le RB200 est arrivé....

[David23 0]

http://www.afrayspeed.co.uk/online_catalogue/rb/rb.html

drunkmunkey6969 a écrit:

Well.....what a little beauty this is! Had a really good look at it tonight, and its certainly a nice bit of kit.....there are some 'quirky' bits n bobs in regard to the cyllinder port layout/specs and other stuff.....but they are very interesting quirks indeed. I suspect they will become a point of speculation amongst the internet community, and add to the raging debate that is.....the RB phenomona!

So lets have a look at the kit then...and bear in mind, everything we (Sean and i) look at is from a tuning/racing perspective, so those concerned with touring may have a different angle on certain elements of the kit.

We intend to build up a nice little engine, that i will play with on the track.....in a similar fashion to my TS1, we will run a fast road tune...nothing groundbreaking, or maxed out....just a nice little toy...and a fast one!

Full kit with, expansion chamber and crank


A few bits i've cobbled together for the build....Li150 box, 16/47 sprockets, 6 plate clutch, rev counter, 34mm Delly (although may try a 35mm Mikuni) re-worked BGM stator, new seals, bearings, gaskets etc..


This is the crank that goes with the kit....58mm crank, 116mm rod, AF 'RB spec' race crank with uprated bearing etc


Cylinder head that comes with the kit




So the cylinder itself..........what about the port layout? Well lets take a look......


Now then....what do you make of that? Looks like a triple boost port, single exhaust, normal transfers right? Or is it.......? It also looks like the triple boost port is out of line/symetry with both the transfers and the exhaust port??? Or are they?

On closer inspection, it becomes apparent that the 3rd boost port (the slimmer of the 3) is actually an additional transfer port of sorts??!! And that the secondary transfers are not the same size. The side that is closest to the 3rd boost port/transfer, is smaller than the equivalent transfer on the opposite side of the cylinder, so we presume that the 3rd boost/transfer port makes up for that in some way.....although the area of that port, combined with the smaller transfer, then become different to the transfer port area on the opposite side....but the 3rd port will flow in a different way to a standard trans, due to the way its fed.

You can see a bit clearer from the underside of the cylinder


And even better with a close up


What you can see much better in the close up picture above, is that the 3rd slim boost port/transfer doesn't enter the cylinder on the same angle as the two main boost ports....they are angled up (schneurle loop etc) and the main transfers are more flat on entry....as is the 3rd boost port/transfer. So the entry angle of the 3rd port is at the same angle as the transfers, but the two boost ports are angled up. Of course the fuel mix that is fed from it it doesn't enter the cylinder under primary compresion as the main transfers do....it's still fed from the reeds, like the 2 other boost ports, but at a different angle. You can also see how that feed will be staggered, in this view from the back/inlet.

Inlet, two main boost ports, 3rd boost port/transfer and boyesen feeders


Just for comparison purposes, see the inlet compared to a TS1...and the difference in reed block sizes!


And again, compared to a Cagiva 125 (and these little fuckers kick out 33bhp!) and given the BHP of the cagiva...its inlet port layout seems so much more restrictive than the RB?


You can see on this shot (below) through the exhaust port, that the two main boost ports do in fact line up with the exhaust port quite well......and that the distance is in fact equal between those two ports and the transfers each side...its just the additional 3rd boost/transfer that throws questions and intrigue into the mix.


The reed block.....same as the 225/250, W-layout, same as v-force.....very big reeds, lots of flow.


They match up to the inlet shown below


My only thought on this, is why doesnt the manifold area match the reed area.....can anyone that has tuned/modified these already let me know their thoughts...seems odd?

Open reed area is 7cm


Manifold is 5.5cm ??


Boyesen feeder ports


So....thats the cylinder....a very good piece of kit, nikasil lining looks good, ports look tasty...a few quirky bits that will throw controversy into the mix, and some other bits that can be re-worked here and there to suit people requirements...touring/racing/reliabilty etc.

As for port timings and port area etc....i did a couple of rough port maps....time was against me, so they're as near as damn it in order to get a rough ideas as to what the kit is about and how its tuned as standard...but of course don't take them as gospel to the mm....always measure your own kits etc first before making alts.

RB20 port map


Lined up against a TS1 225 (70mm) port map for comparison purposes


I then put some measurments to the port maps.....

RB


TS1


Note, the port maps were done quite quickly and are a reasonably accurate for compariosn purposes like this, but not guaranteed 100% accurate for important decisions like porting etc!! Measure your own kit first. Also, the TS1 above was completely standard apart from the floor of the inlet being lowered by a couple of mm.

Also from the specs above, you can start to see how well tuned the RB is in standard trim, in comparison to the TS1.....the RB exhaust port is as big as a 225cc TS1! RB transfers are bigger, boost port area is bigger....its all good stuff, and not surprising that rumours of a TS1 beating kit that kicks out 22+ BHP are circulating. The above port maps also give you an idea of how the ports can be tuned for extra power...lower the inlet floor, leave trans and boosts as is, widen exhaust 3mm each side and raise exhasut only 1mm. At -1mm deck height, that would give 136 trans and 194 exhaust with ahealthy port time area...sounds good for a race scoot to me!!! I think the external exhaust exit may benefit from a fettle also, as on a TS1 it is 36mm (and gets bigger when matches to a JL4 manifold) but the RB is only 34mm....so maybe needs enlarging to help flow the gasses, improve performance and keep everything coool man 8-) 8-)

The last thing worth mentioning is the fact that these kits do of course, marry up to the much more readily available and substantially cheaper small block casings.....pick up any of the 125/150 casings that are kicking about and deemed 2nd rate to a big block casing and you can build a fast engine!! The other bonus is when you inspect the casing transfers on a small block in comparison to a 200cc casing....see below an old Indian GP150 casing that we stripped (ready for the RB! )

GP150 Indian


GP200 Indian


From the above shots, its immediately evident that the small block casings have much more meat around the transfers for tuning purposes!! Room for 'finger' boost ports into the casing from the cylinder inlet tract, and loads of meat to scoop out for bigger transfers.

Also, you might naturally think that the big block has bigger transfers as standard....but it doesn't, so even before you tune the small block casings....both physically, and therefore also as a percentage of the bore, the transfers are larger than 200cc transfer...see below:

GP150 @ 26mm on entry to the case


GP200 @ 24mm on entry to the case


Bigger trans....and more meat, just what we want to work with.

So, thats all we have for now...an initial kit inspection....no hard facts about reliabilty or performance....but all the indications are VERY good...no exhaust bridges, 1mm rings on piston....extra boost/transfer port area, boyesen feeders, W-reedblock....rumours of a TS1 beating 22+bhp in standard 'bolt on' trim....with more to come from tuners and racers!! It all looks very exciting, and has great potential....im sure the 3rd boost port/transfer will raise a few eyebrows....as will a couple of other bits n bobs that we're still 'on the fence' on.....but up to now....it all looks very good and i cant wait to get mine built and onto the race track.

Over to you...... 8-)