Current cars (be they cambelt or camchain) all seem a bit the same to you?
You might be interested to go back down memory lane and check out the Oldsmobile Toronado ( see www.toronado.org/carlif3.htm). Sorry I haven't mastered live links.
If GM could engage in this sort of exercise then, why can't they provide us with a reasonably reliable idler/tensioner today - or have all the engineers been replaced by accountants?
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oh (¨%*#@(, why do I bother to try ??
MARTYN !!!!!!!!!!!!!
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Mark (Brazil) wrote:
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> oh (¨%*#@(, why do I bother to try ??
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> MARTYN !!!!!!!!!!!!!
Yes, dear (sigh)
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I can never understand why motorcycles do not have chain tensioners fitted. Surely all it needs is a jockey wheel and a spring, or am I missing something fundamental (as usual)?
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In the mid '70s (ahhh the good old days) the Honda CX500 had a chain tensioner which had problems on early models, once moded (had a punch mark on the engine case)and on later models it was fine. Mind you the engine was a plodder not a racer.
CV
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wouldn't using engine braking, which puts the stress through the chain the opposite way, rather destroy any tensioner ?
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Mark
Think about that - the crank always drives the cam, even on overrun, so there is no change in the chain/belt tension.
The torque change occurs in the transmission.
Regards
John
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I dunno why we haven't got an edit button. Are you going to fix my screwed up link ? I forgot the http stuff.
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Mark (Brazil) wrote:
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> I dunno why we haven't got an edit button.
Yes you do!
Are you going to
> fix my screwed up link ? I forgot the http stuff.
I just did
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Mark (Brazil)
I wouldn't have thought so, the chain keeps going in the same direction, there's no reverse on a bike (except Harleys?), all you are doing is taking up any slack and stopping the chain flapping.
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Well, I'm trying to picture this in my mind.
When I used to ride bikes, especially in a silly mood, I used to really drop them through the gearbox for a bend.
So, when the engine is pulling the back wheel, the tension is in the top of the chain (top of wheel being dragged towards engine) but when using engine braking then the bottom of the chain is being dragged out of the engine by the wheel ?
I think.
Given that, I would think there was quite a lot of stress in both "directions" ?
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>>I just did
thank you darling.
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Mark (Brazil) wrote:
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> >>I just did
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> thank you darling.
Mark, you're really going to have to learn to use this quote button, otherwise people will start to wonder!
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Oh well, if its like that.
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CV,
You had a CX500 ?? What a dog of a bike that was. I was doing some motorcycle courier work and I bent my Z500 and used a CX500 for a couple of weeks. Absolutely horrible.
The only one I ever had which was worse was the Yam XS shaft driven thing.
On a similar subject, I was just downstairs in the carpark and there is a late 70s Honda 400F. Now that was a great bike.
M.
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Mark,
Yes, I had a CX500 for about a year (Late 1977 to '78), I needed a sensible, plodder and it never let me down, not like the (***this bit deleted in the interests of good taste***) VF750SC I had in the mid '80s, bit of damp and it would just not start...
Remember, the CX Vee Twin was a tractor on two wheels not a racing machine. Thats why many couriers used them (for their realiability) and you still see a few of them around 25 years later...
CV
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CX 500
I've got one in the garage 1982 vintage. I might just get it going for the summer. (that's assuming we have one)
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>>otherwise people will start to wonder!
whereas we know for sure.
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John,
>Think about that - the crank always drives the cam, even on overrun, so there is no change in the chain/belt tension.
Ah, so we´re not talking about the final and primary drive chains then ? Oh. Oops.
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Caught up at last Mark :-)
cx500 is shaft driven.
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Two different conversations Alyn - CX500s & Chains on bikes.
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>>Now I'm confused
At least we can be sure that you know what is going on, then. If you were not confused I would have to assume that you weren't paying attention.
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First post mentions cambelt or camchain - so I asumed that was the topic, but I probably missed something on the way.
Hm, tensioner on final drive would be a bit tricky for a powerful machine, but I recall that the Lambretta scooters had a slipper type 'tensioner' on the (enclosed, fully lubricated) duplex drive chain 'twixt engine and gearbox. Seemed to work.
Regards
John
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Brian said "I can never understand why motorcycles do not have chain tensioners fitted", implying final drive, I think, hence the cross-purposes about reverse loading. Some moto-crossers with large rear sprockets do have an idler or slipper, but I think this is just to keep the lower half of the chain out of the muck.
What puzzles me is why more bikes don't have toothed belt drive, like most Harleys and a a couple of Kawasakis. This takes out just enough snatch to smooth the transmission, doesn't require oiling (and therefore doesn't attract loads of abrasive crud) and is light and mechanically efficient. I suspect a cosy deal with the chainmakers, meself...
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My HOnda trailbike has exactly that.
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To pick up your point re the Harley belt drive. You're right, it's excellent. Extremely long lived, never been known to break and cheap to replace. Any belt which can handle a full handful of EVO 1340 cc thru straight pipes has to be good. It is odd you don't see more use of this kind of belt.
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Yes, if it works on a Harley... I think HD use Gates belts, which is an American supplier, so there may be a bit of mutual support there, but I'm convinced that the Japanese chain makers have got a cosy deal with the bike makers. I'm not overly fond of chains (I used to boil them up in LinkLyfe on the stove, much to my then wife's annoyance) and although shaft drive overcomes the problem, it is relatively complex and heavy. Belts are the answer, but nobody uses them!
(Just because you're paranoid doesn't mean you're not being followed!)
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