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Soot at oil fill plug

ShawninPA

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Dec 6, 2022
Messages
8
Changed my oil at 100 miles (for a magnetic drain plug) and at the filler plug there was black soot/oil build up at the edge. Why? Pressure in the crankcase is coming out there, an area with a tight plug with an o ring. On a car engine the pcv valve would stick shut to cause pressure to escape somewhere else. Is there something similar on this engine that I need to look into? I assume there is, just dont know where.

Also, I ordered a service manual from Helm, website said "in stock". Paid for the next level of shipping, expected it in 10 business days. Nope. So I call and the lady says "in stock means publish on demand, 6-8 weeks" Hmm.
 

dmonkey

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Jul 4, 2021
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The crankcase vents up to the airbox. How is your oil level? Any oil in the airbox? You can check the sight glass hanging out the bottom of the airbox, and squeeze the drip tube to check for fluid.
How tight is the filler plug, and is the o-ring in good shape? If you tighten it too much the o-ring can deform and cause a worse seal than being gently seated.
 

ShawninPA

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Dec 6, 2022
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Thanks for the info. Oil level was/is fine, checked it every ride, center stand, front wheel touching the floor, checking with not screwing in the dipstick. Got the airbox open, not a bit of oil in there, dry as a bone. I disconnected crankcase breather hose at the airbox, had the fill plug just sitting in its place, blew in the hose and the filler plug flew off, so, no obstruction there. Then I ran a pipe cleaner into the airbox nozzle (where the hose connects) no restrictions there. The only thing I didnt check is the inlet to the airbox, under the rack, hmm. Bike runs fine though, cant be that.

I did note that it seems when the filler plug, when installed it makes contact with the base of the plug before I feel any resistance from the rubber o-ring ( a nice fat round o-ring) I wonder if the only seal is at the base of the filler plug and the o-ring is not making proper contact to do it's job? I think I saw mention of aftermarket fancy plugs, dont want fancy, just functional, I'll take fancy though.

No big deal, something to think about, I was just worried about overpressure in the crankcase, there isnt.

After a DL1000 Vstrom (sold that), I have a pristene 2006 Shadow Aero I picked up for a song (what a dog compared to the Vee), and now this thing called a Trail 125, I like riding it more than anything. Just putt around the back roads in southern Lancaster county PA. Eventualy I'll make my way to some trails, I used to dirt bike, a lot. My 1969 Z50A, restored it last winter (my boy had it when he was 5, he's 30 now), I just put around the yard on that, my dogs chasing me.

Love them Honda's
 

dmonkey

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If you clean the soot, does it return? If some oil dribbled during the oil change it could have picked up road grime and dirt making it look like soot there. I wouldn't expect a dealer to be much help with something that could be considered trivial since it's not losing measurable oil, but it's worth trying. At the least you'll learn if your local dealership has a helpful service department or not.
 

Shoot870p

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Joined
Dec 16, 2021
Messages
441
Shawn, post some pictures of that 50!
You are in some pretty country right there.should make for great riding.
 

James

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Joined
Dec 8, 2021
Messages
22
Location
Jacksonville, FL
Thanks for the info. Oil level was/is fine, checked it every ride, center stand, front wheel touching the floor, checking with not screwing in the dipstick. Got the airbox open, not a bit of oil in there, dry as a bone. I disconnected crankcase breather hose at the airbox, had the fill plug just sitting in its place, blew in the hose and the filler plug flew off, so, no obstruction there. Then I ran a pipe cleaner into the airbox nozzle (where the hose connects) no restrictions there. The only thing I didnt check is the inlet to the airbox, under the rack, hmm. Bike runs fine though, cant be that.

I did note that it seems when the filler plug, when installed it makes contact with the base of the plug before I feel any resistance from the rubber o-ring ( a nice fat round o-ring) I wonder if the only seal is at the base of the filler plug and the o-ring is not making proper contact to do it's job? I think I saw mention of aftermarket fancy plugs, dont want fancy, just functional, I'll take fancy though.

No big deal, something to think about, I was just worried about overpressure in the crankcase, there isnt.

After a DL1000 Vstrom (sold that), I have a pristene 2006 Shadow Aero I picked up for a song (what a dog compared to the Vee), and now this thing called a Trail 125, I like riding it more than anything. Just putt around the back roads in southern Lancaster county PA. Eventualy I'll make my way to some trails, I used to dirt bike, a lot. My 1969 Z50A, restored it last winter (my boy had it when he was 5, he's 30 now), I just put around the yard on that, my dogs chasing me.

Love them Honda's
I have noticed the same SOOT on my filler and dipstick plug , it is only towards the front of the bike. I believe it is from the exhaust pipe. Black soot coming off the hot pipe.
my theory anyway.
 

SneakyDingo

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Aug 6, 2021
Messages
1,560
I ordered a service manual from Helm, website said "in stock". Paid for the next level of shipping, expected it in 10 business days. Nope. So I call and the lady says "in stock means publish on demand, 6-8 weeks" Hmm.
We have online versions of the service manual as well if you're looking for something in the meantime.

 

poole.92

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Joined
Dec 24, 2022
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2
Location
Australia NSW
I've noticed the same thing. Noticed it within 50km of my brand new bike. Soot looking substance at the very front of the oil cap. I do not feel it is exhaust related as it's fairly clear that it's originating from the oil cap. I didn't take a picture before I washed it off but I'll keep an eye and post a photo when I can
 

SneakyDingo

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Aug 6, 2021
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You can see it on mine in the maintenance photos.

 

chan2565

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May 12, 2022
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23
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Raleigh, NC
I have the same on mine ~500 miles. I was also wondering about it, but it doesn't seem like a big leak if at all. Maybe a little bit came off the dipstick as I was checking the oil? Not sure.
 

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m in sc

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Feb 2, 2021
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Rockhill, SC
mine does that as well, always has. i think its just a shitty fit on the cap. same on the dipstick to be honest.
 

ShawninPA

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Dec 6, 2022
Messages
8
Wow, several with the same soot, and at the front, like mine. Mine is just at the filler cap. I agree its maybe just a bad seal. I'm not worried about it. I put about 40 miles on it since the 100 mile oil change, no soot, yet, the thing runs great (I am not used to 9hp on the road though). Still breaking it in, I did take it up to 50 mph for a short stretch, I need to run about a mile of 222 to get to the side roads, people are driving crazier every day. I need to make a trail through the fields and woods to get to the side roads!
 

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m in sc

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just for clarification, mine started doing it a few hundred miles in before i modified anything. It doesn't bother me TBH. Im keeping an eye on angies supercub to see if it does it, my grom never did though. just fyi.
 

ShawninPA

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Dec 6, 2022
Messages
8
Hang with it. You will get used to the larger engine and extra horsepower.
LOL, yeah, sold my 100hp Vee, riding the 46hp Shadow now (what a dog but great for puttin) , and the 5hp? Z50 yard blaster, this CT is way faster than the Z50, not by much.
 
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