Author Topic: 440 crank in a 400  (Read 2707 times)

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Offline gus58

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440 crank in a 400
« on: March 12, 2022, 01:18:36 AM »
Ive pulled down my AW and have a 77mm barrel with a clearly marked 440 crank. That gives a 386cc capacity. I was surprised to learn the 400's were only 354cc stock. this extra stroke in theory should give more torque, but Im wondering what piston would fit as the different strokes should dictate different gudgeon pin heights?????? also the degrees before tdc for timing should be a little different to shouldn't they?? Has anyone done this mod? I'm interested to hear the benefits and specs of this setup.

Offline Tomas

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Re: 440 crank in a 400
« Reply #1 on: March 12, 2022, 03:07:00 AM »
or you would have to use a 7mm thick spacer with 440crank?

Offline sleepy

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Re: 440 crank in a 400
« Reply #2 on: March 12, 2022, 10:34:59 AM »
The 400 and 440 cranks are exactly the same.
400 bore is 77mm and 440 is 82mm and all 400's 440's and 490's are 83mm stroke and all have the same conrod.
I don't know were you got the info on 400 only being 354cc as that is incorrect they have always been 387cc.
« Last Edit: March 12, 2022, 10:40:20 AM by sleepy »

Offline gus58

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Re: 440 crank in a 400
« Reply #3 on: March 12, 2022, 12:50:34 PM »

Offline sleepy

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Re: 440 crank in a 400
« Reply #4 on: March 12, 2022, 06:37:41 PM »
The info on those site is all BS. The 350 square barrels had 76mm stroke but all 400's had 83mm just like yours.
But then again it's on the internet so it must be correct.
I'll try and add a link to scanned back page of AW brochure.

https://photos.google.com/photo/AF1QipOc_ixcDyPrxmmZOIIYDtQQBoSnvKMcA61xddrr

Offline gus58

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Re: 440 crank in a 400
« Reply #5 on: March 12, 2022, 06:41:44 PM »
Ok cool, didnt know that, Maicos fault for stamping 440 on it. Thats misleading for a start.

Offline sleepy

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Re: 440 crank in a 400
« Reply #6 on: March 12, 2022, 07:06:01 PM »
I've re-built dozens of Maico cranks and the all have 440 on them.

Offline sleepy

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Re: 440 crank in a 400
« Reply #7 on: March 13, 2022, 01:34:08 PM »
I just noticed a typo on the genuine Maico brochure giving the 400 stroke as 38mm and not 83mm.

Offline Nebo

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Re: 440 crank in a 400
« Reply #8 on: March 14, 2022, 11:41:53 AM »
  Sleepy is correct.    Seen this misleading site several times over the years. Who ever printed it. Knew little about Maicos.
 The only thing you need to be sure of when fitting a new piston to a Maico is make sure you get the deck height correct.
  Even after running the Engine in . Pull the head off and check to see if the piston is hitting the head.
 
 
  Anyway no need to make it a 440 just put a 40mm Bing on it . Instant HP.