84 evinrude 150 to a 175

[thor69]

i may have missed this but did not have alot of time to search. i was wondering what it would take to change my 150 to a 175. i looked in the manual at the specs for both. they both have the same bore and stroke. i have tried to e-mail several places with no reply. any help would be greatly appreciated.

 

[Barnacle_Bill]

Re: 84 evinrude 150 to a 175

Instead of comparing specs, compare parts lists. You will have a better idea then.

 

[Walker]

Re: 84 evinrude 150 to a 175

The blocks are different. Probably different port timing too.

 

[emdsapmgr]

Re: 84 evinrude 150 to a 175

In those years, the blocks are the same, with the exception of the carbs. The 175 (or 200) carbs have a larger throat and larger jets. (You will have to play with the jets on the 200 carbs to get them to run on this low-port engine.) It is a simple swap. You could also add the crankcase filler blocks-322722. They are cheap and will also help. While NLA, there are many around. You may find better overall operating characteristics with composite reeds. A set of heads will help wake up the engine. 235 heads are another bolt on which will greatly help performance. The more you do, the more you need to be able to read plugs to make sure you don't fry the powerhead.

 

[thor69]

Re: 84 evinrude 150 to a 175

In those years, the blocks are the same, with the exception of the carbs. The 175 (or 200) carbs have a larger throat and larger jets. (You will have to play with the jets on the 200 carbs to get them to run on this low-port engine.) It is a simple swap. You could also add the crankcase filler blocks-322722. They are cheap and will also help. While NLA, there are many around. You may find better overall operating characteristics with composite reeds. A set of heads will help wake up the engine. 235 heads are another bolt on which will greatly help performance. The more you do, the more you need to be able to read plugs to make sure you don't fry the powerhead.

i was wondering does it matter that my engine is the xp150. also do know of a good set of reeds and were to get them? thank you

 

[emdsapmgr]

Re: 84 evinrude 150 to a 175

The XP 150 has the same block as the normal 150 and 175 of that year. The carbs are the larger (175) variety with the 1 5/16" throats. Rated at 150, it actually puts out 165 hp. A solid engine. Runs a little more timing than standard engines. Boyesen makes composite reeds for hundreds of 2 stroke engines. They are on the web, and you can order direct from them. The XP has different heads and stiff engine mounts. The 772/773 heads on your engine are the old 456/457 heads from the mid-late 70's, except there is a .40 lip (standoff) cast into the face to reduce compression. You can mill that lip off to increase compression. If you remove the lip, you will need to reduce timing advance.

 

[Dhadley]

Re: 84 evinrude 150 to a 175

Make sure your set up is correct. If you're set up in the low 5000 rpm range larger venturi carbs won't help much and may hurt low end. If you're set up at 5800 or more the carbs will help. The stock 150 XP/GT heads are excellent heads for todays fuel.