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The early belt engines, ie 500 - 600 Pantahs had the same rocker covers as the bevel-drive engines, so I'm guessing that they will fit all 2 valve engines, except the DS.
 

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Discussion Starter #3 (Edited)
The early belt engines, ie 500 - 600 Pantahs had the same rocker covers as the bevel-drive engines, so I'm guessing that they will fit all 2 valve engines, except the DS.
That's interesting, thanks. I like the idea of having fins on the rocker covers. Are these things particularly valuable and rare?

I see that the bevel engines did not have an oil cooler, hence the need for fins on the valve covers.
 

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No, I don't think that they are rare, they come up on eBay regularly.
 

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I'm not sure if it matters to you but there are (at least) two different versions of the covers. The early covers are lower than the later covers due to a rocker arm change. (The early bikes use shims to adjust the valves, later bikes use screws/locknuts.)
 

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Discussion Starter #6
Thanks everyone for your advice. This is an interesting idea, particularly for a belt drive motor that has been hopped up, since it will help cool off the heads a little bit more. I'll keep a look out on eBay for them.

If anyone sees some for sale, it would be great if you could PM me. thanks.
 

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750 GT, 750 Sport, 860GT, 900GTS were all valvespring heads. 750 SS was desmo then the Darmah and desmo went mainstream.
Yes, I know that there were models with springs, but the OP didn't say that he was looking for covers for spring models, rather to fit his 900SSie, which would presumably would be most compatible with desmo, and not spring, heads.

Tom
 

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Yes, I know that there were models with springs, but the OP didn't say that he was looking for covers for spring models, rather to fit his 900SSie, which would presumably would be most compatible with desmo, and not spring, heads.

Tom
Upon rereading I see that not only did I not answer your question but I failed to correctly read the post on why the covers on the early bikes are lower. It has nothing to do with the valve train but the fact that the very early springer bikes used shim adjusters. The high covers allowed the extra height of the screw adjuster on the later springers.

I'll have to check, but I imagine you could ues either - the low should fit and the higher would give some extra headroom over the rocker. I'll take a look when next near my bikes.
 

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Discussion Starter #11
I'll have to check, but I imagine you could ues either - the low should fit and the higher would give some extra headroom over the rocker. I'll take a look when next near my bikes.
That would be great, thanks.

Does anyone have photos of these things by themselves? I can't find any in Google. I only found them installed on the motors.
 

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Discussion Starter #13 (Edited)

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...It has nothing to do with the valve train but the fact that the very early springer bikes used shim adjusters. The high covers allowed the extra height of the screw adjuster on the later springers.

I'll have to check, but I imagine you could ues either - the low should fit and the higher would give some extra headroom over the rocker.

Yep, I guess I should have done a better job of explaining the differences.

Anywhos, I don't see why the low ones wouldn't work - the stock covers aren't "high lift" after all.
 

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Discussion Starter #15
Yep, I guess I should have done a better job of explaining the differences.

Anywhos, I don't see why the low ones wouldn't work - the stock covers aren't "high lift" after all.
yeah, the oem covers for the belt drive engines have maybe 1 cm of concavity, but I have not measured it.
 

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Finding early 750 valve covers is likely pretty remote but the tall covers were the same from the later 750 bevels thru to the Cagiva Allazuras and Pasos.In reality the heat dissapation from the fins would be negligable and the space limitations on the SS around the battery box and rear shock mount may not allow enough clearance for the taller covers. If you don't have an oil cooler you might be able to use two of them on the horiz. cyl. though.
 

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Discussion Starter #17
In reality the heat dissapation from the fins would be negligable and the space limitations on the SS around the battery box and rear shock mount may not allow enough clearance for the taller covers. If you don't have an oil cooler you might be able to use two of them on the horiz. cyl. though.
I have been trying to find some data on aluminum valve covers and heat dissipation, but have not found much. In theory, the heat dissipation is greater, no doubt about that, from convection, but how much, I don't know. The main heat conduction path is through the 4 bolts that hold the valve cover on, and through direct contact with the oil. Oil is not very good at heat transfer, but aluminum is stupendous, so I would guess that most heat goes through the 4 bolts since the gasket is an insulator. Most of the web sites I found were for water cooled engines with steel valve covers, and saying that changing to aluminum would help keep the engine/oil cooler. It's common in the automotive field to change various steel covers for finned aluminum ones. I checked with air cooled airplane engines too, and they all seem to use steel valve covers, but tremendous fins on the cylinders and heads though.

My bike is getting modified so there will be more room around the heads for something like this. The battery is going to be relocated, the air box is getting replaced by velocity stacks, etc. The vertical cylinder runs hotter so it would be better to figure out how to put them there. I have an oil cooler, and it would have to be relocated to accommodate one of the valve covers. It may have to move anyway to accommodate one of the velocity stacks.

Thanks for your help and advice. If you can find some data on the effectiveness of these valve covers over ones without fins, I would like to read it. This may be more about show and not go.
 

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... The main heat conduction path is through the 4 bolts that hold the valve cover on, and through direct contact with the oil. Oil is not very good at heat transfer, but aluminum is stupendous, so I would guess that most heat goes through the 4 bolts since the gasket is an insulator. ...

This may be more about show and not go.
I wouldn't be so sure the bolts are the main heat conduction path considering the area of the valve cover that gets splashed with hot oil, the exhaust cover on the front cylinder especially. It's not splashed with oil, the oil literally pools up in it.

And yeah, I'd say it's a pretty safe bet it's more about show than go. Nothing wrong with that, I'm just saying... if there was a significant advantage to having finned valve covers I'm sure Ducati wold have run with them on the new bikes too. It's been long time since I studied heat transfer but IIRC it's large thin fins you want for cooling, not short stubby ones.
 

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Discussion Starter #19
I wouldn't be so sure the bolts are the main heat conduction path considering the area of the valve cover that gets splashed with hot oil, the exhaust cover on the front cylinder especially. It's not splashed with oil, the oil literally pools up in it.

And yeah, I'd say it's a pretty safe bet it's more about show than go. Nothing wrong with that, I'm just saying... if there was a significant advantage to having finned valve covers I'm sure Ducati wold have run with them on the new bikes too. It's been long time since I studied heat transfer but IIRC it's large thin fins you want for cooling, not short stubby ones.
Oh yeah, I forgot about the oil pooling there. Thanks for that! I guess for the covers exposed to pooling hot oil, then that's probably the main heat transfer path.

I would suspect Ducati's motivation has as much to do with reducing cost as it does with not needing the fins. Making finned covers is probably more expensive than making flat ones. I do note that the Monster 620, which has no oil cooler, has the non-finned valve covers.

Any increase in surface are is going to increase heat transfer by radiation and by convection. How much of an increase depends on a lot of things, like air flow, difference in surface area, surface finish, etc. You're right though, many thin fins are better than a few thick ones, but many thin fins are expensive and difficult to cast. I remember my Alfa Romeo Spyder had a deep aluminum oil sump for the engine that was covered with fins. That must have cost some bucks to make, as opposed to just a flat one.

I've attached an image from a computer simulation of thick vs. thin fins. You're right, thin fins win!
 

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The finning on the covers is all about style which is what Italian designs excell at.The heat dissapated through valve covers is miniscule as they are pretty far from the source of the heat.Now if they were finned internally that would be an advantage as the oil splashing around could absorb it then shed it through the oil cooler.The Ducati engines run pretty cool anyway as they have a gallon of oil in circulation and a relatively large cooler to shed it.If you have an oil temp gauge you will see that the oil rarely gets much over 230F and thats after sitting in traffic for a while. If you look at the later 2 valve heads you will see that Ducati has removed the finning/ribbing on the cam housing area too.I'm sure that if the engineers were concerned about heat in that area they would have left the fins on.The fins on the Alfa sumps were there for style too,If it hangs out from under to bash curbs with it had better look good doing so.
 
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