Stock TRX850 head data *caution LOTS of pics*

[Killerwhale]

Here´s my dump hole....

[phuk72]

Here´s my dump hole....

Look, Cobba doesn't need an invite and yet you open the door for him

[Killerwhale]

Here´s my dump hole....

Look, Cobba doesn't need an invite and yet you open the door for him

Saw a girl whod tattooed "exit only" on the lower back, not fair!

[Quan-Time]

not the best angle, but you can see the floor has been raised slightly. That picture shows the floor at the TOP and the roof at the BOTTOM of the pic. The porter took just about all of the valve guide away. Interesting.. Obviously left the ridge there to try and help smooth the flow. Not too bad. Curious how that sharp edge divider would go. I personally like to leave them a bit wider with a radius, BUT ive not done the exhaust side on mine yet, so that may indeed be the best method.

Cheers for the pic.. Got a inlet picture KW ?

[Killerwhale]

Cheers for the pic.. Got a inlet picture KW ?

Not the best this either but you will see no plastic (ask hansj and he´ll show you one with plastic)
I´ve also got "piranha teeth" in my inlets.

[M.V.]

That's interesting, what's the idea behind the teeth? Promote swirl?

[Quan-Time]

quite the opposite, to PREVENT swirl.. To try and smooth the air stream out to get a nice clear shot to the valves. Its a old technique, not sure how valid it is on a 3v inlet. Ive had a play around with a flag. A flag is a piece of coloured string or thread on a long skinny rod.. Think a piece of welding wire or TIG welding rod. Tape the string to it, and let it hang in the air.. It will show you exactly where the air is flowing. It will buzz around it big swirl areas, or be very straight / linear in smooth areas. I use it a fair bit to try and get some port balance.

Next time if i remember, ill try to take a video of it to show you how it works.

[M.V.]

Cool, that makes more sense!

So swirl in combustion chamber = good, swirl in intake = bad?

[Quan-Time]

No, you dont want swirl ANYWHERE.. or not the type your thinking of.. Let me explain. (hope your ready for this)

In the inlet tract, you want STRAIGHT flow.. no swirl or tumble, you want it as linear as possible. This is so its rushing into the cylinder. If you are swirling around (like a corkscrew) you are creating a bias to one side. You want to be as even as possible. Ive had to struggle with this because one port was getting bias, and thus REDUCING velo to the other port, and cfm too.

So the "piranha" teeth, or vampire teeth, help align the flow of air. You want the air to flow exactly like a "smoke ring". If that makes sense to you.

Now, once inside the chamber, you want it to be "over and over", like a summer-sault, NOT round and round, like a whirly-wind. This is for 2 reasons. Getting air to spin over and over SHOULD be natural, as the path its comming in. If you make it go side to side, the air is turning VERY sharply, and that separates the fuel from the air. Think of a centrifuge. You spin the air around and around, the fuel gets flinged to the side as its heavier.. And the sparkplug being in the MIDDLE of the chamber, you want fuel to be rushing past it. Remember how i was checking flow inside the chamber ? Thats the reason why. I want it to be spinning around, or drawing lines over the exhaust valves.. not drawing along the wall.. It means its creating a bias in one direction. If its spinning around and around, fuel mix is trying to come into the cylinder, and the air rushing over it, wants to come back OUT into the inlet tract. This is "blow back" and you might see it sometimes if you get a flash back up your carb.

A while ago some dude got a small motor, like the size on a tiny toy car, and put 4 blades on it in a cross formation. The blades are vertical, and not twisted in any way. If you blow on it directly, it shouldnt spin,, but any side force, it WILL spin. So spin one way will create a POSITIVE volt signal, other way will make a NEGATIVE signal. faster spin, more volts.. simple.
You place this where the piston would be, about half a piston diameter from the valves.. so about 40mm. Dont forget you have about 1.5x cylinder wall... Many people use clear PVC perspex so they can see whats happening.
With this, you can see and measure how much swirl is happening. Porting inside the cylinder head chamber will effect this, as will port bias. All this adds up to development time and more power / usable rev range.

Hope this explains it well. If not, ill draw some dodgy pics

[Kayla]

Hope this explains it well. If not, ill draw some dodgy pics

It does, thank you. But feel free to draw some dodgy pics anyway

[Quan-Time]

http://www.fuelsaving.info/turbulence.htm

A reasonable link to describe it. They use "turbulence" to explain it.. Swirl is side to side, around the cylinder wall, turbulence flow is the over and over rolling flow. That is relevant to 2v heads, thats 1v inlet, 1v exhaust. That is a completely different animal to a 5v head. Each head much be treated as a specific animal.

For the record, When motorbikes came along, one reason japanese companies prospered and no one else did was because of their unique understanding of this. They started from scratch, with "no" rules or beginnings. They set about making 4v heads, over head cam, full alu engines, etc.. This helped them understand each engines character, which subsequently made them the most powerful engines (per volume) on the planet at the time.

Most modern sports bikes still rival ANY vehicle for power PER volume. Such as a 1000cc 176hp factory engine. This equates to 880hp for a 5litre, 308ci V8 engine.. Normally aspirated. Not many engines around that can boast that, but most supersports bikes all have roughly those figures. When you look at motogp 800cc engines, producing around 220hp (claimed), thats 275hp per litre. Yes formula 1 have around 330hp per litre, but they have a different rule set to enable this.

The long and the short of it is this. You need to try ALL styles of head porting to find what works best, and dyno each one and get results. O2 meter, power output, etc.. Its a LONG process, but the long run pays off.

[Killerwhale]

quite the opposite, to PREVENT swirl.. To try and smooth the air stream out to get a nice clear shot to the valves. Its a old technique, not sure how valid it is on a 3v inlet. Ive had a play around with a flag. A flag is a piece of coloured string or thread on a long skinny rod.. Think a piece of welding wire or TIG welding rod. Tape the string to it, and let it hang in the air.. It will show you exactly where the air is flowing. It will buzz around it big swirl areas, or be very straight / linear in smooth areas. I use it a fair bit to try and get some port balance.

Next time if i remember, ill try to take a video of it to show you how it works.

Was an old fart who ported heads for over 20 years who did it, he swears by it and i got it for free so...
But old tech....yep!

Can add that i got a new lean spike when on dyno after head port and teeth, think that tunable "leak jets" to control acc pump squirt would be interesting to try out....

[Quan-Time]

or you could just go efi

[Killerwhale]

or you could just go efi

Nah, just love the wistle in my flats!!

[M.V.]

Thanks Quan-Time, interesting & informative as ever!