Honda CBX1000 cam chain tensioners and cylinder heads

Honda CBX1000 cam chain tensioners and cylinder heads are now well over forty years old and are showing their age. It’s a simple fact of life that some parts just age and require replacing to keep a machine running and cam chain tensioners are such a component. There are many parts that age well, as long as the maintenance is done correctly. Ducati bevel drives seem to cope very well with age, as long as they have been well maintained, but they have no cam chain tensioners because the cams are operated by the bevel drive. The same is true for many gear drive overhead camshaft motors. Although the CBX1000 motor is great for high mileages if they are well maintained, cylinder heads could be an issue of the weren’t looked after. With age and the constant heat cycles, cylinder heads on these machines are frequently problematic now and if they don’t cause big problems now, then it won’t be long before they do. Age is always a problem with any classic motorcycle , along with the literary of hidden dreadful work done over the decades that needs chasing out. You can see what else we do to all of our Honda CBX1000s included in the purchase price here and of course we deal with the cylinder head, cam chains and tensioners. No other classic motorcycle supplier offers such great value and we can do this because we have the infrastructure and experience of these machines to offer our customers such good value.  

Honda CBX1000 degraded cam chain tensioner close up copy
The bonded nylon tensioner blade is starting to really fail now.

Honda CBX1000 cam chain tensioners

Honda CBX1000 cam chain tensioners are a part that degrades dreadfully with age and have now reached the end of their lives. When I first started working with CBX1000s back in 2004, a crumbling cam chain tensioner was a sign of a motor that had not had the oil changed every 1,000 miles. Today they are falling apart due to age and will result in catastrophic engine failure if this problem is not dealt with. Honda cam chain tensioners are made up from metal a blade bonded with a type of nylon material. After about forty years, as you can see in the picture, these tensioners start to crumble and it is not due to mileage. We have stripped these motors with 300,000 kms and they have been in remarkably good condition. Obviously, this was a very well maintained motor we worked on and it’s unusual to find machines so well maintained for so long. Most machines have changed hands many times over the decades and there was a time when they had very little value. During this period, maintenance was often ignored and the machines were abused and this is particularly the case with UK machines. Motorcycles run in mainland Europe, as a generalisation, were always much better cared for as you can see in this article I wrote back in early 2014 here. This is why we usually source most of our CBX1000s from outside of the UK and there is also, again as a generalisation, a tendency to service motorcycles even when they are not highly valuable in certain mainland European countries. UK machines have always had a much harder life, especially when they are not worth a great deal once they are ten years old. We have taken some CBX1000 engines to pieces recently with just 5,000 miles on from new which have been kept in a heated room all of their lives and found cam chain tensioners such as the crumbling ones in these photos. Owners have bought them to us for servicing and when we’ve removed the sump pieces of cam chain tensioner were found in the sump and around the oil pump filter gauze. The cam chain is running over these tensioners at up to 9,500 RPM and it’s vital that the tensioner has sufficient integrity to to keep those chains tight and running true. 

Honda CBX1000 Cam chain tensioner degraded closes
This tensioner will not last much longer without causing serious damage due to age.

It’s not just Honda CBX1000 tensioners

It’s not just Honda CBX1000 cam chain tensioners that suffer from this ageing condition, but all OHC Japanese motorcycles from this era do. It’s an age problem not a design flaw and over forty years of use, quite often hard use, is really highly commendable. I wish modern vehicles had any component on them that would last this long and take this much use, it’s unthinkable today. Below is part of a cam chain tensioner from a 1976 Kawasaki Z900A5 we’re rebuilding. Again the nylon has failed due to age, not use, however a poorly adjusted cam chain will help this problem along and shorten the tensioner’s life even more. These engines are excellent for very high mileages, but the time has now come to replace these parts.

1976 Kawasaki Z900A5 cam chain tensioner
1976 Kawasaki Z900A5 cam chain tensioner

Honda CBX1000 cylinder heads

Honda CBX1000 cylinder heads need to have been looked after. Again, changing the oil every 1,000 miles is critical, but also the machine being ridden by someone with mechanical empathy is critical. So often you see riders start a cold motor and rev the nuts of it from cold. This is the best way to destroy a motor, as every component is being forced to expand rapidly, due to excessive heat, while having cold oil dumped on them. The Honda CBX1000 was notorious for dropping valves and destroying the motor, but this was usually due to ham fisted, throttle happy owners. The cylinder head is a complex work of art with 24 valves all moving at high speed. After forty years of heat cycles, the valve guides are cryogenically fitted and really need overhauling. This is not something that can be done in a workshop or your shed, it needs to be done in an engineering shop.

Honda CBX1000 cylinder head top
It’s time that CBX1000 cylinder heads are inspected and refurbished by engineering show.

Where to buy parts

Where to buy parts is always tricky today, because we are in a race to the bottom and cheapest is certainly not best. Honda no longer make the cam chain tensioners for the CBX1000 and there are suppliers offering substandard replacements which should avoided at all costs, they are not cheap they are very, very expensive. We have gone through a number of suppliers and settled on Bert at The Six Centre in Holland, who does an exchange service against your worn out tensioners. I’m sure there are other good suppliers but we use them as we’ve never been let down by quality. These parts are very expensive and you also have to allow for a full top end gasket kit at the very least and if you’re doing the cylinder head you’ll need twenty four valve stem oil seals too.

Honda CBX1000 cylinder head
Once the work is done these machines are good for another 40 years.

It’s time to do the work to Honda CBX1000s

It’s time to do the work to Honda CBX1000s or the consequences can be catastrophic. Once the work has been done, these engines are good for the next forty years and a few hundred thousand miles. If you leave these machines alone and fail to do this work, it can result in complete engine destruction, or a very expensive rebuild indeed at best. The CBX1000 is a great motorcycle and an absolute joy to own and ride. Once this work is done, the machine is good for another forty years of reliable motoring. 

Honda CBX1000 cam chain tensioner degraded RHS copy
Age is causing cam chain tensioners to fail on Honda CBX1000s

Two timing chains and two tensioners

The Honda CBX1000 has two timing chains and two timing chain tensioners that all require equal attention at the same time. When we do our CBX1000s, we change both timing chains, both tensioners and the cam chain guide. The guides usually don’t seem to wear out, but it would be churlish not to replace it as we’re in there and they can break up at a later date if they’re not replaced now. Machines that have not had the oil changed every 1,000 miles or six months will suffer from severe cam chain tensioner failure sooner than those that have had the work done religiously through out the bike’s life. Alas, today even machines that have been regularly serviced and been treated consistently to fresh oil at the correct times will still now be suffering from tensioners that are failing. Now is the time to do this work on these machines, once it’s done you can enjoy decades more fun from your machine

Close up CBX1000 degraded cam chain tensioner copy
Would you trust this to keep your cam chain tight and running true at 9,500 RPM?

When you buy from The Motorcycle Broker, the work is done.

When you buy from The Motorcycle Broker, the work is done. We change the cam chain tensioners, cam chains and have the head thoroughly examined and assessed by an engineering shop. Any work that is recommended, we carry out such as replacing valve guides and valves etc. It’s just time to do the work on these machines now and failure to invest in this way will be seriously costly. For this type of work to be done every forty years is a testament to the quality of these machines which you just don’t find in modern machinery. All of our motorcycles go through a rigorous workshop process and anything that needs replacing or attention is dealt with. Only by giving these machines the attention they need now can we offer our one year unlimited mileage warranty we offer on all of our classic motorcycles. If you’re going to ride an investment grade Honda CBX1000 then ride a Honda CBX1000 from The Motorcycle Broker so you know the work has been done.

Paul Jayson
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