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Makotosun

Stuck Piston

  • MarkT
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Replied by MarkT on topic Stuck Piston

Later models are nice because you can (carefully) use a thick plate (could use the head but could warp it) across the top studs and a suitable length block of wood to press the piston out. It can be slow going... have to be patient and don't tighten so hard that you start stripping or pulling studs... just soak with penetrating oil... put pressure on the piston and walk away if it doesn't move leaving the pressure on... Once it starts moving, keep adding shims as the threads have limited travel.
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: yamahahaha
02 Jun 2020 07:16 #11

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Replied by mdscott on topic Stuck Piston


:Ugh :haha
Thanks Mark
Roseville, Ca.

'03 ST1300
'75 Norton
'73 CB500K
'81 Honda CT110
'87 PW50
'64 McClane Edger
'02 Honda XR70R
02 Jun 2020 07:28 #12

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Replied by YZBill on topic Stuck Piston

I just dealt with a similar issue on a 79 YZ. The bike sat outside under a tarp for 30+ years. At some point the previous owner found the motor was stuck and started pouring Marvel Mystery Oil down the spark plug hole which ran down the transfer ports and filled the crankcase. I used an impact gun on the flywheel nut. Less than 10 seconds it started turning. Then I pulled the jug.
13 Jun 2020 11:32 #13

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Replied by yamahahaha on topic Stuck Piston

Got the piston unstuck... Took alot of time, patience and Kroil... This was a first time using Kroil in combination with MMO...
I then soaked the rusty cylinder in Evaporust... WOW what a great job that did.. That was also a first time using Evaporust...

Kroil and Evaporust :OnFire
The following user(s) Liked this Post: Swoop56, Midlife Motor
13 Jun 2020 12:51 #14

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