Springzilla. 1979 AMF Harley-Davidson XLH1000 Ironhead Sportster

The wet multiplate clutch inflicted on later Ironheads has slipped forever, so I'm hoping this new competition clutch spring will give me the edge when competing in that most noble of British motor sports; the traffic light Grand Prix.
Although Britain does have well enforced speed limits, there is absolutely nothing on the statute books about acceleration, and Ironheads do like to bite the horizon.

[@warrenp2022]

That seems like a good idea. Looking back through my brain fog, I think I remember hearing or reading about the hole between the primary and transmission being welded shut to prevent oil transfer. That would allow you to use just enough oil to keep the primary chain damp and the clutch singing happily. But the fog is pretty thick right now so don't grab the welder too quick. I can't remember if there are fill and drain holes in the transmission itself, too busy to stumble out to the garage and look.

[@ImminghamIronhead]

Definitely a filler still there; I'll have a look for a drain plug. The trap door faceplate for the gearbox appears to be cut short at the bottom to allow primary oil in, so it's possible earlier trap doors go all the way to the bottom and seal off the gearbox.

[@winsomniac]

About your slipping clutch, dyou think the taller final ratio after your sprocket change could be exacerbating things? The higher the final ratio, the more the load on the clutch.

[@ImminghamIronhead]

It's an interesting point; the rear is 45t for better A-road plodding which takes some acceleration away, and acceleration is where the problem lies, so to my mind it should lessen the slipping (this is only happening when suddenly giving it full throttle). I have to admit the math of gear ratios is beyond me, so trial and error has been the name of the game 🙂 I have a 51t rear and 23t front ready for when these wear out, so different again.