200hp merc powerhead swap with 150hp?

I have a 1985 200 hp mercury black max outboard with a blown powerhead and have an operatunity to buy a 1986 mercury 150 hp powerhead. Will this bolt right up and operate with the parts I have off the 200hp? Would I have to change anything like carbs, reed valves ect. I am hoping the only difference is the piston size or bore size. Any info would be greatly appreciated.

Thankx
Joe

Re: 200hp merc powerhead swap with 150hp?

The power head should bolt on, but the differences are manifold. The 150 is probably a 2.4 vertical reed motor, and the 200 could be a 2.4 or 2.5 and is probably a horizontal reed motor.

The carbs would be different. The bigger carbs would work, but would need to be re-jetted (a major pita) and still will likely idle crappy. Should wind out good, though. Might be a linkage issue, but probably not.

The 200 tuner should help the 150 on top end a little.

about everything else, ignition, electrics, starter, etc should swap over fine.

The major difference is the port timing. vert reeds slow down a 200 some.

There's lots of parts around for a 150 power head. eBay for instance.

hope it helps
John

PS welcome to the forum. fill out yer profile.

Re: 200hp merc powerhead swap with 150hp?

Thanks John

Re: 200hp merc powerhead swap with 150hp?

if one's a 2.4, and the other is a 2.5, there's a little fussin' to to with base plate.

John

Re: 200hp merc powerhead swap with 150hp?

John, I ran into this site a while back, probably not a lot of help to you but might be to guys like Joe. http://www.biggerhammer.net/mercury/[/url]
Bob

Did not know that a site that does not sell anything and only gives free info was commercial or is this just anouther chance to show your authority Don. If you want me gone just have the guts to say so or revoke my privalage to post free info to try to help members. I have never tried pimping products or myself like some and never suggested anyone going to anouther site to purchase anything sold on this site.
Bob

Re: 200hp merc powerhead swap with 150hp?

Excellent resource. The footnotes read like who's who at screamandfly.

Re: 200hp merc powerhead swap with 150hp?

I was hoping it would be a simple reed valve change. I saw a recently rebuilt 150 hp merc powerhead on ebay for $500. Thought it would be worth it if it wasnt alot of trouble...........

'http://cgi.ebay.com/ebaymotors/Mercury-150-Hp-Powerhead_W0QQcmdZViewItemQQcategoryZ111125QQihZ007QQitemZ170193317926QQrdZ1QQsspagenameZWDVW[/url]

Re: 200hp merc powerhead swap with 150hp?

boykjo said:

I was hoping it would be a simple reed valve change. I saw a recently rebuilt 150 hp merc powerhead on ebay for $500. Thought it would be worth it if it wasnt alot of trouble...........

'http://cgi.ebay.com/ebaymotors/Mercury-150-Hp-Powerhead_W0QQcmdZViewItemQQcategoryZ111125QQihZ007QQitemZ170193317926QQrdZ1QQsspagenameZWDVW[/url]

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Dreamer <grin>