PeWe:
What kind of tensioner do you have? Is it the spring-force tensioner (OEM type) or is it the screw-in pushbar type that must be manually adjusted?
Mark, it is the OEM push bar with a spring.
The metal wheels to be installed in an old tensioner might be the final solution without rubber. I had plannned Honda OEM with rubbers, the metal wheels might be better. The racing guys use similar solution in the racing forum.
Next rubber stuff is the primary chain tensioner... I have a new OEM rubber to be installed unless I get something better within a month that does not cost a fortune...
//Per
Thanks, PeWe: I do know of at least one incident where someone who used the "manual screw" type of pushbar overtightened his chain and broke the same roller. I don't know what "brand" of roller his (chopper) 750 had in it, though.
I'm looking for a possible "cause" here, in case it is not the materials themselves? I remember from the racing days that guys who increased the tension on the chains (by various methods) also failed the tensioner rollers, chunking out pieces of rubber in the process. This was one of the Achilles' Heels of the Daytona bikes (circa 1970) as they were run at (or above) our max RPM for the whole race: they chunked out the rollers from the 'standing wave" that tends to develop when the cam is bowed downward (in the middle) at constant high RPM (10k RPM or more) and making very high drag loads in the cam bearings, creating some slack in the back side of the chain. This then vibrated somewhat, and this battered the roller material, denting, slipping, and bouncing the upper roller on the arm: this in turn reduced the oil in the chain and upper roller, which caused drag in the roller and wear in the chain, wearing both parts. When a "fix" of a metal roller was introduced on some of those bikes (and often, after Daytona), it accidentally improved the oil retention in the chain because the heavier roller resists the chattering motion (heavier inertia) that flicked the oil out of the chain as it rolled over it. This, of course, improved the chain life, which helped the roller life, etc...
It is also interesting to note that the early bikes (before the New Factory K1 appeared) had MUCH tighter clearance in the 2 inner rocker tower bearings. The cams that appeared from this change had typically 0.002" more clearance in the inner 2 bearings (up to 0.0060" brand new), by reducing the cam OD on those inner surfaces (the rocker towers stayed the same). It appears that Honda's engineers surmised that letting the cam flex downward at high RPM did several good things, like less bearing drag loads and reduced tension on the rollers at constant high RPM - like touring on US Interstates, where we can ride all day at 80+ MPH speeds with nothing more than fuel stops (and I have, as long as 16 hours straight, many times!). When the K1 became the K2, the bikes were MUCH quieter, especially reduced cam chain noise, from this change. My K1 was always chain-noisy inside, while my K2 was immediately not so, for example. I also immediately noticed the K2 power did not fade when hot, as did the K1, and I am sure the lesser cam drag has some effect, here.
The steel rollers (and nylon versions) have persisted for racing applications ever since the 1970 Daytona win. Over the years, there have been many vendors of the rubber roller kits (because Honda starts and stops their supply of them): I just ordered some of Honda's tensioner parts to compare with the "Made in Taiwan" kit I have (unused) in my shop. I'll post here the differences I find, if any, when the Honda parts arrive (2/24 scheduled). The Taiwan parts I have seem to be a 60-ish durometer rubber material. I'll see how that compares with the OEM parts.
