drive chain flapping

[GSPD750]

It could be that you have one or more stiff or siezed chain links.

Yes...an old and dried out oring chain with stiff links will make a 'slapping'
sound.

[Oro]

thanks guys will try the basics first.re slider around the swinging arm and readjust the chain tension. but im still encouraged by the trail bike chain tensioner add on

[Wingnut]

Spent most of the morning trawling the forum for output shaft related info , had a cup of tea or two then went down to the shed.

I have a cheap solution but it depends on the amount of spline left on the out put shaft.

My out put shaft is slightly worn . Enough for me to look into the whole "bodge(weld) /replace " debate.


So I took off the old sprocket which had forward and backward play and allot of left play and less right play.

I then fitted my new sprocket and noticed the further on the spline it was all play vanished.

The only trouble was when I fitted the sprocket plate the sprocket moved back down the splines 2/3mm and the play came back into it again .

So I got some washers and forced the sprocket plate back to the off set splines and now the plate is forcing the sprocket up onto the shaft and all play is gone .

[AlanH]

Nice idea but that means the sprocket is now out of line and driving solely on the inside of the sprocket on maybe 3mm of good spline. That will wear rather rapidly as the contact area will be very small compared with the full width of the sprocket that normally contacts the splines.

[Lee Halsall]

Although what Alan says is true, don't be disheartened,you arn't going to make anything worse,just wearing down a bit of spline to match the rest.
and the amount of misalignement over the chain run to the back wheel is
well within the chains limits .

Lee

[Oro]

give it ago.i went for a test run and while the chain was flapping about i looked down and it was the lower part of the chain below the swinging arm which was the culprit,i guess im going to fix up the chain tensioner guide like i said about before,i looked on ebay and typed in chain tensioner,im going for a universal one because they are cheaper and they seem to bend out further .i guess i will have to use a spacer and a longer bolt,but its worth shot,

[StumpyFingers]

I have thought about using one from a pushbike but was wondering if it could handle the rotational speeds.

[Oro]

ummm the chain off push bike is alittle slim compaired to that on the at wont u agree.give it ago though

[stuart]

Don't trials bike tensioners tend to be made from soft rubber?
how long will they last on the road?

[AlanH]

i went for a test run and while the chain was flapping about i looked down and it was the lower part of the chain below the swinging arm which was the culprit

It's quite possible that the chain flapping does not really indicate a mechanical problem that needs a solution. As long as the chain is not hitting anything and is not so loose it's going to come off, then will it really do any harm? Chains do that. If they don't, they are too tight. Tight spots or a knackered cush drive will make the flapping worse. Make sure the cush drive rubbers aren't all sloppy and tired.

From your posts, I'd suggest you take a look at the way you're riding the bike. Lugging one of these motors at low revs in a high gear will hammer the transmission and cause all sorts of issues from premature cush drive wear through to the dreaded spline failure on the output shaft. If you're using low revs and a high gear, the harshness is due to the final drive being hammered as components smack against each other - not chain flap. Are you running taller gearing by any chance? That'll make it worse.

It's a character of these bikes that the power delivery is not particularly smooth at lower rpm. Yes there is enough torque to trundle around at 1500rpm in top but it's really not a good idea. The motor is far happier, far smoother and it's far kinder to the transmission to go for a lower gear and let the motor spin faster on a lighter throttle. It may not be quite so good on fuel letting it rev more but in my book I'd rather spend a bit more on fuel than rebuild the gearbox.