1974 Eldo Timing Chain Tensioner

[DaGootz]

The photos attached are of the tensioner that is in my Eldo now. It seems small and the tension spring seems very light. Also not sure of the marks, like the old tension wore out and the chain was wearing through the case. Is this a legitimate tensioner or should I get the one on MGCycle site? Thanks

[Antietam Classic Cycle]

That appear to be what Guzzi used from the factory, starting around '90. The tension of the spring does seem a bit weak to me, so I've always used the bow type tensioner sold by MG Cycle and others.

[DaGootz]

That appear to be what Guzzi used from the factory, starting around '90. The tension of the spring does seem a bit weak to me, so I've always used the bow type tensioner sold by MG Cycle and others.

That's what I thought Charlie, you should feel how light the tension is. I feel it could cause too much timing fluctuation. Am I wrong? 

[guzzisteve]

That tensioner came on New World motor came here in 93 and enough for all bikes made since then. Have they all taken a sh*t? Then why would it not still be good? Put a timing light on the marks & see if they jump around. I think the bow type is too much tension. All you need it to keep the slack out. How tight is the chain on the back of a bike, not very.

[DaGootz]

That tensioner came on New World motor came here in 93 and enough for all bikes made since then. Have they all taken a sh*t? Then why would it not still be good? Put a timing light on the marks & see if they jump around. I think the bow type is too much tension. All you need it to keep the slack out. How tight is the chain on the back of a bike, not very.

I'm in the process of rebuilding the engine right now, so the engine is on my work bench so I can't put a timing light to it for a while, but I'll keep that in mind. I'm gathering information now and really don't want to have to take it back apart if the timing does in fact jump around. Why do you think it's too much tension? Comparing a timing chain to a final chain drive, keeping in mind the difference in front sprocket center and swingarm center, is a fair comparison....not to mention a 20yr difference in technology. I have time and will see what others say then weigh everything. I still need to get new cylinders/pistons and rebuild the heads. Thanks for the input, much appreciated and I'll keep this in mind.

[guzzisteve]

I have installed both types and the bow type is tight to install, that would stretch out chain right away. I put the factory one in my Cali2 in 93 when they became available. After 75K miles it has stayed the same, no slack.

[n3303j]

Let's drop this into the mix:

I do not believe properly engineered chains stretch in use. Stretching implies permanent metal deformation. Maybe a high powered "drag racing" type machine could pull enough power to permanently deform an improperly chosen wheel drive chain. But we aren't stretching chains by opening and closing valves.

In actuality the chain is made up of many articulated segments. Every pivot point is a wear point. In a foot of chain there are a lot of these wear points. If you put 0.005" wear on each and every pivot it only takes 8 links to add up to a full millimeter of elongation. That chain elongation due to internal chain pivot wear is what everyone is calling "stretch".

New quality chain, new sprockets, conscientious oil changes
and an MG Cycle tensioner and you should be good for 100K miles. The tensioner does ride on the slack side of the chain but it does catch any reverse impulse as a cam lobe gets pushed forward by the valve spring on the closing part of the cycle.





MG Cycle tensioner c 80K miles. Chain side plates cut grooves but rollers were supported by the high ridges. This tensioner does add a bit if a "whirring" sound to the engine and the cover helps amplify the sound. It's not objectionable, just different.

[DaGootz]

I have installed both types and the bow type is tight to install, that would stretch out chain right away. I put the factory one in my Cali2 in 93 when they became available. After 75K miles it has stayed the same, no slack.

Makes sense, thanks.

[Frenchfrog]

Let's drop this into the mix:

I do not believe properly engineered chains stretch in use. Stretching implies permanent metal deformation. Maybe a high powered "drag racing" type machine could pull enough power to permanently deform an improperly chosen wheel drive chain. But we aren't stretching chains by opening and closing valves.

In actuality the chain is made up of many articulated segments. Every pivot point is a wear point. In a foot of chain there are a lot of these wear points. If you put 0.005" wear on each and every pivot it only takes 8 links to add up to a full millimeter of elongation. That chain elongation due to internal chain pivot wear is what everyone is calling "stretch".

New quality chain, new sprockets, conscientious oil changes
and an MG Cycle tensioner and you should be good for 100K miles. The tensioner does ride on the slack side of the chain but it does catch any reverse impulse as a cam lobe gets pushed forward by the valve spring on the closing part of the cycle.





MG Cycle tensioner c 80K miles. Chain side plates cut grooves but rollers were supported by the high ridges. This tensioner does add a bit if a "whirring" sound to the engine and the cover helps amplify the sound. It's not objectionable, just different.

no offense meant but sorry but chains definitely wear ...and stretch.That's just undeniable.
I've used both types of tensioners and found that they are both ok but the Guzzi one is what I've stuck with.
In terms of ignition timing you can make up for the wear /stretch....not possible for the valve timing.On a high mileage engine that might be a slight issue eve if a new chain is used on worn  sprockets.

[Huzo]

I’ll make the point that it is the short length of chain between the driving (crankshaft) sprocket and the driven (camshaft) sprocket, that determines the valve timing with respect to the crankshaft.
It is about 50mm long at that point and any wear/stretch is affecting that short span. All the rest of the accumulated wear is on the “slack” part of the train and is absorbed by the tensioner.
I therefore contend that chain wear has absolutely minimal effect on cam timing.
I could go on…..

[moto-uno]

  I've had the MG cycle one in my LeMans for over a decade now , that's gotta say something  .

[Antietam Classic Cycle]

My '76 Convert had 18k miles on it when I got it. It was in rough condition so a refurb was in order. When I removed the timing cover, the chain had almost enough slack that it could contact the case and cover. Because it was my bike, I could experiment a bit, so I just loosened up the bolts on the original fixed tensioner and slid it over until it once again did it's job and locked it down. That was 40k miles ago and I still have the same light whirring noise as I did at 18k.

If it was a customer's bike, I'd have installed the bow type tensioner.

[moto-uno]

  ^ By the time I originally checked the cam chain on my LeMans (about 4 decades ago) I had to file out the slots to get it to take
up some of the slop . Next time it got the sprung loaded one .