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Stuck Piston

01 Jun 2020 15:56 01 Jun 2020 15:56 by yamahahaha.
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Stuck Piston #1
Got a stuck piston due to rust. In regards to my photo how much further down is the piston down stroke when running ? Hope I asked that right is the down stroke

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01 Jun 2020 17:38
Swoop56
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Stuck Piston #2
It doesn't look to have completely uncovered the ports that I can see .
I'd expect there's still another 10-15 mm left before it hits the bottom of it's stroke .
Some penetrating oil around the bore might free it up . It might take a few applications to free .
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01 Jun 2020 17:46
mdscott
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Stuck Piston #3
That looks like its down all the way, even with the transfer ports, i think. Ive gotten several pistons out of frozen cylinders by lots of liquid wrench and removing the cylinder nuts while lifting the cylinder and hitting the piston with wood. Real common on the old Honda 90 engines.

Thanks Mark
Roseville, Ca.

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01 Jun 2020 18:00
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Stuck Piston #4
Thanks Swoop and Mark... Yes I am a big fan of MMO and Kroil and some heat from my heat gun....I was thinking what you said Mark. I may need an extra set of hands to hit the piston while I pull up on the cylinder. Thanks guys.

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01 Jun 2020 18:02 01 Jun 2020 18:09 by RT325.
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Stuck Piston #5
Looks like it's almost there. Need a good strong flywheel holding tool to add some force to it but looks like you'll have to unbolt the cylinder & put blocks under it. Turn the crank to lift it all up, fit blocks then force the piston down. But it looks a bad case i must say. but might not be much rust lower down as piston is near the bottom. No use trying to turn the nut & needs more force than that. Here's a link to ages ago on my YG1T. The old girl ran perfect using same piston & rings. Might be a page before or after showing more. Can see the holding tool & had a pipe on that too--pretty brutal free or bust job. I can see the pipe looking again, but slid it out longer & thought something was going to break or shear a crank key, then felt a slight movement, so then other way, then see saw back & forth until it freed up. In saying that i think mine was more corrosion into the bore where yours is gross rust & lots of it. Also yours is on first oversize but i'm sure you've seen that.
www.yamaha-enduros.com/index.php/forums/...ildforums=1&start=60
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01 Jun 2020 18:24
yamahahaha
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Stuck Piston #6

RT325 wrote: Looks like it's almost there. Need a good strong flywheel holding tool to add some force to it but looks like you'll have to unbolt the cylinder & put blocks under it. Turn the crank to lift it all up, fit blocks then force the piston down. But it looks a bad case i must say. but might not be much rust lower down as piston is near the bottom. No use trying to turn the nut & needs more force than that. Here's a link to ages ago on my YG1T. The old girl ran perfect using same piston & rings. Might be a page before or after showing more. Can see the holding tool & had a pipe on that too--pretty brutal free or bust job. I can see the pipe looking again, but slid it out longer & thought something was going to break or shear a crank key, then felt a slight movement, so then other way, then see saw back & forth until it freed up. In saying that i think mine was more corrosion into the bore where yours is gross rust & lots of it. Also yours is on first oversize but i'm sure you've seen that.
www.yamaha-enduros.com/index.php/forums/...ildforums=1&start=60


Thanks, yes the blocks under will eliminate needing an extra set of hands and sounds like my best bet...Just slow and easy but not to easy :whistle:
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01 Jun 2020 19:49
RT325
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Stuck Piston #7
Just thinking those deep nuts that hold it on are only alloy by memory so use a good fitting socket or a single hex socket as they can slip over if reluctant to crack free.

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01 Jun 2020 23:28 01 Jun 2020 23:29 by Gr8uncleal.
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Stuck Piston #8
If you have an engine hoist, straps and can fashion a couple of brackets (I used 10mm thick mild steel), then you could try Gr8uncleal's method! :ROFLOL

Obviously the weight of my GT550 proved very useful here. The advantage of doing it "my" way is that you don't have to hit down on the crank.

Good luck!

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02 Jun 2020 04:57
yamahahaha
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Stuck Piston #9
Ya I have a similar setup in our bedroom :woohoo:
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02 Jun 2020 05:16
Gr8uncleal
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Stuck Piston #10

yamahahaha wrote: Ya I have a similar setup in our bedroom :woohoo:


The mind boggles..........!!:EEEK :EEEK :EEEK

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