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23 votes

Do pistons keep moving when the car stops?

The answer to your question is both yes and no. Yes in majority of the conventional vehicles, the pistons keeps moving even when the vehicles is at a stop light. The idle RPM, which is usually ...
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  • 576
16 votes
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What's gonna happen if I disconnect 'single piston'

As you saw with your test, it is possible to disconnect the ignition on two pistons and still have the engine run. The vibrations have nothing to do with engine knock or detonation though. The reason ...
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  • 39k
13 votes

Interference vs non-interference engines

A piston engine is deemed to have an interference design if the normal regions of valve travel and piston travel overlap. In such engines, collision (and damage) would occur if any of the valves is ...
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12 votes

Do pistons keep moving when the car stops?

In most cars, yes the engine continues to rotate and the pistons go up and down in the cylinder bore due to combustion and the engine continuing to run. Some vehicles have an "auto stop" feature which ...
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12 votes
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What exactly is a "knurled piston"?

Knurling is a process where a cross-hatch stamp is pushed into metal. By doing this, the metal is compressed in some areas and raised in others. Here is a picture of a piston with a knurled portion in ...
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9 votes

3 rings vs 4 rings pistons: which design is better?

There are trade offs, so no clear answer here. First of all, just to be anal and clear something up ... what you have is actually a 4-ring and a 5-ring piston. The oil control ring at the bottom ...
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8 votes

Where does the piston stop after the ignition is turned off?

It isn't completely random, as there will always be one piston that is approaching TDC, and the compression building in that cylinder will ultimately cause the engine to stop. Any cylinder that makes ...
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8 votes
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Where does the piston stop after the ignition is turned off?

It's random. Usually won't come to a stop at top or bottom dead center because theres nothing to drive it to that point, and one of the pistons will be building compression at any given time of the ...
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  • 146
6 votes

Cleaning pistons and cylinders with oven cleaner

Why chance it when some carb cleaner will do the trick for you. It should take carbon off of the piston without any worry of damage to the piston. Use an old, broken piston ring to clean out the ring ...
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5 votes

Do pistons keep moving when the car stops?

To add to the other answers, in a manual vehicle, the road wheels are usually disconnected from the engine when at a stop either by putting the transmission in Neutral, or by depressing the clutch ...
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5 votes

Pivoted curved-path piston engine

The only curved bore designs I am aware of are toroidal I have been unable to find a match to the drawing, not even close. I took a hard look at steam engines as well. Here is an example of a ...
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  • 32.8k
5 votes

Why is lugging hard on connecting rods?

tl dr: Lugging the engine is less hard on connecting rods then it is on other parts of the engine. Parts in the engine have their own strength. Some parts are stronger than others. Each part has its ...
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5 votes

What is an inverted triangle piston skirt?

I am very skeptical of the claim that the GSXR150 is leveraging MotoGP technology, even the top of the line sport bikes from Honda, Suzuki and Yamaha do not leverage much of that tech other than frame ...
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5 votes
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Is it really necessary to resurface cylinder and substitute piston?

You can absolutely reuse the piston if it isn't damaged. There are piston compressor tools dedicated to slide the piston back into the cylinder.
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5 votes
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Fourth piston isn't sparking so car is losing power

I am pretty sure the spark plug is broken but I am not sure That's almost certainly the issue. Replace the spark plug and try again, if the problem is fixed, you're all set. If not, then there are ...
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4 votes

Rebuilding an engine: pistons installed, crank rotation "very" stiff

I am concerned with you description of the oil ring - the ones I have fitted come in 3 parts : 2 scraper "flat" rings and a "top hat" mounted on its side that locates the other two. Fitted correctly ...
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  • 34.4k
4 votes

Extracting piston rod's "wire" C clips

Those gudgeon pin clips are the fiddly type! .. Get a sharp engineers angled scribe or similar, and try to lever one end of the C-clip away from the piston just enough the get a small narrow blade ...
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  • 5,022
4 votes

What is an inverted triangle piston skirt?

Given the piston skirt is the bit of the piston under the gudgeon pin on the piston/conrod, it seems this is a way of reducing drag and wear on the cylinder (i.e. less contact patch) and therefore ...
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4 votes

How much force is needed to push a piston down?

I apologize if my question wasn't as technical as you want. I would like to add I have no knowledge of cars and I'm just learning. I thought it was common sense to ask questions if you didn't know ...
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  • 6,449
4 votes
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1986 El Camino: deprecation

6 months won't have done much damage. It might be worth changing those tyres if it's been sat on them flat for months. It started so battery and fuel system are probably OK. Sometimes brakes will ...
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3 votes

Do pistons keep moving when the car stops?

I don't have enough reputation to comment, but the small economy cars (K or Kei cars) in Japan also have this StopStart feature, as Mauro commented (for European cars). I think this feature is now ...
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3 votes

What is an inverted triangle piston skirt?

Engines with a single cylinder can be arranged at any angle but typically upright or inverted. In Gixxer they says, "An inverted triangle shaped piston skirt has also been utilized to increase bottom ...
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3 votes

Cleaning pistons and cylinders with oven cleaner

Dude spend the extra 3 bucks and buy a proper engine cleaner. Spraying sodium hydroxide on aluminum is a bad idea. I would use a nylon brush drill bit to clean off carbon. Although it's ...
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  • 1,925
3 votes

Safe to buy new piston for your two wheeler engine

If the smoke being emitted from the exhaust is white with a hint of blue, it is oil. If the smoke is white with a sweet smell, it is antifreeze. As Anarach pointed out in the comments below, yours ...
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  • 6,017
3 votes
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Should I remove the rings when cleaning a piston?

You have a nikasil coating on your cylinder walls You can't just bore, hone and assemble. You have to have a nikasil coating applied to the cylinder walls before reassembly. Your model year of ...
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  • 32.8k
3 votes

Rebuilding an engine: pistons installed, crank rotation "very" stiff

Ok mystery solved: I have two piston sets, both are identical in look, dimensions and part numbers/marks...only that they are not :) I took the ones I installed and carefully checked measures and ...
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  • 3,296
3 votes
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Can the bottom of a piston be scratched and not damage the cylinder?

I do not see anything that I would call a "scratch". A scratch would be into the piston ( below the surface ) so should not hurt an iron , steel , or even an aluminum cylinder wall. However , I see a ...
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3 votes
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piston damage impact

The piston will be fine - it is the rings that provide the seal with the bore. As long as the rings move freely side to side then it will seal as it should. If the rings stick then that should be ...
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  • 34.4k
3 votes
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How much should you clean dirty pistons and valves when you aren't removing them?

You can do as little or as much as you want, it is your engine. Since you have already done a load of work disassembling the engine, to me it would make sense doing as much as you can while it is in ...
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  • 20.6k
2 votes

3 rings vs 4 rings pistons: which design is better?

Use the piston from the "newer" design ie most recent - the engineers most likely made changes to reduce or avoid certain issues.
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