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My classic Yamahas: RD 125 does its maiden ride & RD 200 growls louder

27th April 2025, 11:10 by Deepankar Sadekar

Since, this bike was lying around I hadn’t renewed the registration and fitness and I still had the original RC book.

BHPian SnS_12 recently shared this with other enthusiasts:

Maiden ride on the RD 125 and the RD 200 growls even louder.

With the engine now running, we could now focus on finishing up the cosmetic bits and especially the seat. My OE seat was rusted beyond repair and I couldn’t find a replacement one on Ebay. So, we had no option but to fabricate one and the seat base chosen was of that the RX. The hinges were made in house and days were spent in just getting the alignment perfect for the seat plate. Also, we had managed to make a spare key for the original seat lock which was opened and serviced and repaired. Once the desired alignment was achieved the seat was sent to a welder to weld the hing bolts in place and add extra metal sheet to extend the base of the seat plate to cover the chassis better. Once, this was done a coat of the rust paint used to coat the inside of the tank was applied. For the RD 200 we had applied fibre glass back in the day to increase the seat strength and prevent it from rusting and that is still holding up well. Next, the seat guy was called with the foam to make measurements before he took the seat base with him to finalise it and apply the seat cover.

Now, the bike was ready for its maiden run and it had to be prepared for its proper long ride as well as I had to visit the RTO with the bike to get its registration renewed. Since, this bike was lying around I hadn’t renewed the registration and fitness and I still had the original RC book. Last year around May I had handed over the documents to my agent and the process took really long as the records had to be pulled out as my details had not been captured in digital format and there was another issue with the engine number which was not common. More on that later. Now, with the papers processed the bike was required for a physical inspection and my agent called me in late December last year enquiring on the progress of the build and when can he made the necessary payments to get an appointment date fixed. With all the delays the day came in really close as my agent was away in May and wanted to get the work done in April and I had only this week as I am travelling for work in the last week of April.

So, the bike had to be ready at any cost and I took for its first maiden spin in the complex and then out on the road. The bike rode and sounded beautiful but the carburettor setting was not perfect. These are very old carbs and had deteriorated quite badly especially the carb bodies. So, even with new internals they were a pain to set up as they would go off with smallest of inputs and we also had to to block the choke off completely as it had a leak even in the off position. So, we did our best to get the bike working and I set off to the RTO office with a small prayer. A few kms in and the rpm started going up on its own when the clutch was pulled in and especially when the bike was put in neutral. I didn’t want to touch the carbs and I managed to reach the RTO office somehow. The bike immediately commanded attention from folks present there and they couldn’t believe that it is a 1979 built motorcycle and especially that it is not an RD 350 and a RD 125 with twin cylinders instead. There was a brand new Ducati V4 on a flatbed which had come in to get registered as well and all the crowd was gathered around my bike instead

Now, I was hoping that I would be done and out of there in 30 mins as the place was really dusty and plus the heat but, then things don’t happen so easily for me do they. I had mentioned that my engine number was unique and that was a reason that delayed the paper processing at the backend in the RTO. Now, that same issue came to haunt me when the RTO officer saw my paper and immediately said this has been re stamped and he can’t pass it. Firstly, its not easy to re stamp the number on the engine block and get the factory groves as well and the other issue is when the engine and chassis number are completely different when a donor engine or chassis is used. But in my case the engine number is just a three digit number for some weird reason and that is what was mentioned on the original RC book as well. The RTO guy was not even ready to listen to our argument and then my agent said that I will have to bring my bike again in May. Now, I was in no mood to go through this ordeal again and said try and convince him and do whatever it takes and I will wait it out till we get the papers signed today itself. So, a 30 min job took over 2 hours but the work was done. Now, came the difficult ride back home as the bike would just not idle and the fuel mixture was feeling lean as the gear shifts had done harder and the rpm continued to rise. Managed to get bike back to Tony’s place and when we checked the carb the left cylinder was running a rich mixture. We did a lot of changes to the air screw mixture and needle setting which made the fuelling much better and the bike more rideable but still it was not 100%. So, now we have decided to see if we can fit the RX 100 carbs instead as that setup is working beautifully on the RD 200, but then the RD 125 is a much smaller engine so need to see what best can be done with the 20 mm carb to replace the OE 18 mm ones.

Speaking of the RD 200 I rode that to Tony’s today and the new clutch plates has made that bike into a complete beast with everyone turning their heads the moment I approach or do a fast overtake. Its a proper missile on two wheels but I felt it had room more improvement and especially at the top end of the power band. So, the main jets were drilled to the next bigger size and what a world of a difference that has made. The intake growl has grown louder and the thing just moves like a mad two stroke on the slightest of throttle input. Just love it..

Some pictures….

Front mudguard goes on the bike

Adaptor plates made from aluminium to mount them on

Top view

Front view is now complete

Speedometer all set to roll in the first km

Metal key. Its an OE key set made for the RX

OE old brittle carbs connected to the OE airbox

Time to manually drill. The long contraption to get the perfect angle

Close up

Seat pin goes in perfectly

Perfecting the seat alignment before the hinge bolts are tightened up to finalise their spot

Metal duplicate key to operate the OE seat lock

Open view

Closed up and the final resting spot

Side view. You can see the cap between the seat and chassis which has to be filled up now with the extra metal piece around the original seat base plate