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are you working on darrell's tw225 parts bike again?
 

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Sorry, that I have to write this.

But this big sh*t!
You'll need the exact piston diameter and the exact inner diameter of the cylinder, and than you'll know the piston clearance.
Without special machines you could get a bigger piston clearance in the middle and a smaller on the top/bottom. And the exact round bore could be round like a egg after this.

No one should do this at home with some cheap tools.
This is a job for professional companies, with professional machines and tools.

If someone don't has a company in his neighborhood, he should send it to them.
 

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Discussion Starter #4 (Edited)
Sorry, that I have to write this.

But this big sh*t!
You'll need the exact piston diameter and the exact inner diameter of the cylinder, and than you'll know the piston clearance.
Without special machines you could get a bigger piston clearance in the middle and a smaller on the top/bottom. And the exact round bore could be round like a egg after this.

No one should do this at home with some cheap tools.
This is a job for professional companies, with professional machines and tools.

If someone don't has a company in his neighborhood, he should send it to them.
Actually I had exactly the opposite problem you describe -- it was bigger at the top and bottom and smaller in the middle -- like an hour glass. I got around this by dressing the stones on the end, removing a small amount of material, then the cylinder "trued up" and the walls became parallel. Well, with very careful measuring it was all within .0005" of perfect. With my small cylinder hone (up to 70mm) I didn't have this problem at all but I had to use the large cylinder hone because it is a 71 mm piston.

As for the out of roundness (egg shape) it was less than .001". Both the taper and out of roundness may not be perfect but are well within tolerance.

I was very meticulous and did many measurements and I have confidence I did a respectable, decent job. I will be the one using it so I will suffer the consequences if it doesn't work out as planned.

I have to add I value your opinion and thank you for sharing it with me. Tony
 

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Discussion Starter #5 (Edited)
Dang it Sebastian, you have me on defense and doubting myself so I had to do some measuring. I took some pictures to make my case.

Here is a picture of the piston with the micrometer on it. The diameter at the bottom of the skirt is 2.7928" and I tried to show that in the picture.

P2120017.JPG

To measure the cylinder I used an inside micrometer and then measured it with an outside micrometer.

P2120018.JPG

Then I measured the inside micrometer and it measured 2.7952".

P2120020.JPG


2.7952" minus 2.7928" equals .0024" Wiseco calls for a minimum of .0020". I think a little bigger is good, especially on an air cooled engine.

OK, I was emphatic it was .0025" and this time it came out a little smaller. If I measure again it will be maybe a little bigger. These are such small amounts it is easy to get slight variations. But now I feel better. Tony
 

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While I agree that precision work is best, and usually, done by dedicated precision machinery let me remind all that some pretty darn accurate work is possible by the dedicated and patient artisan. Witness the back-street gunsmiths of Peshawar and Kabul who turn out accurate firearms using the most basic of tools.
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I want the 12 gauge Kalashnikov.

 

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Discussion Starter #8
I don't think he was saying it can't be done, just that for most folks, it's better to have it done, unless you have the knowledge and tools.
I am not trying to fight or argue. I am just double checking my work and sharing it with anyone interested.
 

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However despite elime's diligence his technique does not allow for precisely maintaining axial alignment. Never the less I am very comfortable using one of elime's earlier honed cylinders in Betty Boop which has perhaps only 500 miles on oversize piston and honed cylinder. I would only trust Tony to do this by hand, would never attempt it myself.
 

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Discussion Starter #10
However despite elime's diligence his technique does not allow for precisely maintaining axial alignment. Never the less I am very comfortable using one of elime's earlier honed cylinders in Betty Boop which has perhaps only 500 miles on oversize piston and honed cylinder. I would only trust Tony to do this by hand, would never attempt it myself.
Thank you Fred.
 

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Well, if she blows up I might sing a different tune. Glad to be your Guinea pig in the meantime.
 

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We did plenty of karting cylinders with a hone similar to that one. Easily got bore straight and round within .0002. Only thing different was that we used a dial bore gauge that had a .0001 indicator on it. Looks good to me Elime. Look around for a dial bore gauge with .0001 indicator on it, makes life real easy. Measure your piston with mic and lock it, zero bore gauge inside mic and then the indicator will tell you the clearance over tithe measured piston. I have a bore gauge I could send you Elime if you wanted to try it out, jts a mitutoyo with a .0005 dial. You ride a tw so I trust that you would send it back. If interested pm me.
 

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Discussion Starter #14 (Edited)
We did plenty of karting cylinders with a hone similar to that one. Easily got bore straight and round within .0002. Only thing different was that we used a dial bore gauge that had a .0001 indicator on it. Looks good to me Elime. Look around for a dial bore gauge with .0001 indicator on it, makes life real easy. Measure your piston with mic and lock it, zero bore gauge inside mic and then the indicator will tell you the clearance over tithe measured piston. I have a bore gauge I could send you Elime if you wanted to try it out, jts a mitutoyo with a .0005 dial. You ride a tw so I trust that you would send it back. If interested pm me.
Thank you for your generous offer but I will pass. The reality is I may never do this again. Though my way of measuring is labor intensive I think it is good enough for a 2 or 3 time use.

I do have an old Starrett dial bore indicator but it is accurate only to .001". I found it at a garage sale in a small wooden box and neatly wrapped in a very old shop cloth. It was obviously prized and well cared for and used a lot. I have a feeling it was used on Model A's and the like but don't really know. I will keep my eye open for a dial bore indicator with greater accuracy than the one I have. It seems now a days I buy tools after the fact in case I might need them some time in the future. Go figure. Tony
 

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I have "bored" cylinders with a rigid hone like yours before. If you took your time and measure often, a decent job is easily possible. Sometimes, you just have to use the resources you have.
 

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Ooooh TWilight, does that mean a 1300cc 4 cylinder Hyabusa engine will fit in my TW?
Let's start wrenching!
 

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Discussion Starter #18
Elime (Tony), I have no issues with the way you did this.....use the resources you have...and that makes sense. You were careful, and it came out fine.

My added points: Do you have a drill press ? "I" would have used that "stone" hone in a drill press, so that the up and down motion of the hone is symmetrical/aligned, and not asymmetrical.

Additionally, I would follow up the "stone" hone with a "berry" hone, to get all the cross-hatching into the walls of the cylinder.

I have done cylinder boring and honing a lot, and am comfortable with how to do it.

Let's all remember, this is a 200cc single........not a 1300cc 4 cylinder Hyabusa engine. :D

This has been the first time I have done this kind of honing (vs. glaze breaking) so I admit I am far from being an expert. Far, far from it.

I have a small drill press, probably to small for this job, but regardless I am not sure a drill press would work. I do not know how true the center line of drive shaft is and the u-joint between the shaft and hone is sloppy to say the least. If the drive shaft is not true then rather than turn on the center axis it would "whip" around. Maybe if there were 2 u-joints, one at each end of the shaft, then it would work.

P2140021.JPG

Below: Close up of the hone. The instructions say the hone aligns on the good part of the cylinder and enlarges it and that eventually encompasses the bad part. I noticed that large areas of the lower cylinder showed metal removal as did the very top, the ridge just above the rings but the area where the rings make contact at the top of the cylinder were untouched. With a little honing this are disappeared and the cylinder wall was one surface. Also notice the less than precision u-joint.

P2140022.JPG

These are the instructions that came with the hone. This has been more of a learn as you go experience than following instructions. The concept of what one is trying to do is easy to understand but the practical hands on experience meant going very very slow for the first cylinder because I didn't have any practical hands on experience.

P2140024.JPG

Lastly, I don't have a bottle brush hone. I have always used a spring hone with flat stones to break the glaze. Again, I figure this knocks off the high spots and leaves the low ones alone and not any deeper. It has always worked well for me. As for these TW cylinders, the instructions that came with the piston said to use a stone of a certain grit for the ring seating surface and wouldn't you know it, one of the sets of stones that came with the hone was that grit!

If anyone is thinking of doing this buy a set of coarse grit stones for faster metal removal. The hone only comes with medium and fine grits.

Conclusion: We all have our favorite ways of doing things and for each of us those ways are the best ways. I have enjoyed doing these projects. If they are less than perfect so be it, but I am sure they are more than adequate to do the job. Tony
 

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I have had "professional" machine shops F' this up. It is fun to do it yourself but I want reliability. My policy is to always go up to the next piston size and find a real machinist and do it right. I only costs about $100.00 in labor. If you do it right it should last as long as new top end (10k+ miles?).
 

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Discussion Starter #20
I have had "professional" machine shops F' this up.........................I only costs about $100.00 in labor...............should last as long as new top end (10k+ miles?).
At least if I "F" it up I learn something............for $100 I do it twice and the hone more than pays for itself and is "free" there after...............I am hoping for at least 3 X 10K miles!
 
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