KT-100 bore sizes

[Sean Cook]

John,
Stock bore is 2.047 in., Max. bore is 2.085 in. Pistons are .05 mm in between sizes or about .002 in.

[John Grinager]

Simple question:
Can someone tell me the stock KT-100 bore size when new, the maximum bore size, and the typical increment per bore job?

Thanks

[Jimmy Moore]

Who makes a piston to fit a KT100 that's 55.10 mm ?

[Dave Malloy]

John,
Most Yamaha pistons are sold in metric sizes. The common sizes available are 52.00mm to about 52.80mm in .05mm increments. The original piston size is 51.97mm for a 52.00mm bore. IKF specifies a max bore (not piston size) of 2.085" which is about 52.96mm.

[ August 20, 2001: Message edited by: Dave Malloy ]

[Jean Stafford]

quote:

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Originally posted by John Grinager:
Simple question:
Can someone tell me the stock KT-100 bore size when new, the maximum bore size, and the typical increment per bore job?

Thanks

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Stock KT-100 starts at 52.00.
Pistons are abailable from KSI from 52.0 thru 52.90, I got them on my shelves.

Maximum bore size might be determined by the absolute upper limit in cubic inches, in some cases 6.2. For this reason you should make your calculations BEFORE, boring begins.

For the most part, bores are increased by .05mm by honing, provided the engine is straight to begin with. If boring is required to square the bore to the case, then you should expect to remove about .1 to .2 mm or 0.004" - 0.008".

If the engine was cared for properly, you can get by with a honing operation that will generally remove -.002", or .05mm.

Hope this helps.

P.S. WISECO manufactures a piston to 54.00 under the Part# 1050P5935, sold without a ring.

[Patrick Hubbell]

quote:

---

Originally posted by Jean Stafford:


Stock KT-100 starts at 52.00.
Pistons are abailable from KSI from 52.0 thru 52.90, I got them on my shelves.

Maximum bore size might be determined by the absolute upper limit in cubic inches, in some cases 6.2. For this reason you should make your calculations BEFORE, boring begins.

For the most part, bores are increased by .05mm by honing, provided the engine is straight to begin with. If boring is required to square the bore to the case, then you should expect to remove about .1 to .2 mm or 0.004" - 0.008".

If the engine was cared for properly, you can get by with a honing operation that will generally remove -.002", or .05mm.

Hope this helps.

P.S. WISECO manufactures a piston to 54.00 under the Part# 1050P5935, sold without a ring.

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Question, wouldn't you be better off using an expanding mandrel to index the bore and remove material from the base of the cylinder in a lathe to square up the barrel. Why remove material from the bore?

[lynn haddock]

Truing the base square to the bore with an expanding mandrel does not remove the taper/out of round/barrel shape/highs+lows etc..etc from the bore surface itself. It only insures the base is square to the average bore plane and that the base surface is flat.