Regrinding Cam Buckets

moto-bossi

moto-bossi

Junior member
Location
Bath, Somerset
My Alpino died (before I bought it) of a failed Cam Bucket. I have managed to get hold of one replacement, but the other 7 don't look too special. The tops are all dished by .002 to.003" and the surface finish isn't great either.
I suppose regrinding is an option, but I have no idea how thick the hardening is?
Suggestions welcomed!
 

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Damage most likely through lack of lubrication. I doubt the hardness layer is very thick, most likely the "dished" effect is because the hardness layer has been breached.

Sorry if this sounds pessimistic, hopefully I'm wrong........

Ian
 
It's not that simple.  They are designed to be slightly dished.  That is the main reason that it is so hard to find someone who can re-surface them.  Wolfgang also tells me that they are the same hardness all the way through - there is no hardened "layer".
 
Correct me if I'm wrong but I believe they are slightly dished (or slightly domed), to rotate the bucket.

Stu
 
Correct me if I'm wrong but I believe they are slightly dished (or slightly domed), to rotate the bucket.

Stu
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I agree with your take: Flat Tappet Cams (Not Roller Cams) with Push Rods require that the Lifters is Flat and the Cam Profile Beveled so that the HFT or SFT Push Lifter and Rods Rotate in order to be properly lubricated and ware evenly.

There are no Push Rods or Lifters but there are Rocker Arms in Hemi-Spherical SOHC Engine. DOHC Engines do not have either push rods or rocker arms but do have Bucket Lifter that ride directly on the cam and in my opinion these lifters should Rotate in order to be properly lubricated.

Just my old school take on engine understanding.

I can't see a Bucket Lifter, Lifter Bore or Cam Lobe surviving unless the Bucket Lifter is not rotating where the Cam Nose is NOT Beveled and NOT Centered on the Bucket and friction causes the Lifter to Rotate. Therefore Cam position is critical.

I got an 84 Volvo with over 450,000 miles on her and had to replace the a rotted out Head gasket - She's a ME23 SOHC None Hemi Cross Flow Wedge inline valve engine. There showed absolutely no ware on the Cam and Buckets and the Tappet Clearance where well within specks - Didn't have to play with pucks.

Aside from checking the Tappet Clearance about ever 2 seasons, all I can say is that I don't have to contend with this on my Breganze 750 SF - LOL

I suggest you change out all your Bucket Tappets and have a machine shop check your Lifter Bores and look onto that the Oil System is clean and up to snuff. You're probably looking at touching up the Valves and Seats plus new Valve Springs, polishing the Cams (Hope the Cam Bushing survived) ...etc and etc = MONEY buit you can save if you been there and know what to do
 
I have thought about this some more and am pretty well convinced that the top of the Buckets, that the Cam runs against should be flat. My reasoning includes:

- The new one that I have is flat
- If they were designed concave the axial profile of the Cam would have to be convex to match, such a design would be very expensive to produce.
- I cannot see how a concave bucket would rotate any more readily than a flat one.
- Starting flat, but becoming concave through wear and deformation appears to me to be a credible scenario
 
beauchemin said:
It's not that simple.  They are designed to be slightly dished.  That is the main reason that it is so hard to find someone who can re-surface them.  Wolfgang also tells me that they are the same hardness all the way through - there is no hardened "layer".
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Was Wolfgang referring to the cam buckets for all Laverdas or just the smaller displacement engines?

Gerald
 
The cam buckets should be flat, not a good idea to regrind as the bucket has already distorted so regrinding will most likely turn out to be a temporary fix.


    Keith
 
No, sorry. See Zane ones come up on ebay occasionally, they fit I beleive. Other alternative is to have some made, can look into this if enough demand.


    Keith
 
The cam buckets should be flat, not a good idea to regrind as the bucket has already distorted so regrinding will most likely turn out to be a temporary fix.
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I believe you're right the cam is off set from center on the flat bucket and that's what rotates the lifter.

I can spell but my cognitive and physical means don't allow it - That's why I got so many EDITS !

Dyslexia is just something I have to put up with.

_____________________

HFT is Hydraulic Flat Tappet.

SFT is Solid Flat Tappet.

HR is Hydraulic Roller.

SR is Solid Mechanical Roller.

And then you got to understand SOHC Wedge/Hemi Vs Hemi and DOHC Mills.

The Breganze SF and SFC is a chain driven Rocker (Cam Follower) Arm Hemi-SOHC Engine with no Push Rods or Lifters but it does have rockers and Please don't get me into the Ducati Desmo Mill as I've cared for a 350 Scrambler and a 750 SS which basically have none of the above save for their God Forbidding Rocker Tappet adjustments. I loved the Ducati 750 SS but my Breganze 750 SF would burn her in the long run.
 
Hi Paul,
What state are the cam lobes I would expect there to be wear on the nose of the lobes considering. the wear on the bucket(s)?
Joy Engineering can/will reprofile the cams if required.
Normal cause of wear is lack of oil normally caused by someone fitting std O rings when fitting cylinder head.Std O rings swell and stop flow of oil!Of course I'm making an assumption here.
Whats the history of the bike?

Andy
 
Andy,

I have already got a pair of replacement Cams so that's not something that I need to worry about.

Know nothing of the history of the bike, other than it came from Spain. Lubrication may have been part of the story, or it may have been down to clearances not having been adjusted.
 
Give the DNA a call, they may be able to help.
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What's Dyslexia Vs CRAFT disease at my age and still in love a Breganze.

It's going to my Grandson, in my Will, providing he don't ride it until he's 21 and by then I hope he has learned something.

Yes I will promote Him to ride 2 wheel's over the protest of my Daughters.

Cam bucket"s kinda hits home to me especially when a an SF cam follower can rattle 8000 rpm.
 
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