2003 Ski-doo Summit Engine Swap to 2003.5

mx1212

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Nov 4, 2012
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I picked up a used motor for my buddies 2003 Ski-doo Summit (zx) out of a 2003.5 Ski-doo rev. We pulled the old motor and set it side by side with the new one and there are a couple obvious differences between the two.

First thing I saw was the extra hose fitting on the new head, there isn't one on the old motor. What hose goes here? Second is the hose fitting located on the block that also isn't on the old motor, what hose goes here? There is also a capped fitting on the new motor that had a hose running to it on the old motor, where does that hose go now? I've been searching for diagrams online but haven't found anything decent enough to decipher my problem. I could use a little help identifying what I'm dealing with here.

Is the new motor an 800 h.o. and thats why some parts are different?
 

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Last edited:
Jun 14, 2008
651
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Southern Idaho
I picked up a used motor for my buddies 2003 Ski-doo Summit (zx) out of a 2003.5 Ski-doo rev. We pulled the old motor and set it side by side with the new one and there are a couple obvious differences between the two.

First thing I saw was the extra hose fitting on the new head, there isn't one on the old motor. What hose goes here? Second is the hose fitting located on the block that also isn't on the old motor, what hose goes here? There is also a capped fitting on the new motor that had a hose running to it on the old motor, where does that hose go now? I've been searching for diagrams online but haven't found anything decent enough to decipher my problem. I could use a little help identifying what I'm dealing with here.

Is the new motor an 800 h.o. and thats why some parts are different?
I would have to say that the old motor was out of an older sled (00-01).Its not a HO motor by looking at the jugs.
1-The new hose fitting on the head is for heated carbs(Came out in 02 ).
2- On the rev sleds they brought the fuel pump hose out in a different place than the ZX sleds.
3- I have installed a 05 800HO motor in my 03 ZX and I used the holes that matched up with my cases and capped the other ones not uesd.
Do a search for ski doo oem parts and should be able to find a diagram
 

mx1212

New member
Nov 4, 2012
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Thank you for the reply. I know that the old motor is not an HO I just didn't know if this new one was. I checked out a couple different diagrams and I didn't find one that showed the hose for heated carbs. In my case I know the carbs on the sled now are not heated. That makes sense about capping the opposite plug for the fuel pump hose. I'm not sure what I should do about the fitting on the head. Should I just cap it too, or am I going to need to upgrade carbs? He's ordering boyesen rad valves for it this week and I want to make sure and get the right ones.
 
Jun 14, 2008
651
39
28
Southern Idaho
Thank you for the reply. I know that the old motor is not an HO I just didn't know if this new one was. I checked out a couple different diagrams and I didn't find one that showed the hose for heated carbs. In my case I know the carbs on the sled now are not heated. That makes sense about capping the opposite plug for the fuel pump hose. I'm not sure what I should do about the fitting on the head. Should I just cap it too, or am I going to need to upgrade carbs? He's ordering boyesen rad valves for it this week and I want to make sure and get the right ones.
I would just cap it as I never turn mine on
 

attatoy

Member
Nov 19, 2012
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Vancouver Island B.C.
Just did this the other way and you can just buy pipe plug for .50 cents, use teflon tape on it when you put it in.....the other issue is the coolant sender in the head.....the new ones use a straight flange seal , where the old ones run a pipe thread again (1/8 NPT i think, same as plug for carb heat) Simple is to swap heads as the newer style plug has four wires not two, but if you can find out which wires have the coolant dummy light from a wiring diagram then you can just crimp them to the old wiring harnes and your dummy light should werk like new. BTW the ho motor is another 7 hp i think so enjoy that( lastly if you change your engine cradle then you should be able to light up your old motor mount hols to save you having to alight the motor to the secondary clutch!) Oh the later style head with the none pipe tap (ho) is the right style for an 03, so if you harnes is unmolested then you should be able to plug that coolant fitting right in.
 
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