Yamaha RR250 1961 Racer

Published Date

Richard Tracey from England likes to have your help…….!!!!!!

Richard has acquired a lot of Yamaha parts and in amongst them was a rather unusual engine....
He was surprised to say the least, when he found a YDS1 engine in the pile of bits, but then on closer inspection he noticed the engine number wasn't right for a DS1 plus it was quite light, and then he noticed the colour of the crankcases and the way they had corrosion He then realised they were magnesium!

Yamaha RR250 engine


Yamaha RR250 engine

So it must be a factory YX24 (Asama or RR250) motor...
The engine came from either Singapore or Malaysia, so he is guessing it probably came from works rider FK Wong (?) The Singapore Champion in Yamaha's early days, as he rode an RR250 along with Sunako & Ito.

The engine number is D6-1045.....  (The "production" Yellow Tankers all had numbers around D6-7277 - These had YDS1 crankcases, although have similar numbering to later YDS2's !?).


You can clearly see the contrast between the aluminium & the darker magnesium cases on crank filler block and the cylinder head face, plus also between the alloy gearbox lay shaft plug and the casting behind the clutch cover...

Yamaha RR250 engine

The gearbox is like new inside, and Ricahrd does not think it's ever been run... or at least never been apart... all the screws are untouched.


Yamaha RR250 gearbox

He is convinced they are magnesium, but we never heard of Yam using magnesium that early? Anyway they will be cleaned up and analysed just to make sure..... 
Is there anyone (maybe an ex-Yamaha person or so) around who may know about them using magnesium cases on bikes this early?

Richard has found info regarding the Singapore riders... see attached.
The bike shown is one of the works Formula ll bikes, or RR250's as ridden at Daytona 1961.
The rider’s names show KC Wong, Albert Lim, Fook Kwong & Hasegawa-san.

Richard asks to put this on the website for any articles or pictures from this early period 1959 - 1962, particularly from people out in the Singapore / Malaysia / Asian sub-continent areas where Yamaha were 1st trying outside of Japan.
He says it would be great to really get a grip on these really early machines ...!

Singapore G.P. 1962

I thought you might be interested to see the crank & internal parts of the magnesium Yamaha YX24 / RR250 engine.

The engine is (unbelievably) like new inside. It does not look as is if it has ever been taken apart before.  In fact it was probably the easiest to strip down "early" Yamaha engine I've ever done. All the screws came straight out and the crankcases pulled apart very easily.


For those of you who are familiar with the Yamaha YDS series you will agree that Richard's early 1960's engine internals are really brand new.



As you can see the crank is in very good condition, but take a look at the conrods!




They have been knife edged ground and polished - although they are still the (CM21 stamped) YDS1 rods with the bronze bushed small ends. This must have been done from new as there are no marks that show the crank has been apart, and there is no way they could have been ground once installed onto the crank (without damaging the crank wheels).

The bare crankcases are at least 1/2 the weight of standard alloy ones, if not lighter.

Anyhow the cases are now going off for glass bead blasting and chromate coating.




The gearbox is the late type YDS1 with YDS2 ratio's, primary reduction is still YDS1.

So far we had no reactions about this engine, hopefully someone knows more!






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