Someone please diagnose these plugs

Thanks for everyone's input. I gapped them at .035" and swapped plugs 1 and 2 with 3 and 4. I use MMO and StayBil 360 regularly.
 
rotorwrench said:
Back when leaded gas was common, the plugs would run a nice medium brown color. The change to unleaded affected normal color from light gray to a bit of a yellow tint.

The insulator ceramic has a tendency to wear a surface porosity that catches anything that doesn't burn off easily. Stuff in fuel and oil can affect the insulator color depending on what it is. There are additives in both. Fuel additives vary depending on what the bach plants mix in for each customer. Spark plugs are generally grit blasted using any number of different abrasive materials and that just adds to surface porosity of the electrode insulator.
Click to expand...


Comment: see red highlighted text above.

Starting in 1970 I was using a sand blaster to clean two stroke dirt bike spark plugs. The Yamaha Enduro dirt bikes were the RT-1 360 ( I bought the first 360 sold in Denver) and DT-1 250 models.

All of the Yamaha models from 125 through 400 used a Bijur style oil pump to inject two stroke oil into the intake manifold. (No mixing oil with gasoline) There is a cable from the throttle to the Bijur pump. As throttle is opened the stroke of Bijur pump is increased injecting more oil.

The point here is that the amount of oil mixed with the gasoline was closely controlled. This kept oil deposits on plugs to a minimum.

As a side note the Bijur oil pump was also used by IBM on many of the punch card machines that we worked on daily at work.

What we noticed was that after a new spark plug was installed that the plug remained clean for quite some time BUT after sand blasting them a couple of times the interval between cleanings got shorter.

My theory is that each time they were blasted more of the glaze was removed from the ceramic and as the ceramic became more rough the burned oil stuck more readily to the ceramic, thus a shorter interval between blasting was needed.

The other thing about blasting that concerned me was that it is very important to remove ALL abrasive from plug to keep the "sand" out of the engine.
 
Last edited:
Benson,
What is a punch card machine ??
HA! I still list “punch card operator” as one of my job skills on my resume, but no one has taken me up on it in quite some time !
What gives ?
W. Michael
 
Hollerith cards for IBM 360
Perforated card stock in long z-fold deck for player pianos (and similar for carousel orchestrions)
Chain of wooden cards for Jacquard loom
Same basic idea going back a few centuries
 
Probably not replaced ?! Less likely to be hacked from outside sources ? Sometimes old technology is the most dependable !
 
You must log in or register to reply here.
Back
Top