Replacing cam chain - Just do it!

**p.dath** · 24th June 2010, 17:20

The cam chain in my bike has been making a rattling noise for quite a while now. Because it's been doing it for a while I guess it seemed "normal" to me. Just a noise the bike has always made.
Anyway a friend told me I really should get it replaced, and so I did.

Wow. It's like I have a new bike. I had trouble blipping down for the first couple of minutes because the bike seems to be producing so much more power. I haven't really had a chance to open the bike up, but the bottom half of the rev range feels so much better.
It's hard to describe, but it's like I twist the throttle and the power is just there. No lag.

If someone had told me that replacing the cam chain/tensoner/shims (seems to be lots of bits on the work order) would make sure a big performance difference I would have done it ages ago.

I can't wait for the next MACC ART day now!

So if you want to learn from my experience, and you know your cam chain really needs replacing - don't delay. Hopefully the tranformation in your bike will be like mine - awesome.

**AllanB** · 24th June 2010, 17:29

I'd be more inclined to stress the importance of replacing a worn camchain etc due to the risk of lunching your engine if it breaks!

Out of interest how many kms are on your bike.

**SS90** · 24th June 2010, 22:31

Originally Posted by p.dath

The cam chain in my bike has been making a rattling noise for quite a while now. Because it's been doing it for a while I guess it seemed "normal" to me. Just a noise the bike has always made.
Anyway a friend told me I really should get it replaced, and so I did.

Wow. It's like I have a new bike. I had trouble blipping down for the first couple of minutes because the bike seems to be producing so much more power. I haven't really had a chance to open the bike up, but the bottom half of the rev range feels so much better.
It's hard to describe, but it's like I twist the throttle and the power is just there. No lag.

If someone had told me that replacing the cam chain/tensoner/shims (seems to be lots of bits on the work order) would make sure a big performance difference I would have done it ages ago.

I can't wait for the next MACC ART day now!

So if you want to learn from my experience, and you know your cam chain really needs replacing - don't delay. Hopefully the tranformation in your bike will be like mine - awesome.

Basically, the reason you are noticing an increase in power, is because with a worn cam chain, as the tensioner takes up the slack, resulting in a slight retarding of your cam timing.

A new chain remedies this.

**CookMySock** · 25th June 2010, 08:49

Originally Posted by SS90

Basically, the reason you are noticing an increase in power, is because with a worn cam chain, as the tensioner takes up the slack, resulting in a slight retarding of your cam timing. A new chain remedies this.

Exactly the same thing happens with worn timing belts on small diesels. They get all smoggy and shitty and hard to start.

Steve

**clint640** · 25th June 2010, 14:12

Originally Posted by SS90

Basically, the reason you are noticing an increase in power, is because with a worn cam chain, as the tensioner takes up the slack, resulting in a slight retarding of your cam timing.

A new chain remedies this.

That & if you haven't had the valve clearances checked for a while they may have also been well out, that's what the shims are for.

Clint

**quickbuck** · 26th June 2010, 22:27

SO, to sum up.
The Cams are now opening the valves when Mr Honda wanted them to open when new, AND they are opening the correct amount allowing the fuel/ air to get in, and the exhaust to get out.

For one to have a constant rattle from the cam chain on a CBR it must have been really tired.
I know mine rattles a little when the tensioner isn't doing it's job properly, but never all the time....

That said, will look at replacing it when I have finished off the track bike.

**pete376403** · 27th June 2010, 16:15

Did you measure the amount of wear in the chain (same way as you check a drive chain, measure a number of pitches pushed together, then pulled out, to get a percentage)? Then if you apply that percentage over the distance betwen the crank sprocket and the cam sprocket, you should be able to work out how much later the valves are opeming. Be interesting to know.

**p.dath** · 27th June 2010, 16:34

Originally Posted by pete376403

Did you measure the amount of wear in the chain (same way as you check a drive chain, measure a number of pitches pushed together, then pulled out, to get a percentage)? Then if you apply that percentage over the distance betwen the crank sprocket and the cam sprocket, you should be able to work out how much later the valves are opeming. Be interesting to know.

Negative. This is way beyond my capabilities. I got a workshop to change it for me.