OK, OK…maybe there are a few more special parts that I forgot about! I’m sure there is more – watch out for “special parts” #3, #4 and #5 🙂
Check ’em out! Most people look at them and go “huh?” Yes that is a vent hose running up into the headlight housing. I have only ever seen this system before on the AG two stroke Yamahas, which aren’t interchangeable either due to their smaller fork diameter. After you get over the initial confusion, its not a bad system when you think about it.
Back in the days of conventional forks, most manufacturers installed boots to protect the fork slider’s delicate chrome from damage and to keep the majority of mud, dirt and dust away from this surface. This helped the dust covers protect the fork seals for an acceptable period before the seals would inevitably fail.
The problem with conventional boots is that they had to let the air in somewhere so when it compressed, it didn’t blow a hole in the boot. To prevent the pressure build up, holes were made in the lower sections so air could move freely in and out. Doesn’t this defeat the purpose of the boot thought? Doesn’t that air movement suck dust in? And if mud and/or water did get in, wouldn’t it stay in? Well yes, sort of.
The designers of this this system were probably assuming that dirt bike riders would check them after every ride and clean them out…bad assumption! They didn’t make this mistake with their AG bikes though, they knew farmers wouldn’t clean or check them!
So this was their solution. A fully sealed fork boot with no way for air build up or easy access to grit. Simple and effective until the boot failed, which is quite common and they are expensive of course. If you wanted to be a total maintenance Nazi, you could put a filter sock over the end of the tube in the headlight, but I would never do a nerdy thing like that. 🙂
Rear sprocket guard
Sorry for the grotty rear drive hub, but in an up coming post I intend to do a full strip down of my clean AG (see above pics) and show the assembly in detail. This little bit of plastic that you see on the left is usually nice and white and clean, but it soon gets like this when enclosed in the rear chain guard.
I think that one of the reasons people rip off this chain enclosure (see parts #1) is because (a) it’s a pain to get back together, and (b) I don’t think most people know this plastic part is even in there! If heavy grass, baling twine or wire gets hooked up in the rear drive (quite common) and left to it’s devices, it will chew up this part.
So? What’s so important about this thing I hear you ask. Well, if you change your chains and sprockets and manage to get the enclosure all back together OK but don’t replace this guard, then dirt, mud and water pass easily into the enclosure where it is convenently stored to keep your nice new shiny bits in a bath of corrosive, abrasive slime. Your new chain and sprockets will soon disintegrate.
Next time they pull them off to do the chain and sprockets again they work out or see for themselves this phenomena and write the assembly off as useless. The reality of the situation is that this bit of plastic stops crud getting into the drive enclosure so you really need to replace it if it is worn for the system to work.
AG200 specific but surprisingly it doesn’t cost too much. Good one Yamaha!