Author Topic: help with first port job on a poulan 4218avx  (Read 252 times)

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Offline farmboy

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Re: help with first port job on a poulan 4218avx
« Reply #10 on: August 07, 2014, 04:51:51 pm »
Another tidbit: don't widen ports over 65% piston size.  Ex:40mm piston x .65= 26mm port width.  Open muffler outlet (no spark screen) to 85% ex. port (length x width x .85= size of outlet) using spark screen do 100% ex port.  This is general info not hard fast rules. 
Shep

Offline aclarke

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Re: help with first port job on a poulan 4218avx
« Reply #11 on: August 07, 2014, 04:54:22 pm »
Kev, thk

Offline bleed_limegreen

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Re: help with first port job on a poulan 4218avx
« Reply #12 on: August 07, 2014, 07:29:51 pm »
Thanks guys for all the input. I will start the project this weekend after some more test cuts is for comparison. I have already modded the muffler and re-tuned and is much better. I had an idea to boost squish on this clam shell and that is to machine the crank journals the same as the base as in if .020 is removed from the base than the same is removed from  the  from the journal areas..... what do you think?


also at what oint psi do you start using hi octane fuel say 100 and up? as a test just tried some 110 race fuel at 40:1 mix with klotz super techplate and not much difference only maybe a bit better throttle response....

Offline Cut4fun .

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Re: help with first port job on a poulan 4218avx
« Reply #13 on: August 07, 2014, 07:31:42 pm »
Just warning as I have been there.  Get away from Super 80% 20% and run the Original 100%
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Offline bleed_limegreen

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Re: help with first port job on a poulan 4218avx
« Reply #14 on: August 07, 2014, 07:53:19 pm »
Just warning as I have been there.  Get away from Super 80% 20% and run the Original 100%

what did you not like about it?

I know it is and can be a bit dirty, but this will not be a daily use saw more of a toy.... i will just have to watch for carbon build up..... I was also thinking good race gas would help as well...thoughts....?

Offline Cut4fun .

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Re: help with first port job on a poulan 4218avx
« Reply #15 on: August 07, 2014, 08:11:40 pm »
Not just me.  There is a reason original is used by the racers. 

I had a piston starting to caramel up like many of folks found out from hard working saw.
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Offline Al Smith

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Re: help with first port job on a poulan 4218avx
« Reply #16 on: August 08, 2014, 05:12:55 am »
You should see some improvement just by reworking the exhaust port and muffler .You may get a tad more if you shift the ignition forward  a few degrees .

Offline Bluegill

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Re: help with first port job on a poulan 4218avx
« Reply #17 on: August 09, 2014, 08:49:01 am »
Quote
also at what oint psi do you start using hi octane fuel say 100 and up? as a test just tried some 110 race fuel at 40:1 mix with klotz super techplate and not much difference only maybe a bit better throttle response....
You wont need more than 89-91 octane. Most of my saws are ported with a couple around 200 psi and they run faster on 91 than 100 octane.

Offline bleed_limegreen

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Re: help with first port job on a poulan 4218avx
« Reply #18 on: August 09, 2014, 09:11:47 pm »
update on my project.... took it apart and did measurements. piston is 41cm ex.port was 19cm so I opened it uo to 24cm. i did nothing to the carb inlet port as it was the same size as carb bore, the strato ports i cleaned up for better flow.


what do you all think? will this make a good improvement or go bigger on the ex. port?

Offline 660magnum

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Re: help with first port job on a poulan 4218avx
« Reply #19 on: August 09, 2014, 10:16:08 pm »
mm?
We should share what we know... someone may learn...
That knowledge can live after us... and that "Pays It Forward".
Be all that you can be . . .

 

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