A bit of progress
This project has been lingering for a long while now due to a busy workshop schedule. We really wanted to get out on it this summer. But, even the best plans sometimes get interrupted by reality.
The engine has been completely rebuilt, both cosmetically and mechanically. The main reason for re-doing the engine was to strip the cases and cylinders of paint and have them vapour-blasted for that bare aluminium look. It was quite a bit of work, though. The other reason was to measure all of the engine parameters, such as port dimensions, timing, etc., in order to model this engine and design the expansion chambers and inlet tracts based on detailed engine simulation. This approach has been so successful on the 95Racer project.
The most amount of work has been on the chassis, though. Front suspension was pretty much a bolt-on aside from a modified stem and new bearings. It's off a Kawasaki ZX-6R 2004. Like on the 95Racer which uses 2006 Yamaha R6 forks, the ZX-6R forks are too long as you can see in the picture below. We'll shorten them eventually like on the 95Racer but will leave them for now in order to get it on the road sooner. The rear swinging arm and suspension are finished with new frame attachment points and adjustable ride height. The swinging arm is off a Honda NC35 and fitting it was surprisingly easy. All it really took was a couple of spacers and new bearings.
The new suspension again was designed using Tony Foale's excellent chassis software, which we've now used on over 20 chassis engineering projects. Every time the results have been extremely pleasing. The shock is a Proflex unit rebuilt to new.
As Intended, the engine is suspended in the frame using the original 3MA front mounts with new brackets that bolt to the bottom of the cylinders. The rear mount is standard YPVS welded on in the appropriate location. As you can see, there is no front subframe, nor any stabiliser bars. We were fairly confident this would work OK to contain engine vibrations, based on the many YPVS engine transplants we've done. We'll see when we run it in, in hopefully about 4 weeks.
The engine has TZ350 magnesium cases with dry clutch and close ratio box. Displacement is 375 cc with TZ750 pistons. Radiator is a TZ350 race item and we are using another electric water pump like on my 95Racer. This is mainly for packaging reasons as otherwise we'd have to cut too much from the fairing. It saves 1.2 kg of weight over the standard, magnesium TZ350 water pump, and reduces the load on the engine.
The other main area receiving some attention of recent is the body work. This was an area we wanted to pay particular attention to. We looked at and considered all manner of sources including the 2-stroke bikes of the era and the various conversion kit, e.g. the Tyga RGV250 body work/ However, we really wanted to bring it imore up to date, and eventually settled on Yamaha YZF-R125 body work.We've also seen plenty of "specials" where the bodywork was at best a compromise and at worst a bodge. We really wanted to avoid that and create a bike that one could easily mistake for an OEM bike of the current decade.
There are side panels which are not fitted for these pictures, but you'll see what they look like if you look at the standard YZF-R125. It turns out that it fits the 3MA frame really well. The biggest job was adapting the nose cone stay to the frame mount, but not too difficult. A bit of cutting and it goes on easily. The tank is still the plastic Belgarda TZR125 tank. The tail section will also be YZF-R125 as soon as weget the chance to make a rear subframe.