I just checked and the distance from the rear of the 1/2” plate to the ring gear is 2 1/8”.

Mine is a 13 B Renesis, but as I acquired the engine from another builder who gave up on the rotary idea, I cannot vouch for the correct counterweight. 

But I can verify it is installed, you can see it in the picture 

On Nov 11, 2025, at 12:28 PM, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:

Measured about 1 3/8" from rear of 1/2" plate to front of starter ring gear teeth. That's on my RV-3B with 2.85:1  PSRU.

On starter that I think I used with my 2.17:1 PSRU I measured about 1 3/4" from starter mount surface to front of (retracted) pinion gear. Eyeballing 3/16" to 1/4" between retracted pinion and ring teeth.

Wrong counterweight?

Or, I think that maybe a different ring gear (plate) is used for the 2.17:1 than for the 2.85:1.

Someone here correct me, or I can dig into the manuals for each.

What are your measurements?

Finn

On 11/11/2025 10:55 AM, David Walker drw.aa@hotmail.com wrote:

Hi all,

Hoping someone can unravel this mystery about why my starter does not fit the RD1 assembly.

I have the Referenced the same instruction manual and re-ordered the correct starter which is for a 1988 non-turbo manual transmission.

Upon doing a dry fit of everything, the result is that the starter is too short to reach the ring gear, as pictured.

The counterweight is attached, followed by a ring gear from an automatic transmission, followed by 1/2” aluminum plate to which is mounted the machine part that mates to the redrive.

The starter pinion gear is about 3/4” short of reaching the ring gear,

Totally stumped…

Thank you,

David Walker

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