Er5 vs gpz500

[si1986]

Hi I have an er5 engine that is in pretty good condition but I want to make it the same as a gpz500 I also have an older gpz500 engine that I would like to use and a donor. I want to make the er5 engine the same as a gpz engine I know the cams are different and also the comp ratio is different apparently this is down to either piston height or con rod length anyone know any more info on this?. Does anyone know any other differences between the two?

[Moo.]

Best bet would be too get the manuals and compare numbers, i'm pretty sure the er5 is a de-tuned gpz sorry im no more help..
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A2 Passed 18/6/10

[si1986]

[crowe]

Si1986,

Sign up here and ask. a Wealth of knowledge

https://www.bikersoracle.com/er5/forum/index.php

Crowe
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Kawasaki ER-5

[Asimo]

Provided theres nothing majorly wrong with the gpz engine, why not use that instead?

To do what you want, you'd need to swap the cams, the carbs and airbox, probably the cdi as well and some other stuff I don't know about

[c_dug]

Agree with the above, I would have thought swapping the engines was a better bet than fiddling with the internals.
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I am a bellend, I am a man of constant sorrow, I am a gummy bear, I am a rock.

[si1986]

I want to use the er engine because it's in far better condition the gpz lump is older and done more miles so if all I have to do is swap a few parts then it makes sense to do it. I'm running the er engine on a gpz cdi anyway.

So...

So far we have established...

Cams
Carb tunin
Anyone know anything about con rod differences?
??

[Kickstart]

Hi

Without checking part numbers I would be surprised if they swapped the con rods to adjust compression rather than just changing the pistons and / or head. Doing it using shorter rods would probably give a lousy combustion chamber shape. However con rod length is used to affect other things to do with the power characteristics (ie, different length of rod changes the angle of the rod onto the crank relative to the pistons position down the bore).

Personal guess would be cams, pistons, carbs and ignition.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[fatpies]

I remember searching about the GPZ and I remember an old thread by Stinkwheel. He transplanted an ER5 engine into a GPZ I don't think it worked.

[si1986]

[si1986]

Could the comp ratio difference just come from the difference in the cam valves opening later etc? I may have that completely wrong?

[Kickstart]

Hi

Effective compression could but not a quoted static compression.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[si1986]

[Kickstart]

Hi

Haven't got any figures to hand for the compression ratios. What are they?

Looking in a service book the compression (ie, when cranking over - so affected by valve timing, etc) is actually a bit lower on the GPZ and varies between the earlier and late shape models.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[si1986]