Author Topic: boring  (Read 3891 times)

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Offline EHP

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Re: boring
« Reply #10 on: February 02, 2015, 09:24:26 pm »
EJ , bore times bore times .7854 times stroke . Those 272's your talking about were not 72cc or 81cc , they were 96cc

Offline ej

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Re: boring
« Reply #11 on: February 02, 2015, 10:04:56 pm »
ed I bought one from m.v at a show germaine was running it it was exactly 54mm 288 piston and cylinder I kept all the port timing specs it was not stroke at all when I talked to maecel he said he did make a bigger one but that was not one of them. he made it specialy for mio Michigan show

Offline Cut4fun .

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Re: boring
« Reply #12 on: February 03, 2015, 01:03:11 pm »
EJ , bore times bore times .7854 times stroke . Those 272's your talking about were not 72cc or 81cc , they were 96cc

Please show me how a 55mm bore x 34mm stroke is 96cc like you say above??   55mm x 34mm is closer to 81cc  in my we brain work. 

Using a  54mm on a stock stroke  272 34mm = almost 78cc  77899.61

Offline Cut4fun .

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Re: boring
« Reply #13 on: February 03, 2015, 01:06:48 pm »
ej going to move this to Modified Ported Work or Race saws board


Offline EHP

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Re: boring
« Reply #14 on: February 03, 2015, 06:27:46 pm »
those 96 cc 272's didnot go west , they went south and were not 55 or 54 mm by 34 stroke , 56 mm bore by 39 mm stroke , It does fit but not much left in the crankcase to spin the crank over . I never built 1 but I might have seen a couple  :o. I did build a 52 mm bore by 38 mm stroke to run in the 5 cu class thou , Use the longer rod off the 372 on the stroked 272 crank , 372 rod is 3 mm longer than the 272 rod so at 38 mm stroke it stops the crank from touching the bottom of the piston . 39 mm is a bit tight in the case but no more than guys putting 47 mm stroke in 3120's

Offline ej

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Re: boring
« Reply #15 on: February 03, 2015, 06:48:20 pm »
thanks for moving it I should have put it here still learning the sight.

Offline Cut4fun .

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Re: boring
« Reply #16 on: February 03, 2015, 07:30:55 pm »
those 96 cc 272's didnot go west , they went south and were not 55 or 54 mm by 34 stroke , 56 mm bore by 39 mm stroke , It does fit but not much left in the crankcase to spin the crank over . I never built 1 but I might have seen a couple  :o. I did build a 52 mm bore by 38 mm stroke to run in the 5 cu class thou , Use the longer rod off the 372 on the stroked 272 crank , 372 rod is 3 mm longer than the 272 rod so at 38 mm stroke it stops the crank from touching the bottom of the piston . 39 mm is a bit tight in the case but no more than guys putting 47 mm stroke in 3120's

Thanks for explaining Ed.   

I was hoping you were talking different saws then we were.

I've heard of a 272 crank etc down in a ( I think husky 50) for a 3ci saw before.  Ran against it and beat it.  So didnt bother me.

 Now the 46mm 325 or 55 top on the 50 490 590 5000 crankcases you could see and hear the difference in the cuts.  Knew of a couple of those out there.

Offline mcbob

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Re: boring
« Reply #17 on: February 04, 2015, 11:34:24 am »
yah I have had a lot over bore by u.s chrome and millieum and max power. I have bored the 166 sachs and put a 3120 big bore 62mm in it and it was a two piece herb gingras got it now I got some 272 pistons 54mm getting made too at the same time as my the big 70mm 090 pistons getting done. m.v used too put 288 cylinders on the 272 bottom and ran real strong I thought it would be easier to just bore the 272 cylinder instead and make it a 5 cube saw

Whats happening with the 70mm Stihl 090 cylinder you getting some made or plan on boring the old cylinder ?
I am a idiot so my pics disappeared.

Offline EHP

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Re: boring
« Reply #18 on: February 04, 2015, 06:38:32 pm »
what you have to understand is crankcase volume , just because you put a bigger crank in a smaller crankcase it doesnot mean its going to make more power as the bigger crank takes up to much space and then you cannot move enough air threw it . I play with lots of these kind of things then just scrap them once I'm finished and they never leave my place , Prefect saw is I put a 3120 crank in a 181 just to see what I could get , that took abit of lathe work on the crank to make it fit and it ran but not as good as a stroked 181 crank to 42 mm , I could not burn near the same amount of fuel threw the motor with the 3120 crank, used the same jug

Offline ej

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Re: boring
« Reply #19 on: February 04, 2015, 08:53:09 pm »
mcbob the guy i'm working with if he wants to much for the cylinders I might just bore and plate the original cylinder

 

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