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Makotosun

74-75 DT175 Piston

  • RustiePyles
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74-75 DT175 Piston was created by RustiePyles

Ok, so I'm tearing down my DT175B, It's bored 0.5mm over with a Weisco 471P2. For some reason I'm not able to find ANY pistons for 74-75 DT175's. Despite having the same bore and stroke the later pistons seem to be substantially taller. What changed, crank throw, rod length, both? Any info on where to find pistons for a 74-75 or what I need to do run later or earlier pistons that seem to be available everywhere.
Fletch

1975 DT175B
1979 XS650
Last edit: 13 Aug 2020 07:10 by RustiePyles.
13 Aug 2020 06:17 #1

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Replied by MarkT on topic 74-75 DT175 Piston

Check with Enduronut for a piston/rings. Are you getting it bored to a new oversize? If not, you'll likely need to use another Wiseco. Wiseco tends to be slightly bigger than other brands.

Other than that, the only thing different enough from 72-81 175 pistons that you have to worry about is the location of the ring locator pins. You don't want the ring gaps going over a port opening. I'm not 100% this morning but the only piston I can think of off hand that won't work due to ring pin is a 77-79 IT175 in a DT175.. but you can use DT in IT.

You can even use a Blaster piston if you trim the skirts slightly.
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
13 Aug 2020 07:25 #2

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  • RustiePyles
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Replied by RustiePyles on topic 74-75 DT175 Piston

I'm not currently planning on boring it 0.75mm. The bore mics out ok now but the piston shows some damage. Id be fine running another Wiseco but I cant seem to find one. I ordered a new piston thats supposed to fit a DT175 but its WAY taller for some reason.
Fletch

1975 DT175B
1979 XS650
13 Aug 2020 07:56 #3

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Replied by MarkT on topic 74-75 DT175 Piston

Pictures or at least measurements would help. Not sure what you bought or if early Wiseco was somehow different in height... I don't recall that it was.

I can measure some pistons I have... I should have a Wiseco and OEM around here.
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
13 Aug 2020 09:09 #4

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Replied by RustiePyles on topic 74-75 DT175 Piston

Here are the slugs in question. The picture of the new piston next to the old Wiseco i actually the wrist pin pushed through both piston. You can clearly see the the new pistons oil ring lines up with the Wiseco's compression ring. with the piston on the rod the compression ring land is totally out of the out of the bore at TDC. Am I missing something or is there no way this piston fits any DT175 at all? Also the piston ports have WAY more duration on the new piston.
Fletch

1975 DT175B
1979 XS650
Last edit: 13 Aug 2020 15:12 by RustiePyles.
13 Aug 2020 15:02 #5

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Replied by MarkT on topic 74-75 DT175 Piston

The "white box" piston you were sold is just plain wrong. In a little while I will take a pic of pistons from the various generations from 69-81 showing they all have the same deck height.
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
13 Aug 2020 15:09 #6

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Replied by RustiePyles on topic 74-75 DT175 Piston

I figured as much. So I keep seeing that all the pistons available do NOT fit 74-75 DT175's. Whats the differance, ring indexing pin location? Can I run a piston for a 76<
Fletch

1975 DT175B
1979 XS650
Last edit: 13 Aug 2020 15:21 by RustiePyles.
13 Aug 2020 15:21 #7

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Replied by MarkT on topic 74-75 DT175 Piston

I will answer in more detail later. One thing is I would reuse your Wiseco WAY before I'd use a "generic" piston sold on ebay if you're trying to save money.

Those pistons might be cheap but there's a good chance it could destroy the engine if it fails... It has happened.
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
13 Aug 2020 15:42 #8

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Replied by RustiePyles on topic 74-75 DT175 Piston

Agreed, unfortunately the Wiseco has a damaged ring land, and needs rings. I don’t see where I can get a new set of rings alone for the Wiseco piston. Wiseco seems to have discontinued most all 175 piston production.
Fletch

1975 DT175B
1979 XS650
13 Aug 2020 16:40 #9

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Replied by MarkT on topic 74-75 DT175 Piston

Okay, here we go... I had to do this fast.

5 pistons. Left to right: CT1 piston port, 74-76 DT175, Yamaha Blaster 200 (wiseco), 77-79 IT175, 78-81 DT175 (Wiseco).





More to follow...
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
The following user(s) Liked this Post: JayB
13 Aug 2020 17:57 #10

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