'83 cam disintegration and oil in alternator cover

Greetings Everyone,

I am semi new here but I am not new to motorcycles. I recently purchased an '83 750 that had been sitting about 9 years. I did get it to run and idle but not without the choke, pilot jets are gummed.

Anyway today we had some unseasonably warm weather for the midwest in February, 40 degrees, and I decided to pull the carbs. Additionally I continued on and pulled the rear valve cover to take a look at the cam lobes. I was hoping I was one of the fortunate unaffected but today was not my lucky day. Pitting on the rear left intake and the rear right exhaust, additionally there was some oil in the alternator cover.

So here is my question, is the upper end oil mod needed to slow / stop this disintegration? I plan on being a casual rider, a couple times a week, 4 months a year, who stays away from redline. Should I find used cams in better condition and then add the oil mod? Can I just be conscientious about oil changes and call it good? Any thoughts on the oil in the alternator cover?

Thanks in advance.

P.S. I don't need to hear the derogatory comments that a FEW members like to post regarding the age and quality of the bike. I did my research ahead of time and knew this might happen. I'm just looking for a little input on the subject.

 

The stator is a wet unit so no worries. The cams were made of warm butter back in the day and is normal , trying to find a set myself. Not a fan of the oil mod myself but will leave it at that.....no need to argue. You should be good to go with a set of cam's, followers, and a carb cleaning.

 

Warm butter... HA! HA!

I thought they were made of melt in your mouth chocolate before '86.

 

I believe the one of the main problems with the cams wearing is in the lash adjustment and the type of oil used. My 83 has 60k w/original cams. I've always used a good motorcycle oil like Spectro and lash was set at a loose .005-.006.
I have read for the 500's and 750's the factory spec for lash got changed about .001 more. Just a guess but wonder if some of those bad cams got lashed a little tight. Spec in my 83 manual is .005. So if the lash was a tight .005 (.0045 actually) or .004 and caused part of the pitting.
I also wonder if transfat in the butter did it!

You can get replacement after market cams you know. Megacycle Cams

 

A question on this topic.

When swapping cams from another bike is it possible that you will run into an issue with the journals? I've read that it is very important to keep the cam with its journal based on the wear pattern.

Regarding the 'great cam crisis' a good read on this subject is Julian Ryder's Honda's V-Force. He goes into specific details on the cause and effect. I'd recommend this book for any V4 owner.

Good luck with your project and let us know how you are making out.

 

Thanks Tink. I kinda had a hunch that this was correct. Am I also correct in thinking that when making a swap you should do a double check on the journal's camshaft oil clearance with plastigauge? If these clearances are outside the service limits is there an option to re-machine the camshaft holders/journals or is this getting into a sticky wicket?

 

The FSM does give a spec on the oil clearance (page 9-7). They note that if the clearance is over the service limit to replace the camshaft. If still over the limit after checking again they recommend to replace the cylinder head and camshaft holders.

As you note, a good set of heads with good cams, followers and valve stems can be found in the $100 range + shipping, if you are patient and have time to find the right eBay auction or salvage yard. This looks to be the best way to go.

 

Gen 1 had a unique cam journal, was a major downfall and why tensioners fail, it was a bore that was laid in and not line bored. It is the reason for that dipshit cam adjustment tool to take up the slack in the wild clearance of the journal. Look at the valve cover gasket, no half moon cut oot in it. The cams rock around the center line (pulling on the tensioners) and run a tighter spec on the inside follower and it is best to run that one a bit on the fat side just to be safe.

 

IT IS BEST TO RUN ALL VALVE CLEARANCE ON THE FAT SIDE FOR GEN 1. A little tick will not kill you but flat cams will.

 

Thank you for the post.

I've read in other threads that this is a good strategy but I was wondering (perhaps this is purely academic) if you set the lash 'fat', to the point where you hear a tick, will this cause premature wear on the tops of the valve stems (i.e. mushrooming)?

Honda issued a FSB regarding this (which recommend special caps be placed over the valve stems) but I am not sure if this FSB is related to the effects of an incorrect valve lash setting, valve float (due to weakened valve springs and sustained high rpms) or a combination of both.

 

My biggest concern about using used cams would be the mating surfaces at the rocker. Car push rod engine cams and lifters mate together. You never put used lifters on new/used cams because they have a very good chance of wiping out a lobe. You can use a used cam with it's used lifter as long as the lifter goes back on the same lobes. You can put new lifters on a used cam, not used lifters on new cam.

Not sure how the V4 cams/rockers are ground. I would be skeptical about using rockers that had wear on them seeing they mate with the cam lobe like a lifter does. As far as adjusting them .001 more loose won't hurt. It won't pound or wear anything prematurely.

 

Being a machinest professionaly, unfortunately you all are correct. I don't need to look at a book either. If the caps were not machined on the head, you then have a difference in centerline per bearing. Let's say .001 per. Which will add up to .002 for two inline. Then factor in clearance for the cam (i'll guess at .002) and you end up with really .004 all said and done before it leaves the factory. After the intitial proper break in of the motor the bearing caps have been beat into something roundish alowing the cam to act like a jackhammer. Butter, chocolate, even platinum cams wouldn't last for a long time in bike hours. I know my numbers are not precise and DO NOT use them for your checks. The point is that due to a poor choice in machine practice the bike has pre wear built in. A loose valve clearance would help prolong the life in your journals. But when dealing with a difference of .001", it's only giving you about 5 more min. As a fix (that would cost you twice as much as a $100 dollar head) would be to take it to a machine shop, manufacture new caps, (new caps, old head) , and have them inline bore them to factory specs. The benifit is you keep your cams. Machined at once is key. If they tell you any different go somewhere else.

 

Interesting post, thank you.

Here is a VF500F cam cap comparison '84/'85 (machined separately) vs '86 (line bored).

photo courtesy sirepair, Yahoo VF500F Users Group


photo courtesy sirepair, Yahoo VF500F Users Group


From your post then, it is possible to machine new caps and then line bore an '84/'85 head to match the '86, using the '86 cam covers & gaskets? How does this affect the bottom journal in the head (i.e. what if there is too much wear on this part to start with)? Is this something your shop can do?

Thx!

 

Thanks Grey. Appreciate the info.

 

From your post then, it is possible to machine new caps and then line bore an '84/'85 head to match the '86, using the '86 cam covers & gaskets? How does this affect the bottom journal in the head (i.e. what if there is too much wear on this part to start with)? Is this something your shop can do? Thx![/QUOTE] The shop I'm in presently is not really the place to do that work. Honestly there are many other shops that can do that for cheaper. Try engine rebuild places. This is how I would approach this situation. After determining the bearing journals are out of spec, write down exactly how much. Or bring the caps and head (dismanled of course) to said shop and have them measure the journals. Plan on the lower portions being out of tollerance as well. Have a machine shop manufacture new caps. TELL THEM TO LEAVE .020" TO .030" AT LEAST ON THE JOURNAL WALL. (sorry for the caps but that is critical) Now the engine machine shop will put the new caps on the head, at correct torque specs, and set up in the mill. the radius u see on the 86 head is a direct result of the line bore. If you watch the cutting process you'll understand. The last most important thing is when the head (with caps) is being set up, the machinest MUST place the centerline of the bore 1/2 the deviation of the old journals. (out of tollerance journal diameter minus original journal diameter specs = deviation. Deviation divided by 2 = how far into the head to move the centerline. maybe another .005" depending on how scored the head journal is.) Machine to manufacture specs. Now this placed the cam (deviation + .005") closer to the rocker arm. I suspect that this can be adjusted out at the valve clearance screws. Please ask more people about this last portion before you go ahead and do it. 4 new journals, with new caps, i wanna guess around $300.00. I could make the caps for you though.... PM me and we'll talk. Lastly, without looking at the rest of the lip design of an 83 to 85 500, you should end up with a head having the radius's like the 86 and so an 86 gasket would work. Need to work cus now you got those big ol line bore holes on the outside.

 

damn it, look at the big hex caps on the outside of the heads. the ones on the 83 to 85 might not work because of those screws. What i said above is correct and will work, but find out (from a shop) if those screws are in the way. I can't say for sure without some calipers

 

Thank you for the post. An interesting idea though I am not sure, as you mention, if there is enough space to allow the journals to be line bored. Also on a side note the '86 camshaft caps have additional bolts which may or may not be possible to add. This said, I have a set of spare '85 VF500F heads and will do a bit more research on whether this idea is a flier or non-flier.