Jump to content

Might as well start a spark plug thread...Autolites burn pistons?


swfraley

Recommended Posts

I took my R1100RT to the dealer last weekend for the 30K service. I'd done the 24K myself and used Autolite plugs. Spoke with the service guy today, who said that Autolite plugs had been associated with holed pistons. I'd never heard of that, and a search here reveals nothing.

 

So, does anyone know about Autolites burning holes in pistons?

Link to comment
Dick_at_Lake_Tahoe_NV

Chalk it up to an old wives tale and forget it. Just use the correct heat range of plug, make sure it's the right length and you have nothing to worry about.

Link to comment

Countless 1100 owners use the Autolite (3923) plugs (including me for over 100k miles) and I'm not aware of a single instance of any problems. More uninformed dealer c..p.

Link to comment

I used the Autolite 3923 on my 1100 for 67K miles, only fix for the non-existent surge, and fine alternative to $15 plugs.

 

Just dealer code talk for "buy ours or the boogey man'll get you".

Link to comment
I took my R1100RT to the dealer last weekend for the 30K service. I'd done the 24K myself and used Autolite plugs. Spoke with the service guy today, who said that Autolite plugs had been associated with holed pistons. I'd never heard of that, and a search here reveals nothing.

 

So, does anyone know about Autolites burning holes in pistons?

 

Did he sell you the nitrogen tire fill as well? Make sure the gas cylinders have the appropriate "BMW approved" stickers on them.

Link to comment

Did he sell you the nitrogen tire fill as well? Make sure the gas cylinders have the appropriate "BMW approved" stickers on them.

 

Well, no. But he DID mention that the problem is more likely to happen when using Valvoline, and less likely when carrying a Glock in the tank bag. :rofl:

Link to comment

Holed piston?

 

Can't imagine burning a hole in a piston with a spark plug..

 

Only thing I can think of is perhaps someone used the wrong Autolite, and the plug "reach" was too long and piston contact was made. (IE, plug extends into cylinder too far and makes contact with the piston.)

 

MB>

Link to comment
Holed piston?

 

Can't imagine burning a hole in a piston with a spark plug..

It is possible and can happen on rare occasions, as in cases where the plug is of a grossly incorrect heat range and runs way too hot, causing preignition and engine damage. And even that potential occurs pretty much only under high-load or race conditions. Very unlikely in normal use, and certainly there has never been so much of a hint of such a problem with the common 3923 usage in the 1100 bikes. The mechanic was, in less than delicate terms, talking out of his ass.

 

Link to comment

This comment must be in the dealer instruction book. I had a dealer service manager tell me that the Autolites in my bike would cause the valves to burn. I let him go ahead and change them to Bosch and paid the price. :dopeslap:

Link to comment

I went in to get a OEM filter at my local dealer. Counter guy asked if I wanted oil too? I said no, I get it at Kragen/WalMart/AutoZone/PepBoys, depending who has it on sale. He said car oil was not designed for my bike.

Another example of dealer BS!!

Yes, I know I don't have to buy a BMW filter either.

Link to comment

Stuart, next time you visit your dealer call his bluff.. Ask him to show you a BMW oilhead piston with a hole burned in it.. I’m sure he will say he doesn’t have any.. Then ask him to tell you of just one of his customers with a hole burned in a piston from Autolite spark plugs.. Unless he lies I doubt that will happen either.. Actually have him just show you one overheated Autolite that he has removed from someone’s motorcycle,, I don’t mean just white as that can be normal but with burnt deformed electrodes & obvious overheat..

 

Then search the Internet for holes burnt in BMW oilhead pistons from Autolite spark plugs.. I think about the only thread you will find on that is your post here..

 

Can it happen? Sure if you use a spark plug is the incorrect heat range & you can manage to run it long enough,, fast enough,, & under a enough load.. With all the people using those Autolite plugs & riding 90 mpg with 500lbs of body weight & 100+ lbs of camping gear on the back you would think if it was even a remotely possible problem you would see some reported problems by now..

 

 

Twisty

 

Link to comment

I've seen holed aircraft pistons, but IIRC they've always resulted from overlean/detonation type problems. Since a given fuel/air mixture is going to burn at a certain temperature, I question whether even a "too-hot" plug would make any difference.

 

So, I'm gonna conclude that this technician was just repeating what he'd heard.

Link to comment
clip~ Since a given fuel/air mixture is going to burn at a certain temperature, I question whether even a "too-hot" plug would make any difference.

 

~clip

 

 

Stuart, as long as it ignites at the correct time..-- If the plug is too hot a heat range & can’t transfer enough of the spark plug heat into the cyl head it will sit there glowing with overheated electrodes & that can cause pre-ignition.. Pre-ignition can be damaging & can burn a piston,, or burn a valve,, or can do other engine damage..

 

Chances of pre-ignition damage in an oihead are lower as you sit over an open engine so can usually hear the combustion clatter & knocking..

 

Twisty

 

Link to comment

It is perfectly possible to burn a neat hole in a piston through using the wrong grade of spark plug. I know, I've done it. Many years ago I had a Suzuki Hustler MkII, a 250cc two-stroke twin. In the manual it specified two sets of spark plug grades, one for 'town use' and one for faster riding. One day I was racing a Triumph Spitfire when my engine suddenly felt as though I was running out of petrol. When I got home and removed the cylinder heads (2 minute job), there was a neat round hole in one piston crown. I also recall that 3 cylinder Kawasakis (or Suzukis, or both) had a different grade plug in the middle cylinder, which ran hotter as it was shielded by the front wheel.

 

That said, the odds of doing this on a BMW twin simply by using an unapproved make of plug must be minute. The engine simply isn't tuned highly enough and it also has a relatively sophisticated ignition system, compared to my old Suzuki, whose spark timing relied upon two bits of metal bashing against each other (points).

 

Definitely one for the old wives tales category.

Link to comment

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...