Triumphrat

mr_hybrid · 02-11-2006, 07:19 PM

I thought I would post on the general topic pages as well in case this isn't just a Sprint phenomenon"

I need to know if anyone has ever had a spark plug, for no apparent reason, get spit out of the head. I've only owned by Sprint for a couple of months now (I bought it used in late October). The bike purred like a kitten until January 4th. The spark plug in #1 cylinder spit out of the head, taking all the threads with it. Luckily it was contained by the coil. Talked to the previous owner and he had the plugs replaced along with all the other stuff they do at the 24000 mile service (the bike now has 27000 on it) . Contact the dealership where the work was done and they want to see the bike. I trailer it down to Denver and they look at it. They are not sure why the plug spit out. They said it could be that carbon build up caused some sort of preignition and that caused some massive explosion that would force out the plug. It couldn't be caused by them overtightening or cross-threading the plug. Now they want to charge me two hours of diagnostic time to come up with this idea of the preignition, plus another $100 to put in a Helicoil (which they won't guarantee will work), plus the cost of new plugs and a coil. I just wonder if there is a logical explanation for the plug coming out other than cross-threading or over-tightening the plug when they did the service about 3400 miles ago. If there is I will shut up and pay my bill

John

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Slinky · 02-12-2006, 03:11 PM

The most likely cause is that the thread was damaged, either by cross threading or over tightening.

I really can't see how a detonation in the combustion chamber could blow the plug out if the thread was sound.

When you get the head repaired, consider using a Time-Sert repair instead of Helicoil, they are said to be superior.

flatspins · 02-12-2006, 10:32 PM

unless you run a high % nitro fuel mix the most likely cause is incorrect installation of the plug in the service, over torque or cross thread being most common...did the plug have aluminum all the way down the threads or only at the end? if only at the tip the plug may not have been torqued enough and rattled lose. If all the way down it was over torqed.

[ This message was edited by: flatspins on 2006-02-12 20:34 ]

tbsrider2000 · 02-13-2006, 09:08 AM

I agree, the spark plug was either cross threaded or over torqued when it was installed. If the mechanic where the work was done is the last person who touched it, that's probably where this all started, but there's really know proof.

Feeding you some line about pre-ignition blowing the plug out though, it sounds like they already know what the real cause was.

I just re-read your message.. They want to charge you for their guess work???? Exactly what kind of diagnostics did they perform to come up with this theory? Is there so much carbon build up that your compression level is now above specs? They obviously didn't have to pull the spark plug, so what work did they do? There is no way on that motor to look inside the spark plug hole and make any kind of a determination. I doubt they pulled the head? Do they have a print out of the work that was performed?

I don't usually respond so much.. lol, but after reading your post, I put myself in your position

vinnyf · 02-13-2006, 12:21 PM

Sorry about your plug, Mr_hybrid. But it's responses such as your dealer made that make us want to AVOID dealers - and I believe tbsrider2000 hit it right on the head - what are they charging diagnostics for? Lunch? Were this world fair and just, you could sue them for their defective work on your bike. Since it is not, I'd trailer my bike away from them as quickly as I could and find someone who could put in an insert - properly. Good luck.

DickBender · 02-13-2006, 03:57 PM

I agree with all of the replies, especially vinnyf's. Find another dealer they are so full of it.
"They said it could be that carbon build up caused some sort of preignition and that caused some massive explosion that would force out the plug" What a load of bull only if you put a block of C4 inside.

Darcy

Mojoinco · 02-13-2006, 06:23 PM

I have had good response at Foothills Triumph/BMW. No experience at Erico. My experience was limited to warranty work.

Will try to find out who a friend had do work for him. Check out www.mra-racing.org and see if anyone is in Ft Collins. You ought to be able to find a mechanic that works on bikes on this page, as installing a thread insert shouldn't be all that uncommon for a bike mechanic (I'm thinking more aobut the difficultyies of working on thin skinned motorcycle heads here -- and tight confines).

Enjoy! You have little choice.
Mojoinco

Dogma · 02-13-2006, 06:59 PM

Maybe you should ask your mechanic, isn't it a detonation that pushes the piston back down when the fuel hits the spark and explodes???? In perspective the head is just a miniture cumbustion chamber.

[ This message was edited by: Dogma on 2006-02-13 17:14 ]

Cerberus · 02-13-2006, 09:13 PM

agreed with all above responses.
Except i can offer one more possible cause, if the plug well is a bit tighter than the rest, it could have grabbed the plug socket before the plug was actually bottomed into place giving a false sense of torque, and being not fully bottomed, the plug could then rattle in place until it stress fractured the threads and tore them out. This is admittedly a less likely possibility, but still valid. Cross threading over over-torquing seem more likely. Either way, someone ***** up good.
I wouldn't pay the 2Hr Diag charge if you can get out of it (since it sounds like BS anyway) and have a better shop install the helicoil.

GaryD · 02-14-2006, 12:36 PM

Been there done that several times. The plug was over-torqued period; the rest of the speculation was BS.

There's not a lot of technology built into spark plugs and you do not have to use the same plug as stock. Rather than use a helicoil or some other insert, simply remove the head, make sure you have plenty of room around the plug hole and then tap the hole for the next larger size plug. Then replace the stock plug with the larger plug of THE SAME DEPTH AND THE SAME HEAT RANGE.

I did this 3 times on a Ducati until I was using a lawn mower plug in a hole about 7/8" in diameter and it was about 1/4" too short for the hole - but it worked fine!