Monthly Archives: February 2014

Fork servicing, part 1.5 – a discussion…

Before I go on with part two of my fork servicing article , I’d just like to talk about a few things here first. It dragged out the second post and I felt it distracted the reader from the job at hand of servicing the forks, but it’s info I feel the owner needs to know so here we go…

About eight years after the release of the AG200, Yamaha removed the drain screws on the fork legs. In the 1991 AG200B owners manual, they deleted the fork oil change description so I’m guessing that this was the first year they removed the drain screw. In fact, there was three iterations on the AG200 fork leg; The first seven to eight years had drain screws, then the forks had the casting on it for the screws but they decided not to machine a hole, tap a thread and insert a screw. And finally they changed the casting and removed the facility to drain the oil altogether.


It seemed to be a manufacturing policy at Yamaha that effected a few of the lower-end models with conventional forks like the TW200 and DT175. If you check out forums on these bikes you will read up on people moaning about Yamaha being cheap and conspiracies flying around that it was a deliberate ploy to reduce the life of components on the motorcycle. The theory was if people can’t easily service the bike they won’t.

I’m not sure if I buy into these arguments – here is my take (in relation to the AG200) on the issue; I thought it was a good idea to remove the drain screw. Why? I think simply dropping the oil in this design of fork is a waste of time. After servicing suspension components for a while, you soon learn that if the oil comes out dark something is wrong. In the case of conventional forks, it usually means you have worn through the low friction coating on the bushes in the inner or outer fork leg. When this coating is worn your chewing into the bush material or the aluminium of the fork legĀ (or both) hence the dark colour of the oil.

With the AG200 forks there is NO bush on the inner fork leg which means you are always chewing into the aluminium of the outer fork leg! The oil is going to get darker a lot quicker and will need more servicing to prevent premature wear of the forks. In the case of the AG200, why bother making something easy to service when it wont get done anyway?


To me there are only two types of people who own motorcycles (or any other machine for that matter) those that don’t care about maintenance and those that do. I’d say that it is around a 95% to 5% split respectively! Those that do can be broken down again to those that do care, but want someone else to do the spanner work for them, and whose expectations are usually let down by their selected service department, Yamaha or otherwise.

So if you look at it from Yamaha’s perspective; why make the thing easy to service? 95% of owners aren’t even going to get them looked at until they spew oil out everywhere and even then they usually just let it fill with water! The other 5% should know better and do the job properly by removing the forks from the bike, disassembling them and cleaning them up properly.

One other thing to keep in mind with the AG200 is that when the fork seals fail, farmers just leave it. Even when it starts topping out and banging away metal to metal down there they still leave it. I suspect that the plastic material they use for the fork boots don’t like oil because they seem to split and fail fairly quickly as well, mainly in the lower sections which is what makes me suspect it’s the oil that hastens this process.

Now that the forks are empty or low on oil, the failed fork boots allow water and dirt to accumulate in them and under some weird act of physics actually suck water into the fork! So don’t be surprised if you drain more water out of the forks than oil, I have seen it plenty of times before. It is also another reason to totally disassemble the fork – you may need to remove old oil, dirt, metal deposits, water and corrosion on steel components!


People have asked me; can I drain the oil out of the forks without removing them? Yes, technically you can but I have never done it and never will. If you follow my part 2 article closely you will see how it can be done, but I wouldn’t. You will never get all the old oil out and with this design you really need to. Even if you decided to flush them on the bike the fork cap directly under the handlebars makes this a pain. I just prefer to remove and disassemble them, clean them up and put them all back together with fresh oil. That’s just me.

If the fork boots are good and there is no accumulation of rubbish on the dust seal, then you can probably disassemble the fork without replacing the seals. I have done it plenty of times before. You just need to be gentle on the seals and make sure it all goes back together clean with nice fresh oil. If there is any rubbish around the dust seal and the oil looks dark and old, replace everything – oil and dust seals. Then you wont have issues any time soon and have to tear it all down again.

This ends part 1.5



Fork servicing, part 1 – removal.

OK folks, it’s time to get serious. Time for some real world maintenance and to show how it’s done. The service manual is useful but it can only get you so far when it comes to common faults due to poor manufacturing or (more commonly) owner neglect. And who really wants to buy all those Yamaha service tools? The AG200 is a simple bike and can be maintained easily and cheaply with some tips to avoid expensive tools. So lets jump in with this first instalment showing how to remove the forks.

AG200 fork tools

So what tools are needed? A couple of bricks(!), 10, 12, 14 and 17mm spanners, #2 Phillips head. You will also need a 19mm hex/Allen key. There are two ways of doing this; you can go to a tool shop and buy one like shown on the left, or you can go to a fastener shop and buy a bolt with a 19mm head and bash/weld it into an old socket, as shown on the right. You may have an old socket kicking around and a 19mm hex bolt so the latter version will be cheaper to procure.

I have both but actually prefer the latter because it can be used to separate the inner and outer fork legs (the black 1/2″ drive hex tool shown wont fit down the inner tube) if required which I will cover in the second part of this “how to”. So why not put some nuts on the end of the bolt and lock them? You can do that but when we get to part 2 you will see where the drive component of the socket may come in handy.

AG200 stand setup

OK, first thing is to grab your bricks and put one under each stand, one on the left and one on the right. This will make the bike nice and solid to work on. Just be aware that the weight will be slightly forward biased, when you remove the front wheel, the bike will want to fall forward – just. Another brick or two might be necessary for your workshop tool kit! Just place them on the rear pack rack.

AG200 front brake lever

Back to the job…back off the front brake adjustment up on the handle bar. This is to get the pads as far away from the linings as possible to aid removal. Remove the front brake (10mm) and speedo cable (#2 Philips) brackets on the left (sitting on the bike) fork leg. If they look corroded they will be a pain to get off. AG200 fork leg cable clampsWith the plastic speedo cable bracket just cut it off and you can either re-secure it with a new one from Yamaha (part # 3R9-23318-00) or a cable tie will suffice if you don’t care about appearances (not too tight though – you don’t want to cause the outer metal sheath to put pressure on the inner, rotating cable). If the bolt breaks off on the brake cable clamp then you can drill it out and put a 6mm bolt through it.

This is what I am talking about with the manual, the two components I talked about above are out in the open and due to the conditions that these bikes are accustomed to, they corrode and become service issues. It happens a lot on the AG200 and the manual doesn’t help you out that much when you have a problem with them.

AG200 fork boot

If the fork boots are OK and you want to save them, pull the vent hoses out of their routing tabs (1) and slide them out of the headlight assembly. The tubes don’t separate from the boot so don’t force them or they will break. Undo the top boot clamp (2 – #2 Philips) and twist the boots so they come free of the fork leg and can slide around easily. A bit of silicon spray or WD style spray may be helpful here.

AG200 fron wheel removal

Now we can undo the axle nut. On older bikes with a castle nut and a split pin, this will be a 17mm item, while later bikes have a 14mm, self locking nut. AG200 front wheel spacerWe can now slide out the axle. Be vigilant of the balance of the bike as you remove the axle. When the axle is out, you can rotate the right leg (this is why we loosen the boots off as well) to aid in the removal of the spacer, this then gives you a bit more manoeuvring room to get the brake pads and backing plate assembly out of the brake hub. This should free up the whole show so the wheel can be removed and put aside.

AG200 fork clamp bolts

Next is fork removal. Undo the top (14+17mm nut & bolt) and bottom (2 x 12mm bolts) clamp bolts and be prepared to catch the fork as it slides down. Corrosion on the fork legs may prevent this! CRC/WD will help if it needs it. OK, its time to get our 19mm Allen key or specially constructed tool into action. AG200 fork cap removalBecause the handle bars run right across the top of the fork cap, we can’t get a tool in to loosen the cap without taking off the handle bars – no need for that! Slide the fork down in the clamps so you can get to to the fork cap with your 19mm tool. Nip up the two lower clamp bolts and you can then pop off the plastic cap cover, insert the hex tool and loosen the cap nut, but don’t remove it.

Loosen off the two lower clamp bolts and you can slide the leg out. Do the same for the other side. Remove the fork boots, give them and the forks a clean up with warm soapy water if covered in crud, dry them off and we have two forks ready for strip down and service.

AG200 fork legs

This ends part 1.