Friday, September 11, 2009

The Cobra Build

I bought my RD in February 2005 after a 10-month search for something that would fit my requirement and budget. But my quest for an RD started about 21 years before that, in July 1984 to be precise. I was 9 years old then, and trudging to school in sleeting rain at 7 in the morning, lugging a bag that probably weighed more than me, when I heard a motorcycle pull up next to me. It was Rinku’s dad. Rinku, my bench-partner in school, despised me intensely for some odd reason, so when her dad asked me “Need a ride?” she piped up “He’s not sitting BEHIND you”. Before I could say anything, I was lifted up and unceremoniously plonked onto the gas-tank, schoolbag and all, and I saw myself staring at 2 huge pods. I knew one was the speedometer, promisingly calibrated up to 200 kmph, but I didn’t know what the other one was. It kept bobbing impatiently….

The last thing I remember hearing was “OK son, hold on tight”.

Even though the ride lasted barely half a minute, I didn’t remember being that scared before. I was grinning like an idiot, even as the Math teacher admonished me for not having done the homework… It was right on that day that I decided I would someday own this bitch – the bike I mean, not the teacher.

Even though I toyed with the idea of buying an RD in my college days, it was June 2004 before I could really afford to buy one.

The first bike I saw belonged to a Parsi guy named Rustom. It was a bone stock LT, cherry red in color, and blew my socks off the first time I rode it. I loved it but the high asking price (60 grand or the equivalent of 1500 USD) put me off.

After that I saw a lot of decent, half-decent, and not-so-decent bikes. By 2004, prices of used RDs had sky-rocketed to unprecedented levels. Most of these bikes had been “sleeved” by local mechanics and hence performance was nowhere even close to stock. Prices varied wildly between the equivalent of 200 and 2000 pounds.

This was also the time that some good bloke on the UK air-cooled RD forum pointed me to RDDreams. And I realized that if I wanted a fast bike, I would have to have it built, rather than buy something that was claimed to be fast but was in reality just overpriced. So I would take a bus to a small town, carrying money with me, and see prospective bikes. This was not very unlike the arranged marriage system in India. People would ask me “Are you going to see a motorcycle, or a girl?”

After seeing about 35 bikes, I finally found one that seemed ideal. Well, almost. The engine was crap (I was planning to redo everything anyway) but the chassis seemed good, it didn’t look like the bike had been dropped too much, and papers were clear. I found her in Nasik, a town 150 miles from where I lived (Pune), thanks to a Yahoo RD group acquaintance of mine – Nikhil. I went to Nasik along with a friend Shrikant, in an ST bus, and met up with Nikhil and his pilot friend Praveen. After lunch and some haggling over the price with the owner, the exchange was made. Nikhil’s mechanic Balu Bhendale (Nikhil had a pristine LT RD) installed a fresh pair of points for me and I rode her back with Shrikant riding pillion. She looked like this when I first got her:















I paid the equivalent of 230 pounds for her, which seemed like a bargain at the time. If only I’d known.

The engine had bad compression, the right-side exhaust had a tiny hole because of corrosion from battery acid, the rectifier was malfunctioning so the battery would get over-charged, gears would not shift beyond 5000 rpm, the air-box was stuffed with sponge pads, and because of all this, she was slower than an Enfield 500. Dragging with the 500 opened my eyes and exposed all the problems with my bike that I didn’t know existed. It also gave me the determination to turn this turkey into a rocket.

My first performance upgrade was a pair of UNI pods and bigger jets from Ron Chinoy. These helped the old girl pick up some speed. My next upgrade was the RDD ignition kit from RDDreams.com and this made a huge change to the performance of the bike. Even the smokescreen that plagued her disappeared and emissions dropped drastically. Things were looking up now but nothing could be done about the soddy compression, because the barrels had already been sleeved badly once, and they were worthless.

So the next thing on the list was to source a pair of unmolested barrels and mail them to Ron. A good friend of mine Rahul (Rash), helped me with that and sourced a pair of seemingly clean barrels from Mysore.

In the meantime I experimented with some local chambers which didn't do much for me, and continued riding my RD on the existing setup and made a few trips to nearby places such as Bombay, Lonavla, Mahabaleshwar, Lavasa, Mulshi etc.




























































However there was some bad news waiting…

When Ron finished porting and reboring the blocks, he found them to be beyond acceptable tolerances. My only option was to give him a fresh pair of barrels or ask him to sleeve the existing ones. Since I didn’t want to look around for barrels, I asked him for a full sleeve. The sleeve job was perfect; the ports matched up beautifully and the chamfering was flawless. Due to a long queue of customers, I was only able to get my sleeved and mildly ported barrels back around December 2007. By this time, I had also picked up a pair of RDD chambers from another RDDreams member Chris (Leppard)...















...EBC clutch-plates, a Vesrah gasket kit, some sprockets, and a pair of Mikuni flat-slide carburetors from Sudco.

















A powerful top-end would’ve been useless if the crank were to be left stock, so out went the stock RD connecting rods, and the crank was split and sent to RDD for a rebuild. It was heartening to see that the bike had the original crank and not one with oversized pins.

It came back from Ron, with Wiseco hotrods and RZ top-end bearings that were sourced by yet another 2-stroke fanatic friend of mine Ravikiran. These were installed onto the lightened crank and sent back to me...














...along with dressed RZ Wiseco pistons...



















...and re-cut (for custom squish) heads.















The speedo and tacho pods were junked in favor of a more accurate (even if slower-responding) electronic tachometer and a Sigma bike computer.
















The feeble front drum-brake setup was also replaced by a more conventional (and infinitely more confidence-inspiring) disc-brake setup and 17 inch wheel (better tyre options in that size) from an Indian motorcycle. The fork-legs of the RD were retained, and the caliper-mount was MIG-welded to the right-hand-side fork leg.


Taller and stiffer fork-springs completed the front-end overhaul.















The shifter forks in my gearbox were toast and new ones had to be installed. Again, Ravikiran came to my rescue and sourced the necessary parts for me.
















I completed the 200 odd kilometer run-in on stock pipes and started pushing the engine slowly. The bike pulled like a locomotive right off idle upto 6500 odd rpm.

However, I noticed that she would bog on really long high-speed runs. For a very long time, I thought this was a jetting issue and kept upjetting to the point that the plugs started fouling. I couldn’t understand what was happening.

Then, one day in March 2008 (the day after Holi) I was riding down from Bombay (on 300 mains no less) and the bike seemed to lose power. I pulled the clutch in, fearing the worst and coasted to a side. After having tea at a roadside stall, I kicked the bike over gently and thankfully the kicker moved; it wasn’t stuck. I started the bike and gently proceeded to Pune.

The next day I promptly took off the top-end and sent it to Ron for inspection. Thankfully, the barrels didn’t need a rebore or fresh pistons; only the top-end bearing on the left barrel needed to be changed. This frightening incident however brought to light one very crucial aspect of running a high-performance RD – adequate fuel supply.

The stock fuel-tap was promptly discarded in favor of 2 TVS Victor pet-cocks – one on each side. Welding the second pet-cock to the right side of the tank completely ruined the paint-job but the surge in performance and reliability more than compensated for that. I rode the bike like that (after downjetting to 220 mains) for a long time, taking her to Surat and Goa, without any problems.

The only thing that had remained stock(ish) on the bike now, was the reed setup (stock cages with YZ petals). This seemed to be the weakest link in the whole setup as the bike refused to rev or make power beyond 7000 rpm, despite playing around with jetting and timing. It was Rohit (Motorhead) who kept insisting that I should try bigger cages, so I finally relented. However, I wanted the throttle response of a carbon-fiber reed and the longevity of a steel one, so he bought me a pair of VF-3s and carried them back to India.

The barrels were taken off and the intake tract was modified by Arun, to take in the huge V-Force 3 reed-cages.















This along with the chambers and 300 mains finally brought everything together and the bike is now a rocket.















There is no joy more profound than owning a motorcycle that constantly conspires to kill you.

August 2010 update:
Replaced the stock front forks with brand new 37 mm forks from a different bike. Bike was dormant in a friend's house for 3 plus months but fired up within 10 kicks. See the video clip here.