Why are intake valves bigger? 

How can up and down make the crank turn round and round ?

Lewis C In some engines right & lift

But they are on a planet that goes round and round, so how do you set the timing to make them only go up and down but not left and right?

do it during an equinox

I'll cop to it, I am probably the recent asker he referred to. My question was because I was thinking about why they weren't the same. Where you can eliminate parasitic drains, why wouldn't you? And my thought process was that evacuating exhaust is one of those. To my mind, actively making the exhaust valve smaller/intake bigger wasn't immediately obvious.

Intake valves recieve higher impact loading. Bigger valve = bigger, heavier valve head. Most valves share the same valve stem size.

@@dirtygarageguy thanks very much! I can now frighten small animals with my new found knowledge!

I thought exhaust valves wear faster because of the added heat

No, the same thing applies.

LOL sorry dude but time will tell on this one. This isn't an engineering question, unless one engine stood out for having a defective design that would inherently fail. I could give you 4 pistons from 4 different manufacturers and say - "which one will fail first out of a sample of 1000?" - Only real world running of 1000's of models can tell you this after 'x' amount of years. Hency why forums and bike magazines still exist, to weed out the common issues over time.

Might be talking out my arse but I believe Matt may have covered it before in a video. I think generally it comes down to the reasons we run circular pistons. Its easier to manufacture, its easier to seal and and I'd imagine its easier to account for mechanical wear

Increase where?

@@dirtygarageguy sorry not sure why wrote intake port! I meant further increase the diameter of the intake valve

Then comes the issue of fitting it into the cylinder

@@dirtygarageguy that means a stock engine will not have space to enlarge the valve seat or just possible to a certain extent?

You mean do they put turbos on poorly designed, inefficient motors to make them better? Yes.. Would you intentionally make your intake valves smaller since you're using a turbo? Not sure.. Only reason i can see doing that is either bigger exhaust valves or more swirl.

No because the same thing applies.

There are turbodiesel engines with same sized (or almost same sized) intake and exhaust valves but rather that was intentional or not is another question ;D. I would guess that turbodiesel engines have a lot more intake time (since their max rpm is limited to something around 5000-6000 rpm due to the slower self ignition process diesel engines use) and therefor don't need the advantage of bigger intake valves. They tend to focus more on turbulences to ensure a fast flamefront (a good diffiusion of the fuel into the hot precompressed air).

"Would you intentionally make your intake valves smaller since you're using a turbo? Not sure.. Only reason i can see doing that is either bigger exhaust valves or more swirl." - that's kinda what i was meaning, as opposed to using it as a workaround for putting the head on backwards! using boost pressure to overcome the pumping issues of the valves being smaller, and having a larger exhaust outlet so there's less resistance and being able to drive the turbo a bit better but apparently not, so never mind....

Leona Labratz Water isn't wet because it is a liquid that wets things. Once you come into contact with water you become wet. Until then water is liquid and you are dry.

Tickover?

Sorry dude I don't understand what you mean?

He's making one on the channel , something like simple engine it's a 2 stroke it's cool

I must of mist a couple of vids here , unless its that one someone sent in ? A kit engine

whatever really - its the oil that matters.

Yes, you can be that would be stupid.

Y tho? Explain!