Interchange 115 hp Power Head for 90hp?

[DSeaBum]

I have a 1998 SPL 90 hp Johnson, Ser# G04471967 (V4, 90 degree, cross-scavenged)with a blown main bearing, requiring a new/rebuilt powerhead.<br /><br />Can I replace it with a 115 hp powerhead? My boat is rated for a 120 hp and I'd like to get the extra HP in the process. What, if anything will need to be adjusted or changed out to go to the 115 hp powerhead??? (re-jet carbs, exhaust, ????)<br />I'd appreciate any help/advice...<br />Tight Lines!<br />DSeaBum

 

[DJ]

Re: Interchange 115 hp Power Head for 90hp?

DSeaBum,<br /><br />The powerheads should swap, as long as both are crossflows.<br /><br />The carbs. are different, I belive the 115 has larger carb. throats.<br /><br />Also, the 115 has a different (bubble shaped) exhaust cover.

 

[DSeaBum]

Re: Interchange 115 hp Power Head for 90hp?

Thanks!<br />My mechanic thinks he can "adjust the carbs" but made no mention of th exhaust cover...<br /><br />Do you think I'm looking at new carbs, a kit, or would adjustments work?<br /><br />Finally, if it were YOUR motor/situation, would you go this route or stay w/the 90 hp?<br /><br />Thanks again...<br />DSeaBum

 

[DJ]

Re: Interchange 115 hp Power Head for 90hp?

Dseabum,<br /><br />I'm pretty sure that the carbs. are significantly different. Also, the reed plates may be different too.<br /><br />I wouldn't mess with it. You may end up with some ill acting "Frankenstein" of an engine.

 

[Dhadley]

Re: Interchange 115 hp Power Head for 90hp?

The carbs will work as is. As will the ignition, intake, shift linkage etc. As long as they are both crossflows and 1978 and newer even the mounting bolt pattern is the same. Dont expect to see any HUGE gains as they are the same bore, stroke and gear ratio.<br /><br />We've done it many many times but if your mechanic isnt sure you might want to find someone who has done it before. Its really no big deal.<br /><br />Good luck!