LRD

One huge advantage to the porting if done the way I will describe is much better cooling which there seems to be a lot of complaining about.

How do I know this, from partly self inflicted cooling issues,.  In order to build a 360 lb mtn sled with just the little 600 carb engine I took anything that might be excess weight off including the front heat exchanger for about 4 or 5 lbs weight loss counting the coolant in it. (My thinking was on a good day going down a mountain it might have 120 HP and stock exchangers were the same as 160 HP 800's)

I have run ported, unported  and now ported again.  The last configuration with a ported down the center (small rectangular hole and two wheel axle) and a snow flap I made goes to within a couple inches of the snow got my temps down into low 120's finally with good snow.  Before was 140 to 150's. 

Why the ported works better for cooling,  snow gets in the skid, as the track rolls over the rear axle the snow in there is carried up and thrown up at the heat exchanger via the holes.

It does hurt my flotation  a little.

Kind of strange to think the little 600 is going away if you look at the new head  introduced in 2012.  Its a shrink wrapped water jacket modern state of the art head.  But even more interesting is the two unused flat bosses cast into the side of the domes on the intake side. Likely for fuel injection is about the only thing I have come up with.  Also a odd threaded hole on the top of the head between the two cylinders, thinking maybe for a detonation detector.  I have one of the heads and will be reworking it over the summer for my big bore nik-a-sil plated iron cylinders. 

Piston speed is stupid nuts for a pressed together crank in stock form, more stroke = higher yet piston speed with forces

near top and bottom dead center going through the roof. And it will totally screw up your port timing,  you'll need someone with really good skills with two stroke port timing software to figure it out or you will end up with less HP than stock.  Oh yeah your pipe will need to be redesigned to work with longer stroke for optimal performance.  

Highly recommend before you try this you spend $25 for a DynoTechResearch.com subscription which will give you access to read the archived old issues from about 15 years ago.  They covered this subject extensively and dynoed these stroked engines with as I remember generally negative results !!

I can verify the UHMW tape works awesome in and outside of the tunnel.  Only needs to be about 5 thou thick as it is

very tough stuff.  I used 10 thou and made it a lot harder to apply as it was so stiff. 

Recently had another idea for my new Iceage Rails on my skid and for the suspension. arms  Very simple idea if

it works, I've used Rain X in a spray  bottle on my FiberGlass shower stall and the water just runs off, amazing how

well it works.  So I'm thinking it might do the same thing with snow or ice.  When I get a chance to try it will post if it

works.  It would have to be reapplied periodically but hopefully not to often.

If it ever snows again will try it on my snowplow blade also.

Never got to add to that discussion that its not that expensive to buy a decibel meter.  I bought a decent one on Amazon a few years ago for

under $50  that measures on both of the decibel scales. 

Hope to get some time to try and do some extra baffling in my noisy Carbon Can. 

If its not possible to quiet it down might have to bite the bullet and invest in the extra gear to add to my Miller 250 Tig so I weld Titanium and build a light weight fully baffled can like a stock can has.

Amazing video showing metal treated with lasers repelling water., and ice

Tracks USA has rail and tunnel extensions to use with a 137 track.  I used them for my wifes 09

TNT and work great, you just add a track.

Increasing back pressure in the pipe will increase HP until you have so much pressure that you are pushing to much heat into the piston.

A lot of the cans if not all likely had to little pressure losing hp because they weakened the negative and positive wave action that makes a two stroke with a pipe into the incredible HP producing engines they can be.  That wave action gives us mild supercharging effect.

My thread here goes into it in detail and how I measured actual pipe pressure http://www.dootalk.c...t-450lbs/page-8 I can now monitor it all the time and record on my dash gauge.  The ideal pressure seems to be about 3 to 3.5 psi.  Drag racers get away with a lot more but they only run for 500 ft or so. If you don't run full throttle across a lake for a couple miles can run more pressure etc. 

Anybody that doubts this just subscribe to DynoTech Research.com and you will learn from their SuperFlow dyno how much difference it makes.

For me, didn't need the extra fuel, but I got the clear tank and will have a real clue on how much fuel I have.

Or if it would cause the sled to over rev, someone mentioned that to me but I don't know if there is much truth to it.

The over rev should depend on your clutching, more weight in primary, more helix angle in rear etc.

If your really geared low you might get into direct drive a little bit, meaning both clutches have shifted

all the way and RPM's keep increasing some more.

But the increasing RPM will also depend on your pipe.  If you have ever looked at dyno sheets you will

notice the HP tends drop like a rock after the HP peaks.  If I am remembering this right a steeper angle

on the taper at the end of the pipe drops the HP radically compared to a softer taper which will make

a flatter wider power band.  The transfer ports in the cylinders also help to make a narrow power band

or wider flatter one.  If the transfers all open at the same time and are low you have higher speed transfer

flow and more will get lost out . 

The handheld infrared is the way to go,  but if you paint a flat black spot on your bare or shiny aluminum clutch

you will get two very different temps.  The black spot will give a truer temp by maybe 20 to 30 degrees F higher

if I'm remembering correctly. Reason  is a black surface emits more heat while the bare aluminum won't radiate as well.

And the shinier the worse it gets.

My heat exchangers have just a dusting of flat black lacquer paint on them top and bottom for this reason. 

For clutches best would likely be a black anodize.  Just google heat emitter coatings sometime and read some

interesting stuff.

Good Luck

Well between this thread and the thread rk tek has on engine & clutching myths its going to be an awful long

summer!!!  Think I'll just make some more light weight parts for my sled for next winter!!

Good Luck

Kind of a cross between Karts and OutLaw circle track in the corners with the  sounds of Formula I thrown in

to get your adrenaline going!!

http://www.youtube.c...PXENKf84V8#t=90

The PowerBlock combined with a Shockwave adjustable helix is what I have run for 4 years and works awesome.  At the trailer or shop I can change weights in about 6 or 7 minutes.  Helix angle change, 45 seconds any where, so fast my buddies don't even know i'm doing it!

Good Luck

On the indexing of the clutchs that Doo has done:  I figured they did it to try to counteract crank runout and

end up with minimal runout on the end of the clutch shaft. 

So when I put a PB80 on my wifes 09 TNT 600 carb I wasted a good half hour or more trying to index it. 

No matter where I put the PB80 I had the same amount of runout, meaning the PB80 was dead nuts

zero runout so it couldn't counter the crank runout.

I will have to check into the Android app, sounds like it should work great.

As for stuff flying off you haven't lived until you've had the primary and an inch of the crank break off

at 8000 RPM climbing a mountain.

Or sitting on the seat of a 200 HP triple when the torque arm of your Land & Sea Dyno snaps off!!   Now that's an adrenal rush!!  Especially when the sled is a customers!