and story by Brett Stubbs
Click here for Stage Two
Beginning : It was November 2004 when I had been thinking
for months that I needed to buy a bike, as I had sold my 1994 Suzuki RGV
250 after I lost my license.
I have been searching for quiet a while and nothing new really grabbed my attention in the show rooms. Yes the new Honda fireblade was good but it still weighed a few too many pounds for my liking. Now I been riding motor bikes since I was 8 years old on the farm and I bought my first road bike when I was 23 (Honda CBR900RR) and that was a lot of fun. In 1997 I bought a v twin Honda VTR1000 now that was a real lot of fun and when you hear of people say once your had a twin you will never go back to a four again as the twin is so usable on the road.
I road the RGV 250 for some time and I had rebuilt it from the ground up. Now the small RGV 250 weighed in at 120kg and had a lot of usable power. The handling was fantastic and the look on some of the guys face on bigger bikes after I had just wiped the floor with them on the windy stuff was priceless.
I then had been searching on the internet for the NSR500 v-twin and the price tag that came with that was too high. That is when I came across Jamie's NSR Homepage website which gave me a few good ideas.
A NSR250 with a CR500 engine, that could work I thought, nice and light plus with plenty of torque and power.
I sourced the model NSR 250 I wanted (MC28) frame and swing arm and a 2000 CR500 motor.
Next, what front end should I use? And the 1999 Honda rs250 front end was sourced with a set of Magtec (magnesium) wheels, Brembo brakes and radial master cylinder.
The tank was also from a Honda RS250 (aluminum) off the later model with out the flutes.
Aligning the engine : The first step was to find out the best way to mount the engine into the NSR250 frame. I decided to go with making up my own cradle to go around the motor but first I had to prop the engine on the bench and slot the frame, swing arm and rear sub frame over the motor and position the motor correctly.
As you can see in the photos I had to use blocks of wood and clamps to hold the motor and frame in place. I used engineering measurement tools to get the position precisely evenly in the frame making sure I would clear all parts of the frame. The rubber mounts were originally from a NSR250 tig welded onto box aluminum 2 millimeter thick sections.
The top mount was the hardest to fabricate and to tell you the truth this is the most important as it holds the motor in the correct position and cops the most vibration form the motor. Once I was happy with the alignment (sprocket as well) I had a mate tig up the mounts for the top and rear of the motor. Now the motor was securely in the frame.
|Making the cradle : This was quiet difficult especially using 2 millimeter thick box tubing. This later was a mistake and was changed. I measured up the lengths and using an oxy torch I gradually bent the tubing into place following the mounting holes for the CR500 engine. After bending both pieces into place I clamped both ends and made up the tags for the bolts to pass through. Again when I was happy with the alignment of the tags I tig welded all joints.|
sourced the Honda RS250 front end from a friend who imports GP bikes
I asked him before he sent them to me to have them Ti-nitrate the inner forks and powder coat the bottoms. The result was fantastic even coming form him he did not realize how good it looked. The Showa internals were also completely redone and rebuilt with all new parts and matched to my weight for and riding style for a massive increase in performance.
|Now as you can see with this picture I now have a rolling bike ready for stage 2.|