I thought hinting a pinch about Nikasil coating & micro arc oxidation ( MAO) etc..while writing about this wankel engine project, so that all pure technical stuffs come in one lot , and thereafter no more pure technical things in this thread!!
Nikasil coating is some what similar to your Hard Chrome , however coating techniques, properties,cost, necessity of application differs.
A fact before going deep:
* till now ( to be precise December 2009) there is no Nikasil coating facility in India, { guess.... our Defense Lab is working...not sure though}
Well, back to business
It is NOT profiling after COATING.....I told about the machining procedure....After Nikasil coating on the component( here it is wankel inner), grinding & lapping is done....in this case ( Wankel inner) as the profile is a EPITROHOID,,,naturally we go for "Profile grinding".
As Nikasil constituents are coated ( actually it should be termed some other way....let me stay basic & not confuse) in very thin layer , in most cases very less than a millimeter , so the Nickel tungsten carbide adhere to the surface to be done( coated) thus maintain g the profile, but with minor undulations & surface finish some thing like a rough machined one.....hence machining procedures like Grinding ( many special types depending on the profile, accuracy, surface finish) is done
As you may be aware the basic alloy combo of NIKASIL is Nickel & tungsten carbide....it has its own properties like HARDNESS, heat transfer & many more....which is best suitable to a IC engine.
So , as the Nikasil coat is removed by machining is few microns...hence its properties is retained.

Here you go Buddy with the pics of the Split single, which I fixed for Grish PV. ( This bike is German TWN Cornet-1955-split single-200cc)
Just that Ignition portion fixed at my end, which was totally buggered up by some over confident mechanics ( for nearly a year or two)
Now made to run......I still preserve the Chopped up portion of this mill's Crank with me..as a memento

Thankyou sir!

Wow what a glorious bend pipe. seem to be like a mini expansion chamber

No !!! Me expected some thing more from you & other tech Spec geeks, about this particular Exhaust ( as found in this TWN's split twin motor)

THINK!!! THINK!! search..............& post some details
PS: a question for you guys....will this exhaust work at least average in a Single cylinder TWO stroke engine????
If yes,.......How?
If NO,........Why??

pps: Thought of posting complete Wankel story today, with pics....let me wait till this EXHAUST discussion is over

Got it! it has a Y-shaped connecting rod, so the pistons are "side-by-side", making the engine little different visually from a regular two-stroke, with the carburetor in the usual place behind the inlet cylinder bore.

Production of TWN Cornet 200 cc motorcycle ceased in 1957.

OH!! Franky!!!
We are suppose to discuss about this particular EXHAUST , it is a Split Twin, agreed.....History is okay....one more detail, this was the fist production bike to have "ALLOY sheet metal wheel rims"..
The special thing is the " sudden diverging of the exhaust, immediately from the Exhaust Port",....that is what all about......Think....search....POST

The special thing is the " sudden diverging of the exhaust, immediately from the Exhaust Port",....that is what all about......Think....search....POST[/QUOTE]
Let me post the schematic drawing of this particular engine from NET!!!& also the pic of the same bike, which i handled ( sorry if , it stamped with some other site's seal...want to post the apt pic)

Me, in hurry to move on with Wankel P _ _ _ _

The idea of a split single was to have the exhaust port open before the transfer ports then close before the transfer ports thus preventing loss of fresh charge out the exhaust. The traditional two-stroke engine allowed the charge to flow straight across the cylinder and out of the exhaust port with the exiting burnt gasses despite port angling and schnerle ports. This layout gave a smooth power delivery with no 'four stoking' and excellent high end performance. Good tractability from low revs and 20% improvement on fuel consumption.

sorry for replying late!

got struck up with some office work .

Regarding bulbous expansion chambered exhaust i think it helps to drive the exhaust gas quickly (to give good low and mids ) from cylinder and allows to charge it with increase volume of fresh air fuel mixture.

also quick cooling of cylinder block since its a aircooled split twin

That is the most beautiful thing i've ever seen....ok the second.

But unbeleivable that it came in the back of car to this.

Wish you were around when my CM250 was alive

Hmm!! next from RE 700 twin.......it started this way>>>>


imported legally , in bits & pieces, with almost all vital parts

Including a twin side brake hub!!


It came clean----> top view of the crank case

Both cylinder head with rocker covers>>


Also the clutch basket!!


Assembled to see how it looks.......


& after this new pistons, valves,push rods( however was home made), cam followers, plenty of fasteners, seals(imported), gasket set....a SR2 magneto( was serviced later), a inlet manifold, Oil tubes ( fabricated)...next complete machine shop work like crank setting, head work, generator & clutch job done.....next.....

Sir, I cannot begin to express how fascinated and in awe I am at your collection and sheer enthusiasm for these lovely oldies.

I keep coming down to Coimbatore every now and then, and it would be wonderful if we could meet up, and if you allow me a quick tour through your garage.

Always Welcome mate!!
Now & then>>>>> to Kari speedway....ah??

Yes sir! To Kari, but haven't gone to the track the last 4-5 months. Been visiting family and friends in CBE of late.

Some more pics.....how it came like......


A clean & beautiful Norton Feather Bed Chassis..




Also a Norton 500 twin engine ( for some of our friend..)

Let us see How is Norton turns up
Just RE 700 is completed & run-in is on the GO>>>>>
just with a Bullet std's Mikcarb, with different jetting...however Airfilter set up needed to be fixed...