I finally got my motor buttoned up and need some jetting advice. The bike is a 78 RD400 barn find.
Expansion chambers of unknown make or model
RD350 y-boot with K&N filter (airbox is long gone)
Stock ignition
Stock porting
Cylinders bored to 65.5
When I got the bike, it had 220 mains. I don't know the pilot jet size as they were trashed in the removal process.
Any advice would be great. Lyn recommended 250-310 for the mains, so that's probably where I'll start.
After looking at your list, it looks like you're on the right track. I've never messed with a 400, but I've dabbled with a few 350. For your pilot, it should be in between 30~40. Establish a solid baseline and work from there. Just listen and feel what the bike is telling you and may small adjustments.
Thanks. That's where I'll start. Any advice on the needle jet? Or will the stock size suffice?
Rob
Sorry man, I am not 100% on the RD400 carbs.
I know that the RD350 needed the Dave F mod to help with the flat spot with changing the needle jet from a bleed to a primary type.