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Discussion Starter #1
Hi all

Hoping to benefit from someone on here with greater knowledge than me (which isn't hard!).

I have a battered 1991 GPZ that I bought a few years back as a source of spares for another bike, however I recently thought it might be fun to try and resurrect it. Although I've had it running, I've realised that it has had an engine transplant. Unfortunately what has been put in it is an ER5 engine not a GPZ engine. Like I say I've had it running, but I know that the ER5 makes less power and has different carbs and timing to the GPZ. I have no idea what carbs are on there - they could easily be either and I know of no easy way to tell. What I'm most concerned about though, is will the ER5 engine run ok with the Gen 1 GPZ ecu/igniter?

My instinct tells me that it won't run properly and if that's the case then I'll probably abandon the project as it just won't be viable. Any help/advice much appreciated!

Thanks (y)
 

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If it is an ER5 engine than the stator/ flywheel/ engine casing will either have been changed, or, the ER5 casing will be hard on the frame as the ER has a larger flywheel and wider/ slightly deeper engine casing.
Assuming the stator/flywheel/casing have been changed then the electrical side should be OK, engine wise your just going to be down around 10HP. Carb wise you would need to remove them and see what jets they are fitted with.
If your doing a re-furb/re-build might I suggest looking at my "unitrak" exchange service in the Europe section, way cheaper than buying just the parts, even though I have had to up the price slightly.
 

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Discussion Starter #3
Thanks for the speedy reply John, most helpful. I suspect your theory on the alternator engine casing is a good one - this engine has a silver casing on the clutch side and a black casing on the alternator side. I thought that seemed odd, but it now makes sense. I can live with being 10bhp down. I want to resurrect it more for the sake of doing so than anything else so power output isn't an issue. I'm already aware of your unitrack linkage exchange and have pointed other people your way. I'll probably take you up on it myself at some stage for both my Gen1s :p.
One other issue I've heard of with ER5 engines is that the shift pattern is reversed - do you know anything about that? the linkage was off the bike when I got it, so i wonder if that's why the previous owner gave up on it. I really don't want a 'race shift' set up! Have heard thatthe Ninja 250 linkage cures this?

Cheers!
 

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hi mate it's all good stuff no worries on the gear shift just get a EX one the ER5 uses a different linkage so it pulls from the btm of the lever the EX pulls from the top that reverses it. it is the linkage I have on the cruiser.
 
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