500 Camshaft Questions

[moto-bossi]

1. I have come across a couple of references to the early 500s having needle roller bearings at their outer ends of the Cams, was this a feature that lasted long and does anyone know why it was changed?
2. I think that I recall Richard Slater telling me that many 500 Cam problems were due to owners starting their bikes and letting them idle and that what should be done is to give them some revs on start-up to ensure good oil flow to the head. Have I remembered correctly?

thanks M-B

 

[Paul Marx]

Don't know about 500 cams but any engine needs to be warmed up held at moderate revs with the choke/enricher off.
Paul

 

[HansL]

I've never heard of this problem.
I can't recall my 1977 500 (engine number #94) having needle bearings, but has been some time since I last opened her.

I do know that the cilinder heads get very hot and that the valve buckets can stick.
Haven't had this problem myself but I did modify this in two of my 500s.

Hans

 

[Paul Marx]

Mike Waugh used to do needle roller conversions, so of some use obviously.
Can't remember if my race bike has them, haven't been in there in ages.

500s get terribly hot when raced or tuned.

Ciao
Paul

 

[Robin Webster]

Keith has recently built me a 500 race engine and he has put rollers in the cam bearings.

If he thinks its a good idea - it is.

Robin. 

 

[Dellortoman]

When I read the thread title, I thought you had a list of 500 questions about camshafts 

 

[Vince]

There was an artical writen in Classic Mechanic years ago by Royce Creasly [sp} that feet first,NOT CHOPPER, style bike builder about doing this conversion.

 

[LaverdaIan]

The OzLaverda Racing Monty has roller bearings on the cams. It's a conversion I did many years ago, due to the collapsed early cam blocks. We are experiencing a bit of wear on the end of the cams though, a bit of scuffing really. The cams are straight, but Red described it as 'chatter' last week while we were at the motor. Easy enough to sleeve it, but we'll be keeping an eye on it during the year..

8)

 

[laverdakeith]

I fit sleves on in the first instance when doing the needle bearing conversion, the journals as supplied are not as hard as the surface of the needle roller sleve they are also generally out of round and all sorts of sizes if they have been run in the standard bushes for any length of time. Also a good idea to torque then ream the bearing caps in situ as they seem to have a tendency to distort a bit. If your journals are starting to show wear I would advise sleving sooner rather than later, if the bearing surface is starting to break up it can very quickly deteriorate and become oil borne spreading potential catastrophe.



    Keith

 

[Simonr501]

if the bearing surface is starting to break up it can very quickly deteriorate and become oil borne spreading potential catastrophe.

    Keith

The last thing you need is a cat arse trophy.

 

[LaverdaIan]

Thanks Keith, good advice. I'm a bit of an 'observer', so after all runs, even just a track day, or a weekend of racing, I tend to dump fluids, take covers off etc...have a bit of a look around.. That's how we found that 'little end issue' last year.. thats half the fun of doing this racing thing for me..

8)  

 

[bob]

Early 500s did indeed have needle rollers on the end of the cams.  I reckon the factory probably ditched them due to cost or to reduce noise rather than any inherent problem, or perhaps they felt they just weren't necessary. As far as I'm aware the Laverda Corse 500s run with plain alloy bearings, my racer certainly does.
Most of the cam issues which 500s are alleged to suffer from are probably down to ham fisted owners mis-aligning the cam blocks when refitting them. The alloy cam bearings work perfectly well in the 500 [and lots of other bikes] both for racing and road use and the risk of harmful oil borne detritus is reduced , although to be a fair a properly fitted needle roller conversion shouldn't give any problems. 
I can see the appeal of a properly sorted  needle roller conversion if you've got excessive wear in the cam blocks, but if it ain't broke , don't fix it.

 

[3patC]

if the bearing surface is starting to break up it can very quickly deteriorate and become oil borne spreading potential catastrophe.

    Keith

The last thing you need is a cat arse trophy.

makes me laugh this forum 

 

[sfcpiet]

Agree with Bob,

The bushes require precise aligning or they will crush upon tightening, jamming the cams with consequent over-heating and seizure of that particular bush, usually ruining the cam journal in the process.  A needle roller conversion is an easy and cheap fix.

500s are not particularly endangered regarding oil flow. 

piet