Spark Plug Threads Stripped - Is this common?

Hey everyone,

So while on a ride a few weeks ago I blew a spark plug out of the head. My brother, the crafty mechanic, managed to get it to stay in place for the ride back using some zip ties and a rock (pretty epic, honestly).

So I was just wondering if this was a common problem on the VF500's? I'm left with the choices of getting a helicoil kit for $45, a used head from ebay for around $70, or a Timesert kit for $135.

Any suggestions or recommendations? Other options I don't know about? Obviously if it's common I'm not going the head route. Which is also way more work that I want to do, and definitely will not pay for it to be done.

Thanks.

 

Probably would never have happened if oil, neverseize, or grease were applied to threads whenever pulg was installed........

 

Well if you want to be insane - you can do what I did on an old CB175.

I tapped the head for a larger spark plug and called it a day. It honestly worked well... Though I don't recommend it. It's ghetto!

Timeserts are better than helicoil kits, as far as reviews go.

Obviously a used, in good condition head, is gonna be the best fix.

 

slick50 on threads best way.......................:thumbsup:

 

I didn't install the plugs so constructive comments are appreciated.

Interesting. Are they 3 times as good? I don't plan on having this bike for an extended period of time after this fix, so is it worth the extra money?

But that's why I wanted to know if it was a common issue. Some engines (at least in certain cars/trucks - not sure about bikes) are notorious for blowing plugs. So another head might not be best - especially one that's 24 years old and without knowing exactly what shape it's in.

 

Try a helicoil kit. If you go to autozone - you'll see spark plug repair kits, appear to be helicoil kits, not sure on the price though.

 

Helicoil

A Helicoil will work just fine, have done this repair many times and never once had an issue. Roll problem cylinder to open intake valve and blow compressed air into intake and perform repair. The air will blow the shavings around the slots in the tap ,install coil and plug and ride.:thumbsup:

 

It can happen when removing a spark plug that has not had enough time to cool down. Also of course cross threading by not installing with fingers FIRST to get the plug started.

The repair.
You have a new option. There is a tool you can get that threads into the spark plug hole that straightens out the threads if any are left.
Try to look in the hole and see if all of the threads are damaged OR if only part are damaged. If you have to do a heli coil kit have a machinist help you or someone that is experienced, or you will be doing a cylinder head R&R.

 

My only purpose for posting is/was to advise how to avoid your problem for other members...,...sorry.

 

+1 Did it myself on my CL175, I was 14 went to the Honda shop bought new plugs. I went out front and took the first one out hot threads came with it. Rode home on 1 cylinder and tapped it out to a larger size plug...worked fine. But over the years I've seen it on corvettes with alum heads many times.

 

common enough that helicoil has made a small fortune

I think its mostly a condition common on aluminum heads. As an ancient VW mechanic I can tell you that I have see scores if not hundreds of olod bug and Bus's with the old upright fan engine running around on helicoils. The problem is related to heat and over tightening the plugs. Cross threading is a common cause as well. There is this sick feeling in your stomach when you are taking a plug out that is stripping away the aluminum thread with it. I've had it happen countless times. It happens on old Vw's because the plugs are installed blind through the sheetmetal. If the engine is hot all the person doing the install wants to do is get the plug in as fast as possible and they often end up cross threading the plug. On Vw's there is also the build up of dirt and crap around the plug which is not seen. This crap gets dragged into the threads when you are installing the plugs blind. I have to second the guy who said "install the plugs with your fingers before tightening. " I think he ment that you should install the plug with a socket and extention using your hand and fingers to tighten until the plug bottoms, then apply torque with the use of a ratchet. I've seen hot shot line mechanics use an air wrench in an attempt to beat the clock on a job and tear up mulitple thread holes on the same car. Then they get beat on the warrantee repair, unless the customer can be bullied into accepting the fault as his own. then I've seen hot shots mechanics make double by getting the job to repair the stripped out theads.

I don't like helicoils except as stop gap repairs to get you back on the road. I've seen them come back out the next time you pull the plugs. Then you have to be three times as careful when you put them back in . I think they are messy and short lived. I'll admit that I prefer getting an exchange head. But in the VW market there is/was a whole group of welded heads that usually were from some low bid shop (often Mexican cross border trade) that ended stripping out the new welded in spark plug threads in the first 6000 miles. I don't like doing head jobs over and over again because of poor workmanship at the machine shop. I don't think to replace the head is the cheap option because of the labor and the cost of gaskets etc.

If you plan on getting rid of it you are really just palming your problem off on some other ridder. That's going to be your problem to deal with if the rider thinks you cheated him and decides to harm you back in some way. Thats my experience with Helicoils for two cents. I can't tell you what the best out is for you. Maybe that third thing you mentioned is the best. I have seen a steel type insert that sometimes has locks that can be used to make it difficult to impossible to remove the insert from the head. Generally I have been impressed by this type of repair. It lasts a lot longer than the helicoil. But if I had a head on the shelf with either a helicoil or a steel insert I always tried to get rid of it in favor of a head with good original threads.