Carbon buildup

[RykerUSA]

Have any of you experienced carbon build up in your cylinder heads in the 998 engine? If so, what causes it and how do you clean up your engine?

[Chupaca]

Don't know anyone who has pull the heads.. I only have close to 40,000 miles and she is running great. If I should ever get to that point I will check. Fuel and mixture would come to mind good quality oil and regular air filter maintenance...

[RykerUSA]

My bike has been in the shop for 5 weeks and I was just informed a quarter sized piece of carbon buildup seperated from the cylinder head falling into the combustion camber resulting in the loud engine nocking that sent my bike to the shop. 2015 ST Limited 13 months old with 19,000 miles on her. Seem very strang to me.

[Bfromla]

My bike has been in the shop for 5 weeks and I was just informed a quarter sized piece of carbon buildup seperated from the cylinder head falling into the combustion camber resulting in the loud engine nocking that sent my bike to the shop. 2015 ST Limited 13 months old with 19,000 miles on her. Seem very strang to me.

Very strang & unlikely at under 20k miles. You would have noticed smoke, horriable acceleration & gas mileage, all would be hard to ignore & miss for all of a sudden noise to develop from it. Crap gas & worse air filter will get you there but still takes some time. Run your finger around inside of cool tail pipe & report back

[Peter Aawen]

Running low quality &/or low octane fuel instead of the recommended octane stuff & then adding insult to the injury by feeding it air thru a choked air filter & lugging the engine too often/much as well as never revving it out often enough to get the engine hot enough to burn off/blow out any small carbon deposits that will likely result from a low/slow burn might possibly do that sort of thing/create that much carbon deposit, but you really wouldn't expect it on a relatively new low milage motor like that one without REALLY working pretty hard to do any/all those things?!? What octane fuel do you 'normally' run, how often do you get the filters (fuel & air) serviced/changed, & what sort of revs do you 'normally' run at & rev out to?!

How do you clean it up? - Run the engine on the approved octane level fuel at mid to high revs for at least 30 mins each time you run it; never let it lug along at low revs in a high gear; make sure the fuel & air filters are clean & of the appropriate (or better) flow rates; and basically ryde it like you stole it!

[RykerUSA]

I run the normal gas brands around here including Shell, Speedway, BP, etc. New air filter at 16,000 miles and old one didn't look bad. I have not changed fuel filter yet but didn't think I needed to. I run in trailer mode all the time and have no trailer. So, It cant shift und r 4500 rpms. No lugging that i know if. I do baby this machine so I don't run at extreme high RPMs Hardey ever. That maybe my problem but I cannot believe that that would result in such a carbon buildup that a piece would fall into the cylinder and cause such a serious engine knock

[Highwayman2013]

Use top tier gas when possible and occasionally use some gas treatment. It's hard to imagine the 998 building up much carbon running at 5,000 RPM.