Burning Grease/Tar Front Sprocket

[Criminal Pilot]

Some may call me an idiot after this, but I just had no idea until I looked.

For the past several rides, I've noticed a slight burning smell coming from the bike. I was worried that something was out of place and rubbing, or I dropped something and it was overheating/melting, or any number of things. I already have a standard inspection/checkup booked and I figured I would just mention the burning and let them sort it out. However, today I did an oil change and noticed some tar dripping from the front sprocket cover onto the exhaust, crank case, oil filter, etc. When I wiped it off, it smelled of hot burned rubber and flesh (pretty nasty).

So I took off the sprocket cover, which I guess is long long long overdue, to find it covered in the most disgusting amount and looking tar/goop ever.

I know many of you are familiar with this phenomenon and regularly clean the front sprocket, but for some ridiculous reason, I never even thought of it. Even when I started my bike for a few minutes to let the new oil slosh around and settle in, I could literally watch the tar burn and start smouldering from the heat.


Maybe this is unnatural, I don't know, but I cleaned it all off and I'll see if that corrects the issue somewhat. I just thought I would at least post this in case anyone might have had similar concerns and was as dumb as I am.

For those who do know of this, is it normal for the grease buildup to start steaming up like that, actually burning to the point I can see it lightly smoking and horrid stink? Did I just leave it for too long to the point that all kinds of gunk built up? I would've figured standard chain grease/lube and such wouldn't burn at such low temperatures, but I guess there's probably grass and whatever else lodged in there, too.

 

[outasight20]

That's nassssty. Sounds like the culprit to me. I've never let it build up that much so I couldn't tell you, but it sounds feasible that the chain was rubbing against the tar buildup and causing it to heat up and smoke. Ugh, disgusting picture in my head of ground up tar and flesh burning off my bike. yuk

 

[Randomchaos]

How often are you lubing the chain? Could be rapid buildup from over lubing the chain and the excess flinging off in there. Good find on it though! It would drive me crazy trying to find a burning smell like that.

 

[Criminal Pilot]

How often are you lubing the chain? Could be rapid buildup from over lubing the chain and the excess flinging off in there. Good find on it though! It would drive me crazy trying to find a burning smell like that.

Finding it was pure luck. Would never have seen it if I didn't do an oil change. The smell seemed like it was coming from the front for a while so I thought maybe I was somehow burning through my brakes or something. First time I noticed it I pulled over immediately and basically took the thing apart on the side of the road trying to find out if something was about to fail. I lube every time it looks like it needs it. I try to aim for every 1000km + after wet or dirty rides, but sometimes it gets pretty dirty and gross before that and sometimes it takes longer. My lube is white though, so I don't think that's what this was.

I wish I took pictures. It was very thick, very black, and smelled horrible. Mind you, this is the first time the sprocket cover has been taken off since 2008 so I'm sure that's how so much gunk has built up. It must be various bits of grease, lube, dirt, bugs, and whatever else gets pulled into the chain over 4 years.

Anyway, I just got back from a 3 hour ride and I couldn't smell any burning anymore. Also the added bonus of peace of mind because it's sparkly clean down there, and I spent the time to freshly grease the joints that needed it, and lube other bits. So theres also the added placebo effect that everything is running better. I could swear it vibrates less now. That's probably mostly the oil change though. So a lesson to any idiots out there like myself - take off the front sprocket cover and inspect it when you do chain maintenance. It's extremely easy - just three bolts and it comes off - and it just makes everything better.

outasight - yup, disgusting image indeed. I couldn't believe how much had built up when I saw it. Like I said, it was literally oozing out of the sprocket cover and onto the exhaust, crank case, and oil filter. I'm never letting that happen again.

 

[Guitar Man]

I just leave the cover off and that makes it easy to clean and makes sure there is no buildup in there. The lube is flinged downward so it will not fling on you if you leave it off.

 

[04fizzer]

I've been noticing a hot rubber/plastic smell as well. I'll have to take a look under my cover. I had just assumed that it was something that landed on the headers as once I got home, I walked around the bike but couldn't find the smell.

 

[Spideyrex]

Yup, about a year ago I experienced that same thing. The smell of burning oil when I got into the garage and an accumulation of black gunk by the front sprocket. Since I cleaned it, it has not come back but I do keep an eye on it. FWIW, I've always used Maxima chain wax.

 

[TownsendsFJR1300]

I probably pull that cover off every 3rd or 4th chain cleaning/lube. It makes it much easier to keep after and it's only 3 bolts to R&R.

I would keep an eye on yours for a bit just to make sure your front sprocket seal isn't leaking oil. Most likely isn't but just to be on the safe side...

While your there, if you have the stock front sprocket, check for any notches in the black plastic (on the actual sprocket) from the chain. Its a sure sign that sprocket (and chain) needs replacing... It also gets a bit noisier with the worn sprocket...

 

[Criminal Pilot]

I probably pull that cover off every 3rd or 4th chain cleaning/lube. It makes it much easier to keep after and it's only 3 bolts to R&R.

I would keep an eye on yours for a bit just to make sure your front sprocket seal isn't leaking oil. Most likely isn't but just to be on the safe side...

While your there, if you have the stock front sprocket, check for any notches in the black plastic (on the actual sprocket) from the chain. Its a sure sign that sprocket (and chain) needs replacing... It also gets a bit noisier with the worn sprocket...

I will keep that in mind and check tomorrow. Thanks for the tip!