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Hydraulic Cam Chain Tensioner

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taysidedragon:

--- Quote from: K2-K6 on March 15, 2022, 12:52:05 PM ---
--- Quote from: taysidedragon on March 15, 2022, 12:45:18 PM ---Well that was a real yawn fest! 😳

--- End quote ---

Glad you appreciated it  ;D if you're here to draw attention to your own ignorance, then who am I to argue with that.

--- End quote ---

Nice. 😂

Laverda Dave:
Well explained Nigel. But why do Honda have problems with tensioning the blade of the tensioner? As you state in your reply, the chain isn't tensioned as such but I guess the 'wear' is taken up by the tensioner blade changing the radius.  I get that bit but why do Honda keep changing the design, the tensioner on the 400/4 is a bit pathetic in design, the horseshoe pivot wears, the tensioner plunger sticks in the tunnel and the adjusting bolt is so thin it will snap at the first oppotunity (although to be fair, by a ham fisted owner). Cam chain tensioners do appear to be a problem area for Honda, that's why my everyday bike is a cam gear VFR ;D

AshimotoK0:
Keep your detailed replies coming Nigel   ;D... I was hoping you would comment  ;).

Evidently , the story on the early CB250/350 K is that the cam-chain rattled like hell for the first mile or so and wore the chain prematurely but I still can't understand why, once the oil pump was pumping oil, that the stack would not be taken up. Perhaps it needed some kind of hydraulic accumulator to store and maintain pressure. There has to have been a Honda Service Bulletin on it but I can't find it.

K2-K6:

--- Quote from: Laverda Dave on March 15, 2022, 01:09:31 PM ---Well explained Nigel. But why do Honda have problems with tensioning the blade of the tensioner? As you state in your reply, the chain isn't tensioned as such but I guess the 'wear' is taken up by the tensioner blade changing the radius.  I get that bit but why do Honda keep changing the design, the tensioner on the 400/4 is a bit pathetic in design, the horseshoe pivot wears, the tensioner plunger sticks in the tunnel and the adjusting bolt is so thin it will snap at the first oppotunity (although to be fair, by a ham fisted owner). Cam chain tensioners do appear to be a problem area for Honda, that's why my everyday bike is a cam gear VFR ;D

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That old phrase "successful design has a foundation of many failures" springs to mind Dave. Obviously, it's ideal if they don't pass all the way through r&d then proof trials while still being vulnerable.
As your VFR,  Honda recognizes that gear driven cams are the ultimate solution, just expensive to engineer and produce for sale.
Designs, they are always trying to fold in details into compact design form to bring such compact engines. Comparison to others of the same era (Italian, British etc) shows how tightly the elements all fit together. 
The CX was an odd one (I believe the experience also influenced them more fundamentally in engine design though) as it had problems with tensioner, thought it was hydraulic and changed to mechanical?  (Trigger would know) but it's the cylinder angle that ultimately promoted the difficulty it appears. Narrow angle 70 degrees ish forced them to put the cam high in the block in comparison to a car V8 for example that has the two sprockets virtually touching each other and usually no means of controlling chain slack at all. Add those longer chain runs to the  firing pulses that give curios resonance, and you've got a challenging design.
But experience here may have led them to two significant engines later on. The F1 V10 that was in McLaren cars was something that most contemporary engine designers thought couldn't be resolved in  purist vibration terms that would give reliable results.  Then came the moto gp RC 211 V a 5 cylinder,  again in the design realm of cx500, those little mistakes seem to breed curiosity there within Honda.

Bryanj:
The CX 500 was semi automatic but not hydraulic, the big problem was that the engine went from not many valves open to most open in a short number of degrees rotation which hammered the hyvo chain and snapped the top tensioner mounting bolt. The mod kit included a large shaped steel plate to support the bolt along with new tensioner and bolt, if they had included a new chain as well it would have stopped the necesity for a further stripdown later.
I still have the deep 27mm socket for undoing the cam drive gear nut that cost me over £20 in the 70's and as usual because i have it never used again, still the best money i spent.
Honda aslo neglected to tell anybody to put the 1st ltr of oil after rebuild down the pushrod tunnel to fill the bath the cam and followers ran in, if you didnt the cam wore in the time it took to fill!

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