750 cam shaft removal

C

chrissoz

Senior member
Location
Sydney, Australia
Should the two camshaft halves come apart easily? I have remove the 3 nuts from the camshaft sprocket but when I try to extra the camshaft using a home made extractor tool it is all moving together - the green book implies that is should come apart easily but that is not what is happening.
 
chrissoz said:
Should the two camshaft halves come apart easily? I have remove the 3 nuts from the camshaft sprocket but when I try to extra the camshaft using a home made extractor tool it is all moving together - the green book implies that is should come apart easily but that is not what is happening.
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They come apart relatively easily.
Paul
 
In theory - but that is not what I am seeing - have tried gentle prising but to no avail. Looking at the diagram once the 3 nuts are removed there is not much holding the flanges to the cam gear - just the key in the keyway?
 
Just that, and what should be a snug sliding fit between a little bit of camshaft which protrudes from the flange thru half of the sprocket. I guess either that bit is bound up a little or the key/keyway is a bit damaged.
If the entire cam assembly is just sliding along rather than separating, I would perhaps try to retain one cam side with the puller, then gently tap against the sprocket in the opposite direction to the puller. The entire head casting needs to be warm, and I would also heat the cam sprocket directly as well. Obviously the cam will need to be rotated around as you tap on the sprocket so it comes away evenly. Will require some mechanical sympathy to avoid damage.

Engineengine-parts-Nockenwelle-C6-fur-Laverda-SFC-Rennmaschine-Laverda-1970-1980_1624658392_3292.jpg
 
You could use the M8 thread to fit a stop to the RH end and as Steve says, with a little heat gently tap on the sprocket or a brass drift on the inside lip of a cam lobe (avoiding the edge). I've never had one refuse to come out very easily - maybe someone has had a flange go loose so they Loctited it together for good measure - not a good idea.
 
Nice for it to be a tight fit, but more difficut to get them apart,the factory race bikes (on many occassions) had the cams and sprocket welded together for reliability, I dont suppose they were overly bothered in the destruction that took place when it was time to get them apart. The factory tool is best for this but strangely, I never saw a "locking device" made up to fit the other cam half that you want to remain static.The Laverda handbook/manual shows the cams being seperated by bashing with a long screwdriver...eeek!
CLEM
 
If this is a motor that the cams have never been removed then it is probably the shrink fit of the head on the bearings that is holding it together. Heat the head up (hot, not just warm) and the cams will come out easy.

Most twin heads have had the cams bashed out of the head with it cold and this eventually removes the shrink fit on the bearings as you are removing a tiny bit of aluminum each time you do this. Also get the head hot to put the cams back in.

The Laverda factory manual showing how to remove them with a long screwdriver and hammer is not a good idea!
 
The fit is so 'loose' from the factory that I doubt it would have that much effect. It's nowhere near an interference or press fit. It requires hair dryer type heat to enable easy withdrawal of the cams/bearings.
 
750's I have worked on that have never been touched by anyone, you have to get the head HOT for the cams to come out. Bikes that have been apart before, yes the cams come out easy.
 
All apart now - looks like a really tight fit of the key into the keyway - it was galled up a bit. Cams are pretty loose in the head once it is warm (could pull the inner bearing through the outer by hand).

Thanks
 
"I have opened a good few works racer engines, Clem, but never saw that, fortunately!"

I cannot remember where I first heard that and I always did have a supicion that it was total bollocks or bar room bull.
Anyone else confirm or deny?
thanks Marnix.
CLEM
 
CLEMTOG said:
"I have opened a good few works racer engines, Clem, but never saw that, fortunately!"

I cannot remember where I first heard that and I always did have a supicion that it was total bollocks or bar room bull.
Anyone else confirm or deny?
thanks Marnix.
CLEM
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Have heard of it with cranks, Clem, but not cams.
 
A mate tacks a spot of mig weld over crucial items like this on his race engines and a few seconds with a dremel has them off. I took his advice on the worn pivots on my rear drum brake, never broken a split pin since ( got sick of it and can redo the whole shitfight some time later) being my own dpo I can do that, and the brake works great.
 
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