2 Strokes Down Under

So you have converted back to 28's and it goes much better?

Its back to PWK28's yeah... overall it goes better.
I just didn't want to spend any more time tuning - just wanted to ride.

I still think it may be a touch rich, so it's probably got even more in it, but I would rather that than a seizure.

Oh and it still needs pipes.

It's got a second powerband that hits around 8,000 or so because of those upper pipes which are now probably 3-4 inches too short.

Mustang should be painted soon, then hopefully I can throw some money back at the bike again.

Good to hear that shes up and running again!!!
great bike!

you want some custom atac valves for it ?

That's an interesting thought.
You should definitely bring these up on the 500 forum (or I can) if they work.

The YPVS system stops the carbs being able to be put in the V on the 500's... the valves would solve that issue.

Still.. there's so much electronics already on my bike.. I don't think it needs any more! Although I guess I could get rid of the PV controller.

Doesn't the PV effectively change the timing of the exhaust port rather than the volume or length of the exhaust?

Oh, and it was great to see from start to finish as well. I have often wondered what the yellow jobbie was.

Is the ATAC additional to port timing?

yep, it changes the exhaust tuning by changing the volume of the chamber or at least the header section of the chamber.

Yep, a simple solenoid (controled by ignitech/zeeltronic) opens a butterfly in the header pipe which has a canister on the other side (perhaps 100-150cc for your bike).

Every time a pulse passes by the butterfly it has to fill this volume before continuing down the pipe so it slows down the pulses in both directions.

So effectively it makes your bike think that the expansion chamber is longer than it really is.

The only pre-requisite is that your bike has a little bit of spare room somewhere around the exhaust flange area for a 100CC canister to sit on top, beside of below the pipe.

If your keen I can send you some pictures of my prototypes for my 421 yamaha.

If you wanted to I could get re-design them to fit your bike, get them CNC'd by my guy in NZ, then you'd just have to make the 100cc canisters and connect them up to some solenoids (Im using car central locking solenoids).

The only development required is that you go to a dyno and play around with the solenoid timing (RPMs that it opens and closes) and also play around with the canister size (larger cc's for bottom end power boost and smaller volumes increase the RPMS that it works at.)

All going well I think we could get you at least a 20% power increase in the bottom end just prior to the PV opening, to really compliment the powervalve and make it drive-able off the bottom.

If you were keen on having a play with this and showing your results on the RZ500 forum Id happily 3D design you a set for free and have them made by my CNC guy in NZ for cost price (no mark up from me, just his CNC price)

Let me know if you'd be interested in that
You can contact me on 6156487@swin.edu.au

Definitely something to consider while Lozza makes some pipes.
My issue is that I can't dedicate time and money on the bike until the Mustang is on the road, so I may not be your best option to get something done any time soon.
Happy to help you out, but it won't be for a while that's all.

Im in no rush. Im going to be getting my prototype going over the next month or two and dyno it.

Lozza has also been involved with my ATAC valve project also.

So if you wish for things to go ahead just let me know and we will get onto it

No worries.
I'll know how I'm travelling with the car in a month or so hopefully.

I will claim credit for the retrofit ATAC idea, all made possible by a very helpful and clever Kiwi with a CNC shop.

With a YPVS your not going to need ATACs does your Zeeltronic do the PV's if not get one as thet will smooth out the curve.

With an ignition/PV control the cylinders done properly and pipes you should have 120HP at the wheel.

I have Zeeltronic ignition and PV control. Mick Abbey (UK) tuned barrels, RZ350 Reed cages with banshee reeds

Have you got any pics or measurements of the cylinders? Were sub exhaust ports added?