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Workshop => Engine and Bottom End => Topic started by: evaneyeball on June 14, 2020, 05:05:07 PM
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So on my new build I rode it yesterday and I had my plug back out a little i wasn't worried about it I just figured that the powder coat under the plug that was pushing it out. I dont think it sucked anything in because it was barely out it was just not snug anymore. But then today we went for a small ride not anything crazy just playing and I got back (my brake line broke) and looked it over and it had happened again so I read up and I found that it might be detonation but at this octane and with the different jets I ran yesterday and today( I swapped them to fatter yesterday when it happened then I went back and it happened today) so I dont think it was detonation unless my timing is messed up wich arlan set the timing so I dont think it was that. Or it could be that the threads in the head are loose and now that I'm thinking about it the old plug that came in it had some loctite on it so I'm thinking that if it's not detonation then it's probably the head. That head wasn't going to last anyhow but do you think that that is the problem? I have pictures of the threads I will post soon
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And when I first noticed it today the plug was still actually tight but there was some black residue around it so I think that those threads are bad. It did have a new plug in. These are pictures of the first time
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Show us many views of the spark plug porcelain tip, center electrode, ground strap, and a well lite view of the porcelain from top to bottom. Show us a view of the top of the piston with it at TDC. Show us a view of the combustion chamber and squish band of the head.
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I haven't taken the head off and dont plan to this weekend im still at the dunes but I am going to call arlan tomorrow and can go take more pictures.
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These are the pictures I can take right now
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Any opinions? I just want to know how screwed I am
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Start by carefully & completely removing all the powdercoat from the plug seat area. It looks like some of it is ready to break off & fall into your fresh cylinder... After getting that cleaned up put in a fresh plug & get it seated properly & take it for a test ride.
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I did remove most of the powder coat after the first time. The pictures were taken the first time. And when I thread it in about half way it is super loose like you can pull it up and down and side to side. If that makes sense.
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Im having this issue in one of my Rs and my sons RM85 too. maybe Im just not getting the plugs tight enough. Running 112 race fuel
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You need to tighten the new plug well, to crush the washer. Make sure the threads in the head are good too.
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I would recommend looking up the torque spec for the plug and tighten it to that spec. Probably going to be in the 10-15 ftlb area. I have never had a plug back out, but as a young man I stripped a few out lol. Your plug should not rock back and forth in the threads or move up and down. Sounds like the threads are compromised and you may need to either get another head or get a helicoil kit for the head.
Loren
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I just looked at my manual! Spark plug torque is 15-20 nm or 11-14ftlb. It may seem silly to torque a spark plug, but the reason I do is it eliminates the possibility of ruining the threads or in your case the plug backing out. I also torque the oil drain plug for the same reason. It protects the aluminum threads and reduces the risk of oil leakage.
Loren
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I do plan on calling Arlan today but I do think that those threads are screwed up and the dome part is also screwed up but I will call arlan
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plug blowing out could be a sigh of detonation. hopefully just junky threads
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I think it's a mix of junky threads and mabey detonation because I dont know what compression I have
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I dont know how it could be detonation because I'm running straight 110 and by the looks of the plug its rich. Mabey a bad cdi and have jacked up timing? When I get home I'll do a compression test.
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I have a shit ton of compression and am running 110 octane. Don't listen to the snake oil salesman on the other site! 15.5:1 is my compression ratio and 13.5:1 is what my kids are running on 92 octane.
What ignition are you using? Do you have adjustable timing? What does Arlen say?
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I haven't called him yet but I am running completely stock ignition I dont know what year though and the only other thing is a Ricky stator reg/rec. And I'm not quite home to do a compression check
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You cranking compression doesn't give you the compression ratio. I had a cylinder that had 225 cranking compression, but was 17.5:1 ratio. My cylinder now has 225 and 15.5:1. So it will give you an idea of what fuel you need, but won't be exact.
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How do I find the compression ratio?
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Plug doesn't look like there is detonation going on. The threads don't look great on the head. Make sure the boss on the head is flat and is a good surface to seal against.
Tighten up. Run a heat cycle and resnug
Is that a new plug. Threads are really dirty. Maybe from blowby?
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That is a brand new plug only ran for break in and the grit on the plug is from the blow by. And in better light I found that the powder that I took off wasn't all of it so I took and put the plug in just a few threads and took a razor blade and scraped it off to bare metal. It was a chrome base powder so i thought it was just metal right there.
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I scraped it off and put a new plug in and gapped it to
.019
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One you get the engine up to temp, turn it off and recheck the torque.
Watch your water temps with that powder coated head. Looks great, but it does act as an insulator.
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Yeah while I was riding it it didnt over heat and the way we ride isnt very fast but constantly on and off the gas wich builds up alot of heat. I DIDNT do this until a whole nother riding day after break in was done. I also am looking to get a inline coolant temp guage. I am not too worried about the powder coat being an issue because if it gets too hot it falls off and I cound this out when my dad powder coated his pipe on a outlaw and it immediately flaked off. So my cylinder is running pretty cool and IMO. Not that the powder coating isnt insulating but I'm not too worried about that being an issue because if it was insulating it too much and was over heating it it would have already flaked off. But you are right and I should keep an eye on it.
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On the in-line temp thing - I swapped the ESR gauge on the 363 for a Trail Tech TTO (https://www.trailtech.net/tto-1 for like $50 with inline fitting). Having the gauge on the bars is so much easier to monitor, especially for newer riders who are usually riding that bike anyways. They come with zip ties and 3M sticky film. I sourced a boating registration clamp and recruited Pete to machine it down for me. Came out pretty clean.
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These are the pictures I can take right now
This is what I see looking at the spark plugs. on Reply #4 on: June 14, 2020, 07:04:14 PM
Pictures 1,2,3:
The first 3 pictures show the spark plug is operating at too low of a temperature too keep the center electrode and porcelain burned off and clean. The steel shell that occupies the area that is about 2mm long below the last thread and the surface the ground strap is welded to, is also running too cold. This shell area should be scorched, blackened or be dry with soot or carbon when the combustion temperature is in the the range of a well tuned carburetor and riden aggressively. Some possible causes for this low steel shell and porcelain operating temperature could be due to one or a combination of the following:
1. Low shell temperature is usually an indication of low combustion temperature and or very brief periods of full throttle.
2. The circuit in the carburetor is very rich in the throttle positions where the engine spent most of it's time running.
3. Periods of wide open throttle are too short and or there is too much time elapsed between periods of wide open throttle.
4. We cannot evaluate the heat range at this point because the shell is running ice cold. A hotter heat range spark plug will raise the operating temperature of the porcelain to keep the porcelain a little cleaner for the current carburetor tune, and riding style that this spark plug experienced. A hotter heat range plug will not change the operating temperature of the shell area below the threads or the area where the ground strap is welded to the shell.
Picture 4 indicates the spark plug sealing washer was sitting on an uneven surface. One side of the sealing surface of the washer is flat while the other side is still round. I would remove the sealing washer from the threads and screw the plug into the head only finger tight and look at the sealing surface on the head and the plug base to determine if the threads and head sealing surface are 90 deg. to each other.
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Every about the wide open throttle is true. That is just my riding style. I generally play around in the tall grass at the dunes and twisting and turning in between going pretty slow some times and very fast other times. And very short blips of WOT and needing sudden power. And it was actually running pretty cold just in general. After about 20 minutes of riding and shutting it off I could almost touch the cylinder. I didnt start riding like this until I had pur a whole day of. Normal people riding riding after break I was done