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BF250 Lower Unit Question

C

clkelley78

Contributing Member
Can someone help me out with this question? I repowered my bay flats boat last year with2018 BF250 with 25” shaft length. Myolder 2007 BF225 had a 20” shaft. I hadjust installed a new lower unit on the BF225 which only had about 20-30 hoursbefore the block corroded a hole and I trashed it. Question is, can I use that 20” shaft lowerunit for a spear on the new BF250? Iknow the gear ratio on 20” was 1:86:1 and new motor with 25” is 2.0:1. I would have to lower the motor on the jackplate mounting bracket if it’s interchangeable. I’m sure it would void the warranty,but I only looking at keep as a spear or do I need to sale it… Also would there be any difference in speedbetween the 1:86 and 2:00 ratio?

Thanks,

 
There would be a big difference, you also risk increased O2 sensor issues if you lower the motor by 5 inches, not to mention possible water ingress.
 
Iang66,

If were to put the motor back to the normal level, it would be the same as when I had the 225 w/ 20" shaft. The motor was raised by 3" on the jack plate bolt holes to offset the longer shaft. With that, I run the jack plate up 2" to compensate for the total 5" of additional new shaft length. My main question, is the drive shaft the same part number on a BF225, 20" as a BF250, 20"?
 
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