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@Karthik - Welcome to the forum. You seem to be pretty new on this forum and not in account of most things that have been done by members in the past. A 2-stroke fan at his best. I m also a great fan (ex-shaolin owner), but I stand on the side of reality and real-world figures and future of engine development.
Well, as for any racing event, you dont have to drag or race something next to each other. You have timings to prove. The TVS factory Shaolins and the Yamaha RXs have clocked a best of 2:02 around the chennai track. With the all-out R15, we are now clocking a 1:58. Thats 4 secs faster per lap. Includes straight line and corner speeds too my friend.
As for a sub-13 secs RX, there is no such bike. The fastest an RX has ever clocked officially is a 13.3secs in the drag with a 45 kilo rider and a bike weighing some 50 kilos. A 4-stroke engine itself weighs nearly 35-40 kilos.
Now, talking about 2-stroke tech. An expansion chamber gives a 2-stroke machine, a super charging effect due to the strong pulse/charge sent/stuffed back to the cylinder and hence doubles the power output. Technically its "forced induction".
A 4-stroke on the other hard, push max with cams, radical cylinder head, compression, GB, freeflow exhaust is still a handicap - technically. Shov a turbo/SC or some nitrous and we can talk about specific output and drag times.
So lets not argue with some factor being a handicap on the other machine.
well, if a 4-stroke engine is still making more power with natural aspiration (NA) and beating a 2-stroke with a chamber (forced induction), its indeed commendable.
Today NA engines are touching 300-350 to even 400bhp/ltr. With forced induction, they cross 700bhp/ltr. Something that is unheard of any 2-stroke which is already working on the principle of forced induction.
Now, regarding the malaysian RXZ, well I have ridden them and they come with a chamber from factory. 20ps from a stock mill means its pushed from factory. The race bikes at the sepang track are not insanely faster than their stock counterparts.
Also, most 2-strokes win on the factor of weight. Engines are much lighter and reciprocation mass is far lesser than a 4-stroke. Internal components are less than half. Which obviously increases the VE of a 2-stroke engine.
I understand that u are a mechanical engineering student and you are learning. Please put more focus into your academics and keep it mellow, you will learn better and faster. Always most things from books dont relate to racing, which is why most race engineers are not actual engineers themselves and they out-do actual engineers coz of practical exp/intuition towards the subject/passion/real-world data/know-how.
Most concepts of the IC engines are still being figured out over the days and some myths from the past and even concepts being taught to students vary with reality. Most books were written decades ago and slightly amended over the years but with little or not much changes. Which means they dont really hold true for todays modern engines.
Also factors of a 2-valve and 4-valve are like comparing a lime and an apple. Thats how your comparision was of the Karizma 225 and the R15. Reciprocating mass of the internals, modern cylinder combustion designs, reduced pumping losses, enhanced flow dynamics, improved and accurate fuelling/ignition, lesser transmission losses etc are contributing factors to a modern engines performance. Its exactly what you see with a superbike.
lastly, about the bigbores. Well, most people have no clue of what they doing and hence no power gains. A cylinder head is designed with a certain valve size, cam design, port efficiency etc and for a given cubic capacity. Most production engines have capability to improve the cfm when working with a bigbore. And too big a bore is not recommended. The engineer/tuner must be qualified enough to understand the needs of the engines and suitably enhance the performance. I have seen many fellow members on this forum who have tried going bigbore, they make little extra torque low down and at the top all the efficiency is lost. On a dyno, it will look sick.
I started the trend of bigbores back in 2004. I have built the fastest bigbores in the country. 195cc Fiero, 206cc RTR, 260cc karizma, 176cc R15, 200cc Unicorn, 178cc CBZ, 160cc CBZX/Uni, 235cc karizma, 170cc RTR, 165cc R15 and a lot more.
Most were my race bikes and also my daily rides. My 195cc Fiero would make 18bhp at the rear wheel on the dyno back in 2007. Dont wanna disclose the others. The circuit-race R15 and my Drag RTR is out of the equation.
So there is a lot that goes into setting up an engine to suit the bigbore application. Its all a radical make-over. The 206cc RTR is currently my project and its quite an interesting engine. We will do a review later.
Some engines like the R15 have a good cylinder head design, can flow more and hence I have developed my 165cc bigbore kit and they give 2.5bhp at the top.
This whole concept of bigbores not working is something that is messing up in the circle coz some monkey tried it and it didnt work.
Joel
Well, as for any racing event, you dont have to drag or race something next to each other. You have timings to prove. The TVS factory Shaolins and the Yamaha RXs have clocked a best of 2:02 around the chennai track. With the all-out R15, we are now clocking a 1:58. Thats 4 secs faster per lap. Includes straight line and corner speeds too my friend.
As for a sub-13 secs RX, there is no such bike. The fastest an RX has ever clocked officially is a 13.3secs in the drag with a 45 kilo rider and a bike weighing some 50 kilos. A 4-stroke engine itself weighs nearly 35-40 kilos.
Now, talking about 2-stroke tech. An expansion chamber gives a 2-stroke machine, a super charging effect due to the strong pulse/charge sent/stuffed back to the cylinder and hence doubles the power output. Technically its "forced induction".
A 4-stroke on the other hard, push max with cams, radical cylinder head, compression, GB, freeflow exhaust is still a handicap - technically. Shov a turbo/SC or some nitrous and we can talk about specific output and drag times.
So lets not argue with some factor being a handicap on the other machine.
well, if a 4-stroke engine is still making more power with natural aspiration (NA) and beating a 2-stroke with a chamber (forced induction), its indeed commendable.
Today NA engines are touching 300-350 to even 400bhp/ltr. With forced induction, they cross 700bhp/ltr. Something that is unheard of any 2-stroke which is already working on the principle of forced induction.
Now, regarding the malaysian RXZ, well I have ridden them and they come with a chamber from factory. 20ps from a stock mill means its pushed from factory. The race bikes at the sepang track are not insanely faster than their stock counterparts.
Also, most 2-strokes win on the factor of weight. Engines are much lighter and reciprocation mass is far lesser than a 4-stroke. Internal components are less than half. Which obviously increases the VE of a 2-stroke engine.
I understand that u are a mechanical engineering student and you are learning. Please put more focus into your academics and keep it mellow, you will learn better and faster. Always most things from books dont relate to racing, which is why most race engineers are not actual engineers themselves and they out-do actual engineers coz of practical exp/intuition towards the subject/passion/real-world data/know-how.
Most concepts of the IC engines are still being figured out over the days and some myths from the past and even concepts being taught to students vary with reality. Most books were written decades ago and slightly amended over the years but with little or not much changes. Which means they dont really hold true for todays modern engines.
Also factors of a 2-valve and 4-valve are like comparing a lime and an apple. Thats how your comparision was of the Karizma 225 and the R15. Reciprocating mass of the internals, modern cylinder combustion designs, reduced pumping losses, enhanced flow dynamics, improved and accurate fuelling/ignition, lesser transmission losses etc are contributing factors to a modern engines performance. Its exactly what you see with a superbike.
lastly, about the bigbores. Well, most people have no clue of what they doing and hence no power gains. A cylinder head is designed with a certain valve size, cam design, port efficiency etc and for a given cubic capacity. Most production engines have capability to improve the cfm when working with a bigbore. And too big a bore is not recommended. The engineer/tuner must be qualified enough to understand the needs of the engines and suitably enhance the performance. I have seen many fellow members on this forum who have tried going bigbore, they make little extra torque low down and at the top all the efficiency is lost. On a dyno, it will look sick.
I started the trend of bigbores back in 2004. I have built the fastest bigbores in the country. 195cc Fiero, 206cc RTR, 260cc karizma, 176cc R15, 200cc Unicorn, 178cc CBZ, 160cc CBZX/Uni, 235cc karizma, 170cc RTR, 165cc R15 and a lot more.
Most were my race bikes and also my daily rides. My 195cc Fiero would make 18bhp at the rear wheel on the dyno back in 2007. Dont wanna disclose the others. The circuit-race R15 and my Drag RTR is out of the equation.
So there is a lot that goes into setting up an engine to suit the bigbore application. Its all a radical make-over. The 206cc RTR is currently my project and its quite an interesting engine. We will do a review later.
Some engines like the R15 have a good cylinder head design, can flow more and hence I have developed my 165cc bigbore kit and they give 2.5bhp at the top.
This whole concept of bigbores not working is something that is messing up in the circle coz some monkey tried it and it didnt work.
Joel
I remember when i came to this forum about a decade ago, i had the same fanatical enthusiasm for the 2strokes so if i was like that, i cant blame others, i guess we are all learning. Over time i've gained a lot of experience broadened my perspectives and accepted certain realities..still learning though. Dont get me wrong, i dont hate 2 strokes..still a fan but now its all about the machine for me...can be 2stroke or 4stroke...if its a good performer, i like. That being said, there is a big misconception in the country over 4 stroke performance, i've probably indirectly contributed to it myself in the past, i think that needs to be set right. In the off season from racing Joel and i will work to correct some of those misconceptions. Should be fun and good learning for the entire biking community.
or else it was considered as the best looking black witch 
and i do not own it (i wish i did)
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