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JT1 Crankshaft questions
- 812smoker
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JT1 Crankshaft questions was created by 812smoker
Would anyone happen to know the tolerances for the assembled length, as well as rod to crank half clearances? I have taken my crank and parts to my local machine shop but they need to know this, i have looked in the service manuals in the tech library and can't seem to find what i need.
20 Jul 2023 11:21
#1
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- MarkT
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Replied by MarkT on topic JT1 Crankshaft questions
Some specs are in the service manual... the flywheel width is shown in the diagram on page 39 (45mm +0.05/-0.10 )
They show specs for "axial play" of the rod... which is "wobble" measure out at the small end without letting rod slide side-to-side 0.8 to 1.0mm with new parts... not to exceed 2mm on a used crank..
I don't see the spec for the big end rod side clearance. It's usually 0.2mm to 0.5mm for similar engines. I have an aftermarket JT manual and they don't show this spec either. (Clymer might, I can't find my copy right now though.)
There is a Yamaha crankshaft spec document for the earlier models but I don't have it.... maybe somebody here does.
They show specs for "axial play" of the rod... which is "wobble" measure out at the small end without letting rod slide side-to-side 0.8 to 1.0mm with new parts... not to exceed 2mm on a used crank..
I don't see the spec for the big end rod side clearance. It's usually 0.2mm to 0.5mm for similar engines. I have an aftermarket JT manual and they don't show this spec either. (Clymer might, I can't find my copy right now though.)
There is a Yamaha crankshaft spec document for the earlier models but I don't have it.... maybe somebody here does.
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: Enduronut, asco
20 Jul 2023 12:34
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- 812smoker
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Replied by 812smoker on topic JT1 Crankshaft questions
Thank you mark! i actually had just noticed where the tolerance for the assembly is, it's almost like they tried to hide it but to be fair i dont feel i was being observant enough while looking. not sure how i make this reply notify you of my reply but i just thought id add that in my searching of tips and tricks for timing and clutch work on my dt400 some of your replies on others posts have been big helps to me so thanks for putting your knowledge out there
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20 Jul 2023 12:59
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- MarkT
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Replied by MarkT on topic JT1 Crankshaft questions
You're welcome!
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
20 Jul 2023 13:33
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