Pictures of inter cams

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Oldmikew- castrol R. I know it is the traditional oil for these bikes but why would a well known builder and racer of these machines sell castor oil but use synthetic oils in his race bikes?
Burgs- maybe I should be stoned, have not put oil gauge on bike but done the bit more than 1 1/2 turns out on adjuster. Have not checked if bores are parallel, will look at that. should the followers be lapped to the cam somehow ??
jseng1- looks similar to my damage. are you saying the weld has failed.?
The cam guy said they were built up with colmonoy, similar to, but not the same as stellite . 60 Rockwell on followers and 55 on cams
Thanks guys for the input so far.
 
Dano said:
Pictures of inter cams

Any one have any ideas what has happened to international cams. Motor has done probably 300 race miles since cams and followers were resurfaced
Click to expand...

Hello,
there could be 2 reasons for this desaster:
1st.) If it is the opening ramp of the cam the reason could indeed be the tearing of the lubrication film and the following metal- to metal contact. Why the lubrication film tore? I don't know. Could be the wrong oil, to high revs with consequent high loads to the lubrication film etc.
2nd.) if it is the closing ramp of the cam it could be cavitation. This takes place if the cam follower loses contact to the cam. The following negative pressure within the lubrication film gets so low that we get very tiny vapour bubbles withion the oil film which implode as soon as the negative pressure changes back to the surronding pressure. The vapour bubbles implode and tear metal- cristalls out off the cam surface. To me it seems that the most destroyed part of the surface is exactly at the place where you have the lowest pressure withion your oil film. So, it could well be cavitation we find here. This phenomenon is very often found in oil pumps, camshafts and every part of the engine where extreme negative pressure and consequently cavitation takes place. By the way, the same phenomenon can also be found at extremly high reving ship- and boat propellers.
The question is: how can it prevented? Well, I think the follower only loses contact to the cam, if you rev the engine too high, if the (Hertz-) contact faces between the follower and the cam is too big, or if the valve springs allow the follower to lose contact to the cam due to too low tension of the valve springs or resonance vibrations in the valve train.
I hope that helps a bit to understand why this happend.
Best Regards
Klaus Monning
 
Dano said:
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jseng1- looks similar to my damage. are you saying the weld has failed.?
The cam guy said they were built up with colmonoy, similar to, but not the same as stellite . 60 Rockwell on followers and 55 on cams...
Click to expand...

I think it is the material that failed. Your hardness specs are in the correct range. And its the correct material. But what happened to you is a rare occurrence. Hardwelding is usually one of the best options. But its a crude process and it would be difficult or impossible to nail down the reason your's failed. Cam welders use the same technique on each cam. So why did yours fail? You're not going to get a good answer from the cam people because they do the best job they can and they don't know what went wrong. Its not the oil or anything you did. You were just unlucky. See the photo below. This one is from a different company than my previous post and its the same type of material and failure. So it can happen to anyone.

I have always relied on hard welded cams - but I'm starting to lean toward the plasma nitrided tool steel (which has not failed so far). There are other tool steels to look at - S7, A2, M4. But testing them all is a lot to ask for.

Pictures of inter cams
 
Klaus- thanks for your reply. I definitly did over rev it on couple of occasions but is going to take a little while for your information to sink in. I will have to read it more than once.
jseng1- yes, unlucky must be my middle name.
 
Hi Dano
Over revving these old Cammy's will mostly cause damage to the valve springs and valves hitting pistons, give Ken McIntosh a ring.
Don't over think these engines as they were originally designed to run a race that lasted over an hour long, for a season of racing with minable maintenance, which usually meant changing valve springs if over revved.
Vegetable oil is a pain in the but if you leave the engine sitting for any length of time, has an affinity with water ruins the roller bearings, I learnt this from experience with my two valve Jawa, smells great though.
That Jawa engine used to get the crap run out of it and never damaged the cams or followers, only big ends, mains, conrods (used to stretch), pistons valve springs and valves, ran Shell 50 oil back in the day after the Castrol veggie oil disaster.
I run Penrite in the Manx now it seems to be doing the job nice although it only gets a run at Broadford Bike Bonanza when I can afford it now.
Burgs
 
Hi Burgs, yes I have bent a valve before. I am sure Penrite is a good oil.
Spoke to the cam guy and his opinion is low oil on start up. From now on will be pre oiling if bike sits more than a couple of weeks, thanks.
 
Lack of oil on start up is a problem and contributes to wear but it would not pit the surface. Your surface was brittle and flaked away. I've posted a video in another thread that shows wear on the cam nose.
 
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When you have two wear surfaces in contact with each other, a softer one does not usually wear faster than a harder one. If you want to cut something which is very hard, you would normally use a softer wheel and have it reduce in size quicker. If the cam follower is soft, the cam will probably wear quicker. That is the reason that some cam followers are stellite tipped, but you will notice the hard facing is not welded. It is usually a piece which has been brazed onto the follower. In early Triumph Tiger 100, the cam followers don't have stellite tips and the rate of cam wear is horrendous. The 1953 race kit for the T100 has E3134 cams and R type followers which had the stellite tips. With the stellite tips it is unusual to get 'picking-up', flats on the cams is the more common form of wear.
 
In Kawasaki 900s, the followers have a replaceable pad of very hard tool steel inserted in them, which the cam impacts on.
 
I can't profess to being a cam resurfacing expert, but the RH cam looks like it's suffering from voids in the weld?
 
I got cams back today after being repaired . They did not charge anything.
Klaus- the pitted cam is the exhaust and damage is to the opening side. The scuffed one is inlet and damage is on the opening side.
Have to go find my bearing blue and check a few things, thanks guys.
 
Dano said:
Oldmikew- castrol R. I know it is the traditional oil for these bikes but why would a well known builder and racer of these machines sell castor oil but use synthetic oils in his race bikes?
Click to expand...

Sorry I missed this, well you would have to ask him... not everyone likes R that is for sure and it can be a pain to live with especially in a road bike , perhaps the clue is in the plural race bikes? An issue with R is that it does not mix ,to change to or from it means an engine strip as well as cleaning oil tank , changing oil lines etc.
 
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