Quick cam-chain questions
Who makes the best cam-chain tensioner?
“Suzuki’s ratchet design is good, once it’s wound out, it can’t (usually) go back. It avoids the problem that some spring only tensioners have, which is when the camchain needs most help at the end of its life the spring is uncoiled and loses tension. It’s the opposite of what is needed!”
Worst Bike for cam-chain replacement? “Kawasaki VN750 – it’s a V-twin that has four cam-chains and four tensioners – it’s bordering on a two-day job to get it done, an utterly crazy design.” Best bike for cam-chain replacement? “Kawasaki GT550 – I’ve done hundreds of them, simple, air-cooled, in and out.” Easy peasy lemon squeezy!
Weirdest cam-chain story from 31 years of working with them? “I did a mobile job in St John’s Wood, the guy was very nice, but definitely part of an alternative fashion scene. Once I’d pulled the old chain out of his bike, he was fascinated with it, saw it as a thing of great beauty. He pondered a while and then politely asked me if it was his to keep! When I said it was, he asked if I could split it and fit it to his wrist. Although surprised, I agreed and suggested fitting it loosely so it came off, but he didn’t want that!” If anyone knows anyone called Spike with a cam-chain permanently attached to his person, Tony thinks he may be due a replacement by now, and can he get in touch?
What was the problem with Honda cam-chain tensioners in the 1980s?
“Let’s use the first CBR1000 as an example for this – I’d be surprised if I haven’t had
almost all of these through my hands at one time or another! The hydraulically assisted cam-chain tensioner on that first model just didn’t work. It had a catch tank in the cam-chain gallery to collect engine oil, which then was supposed to create a hydraulic lock stopping the tension from backing off. “The catch tank wasn’t big enough, and the design was also subject to variation in effectiveness if your oil got hot, or was a lighter grade (Tony suggests using only the correct grade or even a heavier one on bikes that have these hydraulic tensioners) Honda eventually modified the tensioner with a bigger catch tank on a later model and these when retrofitted to the earlier models pretty much solved the issue. It was a painful time for CBR owners though!”
What do you think of manual cam-chain tensioners?
“They’re only as good as the person adjusting them! If you know what you’re doing, and you pay regular attention to your engine, then you’ll have no problem, but set them up wrong or expect them to work forever without looking at them – well, that’s asking for trouble!”
Closing call – what one last thing would you like to say to the readers of CMM about cam-chains?
“I suppose it’s about how much better the chains we use today are than some of the stuff that left the factories in the 70s and 80s. An example is the original Slabby GSX-R, which used a pretty basic roller pin cam-chain. Yoshimura’s tuning work on the GSX-R involved dumping this for something better immediately and the work Yoshi did filtered through onto production models quite quickly. “If there’s a message to people restoring bikes, it’s only that it’s worth taking a look at what cam-chain (and tensioner) is fitted and if it would benefit from being replaced by something not only newer but better while you have the engine apart.” *Although of course if it needs doing in the frame, then you know where to go, right?