A noisy cam chain ??.

This is a story of a friend of mine who thought she had a serious and expensive problem. I sorted it out free and it only took about half an hour.

For those of us with overhead camshaft engines we know (or not) that the camshaft is driven by a chain, powered from the crankshaft. This chain over time will stretch, and when the bike is serviced it should be checked for wear and adjusted accordingly.

Sue and I used to go to the TT races on the Isle of Man nearly every year. We went with friends from the Christian Motorcyclists Association, to run a cafe called Holy Joes. One friend that came with me always stayed with us the night before we went as we lived near the ferry terminal. Later on we used to put our bikes in our van making the ferry costs cheaper for us all. This friend always asked me to check his carburettors when he arrived at our house and this became an annual job for me. I didn't mind as I had a set of vacuum gauges and this is quite an easy job with the right tool.

One particular year he arrived too late for me to check his carbs, but as this was a year where the bikes were being transported in our van I just said I would take my gauges and do it during the week at the TT.

We were to pick up other friends, (a full van is more economical) at the ferry terminal and this is where I heard what everyone thought was an over stretched cam chain. I really had to advise this friend not to ride the bike if the chain was that bad as it was very loud. She had been quoted £250.00 (a lot of money back in the mid 90's) to replace the worn out chain and as she did not have the money, she had decided just to ride it anyway.

We got to the Isle of Man and one afternoon I asked for the keys of my friends bike to balance his carbs. I also asked for the keys of the bike with the noisy cam chain.

I checked and balanced the carbs on the first bike. Vacuum carbs can only really be checked with gauges (and there are two types that I have come across, dial and mercury.) but if you have a set it is not a big job. I have only got a bank of two so for a four carb setup it takes a little longer but can be done.

I then had a look at the noisy cam chain. I set about balancing the carburettors on this bike and what I thought was true. The carbs had not been set for quite some time and they were a long way out of tune. As I worked on each carb the engine started to quieten down until all the carbs settings were equal and the engine sounded quiet, just as it should.

Going inside I gave my friends keys back and told them both their bikes were fine. When everyone went outside to hear the noisy bike they could not believe how quiet it was and asked what I had done.

SO.... before you accept a noisy engine is the cam chain rattling around in the tunnels check your carbs. If they are vacuum carbs, they can make a heck of a noise if they are not balanced correctly. And balancing the carbs is a lot cheaper than replacing a cam chain which is not needed and would not help the noise situation.

She probably got a lot more performance and fuel economy afterwards too.