Author Topic: Rebore  (Read 584 times)

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Offline Al Smith

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Rebore
« on: March 05, 2011, 07:56:52 am »
Since this is called chainsaw repair and since I believe nothing is impossible,here's an example .

The subject was a Mac 125 that had peeled the chrome . Choices,rechrome, costly .New block, rare ! Use for parts not acceptable . Rebore ,cast iron liner tedious .

Do to my tenacity about things the rebore it was . It took longer to make the holding fixtures than it did to do the complete job .What the hell if it were easy anyone could do it . ;D

The block was bored 70 thou over and the liner shrunk fit into the block by heating the block and freezing the sleeve .It was left 2 thou undersize on purpose to assure a good round fit in case of warpage .

Because of the design of a Mac reed engine cutting the ports in was no problem .I did however have a little smart alec that lives on the south shore of lake superior chime in I didn't do it correctly . Arm chair quarter back  the internet if full of them . ::)

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Offline TORX

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Re: Rebore
« Reply #1 on: March 05, 2011, 10:22:36 am »
thats impressive!  so how does it run?

Offline Al Smith

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Re: Rebore
« Reply #2 on: March 05, 2011, 11:19:07 am »
It does fine . Problem is I haven't got enough run time on it in 5-6 -7 years to even seat the rings yet . Maybe an hour 2 at the most run time .

That's one problem with a big  azzed saw like that is finding enough big stuff to put it under load . 20 inch stuff is childs play for that thing . These things run an 8 tooth .404 as standard equipment because of the torque they produce .

With iron bore and tool steel rings it might be a long time until get set in .It does okay though because the rings seat some under pressure .Better of course if fully seated .

Offline mcbob

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Re: Rebore
« Reply #3 on: March 05, 2011, 03:36:03 pm »
Some of the kart 101's used Hartman Super Sealer rings these bedded quicker for a kart application Al.
I am a idiot so my pics disappeared.

Offline Al Smith

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Re: Rebore
« Reply #4 on: March 05, 2011, 04:36:58 pm »
I got the rings from Mike Acres , tool steel .

I looked up the numbers and they are the same ones I think for a 101 unless I'm mistaken . No doubt cast rings would seat faster but this type should last forever especially no more use than it will get .

Kind of funny really .When the chrome let loose it jambed the top ring and I had to break it out .Just a little pinch on the top ring land .I fixed it with my wifes finger nail file . ;D Never say die .

The old gal has plenty of guts .Not quite as much soup as my other but more than enough .