Compression check advice

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japmannslim
Posts: 25
Joined: Mon Dec 26, 2011 6:22 pm
My Bike: zxr400l9
Location: Birmingham

Compression check advice

Post by japmannslim »

Hi Guys, need some advice please. I want to do a compression check on me L9. What do I need to disconnect to protect the ecu when I turn the engine over on the button.

Ps: I have done this in the past but can’t remember what I disconnected!!
Many thanks!!
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banner001
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Re: Compression check advice

Post by banner001 »

Disconnect the 2 cables going into each coil, that's all you need to do
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
japmannslim
Posts: 25
Joined: Mon Dec 26, 2011 6:22 pm
My Bike: zxr400l9
Location: Birmingham

Re: Compression check advice

Post by japmannslim »

Thanks mate! I think that might be what I did last time but I read somewhere that you can damage the ECU because the current has no where to go. Also what about the fuel pump, do you just unplug the fuel relay?
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banner001
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Posts: 2584
Joined: Sat Sep 24, 2011 3:27 pm
My Bike: ZXR400 L4
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Re: Compression check advice

Post by banner001 »

You can do, though I've never bothered myself.

And as for the cdi, this creates a spark by acting as a grounding point for the signal coming back from the coils, so there is no electricity going to the cdi for it to dissapate as long as you have disconnected the coils already
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
japmannslim
Posts: 25
Joined: Mon Dec 26, 2011 6:22 pm
My Bike: zxr400l9
Location: Birmingham

Re: Compression check advice

Post by japmannslim »

Thanks mate, very helpful & informative!!

Much appreciated!!
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