I believe most all of the older ym series use a 13 lb cap. My 220/226 manual says cap should maintain 11-15psi. The cap on my ym2002d is a 13psi. If you browse thru Hoye's parts you will see most all models use the same cap. After more research I do believe the Hoye cap may be a 7lb cap. Aaron may want to confirm that and then again he may not. I do know for certain there is lots of info out there giving 13 or 7lb caps. I certainly can't argue with my service manual so I will stick with the 13lb cap on my ym2002d.