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Old 23-07-2015, 09:40 AM   #1
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Xr2 help required

So I've got this 1998 XR2, one of the first of the 'race' xr2's it'd seem, not a mid 80's Blackmax XR2.
I need to replace a piston and cylinder head on it. Looking at the Mercury parts site it shows the heads and pistons as being the same part numbers as the standard 135/150 from '88?

Firstly, can anyone confirm if this is the case? This would mean therefore that newer xr2 Pistons/ heads are different as they have different part numbers in later years.

If they are the same parts, what made the difference between a 135/150/XR2?

Is the motor going to be 2.4 or 2.5 based? What changes are there to the block which would help me identify it?

Can anyone confirm what changes were made to up the power of the XR2's over the years? Was it mainly a compression thing, as it'd seem compression creeps up over the generations, or is there much more to it?

Any help greatly appreciated.

Cheers, James
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Old 23-07-2015, 10:10 AM   #2
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Early 2.4 based engines can be identified by looking at the transfer port casting which is rounded while 2.5 is square. Had cast pistons which cracked at high rpm later engines had the ART piston. 26cc heads should be stamped on top edge by thermostat. If you have the horrible pump carbs or adjustable jet version throw them away.
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Old 23-07-2015, 12:10 PM   #3
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My XR2 full race version is 1992 fyi.. and is not a black max or anything like it...
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Old 23-07-2015, 12:27 PM   #4
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I'll have a look at the ports in a mo then, how do I identify the carbs?

Thanks,

James
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Old 26-07-2015, 01:58 PM   #5
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It will be a 2 litre motor and Pistons should be same as 135 / 150 heads also same but might need skimming to get to 26cc. I might have a head but won't be back till 4th Aug so let me know if still looking.
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