I just saw this on Norvil's website in their Tech Section;
Seems some "74 and "75 Commandos were supplied with con rods that will fail dramatically at 18K to 22k miles. These rods are identified with a "D" stamped in a circle on the beam. Norvil recommends replacing these rods during a rebuild. See the website for more details.

This is the first I've heard of this problem. Fortunately? I haven't put the bottom end back together yet and my rods are not the dreaded "D" rods.

Scooter

Yes ask my mate about D Rods. Three weeks ago leaving our local bike show he got about 1/4 mile up the road and bang it spat the drive side rod out. Punched huge holes front and rear of the crankcase broke one cylinder spigot, pistons wrecked even dented the front of the gearbox cradle. When he took the bottom end apart the crankcases came of in three pieces. Low mileage bike and he wasn't thrashing it. This is not the first time I have heard of MK3 rods snapping like carrots.
If I had a Mk3 I would open it up and toss them D rods as far as I could.
Regards
Snakehips

so a 72 750 commando wouldnt have these dredded rods?

No, you can sleep easy at night with a 72.

thanks for that mate as i woulda been hating myself for not knowing something like that when i rebuilt the engine.

kommando wrote:No, you can sleep easy at night with a 72.

Oh heck now I'm worried, my '72 Interstate had its engine rebuilt by the factory in '73!! Should I rip her apart or not

Worried of Watford

No. D rods weren't around in 73.