Kz1100 pistons 701= 961?

MB
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Kz1100 pistons 701= 961?

22 Jan 2025 11:24 - 22 Jan 2025 16:27

Can these be used together 107 and 961 pistons? If they weigh the same and measure the same. The top of the pistons above the rings looks like a different alloy. My kitchen scales say the 3 of the original pistons weigh 10.3 oz and 1 weighs 10.4 oz Both the new ones (#107) weigh 10.1 oz a little over 3 grams difference. I've looked at the boxes and they all have the same part number.

Last edit: 22 Jan 2025 16:27 by MB. Reason: it's ounces not grams

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Injected
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Re: Kz1100 pistons 701= 961?

22 Jan 2025 15:56 - 22 Jan 2025 16:01

#908187

That weight difference is nothing especially for a stock street build, don't worry about it.

I think your weights are off by a decimal point, should be over 100 grams.

On a high performance street build I try to be within 1 gram or less, more important on a road/drag race engine where your revving +10K sustained. You want to get them all the same by grinding on the interior casting.

1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike

Last edit: 22 Jan 2025 16:01 by Injected. Reason: info

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MB
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Re: Kz1100 pistons 701= 961?

22 Jan 2025 16:20

#908188

Oh, oops. Yes you are rite. I think the scale was telling me ounces, but I was thinking in grams. A 10 gram piston would be shaped like a pencil. no horse power there. Thanks.

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MB
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Re: Kz1100 pistons 701= 961?

23 Jan 2025 08:07

#908207

I was thinking the numbers might be quality control related, but I had to check with people who knew more than I. This is the first motorcycle engine I,ve rebuilt. I never even considered weighing a cars piston, I have had camshafts balanced. I Thought it might be more important in a 1100cc Z1.Thank you, for the good information. I'll post picks when I have the KZ put back together.

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Re: Kz1100 pistons 701= 961?

23 Jan 2025 09:00

#908212

We like build pics too.

Z1b1000 1975 Z1b
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Injected
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Re: Kz1100 pistons 701= 961?

23 Jan 2025 09:54

#908215

wrote:

I was thinking the numbers might be quality control related, but I had to check with people who knew more than I. This is the first motorcycle engine I,ve rebuilt. I never even considered weighing a cars piston, I have had camshafts balanced. I Thought it might be more important in a 1100cc Z1.Thank you, for the good information. I'll post picks when I have the KZ put back together.

Download a FSM (Factory Service Manual) from this web site, it will have all the procedures for a top end rebuild. It also contains the torque specs for the all the fasteners on the whole bike.

If you don't torque that head correctly it will leak.

1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike

The following user(s) said Thank You: MB

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