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23

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 between 600RPM to 1000RPM, signifies the speed of the crankshaft. The fuel is calculated by the ECU (or ECM or PCM) depending upon the load, which is a calculated ...


16

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 it stumbles is because those disabled pistons were expected to sustain the crank's rotation. In the absence of those pistons firing, the crank will experience ...


13

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 fully open and its corresponding piston is at the top-most point of travel (Top Dead Center) as they share the same physical space. In contrast, the regions ...


12

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 kills the engine when it's not needed, but that's usually after several seconds of sitting still, as long as other parameters are met as well. Most vehicles ...


12

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 the side skirt: The main part of the piston (as in the picture) which gets knurled is the skirt. The reason someone would knurl a piston is one of two reasons....


9

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 actually consists of two rings and a spacer. The main trade off is, the 4-ring piston will have less drag on the cylinder walls, but the 5-ring piston will seal ...


8

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 engine cycle. So without some powering source to force it to a high compression location, it'll stop somewhere mid-stroke. Plus the crank wants to roll off from ...


6

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 it over TDC, will have a "spring" action that will tend to maintain RPM, as the compression energy is now released. This is critical to the brilliant and ...


6

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 lands.


5

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 pedal. In an automatic vehicle, a torque converter essentially does the same thing as a clutch, but does not require manual intervention. These mechanisms ...


5

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 toroidal design Here is a modern mock up of a similar design.


5

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 own job and their own life expectancy. When you lug an engine, you are prematurely wearing on all of the parts of the engine, but that wear is not equal amongst ...


5

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 and swingarm. The new Honda RC213V-S is $184,000. How much did that 150cc bike cost? My point is, the inverted triangle piston skirt is not that fancy. It'...


5

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.


5

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 more things to check: The ignition coil, on this vehicle I believe it's located above the spark plug. Try swapping two of them and see if the problem follows. ...


4

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 screwdriver under it, use the screwdriver approaching at the same angle as the gudgeon pin goes in. Once you have the screwdriver sat under the clip use the ...


4

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 there should be no excess length, unless you were given the wrong ones... As for turning the engine by hand, a long wrench sounds about right. The starter acts ...


4

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 making it more efficient. A similar principle is used in slipper pistons A slipper piston is a piston for a petrol engine, that has been reduced in size and ...


4

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 something. I am sure at one point you had no knowledge either. Its not a hard understand that no one knows anything until they sit down and learn. So do ...


3

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 common, say the last 3-5 years, across all K-cars (multiple manufacturers). On these cars, this StopStart feature is also available on automatic cars, so the ...


3

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 end torque, smaller and lightweight rocker arms and a reduced angle of the valves have all helped better combustion, aided by the good looking dual type ...


3

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 technically not an automotive product, I use CLP to clean gunk and carbon off automotive parts. It's great stuff IMO.


3

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 is an air cooled engine so there is no antifreeze. If you're burning oil, it definitely could be leaking past the piston rings, which would likely be fixed if ...


3

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 BMW has the nikasil coating. I would not simply hone your cylinders, attempt to the coating, it may be required to put then next overbore size of piston in. If ...


3

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 visual inspection against the other set. The difference is that the stiff ones have the oil ring groove 1 mm less deep than the other, this explains why the coil ...


3

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 relatively large amount of gas porosity on the surface from hydrogen gas dissolved into the liquid aluminum . This implies more gas porosity so I would be ...


3

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 addressed.


2

Personally, I replace the rings every time a piston goes back in the cylinder. While I can't speak for motorbikes (*I know they get dismantled a lot more often than a typical car engine) I would assume like with most wear items, you'd want to remove it, then put new ones on after.


2

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


2

did a valve stick? when you take the valve cover off is there one that is stuck? How did it seize up? Is the sound a bang, a schlip, a ping, a clank. Is it sharp or long? Did you put all the conrod bearings back in? In general which parts were replaced and refinished and what was reused? Did all the reused parts go back exactly as they came out or are ...


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