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Bf150 Change 20” to 25”

ColinW

New member
Hello,
I just picked up a 2006 Honda 150hp. And upon checking the the Bay Manufacturing site, I learned they do not make shaft extension kits for Honda. The dealer made it sound like a real pain to change a 20” motor to a 25”. They have to pull the power head and change a bunch of expensive parts.
Selling this one and getting a 25” motor may be wise in the end.
Does anyone know a good route to take?
 
I've done 50's and 90's. It is very definitely a lot of work as the power head does need to be removed, and there are a bunch of expensive parts. I was lucky enough to be able to get used parts by buying dead engines and selling off what I didn't use.

It can be done though.

My advice would be if you aren't up for doing the job yourself, paying a dealer to do one would most likely be cost prohibitive.
 
Thanks for the info. If I’m looking for a 25” parts motor, do you know if it has to be a 150hp or will a 130,140hp motor have the same parts needed?
 
If I know Honda, multiple years and models WILL be interchangeable. The way I get into finding out for sure what years, is through some due diligence in the online parts manuals.

Looking up drive shafts, water pipes, housings will tell you for sure. Be careful with the year as well. The 90's for instance, are the same as 75's, and use the same lower for 97 & 98, then change completely for 99, which they used for quite a while. Takes a while for sure, but there will be no guessing when you are done....
 
Thanks for the info. If I’m looking for a 25” parts motor, do you know if it has to be a 150hp or will a 130,140hp motor have the same parts needed?

If you go to boats.net find the parts you looking for, select the part in question, scroll down to the bottom of the page and you’ll find a list of other models that share the same part.
 
You shouldn't be too disappointed that Bay Machine doesn't offer an extension kit for Honda either. I have heard a couple of things about going that route that would make me think twice about it. They use extension "stubs" on the main and shift shafts along with xtra long adapter bolts to hold it all together. Problems reported have been mostly corrosion related with the bolts failing and the shift shaft stub siezing. One guy said it took him a month to get his lower off because of that. He was just trying to change the impeller.

That coupled with having to make your own drilling adapter out of a hole saw and all-thread to provide clearance for the mainshaft stub shoulder leaves me wondering how many of those jobs ended up being "messy".

At least with your Honda everything will fit properly and be "factory like" and clean when you're done. That is, of course, if you can find affordable donor parts.

Looking forward to hearing that you have success.

Good luck.
 
Update: I was able to find a lower unit with extension case locally. Both drive shaft and extension case were available on eBay ($6-700) and Facebook marketplace out of state. Shipping cost for lower unit can be spendy.
Anyhow, I am now in the process of swapping a 25 inch drive shift into the new lower unit. Is there a special tool to remove the lock nut at the top of the driveshaft? # 20 in the diagram
 

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I don't know the answer to your question but here's a clear picture of it (see link below).
It doesn't appear to have any threads and I am thinking that it might not be an actual "lock nut" but maybe an indexing device for the bearing to the shaft???.
Just a guess, of course, but it wouldn't be the first time translating from Japanese engineering lingo to English resulted in a less than accurate description of a part.

https://www.boats.net/product/honda/90242-ZW1-000?ref=b121a95b52a37f5dee23c0e34b16b8a16da8a9a1
 
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Huh!..???
Well, your tech stuff is WAY better than my phone....I couldn't get it to zoom in at all.
If it has threads then it's a nut. And that would mean to get a hold of it you would need a tubular socket with 12 point external teeth. So that leads back to your question.....where to find one of THOSE????

I think that I have seen a socket or wrench similar to that before but I can't remember where nor for what it was used on. No help at all I'm afraid....Sorry.
 
Okay thanks. I’m pinching and expanding on a 2-3 year old iPhone. It looks like the lower unit I picked up is off a 130hp and won’t work with my 150hp. So I may not have to pull the driveshaft after all. Wish me luck trying to re-sell them.
 
Well, 130 seems to be a common and popular "midsize" horsepower rating and I would imagine there's a decent market for parts if the price is reasonable..
So, yes, good luck and keep us posted.
 
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