| Maybe a long shot, but the sprag clutch could be on it's way out??
The high torque ability of the Gel may be "too much, too soon" for the bearing to get a grip, whereas the "mediocre" performance of the Yuasa gives the bearing time to "get a grip".
I had a customers 996, with some serious compression on board that suffered a sometimes similar starting problem.
At first the battery was thought to be struggling, despite the Optimate, but eventually the starter just spun over with no reaction on the engine.
When it was stirpped, the noses of the sprag clutch had worn away completely.
New bearing in there and it starts just fine now. |