Now This - This is the RD.
Back in 1983, the rajdoot guys blundered big time. Decided to tie up with yamaha and launch their famous RD350 out here in india. Which they did, and the roads began to see the first versions of Rajdoot Yamaha RD350. Of course the bike was a failure. Even the Ads claimed that it was for the "few" who dare to live their dreams. Yeah it proved right as people generally had different dreams or just didnt dare to live them. So it was a failure and blunder and major screwup and mishap and whatever - But God bless each of them cos thanks to their disastrous decisions, we out here in 2003 are lucky to have a true blue performance machine which kicks the shit out of each and every sorry arsed excuse for a bike launched since then.
Now looking at the Original Yamaha RD350 - It put out 39bhp at around 7500 rpm; And yamaha claimed that it eats a quarter mile in around 14 secs; And the guys out here decided that we dont need this sort of performance, not yet. So it was clear that it needed to be restricted.
Looking at the stock RD350 engine, the exhaust port lies
29.5 mm down from TDC; And if you measure the exhaust port width, it
comes to 38mm. And its some 27mm tall.
Note : Go here if you wanna see more of portmaps, engine specs etc.
courtesy: rssarma, geocities
So a rape was inevitable and yeah it was the exhaust port. 2.5mm of the exhaust port had to go; Or rather in other words 2.5mm more of metal appeared. The High Torque model was born with an exhaust port than begins 32mm down from TDC. And the ignition timing was reset to around 2mm BTDC. This guy put out around 30.5 bhp and could touch around 150+ kmphr.
courtesy: rssarma, geocities
So the HT rd350 was launched and it didnt take long to realize that such a fuel guzzler is not gonna sell much. Except for some hardcore performance freaks who would appreciate fast machines and then some ill-informed loosers who would regret or commit suicide later, nobody bought the bike.
So back in the factory once more the exhaust port began to get attention; This time the decision was to bring its size to 31.5mm; A reduction of 4mm. And for this there was a quick fix - Fix a metal stud on the roof of the exhaust port. Yes, the stud has to be 4mm thick. A restrictor plate. And the ignition timing - it was advanced to around 2.4mm to take care of the port reshaping.
courtesy: rssarma, geocities
So out came a series of bikes with restrictor plates on the exhaust port. This was the beginning of the Low Torque model - It put out around 27bhp max. And could do around 140 kmphr. The low end was better than the earlier HT model; This bike used to start pulling from around 3k rpm; but used to hit a brick wall around 5.5k rpm - There was hardly any top end. But yes the better bikes among the lot could do 140 or a bit more.
I guess this model brought some relief to the sales; So the 'quickfix' was soon made permanent. And out came more LTs with ports reshaped to the LT specs. These needed no restrictor plates. The 'restrictor plate' time-window was closed.
Even now its not uncommon for a guy to open up a LT engine, find a strange plate on the exhaust roof, rip it off and throw it away, and then find the bike to have moved to an entirely different power-slot with a totally different torque curve.
I have an LT and opened it up with hopes of finding that plate but heck no there wasnt anything. Mine proved to be among the later model LTs with reshaped smaller ports.
And performance figures - A good LT touches 60 in under 4 secs; say 3.6. I have seen such an LT do 78 kmphr in 4.12 seconds. Assume around 7 seconds for the 0-100. A similar condition HT should do better as far as 0-100 is concerned. And the drag timings - A good stock RD is expected to do 16 seconds. And a 'very' good stock RD is expected to come nearer to 15 seconds. This much is accepted - Basically means that do something less than 15 seconds, and a scrutiny will be demanded. Even a 15 second run may raise objections that the bike is not stock.
Now this much is pretty basic stuff; If you want to know more and much more about the RD, i suggest that you visit this place - rddreams. Its run by a guy called Ron Chinoy and i dont think you will find another person out here crazier abt RDs. He is _the_ authority on the subject. You see a forum out there which is the place to be; You get to meet a bunch of real great guys, and there is a lot of technical info being shared. Whatever i know, every single bit came from there, that place. And i do mean every single bit.
And about the performance level - The top slot goes to a HT which touches 164 kmpr; This bike was tuned by ron. Second spot goes to a maniac called Tom; and its at 158 kmphr. Believe it or not, the bike is a mildly ported LT. Now there is another major madman called killer, and that guy is right now at 156.
Well latest update : The Madman Killer is on top now -
He is on to 167.
courtesy: madman killer
Lucky bugger.
All hell is breakin loose - another update : Madman is onto :
And my bike; It was way down at 142. And that too, with a much lighter rider than me. The max i could manage then was 134; Now its better, and i should be able to cross 140. Guess its one of the slower bikes in the club.
Now if you wanna read about a real nasty monster; You
should go to rddreams and read This.
One of the two best articles i have seen in the net . Check out the other
one too, when you are not so much in a bike-mood.
Oops there is another one too.
Warning : Once out there, always take care to remain highly
respectful and if possible, fearful, of the RD; Say bad things about the
RD, and you can get severely mocked, tarred and feathered. Especially if
you are one of those 4-stroke junkies. Remember - If you stroke four and
mock those who stroke two, you better have more than 2 cylinders.
But make no mistake - None of the guys out there are actually four-stroke-haters. Just look at the situation and you may understand; They launch 30bhp monsters in 1983; 20 years down the lane, there is nothing even as half as powerful. You keep on waiting with endless hope that they will bring you somethin decent, and all they launch is tight-tummied screwedup mopeds which you feel like pissing all over. inevitably you go back to those 20 year old monsters and enjoy riding them and when one guy gets one of the latest screwups and comes to you saying he has a real bike with a self-starter while you are on an ancient bolt-bucket, you tend to get impolite, impatient and sometimes, sadistic with him.
Another great place is macdizzy; Be warned - This place is full of hard-hard- hard-hard core techie guys; Pure stuff, the real thing. Stuff passes around that can cause permanent brain damage. So make sure you have your physics fundas clear before you venture in. I ran for my life.
Another site with some good info is RSS's place. You can find the technical sheet as well as the port maps etc. And other interesting stuff, including the Service manual which you can download.
Take a look at Abhis site; You find everything from technical info to photos and writeups abt their trips.
So say at the end of this all, You feel like buying an RD. Let me suffice to say that there are lucky ones and unlucky ones. Now suppose you are unlucky. Question is how unlucky can you get. Lets assume for a second that you are the most unlucky bastard in the whole world.
Well Osho says that luck and bad luck are same; If there is no luck then there is no bad luck. Bad luck exists because luck exists and viceversa. In fact you just cant separate them; Even though we humans specialize in doing just that.
Well whatever, if you had followed that last link, you would have seen the vulgar extremes of pessimism; So think of it this way. Thats the worst case possible and any given case can only be much much better than that.
Or in a slightly pessimistic yet optmisitic note, any given case will be a much much much smaller subset of the scene which you just left.
So I hope you now know what to look for.
The whole thing boils down to realizing some facts and observing certian others. First digest the reality that most of the RDs run around in atrociously horrible conditions; Chew this fact and carry it in your brain when you go around looking for a bike. And be alert enough to check all details, All. And never ever ever ever buy a bike without confirming that the engine holds what the owner claims. If the owner claims standard bore then he should be prepared to open up and prove it. If he refuses or if the situation just doesnt allow - simple logic, just walk away. Never ever worry abt the time taken in locating a good RD - It will save you a lot more later. And money.
Else if you know what to do to build up a decent RD - then the best course is to locate a scrap bike - not an easy feat - and restore it.
And in the end of it all before you tell yourself that you have a good RD - take a look at the performance - If its an LT, it should do around 140. If its a HT, then it should cross 150.
And gearwise acceleration - I have seen a mildly ported LT do : 40 in 1st gear, 70 in 2nd, 90 in 3rd, 112 in 4th, 130 plus in 5th and 140 plus in 6th.
But its always wise to ensure that all your speed claims
are based on a digital meter like the sigma. Never trust the goddamned
speedo. The tacho may prove better, in fact.