chain adjustment

[speedy231278]

Yes, I know it's both up and down, I did mention that earlier However, as with the poster above, I find that even taking into account the downward movement, there's not enough clearance between the swingarm and the chain to allow the total up and down movement to even reach 25mm. Hence why I was wondering if having the eccentric 180 degrees out of position would have the sprocket sat higher in relation to the swingarm, reducing the clearance? I know that the eccentric has been out of my bike a couple of times (not by me), so I am curious as to whether or not it can be fitted the wrong way up in effect, or if that would not have a serious effect on the fit of the chain? Similar to discussion on another thread where it was suggested that a huge rear sprocket would make the back of the bike quite low due to the position the eccentic would have to be in to adjust the chain correctly.

Or, am I a typical bloke who thinks an inch is about three feet?

[Neosophist]

well from the centre of the chain thats 12.5 mm of movement each way, so about 1cm.

I think theres enough clearnace for that..

[speedy231278]

I agree with the above, but surely at rest the chain is sagging to just about it's lowest position, so while you might be able to heave it down a little bit, the majority of the movement will be up? Having said that, strictly speaking isn't it supposed to be measured when the bike is loaded? That will presumably have a bearing on the position of the swingarm relative to the chain?

[Neosophist]

I agree with the above, but surely at rest the chain is sagging to just about it's lowest position, so while you might be able to heave it down a little bit, the majority of the movement will be up? Having said that, strictly speaking isn't it supposed to be measured when the bike is loaded? That will presumably have a bearing on the position of the swingarm relative to the chain?

Sure the chain will sag to almost its lowest point under its natural weight, but this is that.. the lowest point, not some point your supposed to bend it down anymore.

lifting it about 1cm will put you in the "start" position, and another 1cm will give you the fully up postiions.

and yes.. set the sag while on the bike.

[gepe]

I wondered about the correct chain tension setup myself.

Both the Haynes manual and the original Honda shop manual describe a "generic" chain tension adjustment and neither takes into account that the RVF's/VFR's swingarm might be too thick to allow full travel of the chain to the upper position suggested in the adjustment instructions. Those "15-25 mm" of chain travel in the Honda manual are just a copy and paste you find in many of the Honda manuals (I checked that). Haynes also just copy-and-pasted it, I guess.

What I figured out:
- The little V4 is supposed to be upright on its side stand (so that the bike's weight is on the rear suspension).
- If I tension the upper part of the chain, the lower part will be in an pretty straight line between sprocket and chain wheel.
- In this position (centreline between upper and lower position) I can measure a distance of 17 mm to the max. possible upper position (when the chain fully rests on the chain slide).
- This means, the swingarm is not too thick to hinder the desired 15-25 mm chain slack. The chain should be adjusted in such a way that the slack of the chain is ~ 8 ... 13 mm each above and below the chains centreline (with 13 mm < 17 mm).
- I personally adjust the chain tension in such a way that with the bike on the paddock stand the lower part of the chain just does not touch the chain slide when I push it upwards against the slide. That is very near to spec and I do not have to measure anything (did that once, that's enough).

Hope this is of help to others.

gepe.

There was mention that the chain slack should be adjusted with the rider on the bike. Because most have a problem adjusting/measuring while sitting on the bike and manufacturers realised that, the suggested chain slack takes this into account (I read that somewhere).

[speedy231278]

Surely you can't give a generic figure for an unloaded free play? If we assume that 15-25mm works fine for an imported bike designed for an 8-stone Japanese rider, surely there's going to be a lot less of it left when 13 stone me jumps on the same bike with a ruddy great backpack full of gear? I might go a bit ott this weekend and measure to see where the exact sprocket to sprocket centre is to see if I've not been misjudging it all these years. Still, after my very early experiences with damage resulting from both too tight and too free chains, I haven't managed to get it badly wrong in a decade. That can't be sheer luck, surely?

[gepe]

If one looks at the relation of the swing arm, its pivot point and the sprocket and chainwheel positions, one can see that the longest chain is required when the sprocket, the swing arm's pivot point and the chain wheel are all in one line.
The more the bike's suspension is compressed, the shorter the distance gets between the sprocket and the chainwheel.

I.e. if you adjust for minimum slack with a "13 stone rider with a ruddy great backpack full of gear" your chain might come under high load when you fly over some bump and the suspension is unloaded to the point when sprocket, pivot point and chain wheel are in one line.

If you like, I can add a small drawing which makes this clear.

gepe.