No, all later model Harleys run on low octane fuel.
there is a check valve in the oil system that is stuck open over filling the oil tank will cause the dipstick to blow out of oiltank
It's a Harley. Notorious for hard neutral.
If it filled completely it can cause excess pressure and leak over into the combustion chamber. If the level is below the return fitting it should be ok.
The owner's manual suggests a rating of 91 octane and further comments that 87 can be used but could cause knocking in the engine.
Yes, it could.
Possibly but fyi most jet fuels are mostly like diesel, i.e. they have a much LOWER octane rating. Avgas is the exception
Use exactly what your owner's manual states. If it says 89 or 91 octane then do not use 87 octane. Using a lower octane that required may cause pre-detonation or what is commonly called (Pinging). Pinging may be harmful and may cause engine damage. Bottom line is to use no lower or higher octane fuel that the engine was designed to run on. Using a lower octane can cause engine damage, and using a higher octane is a waste of money that will provide not benefits whatsoever, and is nothing more than a myth.
87 Octane Regular. Using any higher octane is a total waste of money and will provide no benefit whatsoever. In fact it may cause hard starting. Use only 87 Octane.
The same gasoline you use in domestic cars. Just be sure and use the octane recommended by the manufacture. Do not use a higher octane than is recommended. Doing so, is a waste of money and will provide no benefit whatsoever. Also do not use a lower octane or you may cause pre-detonation which could result in engine damage.
spark plugs need changing- ignition wires could be changed- put octane boost into your gas, or fuel injection cleaner.
91 octane petrol will ignite at a lower temperature and burn faster, which can cause knocking in an auto engine. Lead compounds were added at one time to raise the octane rating, but recently engines have been redesigned to work on low (<98) octane petrol (or gas in the US colonies)
This vehicle requires Premium Unleaded. You can try using 89 Octane and see if it pings or not. If it does then you will have to move up to 91 Octane. Do not use Regular, as it will cause pre-detonation and may do harm.