I'm a big believer in making sure I'm acquainted with not only how my bike works, but how it's working. I know there are a lot of riders out there who aren't interested in diving into the regular scheduled maintenance of their bikes—but there are a couple of things you should do to ensure your bike is safe and running properly in-between your regularly-scheduled service intervals, regardless of whether you take your bike into the dealer or take care of it yourself.
Not too long ago, one of the YouTube channels I follow, John Maxwell's channel (he's a Harley mechanic for a dealership in Georgia), posted 3 TIPS for Maintaining your Harley. I liked, and have been following, these tips for a long time and will not only share them here, I'll add an additional fourth tip on the end.
Number 1: Regardless of how well your bike is running, if your tires aren't making a positive connection to the road, it won't do you any good (and it will be unsafe). Inspecting your tires should be something you do every time you get on your bike. For the cost of a few bucks, you can purchase a very valuable little tire tread depth gauge, so you'll know exactly what the condition of your tread is and be able to replace your tire before they're a danger to you or a passenger who might be riding behind you.
The gauge is cheap enough and small enough that you can carry it with you on the road as well as have another gauge in your toolbox in the garage. That way, even when you're on a tour, you can give your tires the once over before you mount up for the days ride.
With the measuring pin extended beyond what the tread depth will be, insert it into the tread and when you depress the rest of the gauge, it will collapse inside the gauge to give you a reading.
Similar to a vernier caliper or your torque wrench, the gauge will line up on a scale to tell you how much tread you have left on your tire. On this gauge anything below 3, and my tire should be replaced. You can see by the reading on this gauge, the tread on this tire is at 4, so I still have plenty of good tread left.
You should also check for any cracks, signs of uneven wear, or obvious damage to the tire in addition to the remaining tread depth. I tend to go through two rear tires for every front tire, so I pay particular attention to my rear tires.
2) Check your air filter: It doesn't matter if you use a paper filter or a cleanable filter like I do, you should periodically check the condition of your air filter. The dealer will do it when you have your bike serviced at the dealership, but it's not uncommon for the filter to get dirty and potentially cause your engine to perform poorly. What's more, your filter's primary job is to make sure the gunk that's in the air or blowing up from the road doesn't get invited directly into your engine.
Start by removing your filter cover. If you don't have a stock cover, you might need to inspect it to determine if there's only one fastener like this one, or more than one.
A stock filter assembly might look a little different than this once you get the cover off (this is a Screaming Eagle filter assembly), but there will likely be a bracket that holds the filter in place you'll need to remove, to remove a dirty filter.
This filter looks dirty to me, so I'm going to remove it so I can clean it before I put everything back together.
Your filter might be different than what's on my bike. If you have any questions, there will be removal instructions in your shop manual. If you are interested in an alternative to the shop manual offered by your manufacturer, both Clymer and Haynes offer alternatives. There are things I like about all of them, so I have several different types of shop manuals in my garage for the bikes.
I've been running with K&N Air and Oil Filters on my bike for a long time, and like how I can clearn them when they look dirty. I use the K&N Power Clean, which comes in a convenient Filter Care Service Kit, that also includes the oil.
I liberally spray the cleaner all over the filter and run it under warm water until it looks like it's clean.
Once it looks clean, I set it aside to dry before I re-install it on the bike.
While the filter is drying, I inspect the inside of the filter cover to see how clean, or in this case, dirty it is. You can see it's collected some crud over the miles, so I want to make sure it's also clean before I put the assembly back together.
I don't think it matters what you use. Any multi-purpose cleaner will do. You just need something that will cut through the oil and other gunk that might collect inside the filter cover.
Just spray the inside of the cover with the cleaner and wipe it out with a shop rag. Once that's done and the filter's dry, you can move on to the next step.
Once the filter is clean and dry, from three to four inches away, use the filter oil included in the kit described above to spray a light film on the entire filter surface. I use the white spot above so I'm sure to get the entire filter without putting too much on.
If you use a paper filter, you can skip the cleaning steps and just replace with a new clean filter.
Once you have a new filter or your filter has been cleaned and oiled, put everything back together in the reverse order you took it apart. Once you've taken your air cleaner apart the first time, it will be easy and obvious how to put it back together and take it apart the next time you want to check the condition of your filter.
3) Inspect your shift linkage: This is one of those things that is kind of "out of sight out of mind," but it's so easy to do you might as well just make a habit of doing it. Simply reach down and give the linkage a wiggle. If it feels really loose, you'll want to dive in a little deeper and make sure everything is tight. If it's still loose, you may need to replace your linkage, which is a lot easier to do when you're not several hundred miles away from home.
4) Give your bike a bath: I've already described how I feel about keeping the bike clean and what I use to do it, but I have a friend who feels like the only time his bike needs a wash is when the dealer does it following a service. That might even work for him, but I'm convinced giving the bike a bath is a great way to make sure there isn't anything loose or damaged that could cause a failure down the road. He didn't notice that a swing-arm bushing had started to fail until he was on a trip several hundred miles from home and his rear wheel wasn't tracking right and he couldn't keep the bike up straight. I think that was a potentially dangerous situation he would likely have noticed (and been able to have repaired), before his trip, had he been regularly cleaning and inspecting his bike.