I think we need to have more info here.. like what "EXACTLY" was done to the motor in 2019 repair wise. I still don't possibly see the cam gear disintegrating.. You sure it wasn't the pinion gear on the pinion shaft for the oil pump that disintegrated? Cause that would mean that everything from the cam and beyond was set up (or siezed).. I would like to know so I can make better sense of what your trying to describe to us.. And did you do a compression test yet? We really need to rule that out...

One more thing.. A video showing us the condition would really help as well...

 

i kind of would like to know more about the battery and charging system also. is it possible to do some testing in this area also. what is charging voltage when hot, what is starter amp draw hot and cold? how does battery load test, hot and cold?
m

 

UPDATE Putting all requested information in this post.

1999 FXSTC with Evo Stock motor.

Battery is strong and tested several times but never when hot or when the failure occurs as I am normally out somewhere not in the garage. All connections are good.

The previous owner put 10k on the bike in the first couple of years he owned it then got sick and couldn't ride it but he wouldn't sell it so it just sat in his house. After he passed his daughter listed the bike with someone that knew I was looking for another Evo FXSTC and thought that it would be a good fit.

2019: With no oil splashing around in there for 15 years some corrosion developed on the oil pump shaft causing the shaft seized up. The oil pump pinion shaft gear stopped turning and shredded the pinion gear (Sorry not the cam gear as I previously stated incorrectly). The mechanic removed all destroyed parts then replaced the oil pump, oil pump shaft, sleeve (I think there is a sleeve), oil pump pinion shaft gear and the pinion gear. During reassembly he didn't tighten the Cam position plate and it vibrated to the full advance position but this was not discovered for several months and two starters later.

Since having all of that repaired I have been tearing up starters when I try to start the bike when it's hot from long rides and has only been sitting for a very short time such as when getting gas. If the bike sits for an hour the starter would spin normally. When trying to start it when it's HOT the starter does a very short starting sound and then there is a loud snapping of a gear and the starter is finished. I still have the last starter that went bad and it looks like the gear on the armature is what is stripping out. I have had it at a different mechanic to try to get this fixed but he is out of ideas. So I am looking for new ideas.

 

well mr. fat
who said anything about valve action, it is a given. but you forget, that is controlled by, you guessed it, rpm, it is purely fixed mechanical unless you have a variable valve timing system.
i would suspect that millions if not BILLIONS of engines start each day with hyd lifters and where do you see an issue as probably the majority start with lifter collapsed due to time under spring pressure, all it takes is less than 15 minutes. another thing, fairly rare these days due to machine tolerance, have you not heard engines going down the hwy with a ticking lifter, dude hears but dude does not care if it gets him where he wants to go.
if the lifters are adjusted correctly, cannot do as you say.
have you actually confirmed timing with a strobe? if you have a dial back, check adv lead also. also, after all that internal work, are the timing marks correctly lined up.

 

Who are you referring to?

And absolutely lifters do bleed down under valve spring pressure..

 

The mechanic I have been working with is suggesting that we install compression relief valves that I would have to remember to use every time I start the bike when it is hot which I don't see myself doing. After all if I rock the bike while it is in gear before starting it when it is hot I accomplish the same thing but I never remember to do that.

Is this just a Band-Aid or a good solution?

 

Dude, this is last time I'm going to tell you... Till you do a compression test you don't know what the hell to do, so stop with the crap and do a compression test and list your numbers that's the only way we can help you right now..m if you don't want to do that then just take it to the guy and do whatever he says...

 

Band-Aid
Unless this motor is supper high compression and running stock cams you got something wrong. Adding compression releases only masks the issue. I expect that the ignition timing is still off. If when the oil pump driver gear broke, they had to replace the cam gear, they might have pressed the gear on wrong. This is an 80 ci stock motor. There is something that you are missing.

A couple things to do are:

Compression check

Battery cranking voltage with spark disabled.

 

Coming back to finish this thread after enough time has past to prove the solution is correct. It turns out that the ignition module was bad, it would fire on the initial rotation causing compression spark before the motor had a chance to get rotating. The pushback on the piston was too much for the starter idle gear to over come causing it to shatter. We replaced the ignition module with a Dynatek 2000P and all has been good ever since. Today was the final test as the temperatures were in the 90s and I had been doing long rides then testing it 10 minutes after it had sat at each stop and it started fine every time with it being extremely hot.

So I may have mislead some of you with my description of the issue directing you down the wrong path by suggesting it was retained compression, but I was close. Bill at Will Bills Motorcycle Repair in Florida never gave up and finally figured it out.