy @ RPM did the cleaning and rebuild, your vacuum should be set dead nuts.

Re: Plug color. White plugs are common on the FJ so don't freak out. The FJ has a vacuum advance (part of the emissions control system) where the TCI or DCI advances the ignition timing when the throttle plates close sending a high vacuum signal to the TCI/DCI.
This advance flashes off any unburned fuel and turns your plugs white (and keeps them clean)

If you want to get a true reading of the plugs you need to disconnect the vacuum advance (cap the #2 vacuum port) Again, this vacuum advance happens when the throttle plates close so disconnecting it won't affect the performance of the engine (it's opposite of what typical ignition advance systems do)

Further reading of the FJ vacuum advance can be found here:
http://www.fjowners.com/index.php?topic=11690.0

Hope this helps.  Pat

[jyrki]

Hi Pat!

Many thanks for your answer! Good to hear that bright color of spark plugs is ok, allthought these european bikes do not have vacuum system at all..my bikes origin is in Germany, I live in Finland.
Hopefully I get new membranes soon (I ordered those from Germany yesterday, only membranes without glides), after new membranes installated I'll do balancing, longer driving and controlling of spark plugs color ocassionally.

Jyrki

[Pat Conlon]

Thank you Jyrki, I did not know that the EU bikes didn't have the vacuum advance system.
I've known about the power limited FJ's sold in Japan and Switzerland (and France?) I've recently found out that the Austrailian FJ's didn't have the side stand switch.

Seeing as though this is a world wide forum, I would like to compare notes with forum members and come up with *all* the differences between FJ's sold in different markets.

I think I'll start a new topic.

Thanks again!  Pat

[balky1]

FJ 1100 has the vacuum advancer. My bike is from Switzerland.
I think they were restricted in Germany also.

[jyrki]

Hi,

Pat gave me a link:

http://www.fjowners.com/index.php?topic=11690.0

My FJ 1200 do not have such of a hose to ignition system, if that is what is meant by vacuum system? My bike is not restricted. I need now to read through this link what Pat gave me..

I have a harley from 80's, in Harley models there was on that time kind of system which collects gasoline "steams"..

br Jyrki

[Pat Conlon]

The vacuum hose does not have to run to the ignition box.
The '88+ FJ's have a vacuum sensor that is tucked away under the fairing with wires that run to the ignition box.
A sure way to tell is look for a vacuum hose connected to a port on the intake manifolds.
If there is a hose connected to one of the 4 ports (typically #2) follow the hose to the vacuum sensor.