Honda CBF125 Wheel Alignment & Chain Tension Troubles

[Jack Edge]

Hi all,

I have been riding a Honda CBF125 M9 2009 for around 6 months now and the bike is overall in a superb condition with over 18k miles on it.

It is important to note that the chassis of the bike is not straight from a prior crash + repair prior to my ownership of the bike.

The trouble is recently I have started having problems with the wheel alignment and chain tension.

One evening I had noticed that for no apparent reason the chain has come completely floppy and far looser than spec.

I consequently undid the rear axle of the bike the next day and used the alignment guages along the side of the wheel correctly.

After lining the guages up with a good chain tension, I noticed that, because my chassis was bent, the centre tread line of the wheel had no line up with the front wheel when both wheels were straight.
As a result I now choose instead to look down the base of the wheels to align them rather than use the alignment guages at the side of the wheel, this seems to make more sense to me because the bent chassis would ruin the guages from accuracy anyway.

After sorting out the problem using that method, my chain is now extremely clunky and feels tight (clearly sprockets are not in alignment). It then follows a few days / weeks later by becoming loose again. I fix it using the same method with the chain ending up in the same tightness (I am aware that this does wear the sprockets and chain links but feel that the alignment of the WHEELS is a more important thing to achieve).

So in conclusion, if the WHEEL alignment is correct, the CHAIN (sprocket) alignment is incorrect. The same goes for vice versa.

My question is this:

1) What has caused my chain to suddenly loosen like this after a while?

2) Is it more important to have the wheels aligned or the chain (sprockets) aligned? And, with a bent chassis, is it possible to get a combination of both?

3) (As a follow up to both) Whats the best way to fix a problem like this?

 

 

All help is greatly appreciated!!!

 

Edited April 10, 2023 by Jack Edge

[Davidtav]

I wouldn’t be riding a bike with a bent frame. 

[billy sugger]

As @Davidtav has said, it's not a good idea to ride a bike with a bent frame. You will cause uneven wear to the tyres at the very least, and having misaligned sprockets is pretty dangerous and there is a risk of steering wobble at motorway speeds, and possibly highsiding on bends (trust me, I know that all too well, and my frame was only 1/4" out of true) 

[KiwiBob]

If the frame is still bent after a previous crash and subsequent repair I would suggest that the bike hasn't been repaired properly! 

[Capt Sisko]

IF the frame is bent and the Police catch you using it on the road they would probably consider the bike as unroadworthy. It will get impounded and very likely you'd be fined and get points, and maybe a substantial fine as you are admitting that you know the bent frame is causing damage to the drivetrain, which may lead to loss of control of the vehicle, which may cause an accident. In theory you could even be banned. . Similarly your insurance would also be null & void as it is a condition of all vehicle insurance policies that the vehicle must be roadworthy. That could lead to more fines etc. Sorry if that sounds harsh, but that's the law and the Police take a particularly dim view of people using unsafe vehicles on the road. 

 

So, what can you do? If you bought the bike through a dealer, then you are entitled to complain and make them fix it. A dealer cannot sell an unroadworthy vehicle. If you bought it privately, I don't think you've got any come back on the seller, particularly as it was six months ago and by the sounds of it you knew about the 'repair' beforehand. Either scrap or repair the bike, but absolutely don't ride it on the road. It's your neck on the line.

Edited April 15, 2023 by Capt Sisko

[Tinkicker]

Surprised it got through its MOT.