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Author Topic: 1974 cb750 Pistons needed  (Read 2225 times)

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Offline chadayres10

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1974 cb750 Pistons needed
« on: January 18, 2012, 03:33:09 PM »
Hey everyone, does anyone know the standard size of the pistons in a 1974 cb750? I either need one replacment piston or a new set with rings. Looking to go the least inexpensive route poss. Any help would be great.
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Offline Frostyboy

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Re: 1974 cb750 Pistons needed
« Reply #1 on: January 18, 2012, 03:40:42 PM »
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Offline HondaMan

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Re: 1974 cb750 Pistons needed
« Reply #2 on: January 18, 2012, 10:02:43 PM »
Standard size is 61.0mm.
They come in 0.25mm oversize steps: 61.25, 61.50, 61.75 and 62.00mm from Honda.
You can get some real nice oversize ones from Z1 Enterprises for $199.99 per whole set today: check for them on their website. I use these in my own engines.

You will have to bore the cylinders to fit them, but you get more HP for the effort. Automotive machine shops who do motorcycle cylinders can help you out: tell them you want 0.0015" clearance if you use the Z1 pistons. If you use Honda pistons or Rocky (or MC brand), use 0.0010" to 0.0012" clearance. If you go big-bore with forged pistons, contact me again and we'll talk those details instead.
 ;)
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Offline ekpent

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Re: 1974 cb750 Pistons needed
« Reply #3 on: January 19, 2012, 05:58:21 AM »
I, like others I am sure, have old pistons laying around from pre 76 K engines. Always contemplated making a weird lamp or something out of some old engine parts. What happened with your piston and is there damage to the cylinder bore also ?
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Offline chadayres10

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Re: 1974 cb750 Pistons needed
« Reply #4 on: January 19, 2012, 01:56:39 PM »
Ok guys this is the story, Well i went to get the bike that has been sitting for about 20 yrs. It would barely turn over with the kick starter. So i tore in to it when i got home and it looked like the #3 piston hole was the issue. No scaring to the cyl walls or piston. The top ring on the piston was basically welded to the piston, so i froze the piston then threw it in the oven about 400, took it out and stated to chip away at it with a screw driver. It was coming out in pieces but there is one piece i couldnt get out. So one good whack and not there is a small gouge from the screwdriver piece still stuck. So i can either put in a used piston with all new rings or wait awhile till i can afford new pistons. If anyone want to get rid of an extra piston ill will pay for it and the shipping. Thanks again Chad
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Offline Grnrngr

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Re: 1974 cb750 Pistons needed
« Reply #5 on: January 19, 2012, 03:28:18 PM »
As luck would have it, I'm rebuilding a 74 k motor with an 836 kit, had the same issue, three good ones, one toasted. I'll get back to you....
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Offline chadayres10

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Re: 1974 cb750 Pistons needed
« Reply #6 on: January 19, 2012, 04:21:52 PM »
That would be perfect and low cost to as your right down the river. I live in Hermiston Oregon. Let me that would be great.
Thanks
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Offline Whaleman

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Re: 1974 cb750 Pistons needed
« Reply #7 on: January 19, 2012, 05:05:43 PM »
ekpent, I made a lamp out of a scrap engine. Lamp turns on and off with the shift lever. Dan
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Offline sixthwisconsin

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Re: 1974 cb750 Pistons needed
« Reply #8 on: January 19, 2012, 05:43:56 PM »
The lamp is too cool...
How much?
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Offline ekpent

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Re: 1974 cb750 Pistons needed
« Reply #9 on: January 20, 2012, 07:45:03 AM »
Quote from: Whaleman on January 19, 2012, 05:05:43 PM
ekpent, I made a lamp out of a scrap engine. Lamp turns on and off with the shift lever. Dan
                          Now that's what were talking about !!  Be a great conversation piece in an office or something. Have to start a new thread "Show me your lamps"-------- ;)
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