I installed the new ignition system on the Ural this weekend. The photo on the right shows the original hall sensor and interrupter which is mounted on the end of the cam. The hall sensor cable exits the cover at the 10 o'clock position. This is the path for water to travel into the housing. All of these pieces are replaced with the new system. I measured the resistance of the coil and it the ohm meter shows an open circuit meaning that there is a wire broken within the coil on the sensor.
This is the replacement circuit showing the electronics board with it's optical sensor. The interrupter is replaced with the slotted disc with two sets of openings. One set is spaced about 2° apart around the circumference and there is one slot closer to the center which you set with the engine at top dead center (TDC). There is an LED at about the 3 o'clock position. You set the engine at TDC then turn the slotted disc until the LED just turns on.Then tighten the bolt (with medium strength Loctite) to clamp the disc in that position. That's all there is to setting the timing. The vendor says that you can't really use a timing light as it fires the plug three times instead of the normal one time. Since there isn't as much time to saturate the coil, the plug gap needs to be set narrower (0.025" - 0.032").
A bracket was included to mount the new coil but no directions were included as to where to install it. After much trial and error, I found the proper location. It mounts the coil such that the plug cables go straight down which would minimize water getting into the connections. This also locates the coil away from the engine for cooler running. The mounting bolt for the new bracket was also used to mount the horn so I'll need to find a new location for the horn.
Only a couple of electrical connections were needed and I took the opportunity to clean up the wiring underneath the gas tank due to the extra room that used to be occupied by the stock coil. When I first started the bike, the idle speed seemed kind of high but I took it for a short run. By the time I returned, the idle speed was around 2500 rpm. After ensuring that there was slack in the throttle cables, I connected the Twinmax to the vacuum ports on the carbs. Using the bike tachometer, I just cranked down the idle stop screws on both carbs a couple of turns to get the idle around 1000 rpm. I then adjusted the each idle screws until the carbs were balanced at idle and the rpm was around 1000 rpm. I then ran up the engine to around 3000 rpm and the needle stayed centered. No cable adjustment needed. Carbs balanced.
On the next test ride, the rig ran great. The acceleration seemed better but maybe that is just a perception due to installing something new. On the right you can see that I rotated the cover 120° counter-clockwise so the opening in the cover for the wire is now at the bottom. I think that this would not only prevent water from getting into the housing along the wire but will also allow any water that does get in to drain out. It does mean that the logo isn't oriented right but I can live with that. Maybe I'll make a new slot at the bottom and plug the existing one with some silicone.