Mercury Black Max 135 Carburetors

bmatlock01

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Jun 3, 2014
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I bought a 1995 Ranger R77 Sport with a 1991 mercury black max 135 a few months ago, and it has ran great with the exception of a rough idle. I finally got around to ordering the carb kits and pulled them off and rebuilt them yesterday, after putting them back on it ran better but still a little rough. So I did some research online and discovered that they are not the original carburetors for my engine. They are WHM-31 carbs that go to a 150hp black max, and my original carburetors are supposed to be WMH-8. They look almost identical, so my question is can I order the proper jets that would have been in the original carbs and install into the WHM-31 carbs and essentially have the same thing?
 

bmatlock01

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Well it looks like I was completely wrong again, and I am really confused now. According to my Serial #0G385141 my engine is a 1996, but what confuses me is while looking up the year by the serial number, it looks as if that serial # could have been assigned to a 1996 135hp or a 150hp. Since my engine has 150hp carbs, is it possible that I could actually have a 150hp engine fitted with a 135hp cowl? How can I tell the difference other than the decals on the cowl? Thanks
 

wired247

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That serial number is for a 1996 200 HP motor. Where did you get the serial number from? Was it the block or the clamp?
 
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bmatlock01

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That serial number is for a 1996 200 HP motor. Where did you get the serial number from? Was it the block or the clamp?
I got that off of the clamp, but I just found another one on the freeze plug, it is 0D081204 The previous owner told me the motor had been rebuilt, but it's starting to look like it is pieced together from different motors. Can you tell me what the serial # on the freeze plug brings up?
 

wired247

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That is a 1991 2.0 liter 150 HP powerhead.model number 1150412LD. . Those WMH 31's arent exactly correct for that powerhead but they are still 2.0 150 carbs that are correct for a fat block 2.0 / 150..

You have a 150.
 
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bmatlock01

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That is a 1991 2.0 liter 150 HP powerhead.model number 1150412LD. . Those WMH 31's arent exactly correct for that powerhead but they are still 2.0 150 carbs that are correct for a fat block 2.0 / 150.. You have a 150.
Thank you for your help, according to the information you provided it looks like the original carbs for this block were WMH-9's. Would it help or hurt if I changed the jets in the WMH-31's to the same that we're in the 9's?
 
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