Engine Suspension Frame too narrow?

[Dave J]

Building a 12iS but thought this might apply to most any model.

I started the process of installing the suspension frame on the back of my Rotax motor. I ran into the problem of an interference fit on the lower frame mounts being approximately .050” to .055” narrower than the engine casting that I could measure with a caliper/micrometer.

I can’t measure the upper engine casting but did find some online engine specs that might be correct and my frame upper interference is only showing approximately .012” to .026” too narrow. These mounting flanges seem more out of square than the lower pair.

The kai suggest correcting over width frames by shimming with .032” washers if the gap was approximately half the washer thickness or more. With that error being only .016” my concern is over stressing the frame by wedging it open enough to install on the engine. I also wonder how much added stress the out of square frame mounts would add after setting to torque specs?

Has anyone had this situation with your frame and what advice did you get to proceed or modify?

Thanks, Dave

 

[dsm8]

DAVE:

I am a ULS builder, but in my experience if it does not fit I did something wrong. THE CS at Vans is great, 1-2 day turnaround on email messages. Be very specific with lots of pitures, arrow and comments. Include waht section of the KAI you are referring to. A little time spent composing your questions will save you and them a ton of time.

Godspeed

 

[jhrubos]

I had a similar issue and after talking with Tom at Van's I buffed the mounting points out and the motor mount went right on- well with a TINY bit of old man strech

 

[Rv-12David]

I had thought my mount was too narrow when I began to install it. Turns out that it’s sensitive to being aligned perfectly. After about 15 minutes of wiggling and realigning it managed to slip right into place. No bending was required.

But for about 10 minutes I was convinced it was too narrow.