Why does jackshaft pinion keep trashing

[Uthud]

Hi all, I am new to this forum, and not really savvy as to protocol on these types of things.
Hopefully, I am not going to offend anyone.
I am looking for an Evo guru that may be able to help diagnose an issue with my 1997 FLHTCU (carb, not FI).
In the past 5500 or so miles, I have had 3 OEM jackshaft pinion gears break, each time also ruining the ring gear on the clutch basket.
The repairs have been done by my local dealership. I paid the first time, and the second time (about 4500 miles later). My machine is at the dealership now, and they have agreed to replace the damaged parts, no charge. On each earlier repair, I asked them what would cause this to happen, and asked them to inspect the compensator sprocket.
I was assured that the CS was not the issue. They replaced my starter clutch while repairing the second failure, saying that was often the cause or pinions breaking.
This time, I have asked them to replace the ignition sensor and set the ignition timing, at my expense. The bike runs and idles great, but occasionally will backfire while starting (a recent development); and, I noticed milky-white goo oozing from the nosecone.
I have owned this bike since new. It has 130,xxx miles on it.
There is more to the story, but I hope this is enough info to help a guru make a suggestion.
Any ideas or similar experience??
Thanks.

 

[Frenchie]

Wonder if they are installing the correct pinion gear? you bike calls out for a 10 teeth pinion gear if all is stock. You should also have a brass bushing in your outer primary cover it is used to keep the jackshaft assembly aligned. Have them check the bushing ID. The milky whit stuff coming out of the nose cone is the epoxy that is used to encapsulate your ignition module electronics. Your module is beginning to fail, when it completely fails the bike will not start. While they are checking bike have them do a vacuum test on your voes switch to see if it is holding vacuum though it will not effect the starting of bike it controls the advance and retard of timing if it is inop fuel mileage will be low. Just some thoughts

 

[Uthud]

Thanks for your thoughts, Frenchie. Each time, the pinion has been the HD oem 10 tooth gear.
I have been reading a lot and am thinking that kickback while starting is the most likely cause of the gears busting. So, I am hoping that replacing the ignition sensor and setting the ignition timing will get things back to normal.
For 125,000+ miles, I never got backfire while starting, so I am suspicious that the problems are related.
I will take your advice and mention the vacuum switch to them. Is that voes also what allows fuel to flow through the petcock? I always used to close the petcock on my old shovelhead, but generally don’t bother on the Evo because fuel is only supposed to flow when vacuum is present, so I was told.

 

[Frenchie]

The voes switch and petcock just share the vacuum source through a tee.

 

[Blue Wide Glide]

I had the same problem with my 98' Springer Softail, broken teeth on jackshaft and finally teeth torn out of the ring gear. It was kickback that was causing it. When the bike was hot, it would kick back when I tried to start it, and break the teeth, it also took out a starter clutch. I had the ignition module replaced with as SE ignition module, and the problem was gone.
Hope this helps.

 

[Uthud]

I had the same problem with my 98' Springer Softail, broken teeth on jackshaft and finally teeth torn out of the ring gear. It was kickback that was causing it. When the bike was hot, it would kick back when I tried to start it, and break the teeth, it also took out a starter clutch. I had the ignition module replaced with as SE ignition module, and the problem was gone.
Hope this helps.

Thanks BWG. Your experience supports my thinking that kickback due to faulty ignition module/ sensor is what is causing the damage. I had Dealer order the stock replacement for me. Hope that takes care of it.

 

[Frenchie]

Thanks for your thoughts, Frenchie. Each time, the pinion has been the HD oem 10 tooth gear.
I have been reading a lot and am thinking that kickback while starting is the most likely cause of the gears busting. So, I am hoping that replacing the ignition sensor and setting the ignition timing will get things back to normal.
For 125,000+ miles, I never got backfire while starting, so I am suspicious that the problems are related.
I will take your advice and mention the vacuum switch to them. Is that voes also what allows fuel to flow through the petcock? I always used to close the petcock on my old shovelhead, but generally don’t bother on the Evo because fuel is only supposed to flow when vacuum is present, so I was told.

That is correct as long as the diaphragm in the fuel petcock is good. You will know if the diaphragm failed from age as you will see fuel leaking from petcock around diaphragm housing weep hole and bike will not want to stay running

 

[Blue Wide Glide]

Thanks BWG. Your experience supports my thinking that kickback due to faulty ignition module/ sensor is what is causing the damage. I had Dealer order the stock replacement for me. Hope that takes care of it.

I believe that the SE unit costs less than the original equipment replacement, that's why I used it. Please let me know if this does the trick.

 

[Uthud]

That is correct as long as the diaphragm in the fuel petcock is good. You will know if the diaphragm failed from age as you will see fuel leaking from petcock around diaphragm housing weep hole and bike will not want to stay running

I copy that. Thanks. No fuel leaking there, and bike runs great (once it starts), So, I don’t think there’s an issue with the vacuum at that spot. But I am gonna ask Dealer to check out VOES as you suggested earlier. It is making sense to me that I’m getting kickback due to my sensor in the nosecone going wonky.
So, the VOES, is it supposed to keep the ignition timing at base when engine is not running yet, and advance it after the engine starts?
I understood centrifugal advance on shovehead, but I am uneducated on electronic ignition on Evo. I will have to do some research.
Thanks for your input.

I believe that the SE unit costs less than the original equipment replacement, that's why I used it. Please let me know if this does the trick.

I will check on that SE option tomorrow. I’m guessing it will be a week before I get bike back.
Parts had to be ordered. I just hope we get to the root of the problem. I will definitely update here as situation changes. Thanks for your input.

 

[Frenchie]

I copy that. Thanks. No fuel leaking there, and bike runs great (once it starts), So, I don’t think there’s an issue with the vacuum at that spot. But I am gonna ask Dealer to check out VOES as you suggested earlier. It is making sense to me that I’m getting kickback due to my sensor in the nosecone going wonky.
So, the VOES, is it supposed to keep the ignition timing at base when engine is not running yet, and advance it after the engine starts?
I understood centrifugal advance on shovehead, but I am uneducated on electronic ignition on Evo. I will have to do some research.
Thanks for your input.


I will check on that SE option tomorrow. I’m guessing it will be a week before I get bike back.
Parts had to be ordered. I just hope we get to the root of the problem. I will definitely update here as situation changes. Thanks for your input.

The VOES is a motorcycle part described as a vacuum ignition retard device. That is, under low vacuum conditions the switch is open and has no effect on ignition timing. Under high vacuum, the switch closes and advances ignition timing. Essentially, the VOES is like the vacuum advance in older type automotive distributors.

The VOES is a normally open vacuum operated switch that closes under 3-5" of vacuum. The switch is connected to a lead from the ignition module. Under high vacuum, 3-5 inches or higher, the switch closes. A lead from the switch to ground closes a circuit in the ignition module. This circuit advances the timing of the spark. The advance increases throttle response and decrease fuel consumption and emissions.