Spark Plugs - NGK BP6ES

[Bill]

Fellow XSives -

I decided to put a new set of plugs in "unXSpected", so I consulted my trusty Haynes manual. It specified NGK BP8ES, so I went to the local Yamaha dealer and bought a set. Since I had looked it up, I didn't ask them for '79 XS11 plugs, just gave them the numbers.

As I was removing the old plugs I noticed that they were NGK BP6ES... and #3 is a little too black.


So, I checked the original owners manual that came with the bike and, sure enough, it specifies BP6ES. It's the first error I've found in the Haynes XS11 book. Lesson learned... refer to the source whenever possible. I'll go exchange them tomorrow.

Still curious, I checked the NGK web site to see if I could find out the difference between the two plugs. Here's a link to a very good tech information page there:

NGK Tech Info - Spark Plugs Overview

So, now I know that BP8ES is a colder plug than the BP6ES. Another lesson learned...

[Bill]

Re: Spark Plugs - NGK BP6ES

A little earlier I wrote:

#3 is a little too black.

Now I know why... I just did a compression test.

• #1 - 150 lbs
• #2 - 135 lbs
• #3 - 90 lbs
• #4 - 150 lbs

I haven't yet tried putting oil in each to see if it's rings or valves. I'm surprised that #3 could be that low at only 20K miles. Any chance that it's just an adjustment problem?

[fusionking]

Lucky guess??

Maybe the valves are too tight or stickin'. Have you checked them?

[Bill]

Re: Lucky guess??

Garry "Fusion King" wrote"

Maybe the valves are too tight or stickin'. Have you checked them?

Thanks for the reply!

Valve check is next I suppose. It was getting dark after I did the compression check. Outa time for today!

[sixtysix]

Bill,

It could be a valve adjustment, (you can only hope). If you check the valves on the XS they are exactly the same as the GS 850 we did only no nearly so tight. Make sure engine is cold..sitting overnight cold, before you check them.

[mitch]

rings ?

Bill, could it possibley be a compression ring sticking from not driving it much . I would put the plugs in and run it a bit ,then do another test as your bike wasnt smoking so the oil rings are good , just a thought, i have had old bikes that didnt check out well on the compression till i run them for about 5 to 6 hundred miles. worth a try , good luck Doug M

[Jeff]

Run a little Seafoam or something similar into the spark plug holes and let it sit for a bit. You can also suck some Seafoam into that cylinder with a rubber hose on the vacuum nipple on the carb rubber while it is running. Be prepared for a lot of white smoke. I've heard of guys restoring lost compression and reducing oil consumption just from using this method to clean and free up sticky rings. Also a good way to reduce deposits on the valves.

[Jerry]

FWIW....

I run BP7ES plugs in summer. With temps regularly 90 deg F and over, me at 265 lbs, and often pulling my trailer at 180 pounds ready for camping, going a range cooler doesn't hurt a bit.

[Huron52]

OK? What is Seafoam? and what does it do? Who makes it? Where could I find it? There is a product up this neck of the woods called " Lucus" It is a product to coat the walls of the engine.

[fusionking]

Seafoam revisited

Parts store got it, so do marinas and small engine shops. It is a line of products but most people are talking about their fuel additive that can also be used in other ways like the crankcase or directly in the carbs airflow path. A very similar and less expensive product is Berryman B-12, also easier to find. My wife carries both products in her store and also Lucas, which by the way is also an entire line of High performance additives and heavy duty lubricants. Just go to Wal-Mart or your local partstore and start reading cans.

[xssiveone]

Originally posted by Huron52
OK? What is Seafoam? and what does it do? Who makes it? Where could I find it?

Tom, check it out here:Sea Foam

[Shuriken]

I have used SeaFoam on my XS11. It was quite awhile ago, but someone recommended it and I try a lot of things once....

I had the airbox off that day and sprayed right into the carb intakes. The bike will smoke and sputter and try to quit while it pisses off the neighbors and ... everyone else on a windy day...

The results I could see were that it completely cleaned the intake ports in the head when I examined it later with the carbs off. My bike has $@$#@!!!! compression - worn engine and 6,660ft elevation - but I'll definitely use SeaFoam again.

Ben