Author Topic: 6400 Dolmar  (Read 1233 times)

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Offline mdavlee .

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Re: 6400 Dolmar
« Reply #20 on: February 06, 2014, 09:27:54 am »
I'm not sure why they changed to that. It seems to be a good change though.

Offline aclarke

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Re: 6400 Dolmar
« Reply #21 on: February 06, 2014, 09:36:33 am »
New crank is stock stroke. 

Any ideas why the original 7900 had asymmetric (one smaller) windows in the piston? Seems like some thought went into that design, kinda odd they'd ditch it for the New piston unless it was a fix for something

Offline mdavlee .

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Re: 6400 Dolmar
« Reply #22 on: February 06, 2014, 10:27:56 am »
I can't remember when they come out. Cutting Scott would know a lot more.

Offline farmboy

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Re: 6400 Dolmar
« Reply #23 on: February 06, 2014, 01:30:15 pm »
The only crank failures I heard about (from Dan Henry) were on the Solo 681.  I haven't heard about 7900 failures.  But taking an appreciable amt. of piston wt off can't be a bad thing.  I had originally wanted to use the slab piston in the 665/681 for the lighter wt. knowing about the 681 crank failures.
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Re: 6400 Dolmar
« Reply #24 on: February 06, 2014, 06:54:13 pm »
I was under the impression that slab sided pistons work better with open port transfers and windowed pistons worked best with closed port transfers.   Interesting thread.
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Offline aclarke

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Re: 6400 Dolmar
« Reply #25 on: February 06, 2014, 07:30:19 pm »
Hard to say how this piston will work.  Should be interesting

degree'd it this afternoon
stock:

Ex-106
trans-129
intake-143 (duration)

Ported:
Ex-101
trans-129
intake- 150 (duration)

Offline Cut4fun .

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Re: 6400 Dolmar
« Reply #26 on: February 06, 2014, 07:46:32 pm »
About new 7900 piston from 2011. Copy and pasted info below.

New "lightweight" piston for the 7900 for "better motor operation". Weighs 1/2 oz less than the original piston, 14.17grams lighter
It's still Mahle. According to the bulletin, "The light weight piston is required for a better motor operation."

Most dealers  probably still have old stock in the 038130031 piston/cylinder kit. The new kit is 038130070, but you won't see it until the old inventory is cleared out.


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Offline aclarke

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Re: 6400 Dolmar
« Reply #27 on: February 06, 2014, 07:53:46 pm »
Thanks kev. Sheds some light...,

Offline KilliansRedLeo

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Re: 6400 Dolmar
« Reply #28 on: February 06, 2014, 08:16:55 pm »
I tried to buy the old OEM windowed P/C kit from Edge and Engine a year ago and was told by them that they could not get the old kits any longer. I could not get the Mahle windowed piston either!
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Offline mdavlee .

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Re: 6400 Dolmar
« Reply #29 on: February 06, 2014, 08:19:44 pm »
That's not a real long blow down. That seems pretty normal for a dolmar to make better power.

 

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