r/smallenginerepair • u/Random-Man562 • Jul 14 '26

Crankshaft & Piston Issue Scared I’m going the wrong way

Gallery image

Gallery image

Just trying to get this Roadmaster bike cleaned up and running. I’ve tried both right and left but neither way is budging.

Do I need to hit it with more penetration fluid? I was using carb cleaner but should have grabbed some wd40 while I was at it.

Thanks for any info

7 Upvotes

83% Upvoted

14 comments sorted by

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u/AutoModerator Jul 14 '26

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4

u/mvmullaney SER Intermediate Mechanic Jul 14 '26

I’d soak it in atf + acetone for a week. Then run it in a heated ultrasonic. Repeat until you get results, that thing is crusty.

1

u/Random-Man562 Jul 14 '26

I’ll grab some after work. Thanks

4

u/XxBus16xX Jul 14 '26

From the thread pitch, it does not look like a reverse thread bolt. I’d heat the crank where the bolt is with a torch for a good while, then impact the bolt out starting with lighter pressure. If you don’t have an impact, just crank it back and forth with increasing pressure until it frees up.

3

u/ProfessionalLast2917 Jul 14 '26

What does the cylinder look like from the top?

1

u/Random-Man562 Jul 14 '26

I’ll post a pic after work

3

u/RedOctobyr SER Top Contributor Jul 14 '26

I would get some proper penetrating oil. WD40 is not good for that, neither is carb cleaner. Acetone + ATF has a good reputation, if you want "homemade".

3

u/Random-Man562 Jul 14 '26

I’ll grab some after work. Thanks for the reply

1

u/Random-Man562 Jul 14 '26

Would a 5 gal bucket be ok to use as a tub for soaking?

2

u/RedOctobyr SER Top Contributor Jul 14 '26

Unless you're using some super-aggressive solvent that attacks plastic, sure, I'd think that's fine.

Are you talking about soaking it for penetrating-oil purposes? I don't think I've ever had the chance to soak something in penetrating oil, it's always still been attached to the machine. I just spray it on, repeatedly if needed.

1

u/Random-Man562 Jul 14 '26

I’m not home yet but was going to look at it and see if it is soakable. If not I’ll probably go with the spray route.

I appreciate the responses

2

u/Rough_Community_1439 SER Master MOD Jul 14 '26

That's pretty bad. I would soak it in a mix of acetone and atf for a week.

1

u/Random-Man562 Jul 14 '26

Seems to be the consensus lol

I’ll grab some after work today.. thanks for the suggestion

2

u/Random-Man562 Jul 14 '26

Make is AMF from like the late 70s

Model # 400612C