It looks to me like a relevant place for your question. I guess I spoke too soon earlier. It seems there are a number of people who run chain wax or grease on their primary chain like you described, with the chaincase otherwise dry. It still seems strange to me, but I'm willing to learn.
In your searching, did you see this post by beltdriveman who used to post on the forum?
'64 TR6R Plus some Twins from other countries (U.S., Germany, Japan)
Re: And another kinked primary chain
#614133 08/22/1511:25 pm08/22/1511:25 pm
Ha, I've tried to read his posts but had difficulty getting through them, mostly because his lack of paragraph breaks. They are large blocks of text!
I did read that through just now and it was interesting. The more i think about my scenario, i think that without an oil bath and not enough ventilation, everything just got too hot. The tensioner blade melted off. The stator expanded and rubbed on the rotor. That generated more heat. The chain was dry on disassembly. The heat and centrifugal force flung it off.
John i found the post I was referring to, and not only was it not you, it was on another forum altogether. My apologies to you, sir.
I'll run an oil bath until my belt system comes back. My crankshaft to mainshaft CTC distances were wide resulting in a very tight belt. A smaller pulley is being made and I'm running the stock clutch now in the meantime. I'll look at more adequate ventilation at that time.
What I 've found over time is that the button on the end of the trunnion adjuster rod is too small, and as a result, suffers from wear which could cause it to pull through. Adjuster slackens off! I fit a thicker, larger diameter washer which spreads the load here.
My crankshaft to mainshaft CTC distances were wide resulting in a very tight belt. A smaller pulley is being made and I'm running the stock clutch now in the meantime. I'll look at more adequate ventilation at that time.
who made the belt drive, tommy?
i have a newby i'm going to be putting into a 1970 T120, and i don't know yet if there will be any CTC issues on it. i'm curious about your solution, should i have difficulties.
Bob's current belt design (twenty years old now) was based on a set of "wide cases". He claims he hasn't run into a problem since. But when I sent my measurements he confirmed that my CTC distance was .070" wider than spec, and .040" wider than the set of cases he based his design on.
He is currently working on a smaller pulley/basket to accommodate this. My belt was very tight when cold, and of course it only gets tighter as the cases warm up. This can lead to all sorts of problems, including broken gearboxes.
I did have an issue with the end of my gearbox mainshaft being uncomfortably close to the pressure plate. Bob sent another steel clutch plate, but said that the feel of the clutch engagement would be different. Bob's normal clutch setup has the pressure plate engaging with a fibre plate, not steel. I chose to have my machinist take .200" off the mainshaft instead. Bob said he hadn't come across that type of clearance issue before, but I did find a Vincent owner on another forum that had to turn down his mainshaft as well.
The clutch pushrod will need shortening, and I would get your machinist to round the end into a bullet shape. The adjuster pin on the PP is concave, so if the pushrod is square it has a tendency to try to walk out.
I would also consider an MAP belt system as it retains the cush drive. There is worthy debate about wether or not the belt alone is adequate. I am not qualified to answer that, but in retrospect I would probably opt for a cush drive on a street bike. I haven't asked Marino if he has provisions for extra wide CTC cases, but you could certainly give him a call and ask.
It's a Bob Newby belt drive. It really is a work of art. But the belt was tight when the engine was cold, which just means it gets tighter as the engine gets hot. This can introduce a number of problems, from broken gearboxes to crankshafts.
I'm not sure if 1970 was a particularly bad year for tolerances and quality control at the Meriden factory, but John Healy has a set of very wide cases here:
Bob said that he based his most recent design (twenty years old now) on a set of wide CTC cases. My measurements were .040" wider than that, and .070" wider than what it is supposed to be. John's Bonneville cases were .100" wider.
Bob is attempting to make a pulley/basket combination to accommodate this.
I would also consider the MAP belt drive as it retains the cush drive. There is some worthwhile debate about wether or not the belt on its own is adequate. I'm not qualified to answer that, but in retrospect I would be inclined to retain the cush on a street bike. I have not asked Marino at MAP if he has solutions for wide cases, but you could certainly give him a call.
I also had an issue with the end of the gearbox mainshaft being uncomfortably close the the pressure plate. I had my machinist take .200" off the mainshaft. Bob sent me another steel plate, which would have moved the pressure plate further out, but also said the steel plate would feel different on clutch engagement. He said this was a first for him, but i did find a Vincent owner on another forum that had a similar clearance issue.
The clutch basket has no wobble when the clutch is disengaged. It feels lighter and smoother. I am hoping he can work it out for me, because i really do prefer the feel and action of his clutch and belt.