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DanielB

Aluminum Cylinder Honing

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DanielB
I have an aluminum bore engine out of my 4208 that I need to hone. I’m looking for any tips or information that may help me. The Briggs repair book makes it sound like you can hone to the next piston size, is this correct? Can I use the standard stones for aluminum? What lubrication should I use, kerosene, WD40, motor oil? Thanks, Dan

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BrianP
Dan, For what it's worth, I'm working on an aluminum Briggs (verticle shaft design), myself, but the machine shop I took it to is going to bore the block, press in a cast-iron sleeve, which will then utilize my (new) standard piston and rings. In my opinion (and my father-in-law's, it's his machine) it should hold up better than the all aluminum design. Once I get the block back, I plan on taking pictures to post on this site to maybe help others in the same boat. Right now though, I have to wait on the machine shop.

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debshirl
dan, i would probabbly take block to a machine shop to be honed to next size. you will need a new oversize piston and specs.if you dont have a dial bore indicator available it will be hard to get clearence correct between piston and block.

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D-17_Dave
Brian, remember that the pistons between the alum. and Cast iron blocked engines are different and won't interchange. Dan, the difficult part is as describbed above. Keeping the bore true to match the piston from top to bottom of the bore.

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patrician12
Don't the aluminum bore engines have a special chromium plating process that is unduplicable in the field?What may appear to be a shiny glazing is actually chrome.

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Kenh
If you want a bullit proof bore. Send your block and new piston and rings to US Chrome. They are located in Wisconson. The specilize in replating two stroke motorcycle jugs. Here is the web site. http://www.finishing.com/Shops/uschromewi.shtml This material is so hard that you have to use a diamond home to be able to finish to size. I don't remember the exact cost but the last MX bike I had done cost me about $250??? plus the cost of a new piston. In a four stroke garden tractor engine I would expect to never have to replate the bore ever again unless you do something really stupid, like over heat and run out of oil at the same time. I've seen engines in MX bikes seized that have had metal transfer to the bore from the piston. The piston material was "scraped" off the bore, which was lightly honed with convential stones (they won't touch the Nikasil) a new piston installed and away they go as good as new. Ken

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TimJr
The aluminum bore engines use a piston that has a coating on it to keep it from sticking to the block. Depending on your engine, at times Briggs built a given hp engine with aluminum or iron bore, just pick the piston for the iron bore version.

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MrSteele
The only way I would hone an aluminum block is with a long cylinder hone, definitely not with a spring loaded glaze breaking hone as most have. With a glaze breaking hone, there is NO WAY to control the depth of cut, and not a good way even with a cylinder hone. Best is to have it bored to the next size, and let the machine shop do all honing, if any is required after boring, if you want to keep the aluminum bore. What Brian describes is the best way to bore an aluminum engine. What he will wind up with is going to be similar to an IC engine, and the bore will last a long time. If the air cleaner is kept clean, and if chrome rings are used, the cast sleeve will be able to have at least a couple sets of standard rings installed at repair time, before a new sleeve is required.

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Al
Hi, Be sure they leave a step at the bottom of the bore at least 1/16 ti 1/8 in long and push the sleeve against it. Then take the bar and bore the top off flush. This keeps the sleeve from moving. The interferance fit with the cast iron sleeve in an aluminum block will diminish with temperature and the block will cxpand more than the sleevee. In air cooled engines the step in the bottom of the cylinder insures that the sleeve won't come down in the crankcase and cause a major catastrophe. Good luck, Al Eden

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Marty-MN
Thanks Al, great tip. Makes since but I would not have thought of it till I had lost one. I've always cooled dry liners in liquid nitrogen to shrink them before installing. Ya gotta be quick and of course use gloves and tongs but makes a tight fit easy.

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tipspeed
I just had a Briggs 16 hp. twin L-Head honed to .030 over. Both cyls were badly scored up. Likely someone ran it hot as the cooling fins were really packed with dirt and grass, even found the remains of a mouse nest. Anyhow, just how far must a given cylinder be opened up to install a sleeve? I have a cast iron Kohler K 321 which is already .030 over and the head bolt pattern looks to be too close to the bore to be able to go big enough to fit a sleeve with decent wall thickness. Wish I could find a .040 over piston for it without going the custom route. I'd have more in the piston than the engine is worth!

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