Evinrude 90 and Johnson 90 Carb Difference?

[RBuch1974]

Hello,

I have two 90hp's which I am building one good (fingers crossed) motor out of. One 1996 Evinrude (Best I can tell, have posted to try and figure out year) and one 1982 Johnson 90.

Between the two motors I have not found found any difference in the Powerheads (castings and part No. all the same) but, the only notable difference I have found are in the carbs (although same rebuild kit for both). The Evinrude has #38 idle jets and the Johnson has #34. Doesn't make sense to me.

Can anyone shed a little light on why the idle jets are not the same? Thank you.

 

[jimmbo]

Re: Evinrude 90 and Johnson 90 Carb Difference?

Different air bleeds in the idle circuit could be one. Another could be a different size carb, the 82 is crank rated while the 96 is prop rated. A bigger carb might be the few extra ponies

 

[RBuch1974]

Re: Evinrude 90 and Johnson 90 Carb Difference?

Different air bleeds in the idle circuit could be one. Another could be a different size carb, the 82 is crank rated while the 96 is prop rated. A bigger carb might be the few extra ponies

That makes sense. Both carbs have the same barrel diameter. 1 3/16 I think.

 

[emdsapmgr]

Re: Evinrude 90 and Johnson 90 Carb Difference?

Both carbs have .056 main jets. If the throats are truly both 1 3/16" they should both make approximately the same hp. Over the years OMC changed the internal design and location of jets in the carbs. For instance, the mid jets are in different locations on the carb bowls and they changed internal tubes, passages over the years. Block porting and port size also makes hp differences with same carbs. The machined blocks use a different part number.

 

[Bob_VT]

Re: Evinrude 90 and Johnson 90 Carb Difference?

Is the newer power head from a VRO motor? That might be the difference. The older one is regular old school 2 stroke. The newer one is actually a 110-115 hp at the head.

 

[jimmbo]

Re: Evinrude 90 and Johnson 90 Carb Difference?

OP said both blocks had same part number

 

[emdsapmgr]

Re: Evinrude 90 and Johnson 90 Carb Difference?

The casting number on the block may be the same. The factory parts lists show the final machined number is different between these years. 1982 90 is p/n 389912. 1996 90 hp block is p/n 431659. Actually, the 912 part number supercedes 3 times and winds up being the 659 part number, so functionally the powerheads are the same. Likely the later block may have changes for: the VRO system, recirc system, mounting holes for the later single power pack, even block porting from when these blocks changed hp ratings to prop ratings from crank ratings.