Almost ended up pushing the NSR home

NSR125-Kid-UK · Attention Whore Joined: 03 May 2003 Karma :

Well after finishing late, I went on a little early morning razz on the NSR. I was happily settled into it, and had been riding for about 30 minutes, when all of a sudden I hear a loud (even with earplugs in) pop from under the tank, and the normally quiet buzzing of the NSR got much louder. At the same time, I lost all throttle response and the revs/speed started dying. I coasted over to the side of the road under a streetlamp. Helmet by the back wheel, gloves off. I got down by the side of the bike and lifted up the tank to take a look.

I looked at the engine, and the spark plug wasn't there. It was dangling by its cable alongside the cylinder. I screwed the plug back into the cylinder as tight as i could (with no plug spanner) and fired it up again, half expecting the engine to blow up, and It fired up perfectly.

Sighing with relief i climbed back on the bike, expecting the engine to fail again at any moment. I pulled away, rode about another mile down the road, and the revs died down again. I pulled over again, took the plug out and looked at it. The tip was kind of whitish, which didn't strike me as good. I laid the plug against the frame and pressed the starter, and got a weedy spark. I refitted the plug, fired the bike up again, and rode home.

I'm replacing the BR9ES plug with the only spare I have, which is a new and sparkly B10EG, but I'm still wondering, what the heck happened to my bike??

The only theory I have is that the plug vibrated loose and the pressure from the explodiness in the cylinder forced it out. The thread on the plug wasn't stripped, and neither was the thread on the cylinder, which doesn't add any weight to my theory, but it's the only theory I have.

My theory also fails to account for the bike failing again without the plug being blown out of the top of the engine, so basically i'm clueless.

Can anyone tell me what's going on? Confused

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Hex · Party Boy Joined: 04 Feb 2002 Karma :

The plug probably hasn't been tightened up correctly or over time has just worked itself loose.

I personally wouldn't use the plug your about to, and instead just get a direct replacement one. If you do use the other plug you may find performance will be off etc. But if it means you can limp to a shop to get the right plug so be it.

As long as the threads are fine in the head all should be ok.

As for why it died the second time? Could be the plug is dieing, could be in your head, could be the fact you never got it in tight enuf.
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Danny · Ask Me About Stoppie School Joined: 26 Jan 2003 Karma :

I had this happen twice to me on my NSR, first time was on the way back from my first ever BCF meet at Boxhill. Laughing

The second time was on the M4 bus lane. Shocked

When it happened the second time the bike had a hard time starting and felt a bit dodgy for a while. It was well over due for a re-build so that might have something to do with it.

GFK · Scooby Slapper Joined: 02 Apr 2003 Karma :

Plugs can work loose over time if they aren't properly tightened in the first place.

As for losing power the second time, maybe you put the plug in cross-threaded (its easily done), and it wasn't in as far as you thought it was (even though it wouldn't turn any more)?

Kris · World Chat Champion Joined: 03 Feb 2002 Karma :

Plug should be BR9 ECS as far as I can remember...

Unlucky though Confused

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McJamweasel · BCF Junkie Joined: 22 Mar 2002 Karma :

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

A "10" spark plug will probably work, but will be more prone to fouling up around town. Also an EG is quite expensive I think.

I have had spark plugs pop out occasionally. Normally when I have fitted them to a warm engine and so not done them up that tight (slight paranoia about doing them up tight on a hot engine, then having the head crack as it cools and contracts).

As to the problems afterwards, it is likely to have done some odd things without the plug, such as drawing in extra fuel so running rich for a short distance. Also the plug could easily have been damaged.

All the best

Keith
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NSR125-Kid-UK · Attention Whore Joined: 03 May 2003 Karma :

Well I've managed to fit the new (B10EG) plug after a little work with some pliers (getting the little adaptor thing off the end) and only one or two electrical shocks. I've taken out the old plug and found out to my horror that while the NSR was supposed to be running a BR9ECS plug, it was in fact running a BPR6ES! Shocked

.

While these letters and numbers do in fact mean very little to me, here's a snapshot of the plug so I can learn what was wrong with the plug.
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Robby · Dirty Old Man Joined: 16 May 2002 Karma :

Running lean, and hot.

NSR125-Kid-UK · Attention Whore Joined: 03 May 2003 Karma :

Ouch

. So now I have to get someone to play with the carb for me? (I'd just break it).

What do all the little numbers and letters mean?

Cheers for telling me anyways Thumbs Up

.
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Robby · Dirty Old Man Joined: 16 May 2002 Karma :

Just get the correct plug and fit it. Job done.

NSR125-Kid-UK · Attention Whore Joined: 03 May 2003 Karma :

Ack! Now I'm getting a spark with a new shiny plug, but the bloody engine won't fire and the battery's almost dead Sad

.

It was almost dead this morning too just after I fitted the new plug. Any reason why the battery should be on the way out? Confused

.
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"I'm either going to teach andy to get his knee down, or I'm going to get him killed. One of the two" - Teaman

Sparks! · Sir Tart-a-lot Joined: 30 Aug 2003 Karma :

Because you kept trying to start it and test for a spark Rolling Eyes

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NSR125-Kid-UK · Attention Whore Joined: 03 May 2003 Karma :

Nooo, because it fired up after that, although I didn't run it long enough to charge the battery.

And i've lost a big huge battery charger somewhere Doh!

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Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Yes it does look lean, but that could well be just from the plug. A 6 plug will have a better insulated electrode to keep more heat in the combustion chamber, and will this run hotter. That plug is probably blistering from overheating.

I suspect you have killed the battery from lots of quick attempts at starting it.

All the best

Keith
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