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Discussion Starter #1
Kwizard said:
Howdy Y'all,

Can anyone confirm or deny that a Wiseco YTM200 high compression piston will fit the TW200 cylinder?

I appreciate ya



The midget fortune-teller who escaped from prison was a small medium at large.




The YTM 225 piston fits the TW crank and the TTR225 cylinder. Not sure of the YTM200?



Ronnydog
 

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"High compression piston". This is an interesting thought. Does anyone know if there is a down-side to installing a higher compression piston in the TW200?
 

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Can the stock TW200 barrel be bored out to 71mm?
The biggest possible size is 70mm for the original 200 cylinder.

You have to install a bigger sleeve, if you want 70.5 (or bigger) piston.

The biggest possible size is the 73mm piston from Wössner piston. These pistons should be also available in the US.

-> You can contact me, if you can not find a US-reseller/dealer for Wössner.
 

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"High compression piston". This is an interesting thought. Does anyone know if there is a down-side to installing a higher compression piston in the TW200?
Please use the service manual. Everything is written into it.

It doesn't matter which piston do you use (original or high compr.), the procedure is always the same.
 

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How much wear do you have on the cylinder? I know that I could get away with a hone but that's because I only have 3700 miles on my 2010.
 

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So I could turn my 200 into a 233cc beasty with a re-sleeve?! Is the mouth of the stock case wide enough to accept a 73mm piston? If so, I may have another winter project? Has anyone done this before? Is this or a 72mm bore the set-up of the european 225's?
 

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2487 miles, that's not much. The 67mm piston should fit.



But if you want a save result, than you should use the 67.5mm piston.
 

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It probaly varies considerably, but the going rate for overbores around here nowadays is about 75 bucks a hole.
 

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The overbore shouldn't be expensive.



My customers are paying for a +0.50mm oversize 46 Euro (~60 USD).

If one a customers would go to the same shop (a really good shop), he would get it cheaper (not much, but a bit cheaper).



75 USD (55 Euro) is OK, not a really good price, but OK.
 

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Does anyone have experience with precision hones for enlarging cylinders? If so please tell me any tips or secrets.

I have had one for years and have never used it but maybe I will give it a try with an oversize TW piston.



 

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Yes, you can do it with this tool, but.....



Only a professional should do it.

You need the exact rpm and up/down movement to get the perfect cross-grinding.

The other problem is to get the same diameter on every position.



A friend of me told me about a new honed cylinder, but the form was like an egg not a circle.
 

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Yes, it's just 0.25mm, but the bore must be exact.

The tolerance must be 0.01mm, not bigger or smaller.



Do you have a micrometer gauge?

If not, forget it.



The question is:

-> Do you want to save a bit money?

But you have the risk, that your piston could die after some miles?

- too small piston clearance -> piston squeezing -> new piston, new bore

- too big piston clearance -> low compression, exhaust gas into the crank case -> new piston, new bore

The result, you will have to pay much more money and you will have a lot of trouble.



-> Or do you want to pay a bit more money?

But you will get a perfect result.
 

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Touche' Tony, touche'.
Grab a spare cylinder and practice doing .25mm bores on it. When your confident, go for it. It's not rocket science, just make sure to practice and get the cross-hatching right with different drill speeds and the plummeting speed into the cylinder. Don't try to do it with a hand held drill!
 
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