The tensioner adj bolt is located on the top of the case on the stator side with a rubber grommet covering it.
If you pull the stator cover you can watch the spring loaded action of the self adjusting feature at work when you loosen the fastener.
Many times older 200's will require assistance via a long screwdriver to pry the cam chain buffer over if the spring is at the end of its travel.
Hope this makes sense...
SFO; I will try to confuse him a bit more, but I am afraid he might have the RFVC motor (two carbs). I am not sure they will adjust the same.
Maxkixs; look for the adjuster right where SFO says it is. It is a big nut (14 mm wrench) with a rubber cover over it. If the rubber cover is gone, there will be a small 6mm (10mm wrench) bolt screwed down into the top of it.
In a perfect world, if you were to loosen the adjuster nut (the 14mm one) the aforementioned spring will pop the adjuster up to tighten the chain. As SFO has indicated, it rarely works that way, and is a little scary if performed on a idling engine, as if the chain is worn badly, it could jump. I like to help the adjuster to assure this doesn't happen.
Most often, the adjuster will need some help. This help can come from a bicycle spoke. I have no idea what size to call it, but there is a small bicycle spoke that will thread down into the guts of the adjuster. To use it, remove the rubber cap and remove the 6mm (ten mm wrench) bolt from the top of the adjuster.
The spoke will screw down into the guts of the adjuster and give you something to pull up on to help it do it's job. Make sure it is the right size, it need to grab good and not pull out of the threads.
With the engine idling and the spoke screwed into the adjuster guts; loosen the big nut, but this time you can manualy pull up on the adjuster (spoke) to be sure you are getting all the adjustment.
I NEVER attempt to adjust a chain in a running motor unless I have the spoke in my hand. Actually, I would grab the spoke with Vise-Grips to keep it under control.
If you clamp the Vise-Grips on the spoke at the point where it exits the adjuster, the adjuster cannot move down (loosen) and you are pretty safe doing this with the engine idling.
I like to have the engine idling so I can hear what I am doing.
I have never actually had a chain jump during this procedure, but be warned; it COULD happen. :eek:
Be careful, you can actually overtighten the chain if you haul on the spoke too hard.
Isnt there an eccentric on the cyl head that might need to be rotated?. You know Parts Unlimited has a chain and sprocket kit for like 25 dollars for the ATC200 that has the same chain and top sprocket in it its like one third the price of honda parts.
Just wanted to add the following: the rear cam bow is held tight by the compression of two small collars that are cut on an angle aprox. 30 deg. as you tighten the 14mm nut they slide apart from each other and lock the shaft, Unfortunately Honda forgot to radius the inside edges of these collars and they cut into shaft which is why you have to use the spoke to pull up on it. the best fix is to remove collars and radius (thier :clue: under the 14mm nut, use a magnet) also nice to smooth the shaft. This is why the chain noise goes quiet when you loosen(raise) the 14mm nut and then rattles again
The top 6mm bolt is not eccentric on the 200, it just captures the top of the rear cam bow. The little collars are just under the 14mm nut that has the little black rubber cap over it. If you want to smooth things up, you will have to pull the flywheel and remove the metal piece that attaches to the bottom of the cam bow. Look on the web for a honda microfich, that will clearly show how all the pieces fit together. Hope this helps.