Kz1100 pistons 701= 961?

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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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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

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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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

The following user(s) said Thank You: MB

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