While looking over the bike yesterday I noticed that a bolt is missing under the generator behind the clutch slave cylinder. I have no idea how long this has been missing but fortunately noticed it before something more serious happened. No problem, ordered new mounting bolts for a couple of bucks along with a few other things I've had on a list. Here's the problem. Looking inside the bolt hole with a flashlight it appears as if the now missing bolt took with it the threads needed to keep it in place. Does this mount onto the engine block? Hopefully when the new bolts arrive I can simply replace the missing bolt and nothing more needs to be done. But has anyone run into a similar problem with threads damaged in such a location?
I have not had this happen. Yes, these bolts do thread directly into the case. To be certain of the condition of the threads. I would remove the alternator and verify the condition of the threads. The alternator is easily removed while the bike is on the centerstand or rear paddock stand. It is easier if you remove the clutch slave cylinder first.
Fred
If the threads are stripped out then we can repair it with a Heli-coil like product. Hopefully just a missing bolt.
Quote from: fjbiker84 on April 17, 2017, 04:28:00 PM
Looking inside the bolt hole with a flashlight it appears as if the now missing bolt took with it the threads needed to keep it in place.
If you haven't cleaned out the threads yet, they may be plugged up with grime. If you have/or can find a small "bottle brush" try and clean them first. Then get the proper size tap and dress the threads to clean out any other grit. Use a little oil on the tap to help it along. When you get the replacement bolt test it out first and if it's obvious or you suspect the threads are damaged then you can go the insert route. Just a quick check that might save you some time/money.
Be careful that the old bolt did not snap from overtorquing from a PO then unthread itself. If your new bolt bottoms out, well you know the story from there....
Thanks for the input. I'll know more in a week or so when the new bolts come in the mail. I am a little concerned that the old bolt sheered off and that's why I can see any threads. Not sure how deep the bolt is supposed to be. I know the previous owner and will ask him if he ever took the generator off but if I had to guess I'd say this is original factory installation. Will update this when the parts come in.
Got my new generator mounting bolts in the mail today. Unfortunately, what this shows is that the bolt broke off at the point where the threads start. Since that is the case, it would seem to me there shouldn't be that much pressure on the threaded part of the bolt that is remaining. The bolt is only supposed to be installed with 14 ft lbs of torque (I did confirm that the PO never removed the generator) and all of that pressure would be on the head. Going to try to unscrew broken bolt with a screwdriver or something? Will follow up on this after I have a chance to work on it tomorrow.
A good set of Left handed drill bits can actually spin a broken stud out. I have had to do it before on other things.
Fred
Quote from: aviationfred on April 24, 2017, 09:26:01 PM
A good set of Left handed drill bits can actually spin a broken stud out. I have had to do it before on other things.
Fred
Never knew you could get left hand drill bits, ( good job its not April 1st ).
A set ordered for the shed
Thanks Phil
I was not aware there were drill bits like that. I'll check the hardware store for a left handed bit that will reach. Thanks!
The left handed drill bits will still drill a hole in the stud if it has any torque remaining. That should not be an issue. A good quality EZ out should do the trick
Fred
The broken alternator bolt is all too common on the FJ1100 - which is probably why Yamaha FJ1200 bikes have three bolts instead of two. The broken bolt will probably come out easily like mind did.
Good luck!
J
Quote from: fjbiker84 on April 25, 2017, 06:36:28 AM
I was not aware there were drill bits like that. I'll check the hardware store for a left handed bit that will reach. Thanks!
Harbor Freight sells a set of left twist bits with EZ-out. THROW THE EZ-OUTS AWAY - preferably in a garbage can outside the door is the store! Then take the drill bits home. A broken EZ-out is not a fun problem to add to the middle of your broken bolt. I think I'm 2 for 3 for breaking off EZ-outs -- takes me a while to learn sometimes...
Use a good penetrating oil with the left twist bits. If you can, center punch the broken bolt so the drill bit will stay centered as you start to drill. Start small and work your way up. The heat and torque from the drilling helps break free the broken bolt. In my experience I usually work up to a drill bit nearly the size of the broken bolt (why it's so important to be centered!) before the edge of the bit will "bite into" the remaining metal and back it out. First time I tried it I was about to give up on the "whole stupid idea" in frustration - then then the drill "bit in" and spun it free like butter. I became an instant convert and threw away the easy outs!
Well, I went to the local hardware store and bought a bit with left twist that the salesman said would do the job. Problem is I can't get at the broken bolt without taking off the generator. And that's the problem...... the remaining bolt is frozen. I pretty much stripped the bolt trying to get it off. So then took off the tank and carbs to get at it with my vice grips but even that wouldn't work - they slipped because there is very little clearance above the generator. Maybe I can ride this thing to the WCR as is and get help there? :Facepalm:
Bring it to my house, we will get it fixed.
Can you reach in there with a Dremel with a cutting disc to cut a slot into the head of the frozen bolt?
That way you could use an inpact driver with a straight screw driver bit to fit the slot.
If not, you will have to reverse drill the frozen bolt.
To help unfreeze the bolt, some penetrating oil and heat on where the case threads are located will help.
This is now several times (over the years) where I have heard of the 2 bolt mount generators breaking the bolts.
I wonder if a bolt upgrade to a SAE 10.9 would be a good idea?
Mark, thanks for the offer! This weekend looks good weather-wise. Would you be available Saturday or Sunday?
PM sent.
Quote from: Pat Conlon on April 25, 2017, 08:31:56 PM
Can you reach in there with a Dremel with a cutting disc to cut a slot into the head of the frozen bolt?
That way you could use an inpact driver with a straight screw driver bit to fit the slot.
If not, you will have to reverse drill the frozen bolt.
To help unfreeze the bolt, some penetrating oil and heat on where the case threads are located will help.
This is now several times (over the years) where I have heard of the 2 bolt mount generators breaking the bolts.
I wonder if a bolt upgrade to a SAE 10.9 would be a good idea?
I replaced my broken bolt with a hardened one and tightened it 'just snug' using a dab of low strength Loctite. It's still there after over 2 decades.
Quote from: Dads_FJ on April 26, 2017, 07:24:03 AM
I replaced my broken bolt with a hardened one and tightened it 'just snug' using a dab of low strength Loctite. It's still there after over 2 decades.
Yes, I second that, high tensile bolt and don't over tighten. I wouldn't bother with loctite but it can't hurt either.
IMO
Noel
That broken bolt should twist right out.
Any stress on the threads would have been relieved when the shoulder of the bolt broke off.
Try some heat on the other stuck bolt. Or, you could possibly drill the head off of it and it should twist out like the broken bolt (assuming there's no aggressive thread locker on the bolts)
Quote from: fjbiker84 on April 25, 2017, 07:59:52 PM
...... the remaining bolt is frozen. I pretty much stripped the bolt trying to get it off.
Did you strip the threads (bolt turns but won't come out) or did you round off the head of the bolt? I'm guessing that you meant the latter. I will also guess that this was caused by using a 12-point socket...
Tip 1: Never use (buy) 12-point sockets; they just don't have the gripping power of a 6-point socket.
Tip 2: I always spread a dab of anti-seize compound on any bolt (and sparkplug) that threads into aluminum. This prevents seized bolts. No, it will not cause the bolts to loosen in use.
Tip 3: For some reason (cost?), Yamaha really liked using low-strength bolts on the FJ's. Going stronger (12.9) won't hurt a thing.
Tip 4: You can buy pretty much any bolt you want... metric, high-strength, hex-head, flanged hex-head, socket-head, silver or black, any length... from McMaster.com Their online catalog is awesome.
Tip 5: NEVER use those damn Easy-Outs. They will only wedge themselves into the hole you drilled and then snap off. Then you're REALLY screwed. Left-hand drill is the best method, with patience, penetrating oil, heat and patience; I've never had one not work.
Tip 6: It's been said before but to repeat... the "phillips-head" screws on Japanese bikes are NOT phillips-head. They are JIS-head screws. They are NOT the same. Do yourself a huge favor and buy the nice #1, #2 & #3 JIS screwdrivers from McMaster. A touch pricey, but you won't believe how much better they work.
Good luck with that lower bolt.
Bill
+ 1.
All solid advice. Use at your own risk :drinks:
I rounded off the head of the remaining bolt. I did use a six point socket and tapped it in place to make sure it was completely seated but still didn't work. I'm was thinking that the easiest thing may be to just break off the head of this bolt in order to remove the generator. Once that is off I think there will be room to use a reverse drill bit. Will update this on how it worked out.
Just a word of caution and Murphy's Law. You are getting close to the FJ Rally Cardinal Rule...
No Major Repairs or Modifications within 30 days prior to the Rally you are planning to attend.
If there are no issues with the operation of the alternator, you may want to consider leaving it as is until after the WCR.
For those with more knowledge of the early FJ's with the 2 bolt alternators. Please chime in if my advise is wrong and having 2 bolts securing the alternator is a critical function
Fred
I have LH drill bits if you don't get to it by Sunday. And a Dremal, impact driver (air and hammer), and maybe a few new swear words to add to your vocabulary. And the coffee you mentioned.
Quote from: CutterBill on April 27, 2017, 06:54:49 PM
Tip 2: I always spread a dab of anti-seize compound on any bolt (and sparkplug) that threads into aluminum. This prevents seized bolts. No, it will not cause the bolts to loosen in use.
Bill
No....Quote from: racerrad8 on October 10, 2016, 01:57:07 PM
...As far as the lubricants, they are a no-no, at least with NGK plugs: https://www.ngksparkplugs.com/about-ngk/spark-plug-101/5-things-you-should-know-about-spark-plugs (https://www.ngksparkplugs.com/about-ngk/spark-plug-101/5-things-you-should-know-about-spark-plugs)
The problem I see with anti-seize is as the combustion temps are enough to carbonize the oil of the anti-seize, the only thing left in the threads is the powered metal component. That then galls the threads on the way out, pulling the weaker aluminum from the head.
Randy - RPM
Quote from: simi_ed on April 27, 2017, 08:00:40 PM
+ 1.
All :mocking: Mostly solid advice. Use at your own risk :drinks:
Quote from: CutterBill on Yesterday at 03:54:49 PM
Tip 2: I always spread a dab of anti-seize compound on any bolt (and sparkplug) that threads into aluminum. This prevents seized bolts. No, it will not cause the bolts to loosen in use.
Bill
No....
Quote from: racerrad8 on October 10, 2016, 10:57:07 AM
...As far as the lubricants, they are a no-no, at least with NGK plugs: https://www.ngksparkplugs.com/about-ngk/spark-plug-101/5-things-you-should-know-about-spark-plugs (https://www.ngksparkplugs.com/about-ngk/spark-plug-101/5-things-you-should-know-about-spark-plugs)
The problem I see with anti-seize is as the combustion temps are enough to carbonize the oil of the anti-seize, the only thing left in the threads is the powered metal component. That then galls the threads on the way out, pulling the weaker aluminum from the head.
Randy - RPM
====
I also have used anti-sieze or grease on my sparkplugs for years, without any issue. I still think Bill is offering sound advice, but I will defer to the experts from RPM and NGK.
Ed
I used high temperature Permatex Anti-Seize on the sparkplugs of my '85 and had the exact problem that Randy described.
One day when pulling the plugs for a valve check, it seemed like they were stuck in some kind of gooey muck. It required quite a bit of force to unscrew them, but I took my time (and even sprayed some WD-40) and slowly they came out.
Then, as I was cleaning the dried anti-seize off of them, I noticed there was aluminum in the threads of the #2 plug. Sure enough, I unpeeled the cylinder threads right off of the plug. That incident lead to the discovery of Time-Serts. I managed to clean the a/s off of my '93 before it caused any problems.
Now I just give sparkplugs a quick shot of WD-40 and install them.
Maybe if you change your plugs often and reapply then it's not a problem, but my experience says to stick with Randy's advice.
Sorry for the thread jack...
We fixed two spark plug holes yesterday in a guys race car.
He brought the car over to adjust the valves. We went to remove the plugs and two pulled the threads. He went on to tell me he "always" uses anti-seize on the spark plugs.
That makes six so far this year I have had to heli-coil, I usually do 25-30 a year. I do so many I bought a kit specifically for the spark plug repair that dies not require the use of a drill. The "tap" is a two step ream & tap combined. I have a fitting I put in the intake manifold, I open the intake valves and pump in a few pounds of air. The chips fly out of the hole as I am tapping it.
The tool has a stop to ensure the heli-coil insert is not installed too deep into the hole and extending into the combustion chamber.
The spark plug holes are almost as often as the drain plug in the oil pan, we probably forty or more of those per year.
A least once they are heli-coiled they never strip out again...
Randy - RPM
Quote from: racerrad8 on April 29, 2017, 04:37:26 PM
.....We went to remove the plugs and two pulled the threads. He went on to tell me he "always" uses anti-seize on the spark plugs.
......The spark plug holes are almost as often as the drain plug in the oil pan, we probably forty or more of those per year.
Randy - RPM
This is at odds with everything I was taught, everything I learned, everything I've practiced and everything I've experienced in a lifetime as a mechanic.
I actually read that NGK link and other than saying anti seize is not needed, the only warning it mentioned against using it is the risk of over tightening and I can't help but feel that may be the root of the problem, not the anti seize itself.
The greater number of sump plugs to spark plugs Randy mentions repairing (which is actually even higher number given the 4:1 ratio of spark plugs to sump plugs per engine) is telling. Sump plugs are metal to metal and refitted
without anti seize and yet these get stripped at 4 times the rate of spark plugs. I suspect torqure is relative to the fear of them falling out and that leads owners to over tighten them "just to make sure"
Randy's observation in itself suggests anti seize if not the problem, but over tightening. One thing I have observed over the years is chronic over tightening of plugs by owners. Torque being determined by importance. Wheel nuts for example, can't have the wheels falling off, tighten the living daylights out of them, can't have the sump plug falls out, tighten........, can't have the plugs flying out, tighten.... with no concern for diameter, thread, depth or materials, just tighten the shit out everything.
Although the FJ plug has a long engagement, the fine, shallow pitch going into aluminium makes it easy to strip and unforgiving for ham fisted DIYer's.
There is also the issue of using the right product.
Closer to home, I recently removed the plugs from my own bike after 50,000km (at least) After a light 1/4 turn with a spanner, not even a "crack", I spun them out with my finger tips, the threads still have AS on them, wet.
Other than crediting Hooli with more sense than to over tighten, I can't offer any suggestion as to what might have happened with his misfortune, but it is not something I have ever experienced. Sure, I've pulled plenty of threads over the years, but they were all dry and corroded, that's what happens when you put steel bolts into aluminium.
It is interesting that NGK did acknowledge the need for a "release agent"
Just another opinion and some one else's' experience into the mix.
Noel
Quote from: FJ_Hooligan on April 29, 2017, 08:29:16 AM
...Then, as I was cleaning the dried anti-seize off of them, I noticed there was aluminum in the threads of the #2 plug. Sure enough, I unpeeled the cylinder threads right off of the plug.
Interesting. Now I'll tell my story...
Back in the days of the Red Dog Saloon, I owned an auto repair shop. I had 3 full-time mechanics and a summer-time helper. We were busy. It was common to have 30-40 cars in the back, waiting to be worked on. Needless to say, we changed a LOT of spark plugs. (This was before the use of unleaded gas and 100,000 mile spark plugs.) We worked on pretty much everything, with a lot of aluminum heads. Porsche, Mercedes, a thousand VW's, Japanese stuff, American stuff... One of my mechanics owned a Formula Ford race car so that was in the mix. And we always used Permatex High-Temp Anti-Seize on any spark plug that went into an aluminum head. And not once in the 7 years that I owned the shop did we have a problem with the anti-seize. I also used it on exhaust systems, which get a whole lot hotter than a cylinder head. Four or more years later when the exhaust system had to come back apart, the nut and bolts simply unscrewed. They looked so good that they could be reused. And even at the crazy high temps that exhaust systems run at, I never saw any evidence of the anti-seize breaking down.
Aircraft exhaust systems commonly have slip joints. This is so that the pieces of pipe can expand and contract without undue stress. The joint is a rather snug male-female type with no clamps. I use the same anti-seize on these joints when I put them together. And I have taken them apart years later, and the pipes just slip apart with no galling or rust. And to explain further, some aircraft exhaust systems (usually with turbos) are made of Inconel because they run so hot that normal stainless steel won't hold up. And I have never had or even heard of a problem with anti-seize.
Did you know that we are required to use anti-seize on airplane spark plugs? But this may not be a direct apples-to-apples comparison because all aircraft heads have heli-coils installed. But no one ever worries about the anti-seize breaking down.
Backing up a bit... I got my first motorcycle (a well-used Honda CL350) when I was 15. I didn't know
anything about turning wrenches. The spark plugs were so tight that they would squeak coming out. The local Yamaha shop owner (good guy, took me under his wing) told me about using anti-seize. And I have used it on every bike since. so... 48 years. Forty-eight years of using Permatex Anti-Seize on motorcycles, cars, boats and even airplanes... and I never, not once, had a problem. Now Hooligan, I'm not saying that your experience didn't happen. But do I have an idea why...
Obviously, the anti-seize did not dissolve the threads. And I don't believe that you stripped the head threads when you loosened the plugs. Aluminum threads wrapped around the spark plug is the classic symptom of an over-tightened plug. But you didn't over-tighten it, so how did the threads pull out?
First, it's important to realize that heat is a really bad thing for aluminum. Aluminum gets weaker as the temperature goes up. By 400 degrees (F) it has lost
half of it strength. And it's really easy to hit 400 degrees. I know this because airplane engines, being air-cooled, have no water temp gauge, so a cylinder head temperature (CHT) gauge is installed in the instrument panel. And on warm days or slow speed we watch that gauge like a hawk. When an engine overhaul costs around $25,000, you tend to pay attention to such things. And it's alarming to see how easy it is to reach the 350-degree maximum. (I think it would be really interesting to put a CHT gauge on an FJ.)
I believe that you applied anti-seize to the spark plugs and carefully tightened them to the recommended torque value. But because anti-seize is such a good lubricant, you actually tensioned the plugs too much. (Hence, the warning on the NGK website that Randy referred to.) So now the plugs were too tight, but the aluminum threads held just fine... when the engine was cold. Then you rode the bike and, somewhere... summer, stop-and-go traffic, high-speed... the engine got hot. Really hot...
Once it got really hot, probably 400 or higher, the aluminum became much weaker. The plug still had tension on it. So now you had a plug with the proper torque, but too much tension, threaded into aluminum that got weaker as the temp went up. Finally, the tension was more than the weak aluminum could withstand, and the threads sheared off. But the plug didn't pop out because the sheared threads jammed the plug in the head. Later, you unscrewed the plug (with great difficulty) and the threads came out with it.
Sorry for your troubles.
Anti-seize is good stuff, but you need to have a very light touch with the wrenches when you use it.
Bill
With the considerable help and expertise at the FJMonkey Garage we were able to extract the one remaining bolt and then gain access to the broken off bolt. Mark was able to unscrew the broken bolt by hand with a sharp screwdriver. The remaining bolt was in very tightly so I'm assuming it is a combination of being installed too tight (by the factory) and 33 years of aging. One problem we noticed while reassembling everything was that approximately half of the surface around the bolt hole was cracked and that piece of metal actually came off. Mark was able to "glue" this piece back in place with a gasket sealant compound (I think that's what he said he was using) such that the generator could then be reinstalled and the flange would have a flat surface to secure to. Clearly, the broken bolt must have been way over tighten also. Many thanks to FJMonkey for his help today with this and, in addition, teaching me how to adjust the valves, properly clean and oil the pod filter, and do other maintenance - he also synced the carbs - which is something I'll leave to a pro!
This is the broken off bolt that Mark removed.
Today was a great example of "I would rather be Lucky than Good". The alternator bolt broke loose with a 6 point socket (a few hits with a hammer to seat it). Way harder to turn than a bolt that size should be. I did not see any evidence of thread lock but clear signs of corrosion. Then when figuring out how to hit the broken stud with a center punch, it moved. Grabbed a pick and the stud just backed right out. I thought the worst after the difficulty with the corrosion of the upper bolt. Cleaned up some over oiled UNI pods and reinstalled. Checked the valves just cuz we nearly had it all apart anyway. Found some out of spec gaps and made the corrections. A quick balance of the carbs and adjust idle and we wrapped it up. I enjoyed the day and the company.
Tim, post the picture of the part of the boss that broke off for Randy to see. I only used blue lock-tite paste to hold in place so the alternator flange did not get any funky side loading. It will fall off next time the alternator is removed. Maybe some JB weld when there is time for it to cure.
way to go Monkey , you are a fine example of the FJ group. always there to help somebody out. :good2:
Yea, good on ya Mark :good2:
Unfortunately I didn't take a picture of the little piece of metal that broke off. If you look closely at the bolt hole you can see that the left half of the metal surface is where the piece broke from. I would think in the future if it became necessary I could grind down the metal around that hole and use a small washer was a shim.
I forgot to mention that Tim's engine runs very quiet. I was a bit shocked because he has stock pipes, so little noise from exhaust. No starter chain rattle or the other "I am talking to you" noises from the engine. Aside from the age of plastics it is clear that the PO took very good care of his FJ. Tim is doing the same and keeping the '84 alive and strong.
Quote from: ribbert on April 30, 2017, 07:18:20 AM
Quote from: racerrad8 on April 29, 2017, 04:37:26 PM
.....We went to remove the plugs and two pulled the threads. He went on to tell me he "always" uses anti-seize on the spark plugs.
......The spark plug holes are almost as often as the drain plug in the oil pan, we probably forty or more of those per year.
Randy - RPM
The greater number of sump plugs to spark plugs Randy mentions repairing (which is actually even higher number given the 4:1 ratio of spark plugs to sump plugs per engine) is telling. Sump plugs are metal to metal and refitted without anti seize and yet these get stripped at 4 times the rate of spark plugs. I suspect torqure is relative to the fear of them falling out and that leads owners to over tighten them "just to make sure"
Noel
Actually I chalk up the oil pan stripped thread to the 80% thread engagement of the oil pan threads and the fact in the race car some people change their oil after every race day/night. If it comes in & out 2-4 time a month the aluminum is going to fail. Plus people very seldom replace the oil plug gasket...
Plus the torque value Yamaha has on the plug which is double of the spark plugs.
I only use the Heli-Coil so the oil can still drain through the insert. Other solid inserts leave 3/4" of dirty oil in the pan.
(http://i1215.photobucket.com/albums/cc517/racerrad8/003_zpscc5437e6.jpg~original) (http://s1215.photobucket.com/user/racerrad8/media/003_zpscc5437e6.jpg.html)
(http://i1215.photobucket.com/albums/cc517/racerrad8/002_zps4ba10310.jpg~original) (http://s1215.photobucket.com/user/racerrad8/media/002_zps4ba10310.jpg.html)
That's my opinion based on
everything I was taught, everything I learned, everything I've practiced and everything I've experienced in a lifetime as a mechanic. As well as working basically solely on the FJ lump for the past 23 years and not just my personal bike.
Randy - RPM
Quote from: racerrad8 on May 02, 2017, 07:13:58 PM
(http://i1215.photobucket.com/albums/cc517/racerrad8/002_zps4ba10310.jpg~original) (http://s1215.photobucket.com/user/racerrad8/media/002_zps4ba10310.jpg.html)
Randy,
Do you snip the coils off after installation?
Thanks,
Jeff
Quote from: jscgdunn on May 04, 2017, 10:11:30 AM
Randy,
Do you snip the coils off after installation?
Thanks,
Jeff
No, the spiral heli-coil allows the oil to drain through. I will snap a photo of the next one I heli-coil.
Don't let me forget...
Randy - RPM
Randy, if you don't cut the coils, what am I looking at in the picture?
A trimmed Time-Sert?
Quote from: Pat Conlon on May 04, 2017, 05:41:17 PM
Randy, if you don't cut the coils, what am I looking at in the picture?
A trimmed Time-Sert?
A stock pan
Here is one with a the heli-coil installed.
I took one with a light showing through the gap in the heli-coil.
Randy - RPM
Thanks got it!
I got an email last night from the guy with the two XJR1300's in SoCal. He pulled the #4 plug and the threads galled at the very top.
So, since all of the threads did not gall, how does one explain the galling of the upper threads?
Randy - RPM
Quote from: racerrad8 on May 25, 2017, 10:32:48 AM
I got an email last night from the guy with the two XJR1300's in SoCal. He pulled the #4 plug and the threads galled at the very top.
So, since all of the threads did not gall, how does one explain the galling of the upper threads?
Randy - RPM
My initial thoughts from looking at the photo is.... Possibly at some time in the past. The #4 spark plug was cross threaded and damaged the upper threads in the head. The offending plug was removed and the threads cleaned up. I new plug was installed and threaded in ok and gripped well enough on the lower threads. Just a WAG actually.
Fred
Quote from: aviationfred on May 25, 2017, 10:40:28 AM
My initial thoughts from looking at the photo is.... Possibly at some time in the past. The #4 spark plug was cross threaded and damaged the upper threads in the head. The offending plug was removed and the threads cleaned up. I new plug was installed and threaded in ok and gripped well enough on the lower threads. Just a WAG actually.
Fred
I deleted the photo somehow from my phone last night. It was kind of fuzzy, but there were indications the aluminum galled into the end of threads as he removed it. He said it took a bunch of effort to remove and the new plug will not start into the head.
The other three plugs came in & out just fine.
Randy - RPM
Quote from: racerrad8 on May 25, 2017, 10:32:48 AM
how does one explain the galling of the upper threads?
If they galled evenly, you'd have perfect mating of the lands and grooves for the entire time with even pressure everywhere... I've never seen this happen and the galling is a bit random depending on where the load is or where it is hottest. The upper threads make it sound like a bit of an off-spec (too wide spacing?) hole loaded up the upper end and caused the galling.
Then again, wtf do I know...
Frank
Quote from: aviationfred on May 25, 2017, 10:40:28 AM
Quote from: racerrad8 on May 25, 2017, 10:32:48 AM
I got an email last night from the guy with the two XJR1300's in SoCal. He pulled the #4 plug and the threads galled at the very top.
So, since all of the threads did not gall, how does one explain the galling of the upper threads?
Randy - RPM
My initial thoughts from looking at the photo is.... Possibly at some time in the past. The #4 spark plug was cross threaded and damaged the upper threads in the head. The offending plug was removed and the threads cleaned up. I new plug was installed and threaded in ok and gripped well enough on the lower threads. Just a WAG actually.
Fred
Occam's Razor... we have a winner.
Frank
Quote from: racerrad8 on May 25, 2017, 10:32:48 AM
I got an email last night from the guy with the two XJR1300's in SoCal. He pulled the #4 plug and the threads galled at the very top.
So, since all of the threads did not gall, how does one explain the galling of the upper threads?
Randy - RPM
He installed his spark plug upside down?
:Facepalm: