Topic: Strange question - anyone flipped their cylinders/head around?

[nick5446]

That explains some. I've heard of the lenient pot laws there.

Hey man! That's Washington!! Way different down here...

[nick5446]

It actually does make sense from an efficiency standpoint, as the intake and exhaust flows wouldn't have to turn 180 degrees each to get where they are going.

Yamaha started using the "reverse head" design on the YZ450F in 2010.

Exactly what I want to do. When I was about 10 I was looking at my dirt bike and asked my dad why the intake was on the back and the exhaust was on the front and he said something like "don't ask stupid questions" (read: I have no idea). It didn't make sense to me then, doesn't make sense to me now. Now I rub that YZ in his face every chance I get.

[brewsky]

Have to keep in mind that on an air cooled motor it is especially important to keep the exhaust valves / seats / ports cool to prevent distortion / cracking. hard to do when they would be on the back side.

That seems to be the best reason not to do it.
But........it hasn't stopped air cooled v-twins, which have that orientation on the rear cylinder?

[nick5446]

Have to keep in mind that on an air cooled motor it is especially important to keep the exhaust valves / seats / ports cool to prevent distortion / cracking. hard to do when they would be on the back side.

That seems to be the best reason not to do it.
But........it hasn't stopped air cooled v-twins, which have that orientation on the rear cylinder?

Exactly what I was thinking. Plus, I'm not gonna be running it super hard.

[lucky]

It has been done before but it is very complicated.
The cylinders have to be turned around too.

[nick5446]

It has been done before but it is very complicated.
The cylinders have to be turned around too.

Yeah I know the cylinders will need to be turned. I have an extra CB750 motor I've been looking at and that seems totally do-able without any real work. I need to look a little more closely and make sure that oil will still flow correctly.

[phil71]

The valves are different sizes. It'll make less power. with the flipped  cams, you'll also have the crank running the wrong way, so the kick and electric start are no go.
You'll have to do some math to figure out ignition timing.

[nick5446]

The valves are different sizes. It'll make less power. with the flipped  cams, you'll also have the crank running the wrong way, so the kick and electric start are no go.
You'll have to do some math to figure out ignition timing.

You're making it sound like I'm gonna have to use my brain...

It's electric start only (Honda-magic). That's a good point about the issues with flipping the cam...


hmmmmm......

[phil71]

bump start only!

[crazypj]

That's not an engine. It's a sculpture... Anyway triumph is easy coz its twin cams which can be switched front to back

 On a four you need a different cam specially ground to run 'backwards' the crank has to turn in normal direction or you'll have to make a gearbox to reverse the drive
 The 550 head isn't reversed, I'm pretty sure it's trying to breath through exhaust valves then exhaust through intakes.
Why would you reverse the cylinders?
You'll also need new 'intake=exhaust' valves as the stock intakes will fail when overheated by using them as exhaust valves

Hey, never forget, some lunatic built one with a sideways engine: http://forums.sohc4.net/index.php?topic=116469.msg1337072#msg1337072

 That was much simpler to engineer, just remove transmission.
 I think it was inspired thinking (plus it won world chopper championships or some such?)

[nick5446]

Fair enough. So that's probably not going to happen since I don't really want to be the first person to do it.

On to the next crazy idea...!