Ejected the rear plug?!?!
 

I took the bike out the other day for a leisure slab ride. I was pulling away from a red light and gave it a little gas and heard a pop. I really thought I popped the head gasket or threw a rod.
I limped the hawk back to the house since it wasn't knocking or blowing oil to find out the rear plug under the tank had literally just popped out.
I threaded it back down but was concerned it wont thread in tight.
This worries me. I don't know if it was stripped before by my paps or if this is new territory.
Has this happened for anyone else? Should I just replace the plug?
The threads on the plug looked decent... not sure what to make of it.


Any advice guys?


:confused:

I'm sorry this has happened to you after your fathers untimely passing.

The spark plug won't back itself out after being torqued down. So, either your Dad didn't install it correctly, or he simply hand tightened it and expected to torque it down eventually. I'm assuming the latter. He might have installed new plugs and never got around to torquing them down.

If the threads are indeed messed up, then your best bet is to get a helicoil to fix this.

Hey Crux,


Thanks for the advice. I fear for the worst. I threaded the plug back in but it wont torque down. Looks like I'm gonna go with the latter. After I threaded it in I was still able to ride it for a couple of hours. I babied it at first but still did some up on 1's towards the end of the ride. I think I will wait till it spits it again. Then tear it down.


I think I'm going to sell the VFR 800 (the devils bike) we were both hit by cars on it and dropped it multiple times. What a bad omen. He loved it though. I think an RC8 would look much better in its place.

I had this happen on a different bike. It wasn't stripped it just backed out over a long period of time on a race bike.

How do the threads on the plug look? I would tackle this now way before it does any more damage to the bike.

If it popped that hard then I recommend replacing the plug asap because the ceramic could be cracked. There's a pretty good list of replacement plugs on here some where.

Hope you don't have to tare into the bike this soon after getting it.

Bummer! I'll second resolving the issue sooner rather than later. It isn't good to be running the engine with a cylinder down. The unfired gas washes oil from the cylinder walls. Correct repair involves head removal. Is that within your comfort zone?
technical-discussion-28/spark-plug-problem

Thread Repair
 

If the threads in the cylinder head are messed up (which they must be if the plug will not torque down) a better repair than a helicoil is made by the Timesert Company. Google them they have repair kits for all plug sizes and kits for deep plug holes. You do not have to remove the head.

Happy to have a look..would not be the first time I've worked on that bike.
Waiting for it to fail again is not a better plan and may cause more damage than done already.

This motor is not know for plugs to do this, so as already stated, it was mis installed at some point (not necessarily Doug) or just not installed all the way.

Push come to shove, pull the head, and replace (I have a used one that can be rebuilt) or use a thread repair bushing on that current head. I know many have installed spark plug repair coils or bushings with the head installed...counting on grease to catch the chips. While I might do that in a parking lot in the middle of a 3 week ride....Im a believer in doing it right the first time, not chancing it and having to do it right the second time.

Pulling the head is pretty basic and gives the best chance of a correctly installed thread repair coil or bushing and what I would recommend.
Time Sert thread repair bushing is the "better" option for sparkplugs I feel, even if a bit more involved and pricy.

I'm going to pull the plug and replace it and see if I can get any torque on it. I'll probably get into it this weekend. I'll let you guys know what we find out.

The recommended torque for a spark plug is surprisingly small, just 14 N-m.

I thought I posted but maybe not. Erik is right. Get that bird fixed up right. If the head is wallowed out you can have it welded there are actually three options. The other two are a sleeve or you can run a plug with a wider body. All require the head off but you could fix it up as a spare.
Best of luck.

Any updates? Been thinkin' about this bird that can't fly...