1998 Mercury 200hp block/part identification

[Jay0016]

Hey all, i have a 1998 200hp EFI by serial number. When i pull the cowling off the motor appears to be carbed. I am assuming someone repowered the motor with a carbed powerhead at some point.
The motor starts up great idles great even sounds pretty mean, but bogs down when i go to punch it but can get an extra 1000rpm by holding choke in so i want to go through the motor and replace fuel lines, pumps, the normal stuff (yes i know the issue is probably in carbs/reeds but I want to have peace of mind after knowing everything is new).
What i need to know is how i can identify what power head i have so i can order parts. Can I backtrace from carb S/N if they are even the right ones?
Any suggestions on aftermarket performance parts for this era/size motor since im gunna tear into her anyway?

Thanks for any help

 

[Dukedog]

pictures of power head.. both sides and from top... any numbers/letters stamped on block half flange/port side?.. number stamped on welsh plug?.. build date at base of #2 block half, kinda behind tha bend in tha timin' arm.. will be 1/8" numbers mo/d/yr.. might be hard ta find but its there.....
carbs WH, WMH or WMV's???

 

[Jay0016]

Was able to get some pictures of some different numbers around the motor and those requested. For ease: cylinder head stamp starboard 18488-C4 and on intake right behind carbs when i took them off 96770-C1. WMH carbs. Based off these numbers and googling, I'm thinking may be original block to the EFI and they just removed the fuel injection? Couldnt find any date by the timing arm and welch plug is scratched up. Will these carbs work with this motor i guess should be my first question.

 

[Dukedog]

tha "CC" stamp tells its a 175, probably carb original.. look on tha linkage side of tha carb.. should be some numbers like those on tha one in tha picture.. not necessarily same as those but numbers of some kind... will be a number then - 1, 2, or 3.. top middle and bottom

 

[Dukedog]

don't fret to much 'bout it being a 175 block.. best i remember tha only difference in it and tha 200 is it has exhaust (idle) relief slots in tha sleeves..

 

[Jay0016]

34-1 to 34-3. When you say the "CC" stamp where is that from? Im not too worried about if it is a 175 because i know compression is good if i get it going 55 ill be happy. Paired with my boat i should be able to get 65 though.

 

[Jay0016]

Finally got around to getting into it. Have carbs off now, will likely pull adapter plate to check reeds. Probably go with carson reeds new gaskets (as there were apparently none between airbox and carbs and carbs and adapter plate probably atleast part of my issues to start anyway). If i need to reconfigure anything i'd like to while its apart.

 

[Jay0016]

Also you can see in this picture there is a "T" style fitting on the bottom carb that has no line on the bottom am i missing a line or was a wrong fitting used?

 

[Dukedog]

are tha 34's not on your motor now?... tha 34's are for a 200 so will work fine... look like ya might wanna clean n kit 'em ta be safe.. last year for wmh's was '95 for parts reference.... tha "CC" is a factory code number.. stamped on tha block half by tha timin' arm.. there should be a build date somewhere in tha same area.. might jus be hard ta see... sometimes tha "stamper guy" is a little weak and tha "painter guy" is a little over bearin'.......

 

[Dukedog]

there is a thermal valve in tha starboard head with 2 bibs.. some get rid of it.. why i don't know???.. its right below tha plug for number 3.. if its there it will have two bibs.. one will ne naked and tha other with a hose goin' to tha open bib on tha bottom carb... it richens up idle circuit when motor is cold.. i never use 'em myself.. up ta you.. not havin' one could point to it being an efi at birth from mercury....

 

[Jay0016]

Ok that makes sense, yeah the motor by factory stamp on transom bracket is an EFI. If leaving it naked doesnt do anything too crazy ill leave it alone, rather run rich while im figuring her out anyway.

I just took the carbs off after taking pictures, getting ready to do something to them. Havent had much success rebuilding carb on an old evinrude 35 in the past. Had it together fine just bad adjustments, so i dont know if ill attempt to rebuild these. I was thinking blow out as many jets as i can without a complete dissasembly.

What i really wanted to get to and replace are the reed valves and gaskets. Then fuel lines maybe fuel pump. And see if she'll get over 3 or 4 thousand rpms. If she doesnt then ill just take her in for a carb rebuild.

Just wanted to make sure all of the components would work together as its a bit of a frankenmotor but she idles so nice haha

 

[Jay0016]

Also ill look closer around that CC for date stamp i was looking harder on other side of the timing arm

 

[Dukedog]

date should be on tha "block half"..... same half as tha "CC"...

 

[Faztbullet]

From the looks someone dropped a carbed powerhead on the EFI midsection. If it was a EFI block someone did and good conversion as they installed the recirc system.

 

[Jay0016]

First pic left of timing arm by the cc stamp second pic behind timing arm

 

[Jay0016]

Faztbullet, slowly learning more but yes. Anything i need to pay special attention to knowing this has been done?

 

[Dukedog]

its tha small numbers in tha second picture but looks like it was one of girls or one of tha weak guys doin' tha stampin'..........

November 2nd ????

 

[Jay0016]

I think i might be able to make out of of the year numbers. Ill try to clean it up a little tonight and use flash and zoom in see if i cant get the year too

 

[Faztbullet]

Faztbullet, slowly learning more but yes. Anything i need to pay special attention to knowing this has been done?

No...