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TOPIC: Wiesco 232M08550 Piston Kit For Sale

Wiesco 232M08550 Piston Kit For Sale 16 Aug 2018 18:35 #11

  • darinm
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Almost sorry to derail the topic due to curiosity, my first car was a 1965 Corvair (Air Cooled Flat Six) and when we rebuilt the engine it was with forged pistons. Nothing special for tolerance vs cast in the process, is this because a four stroke is less stringent about tolerances/a two stroke heats up faster?

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Wiesco 232M08550 Piston Kit For Sale 16 Aug 2018 19:08 #12

  • KennyV
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asco wrote:

bluntz465 wrote: Most Wiseco call for 3 thou, not sure what it may be in mm.


Still want to hear from ENDURONUT.

0.003 is huge and potentially slap city

My CT1 was at 0.002 and was/is not in spec.

I think the AT1 / CT1 book calls for
0.016 - 0.017 to get a desired ring gap.

Wiseco could sieze at those #'s ..

The difference between 0.017 and 0.002 is 3/10,000ths.

a


Wiesco, same as Yamaha, has min and max new piston to new bore clearance specs. Meaning the machinist doing the boring has a target to "shoot" for. If you are dealing a good machinist they can hit the "target" where you want them to.
I don't remember what the Wiesco min / max piston to bore clearance specs are, I do know that the shop / machinist that bored this cylinder, based on their experience building performance engines talked me into boring to max of Wiesco specs. I wanted the bore to be at the min spec at the largest. Hope you understand all this. If you have more questions, please ask. I am a retired machinist, 36 years of working with precision fits.

Piston kit still for sale, $40 + shipping.
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71 Z50 Minitrail
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74 250A
78 XT500E
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Last Edit: by KennyV.

Wiesco 232M08550 Piston Kit For Sale 16 Aug 2018 19:20 #13

  • RT325
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Good deal for someone at that price, just follow the wiseco clearance & let it warm up good before thrashing it & she'll be good. If you bore it to yamaha clearance she won't be good--the first time you open the throttle. One hand on the clutch trick. Had one just like it, except 81mm in my 360 RT2MX cylinder & all good, but audible when cold.

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Wiesco 232M08550 Piston Kit For Sale 16 Aug 2018 20:22 #14

  • Enduronut
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asco wrote:

bluntz465 wrote: Most Wiseco call for 3th, not sure what that is in mm

.75mm

Still want to hear from ENDURONUT. < < < OK . . . but I'll need to correct some numbers below

0.003 is huge and potentially slap city < < < bluntz465 is correct . . . this particular piston's clearance is suppose to be .003"

My CT1 was at 0.002 and was/is not in spec.

I think the AT1 / CT1 book calls for
0.016 - 0.017 to get a desired ring gap. < < < add another zero behind decimal point if talking about piston clearance / .0016 ~ .0018"

Wiseco could sieze at those #'s ..

The difference between 0.017 and 0.002 is 3/10,000ths. < < < .015 = fifteen thousandth
You probably meant to say . . . "The difference between 0.0017 and 0.002 is 3/10,000ths."

a

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Control your thoughts . . . or your thoughts will control you!.
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Wiesco 232M08550 Piston Kit For Sale 16 Aug 2018 21:15 #15

  • MarkT
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It's so darn common for shops to "add a little clearance" when boring. I know they mean well, it's just almost never a good idea or necessary.

Back in the old days, Wiseco had a chart for clearance based on bore diameter. Wiseco clearances back then were more than they are now.

These days, they give you one number on the box. With a note in the instructions that "added clearance may be necessary" and notes about supercharging, high compression, or some such mods that don't normally apply to a stock engine.

Correct piston clearance is based on a lot of factors... material (alloy) and manufacturing process are two major ones.

OEM Yamaha pistons are cast and are made of a very good alloy. Cast pistons are inherently more "brittle" than forged. Yamaha cast pistons have low expansion rates and are among the strongest and best wearing cast pistons available. They might even be the best cast piston available!

Wiseco is forged. Different process and forged usually requires more clearance than cast. Wiseco has come a long way since the early days. Their new designs (pistons are not "round") and alloys make for a strong piston that require less clearance than the Wiseco of the 70's many of us grew up with. The reason for the extra clearance is that forged tends to expand more when hot than cast.

How much has Wiseco changed? The 175 piston clearance for an OEM Yamaha piston is 0.0016" to 0.0018" (just under 2 thousandths of an inch). I have a brand new Wiseco for the 175 that has the recommended clearance listed as 0.002". We're literally splitting hairs here. Not much more clearance at all!

(Maybe EN has the 175 specs for the early Wiseco's... I'd guess it was somewhere near 0.003" to 0.0035" range.)

When I can get them, I prefer Yamaha cast pistons. The new Wiseco is not a bad choice at all... even though it will rattle slightly more when cold. I like the thin rings of the Wiseco if revving high. The big plus is if you hit the skirt of a Wiseco with a sledgehammer, it might dent or bend. A cast piston will likely break or even shatter. Forged is a much tougher piston.

If I get a bad piston rattle with a cast piston, I worry it will crack or break. With a forged piston, I don't worry about breakage.

Just my two cents on pistons... and probably not worth that. :Buds
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1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250

Wiesco 232M08550 Piston Kit For Sale 16 Aug 2018 21:15 #16

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Enduronut wrote:

asco wrote:

bluntz465 wrote: Most Wiseco call for 3th, not sure what that is in mm

.75mm

Still want to hear from ENDURONUT. < < < OK . . . but I'll need to correct some numbers below

0.003 is huge and potentially slap city < < < bluntz465 is correct . . . this particular piston's clearance is suppose to be .003"

My CT1 was at 0.002 and was/is not in spec.

I think the AT1 / CT1 book calls for
0.016 - 0.017 to get a desired ring gap. < < < add another zero behind decimal point if talking piston clearance / .0016 ~ .0018"

Wiseco could sieze at those #'s ..

The difference between 0.017 and 0.002 is 3/10,000ths. < < < .015 = fifteen thousandth
You probably meant to say . . . "The difference between 0.0017 and 0.002 is 3/10,000ths."

a


The only way to learn is to be incorrect. For that I am truly grateful. I just learned something.

Back to the regular scheduled program

a
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Wiesco 232M08550 Piston Kit For Sale 16 Aug 2018 21:19 #17

  • MarkT
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P.S. Here is a picture of the box of your Wiseco showing the recommended clearance... installation guide can be downloaded from the Wiseco website.

Great price... good luck with the sale!

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1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250

Wiesco 232M08550 Piston Kit For Sale 11 Jan 2019 18:36 #18

  • KennyV
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Piston kit still for sale, $30 + shipping

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71 Z50 Minitrail
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78 XT500E
06 F650GS Dakar
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