That’s rich!
Things have been a bit slow again this month with my bike projects as I’ve been waiting for parts to arrive and the chrome plating, the tank, etc., to return for my Z1B Super Six.
Mrs M. then hinted that the house could do with a bit of a spruce up, so for the last couple of weeks I’ve been sanding and painting walls rather than bike parts! It’s always nice when the doorbell chimes and it’s the parts to finish my KDX200A engine rebuild. Luckily I was at a convenient point to stop painting so could spend some time in the garage to reassemble the KDX engine.
As I said last month, the engine was in great shape and only needed new main bearings and seals, so it was a straightforward task of pressing on the new bearings and bolting it back together. With the engine in one bit again, I dropped it back into the frame and fitted the exhaust, carb and tank ready for a test run. The engine started immediately and ran great, but I felt it was slightly rich at lower throttle openings. I’ve been using Silkolene fully synthetic two-stroke oil in the pre-mix fuel and after doing some research on line I had reduced the amount of oil mixed in the fuel from 32:1 to 40:1 in the hope of cleaning up the exhaust emissions a bit. With less oil in the petrol the fuel air ratio would be slightly richer so I dropped the pilot jet down one size from 40 to 37.5, which made a significant improvement to how the engine feels, and when I removed the spark plug the central electrode was straw brown, proving the mixture wasn’t far off.
I’ve also been taking advantage of the bright sunny weather to take regular breaks from home improvements to ride my candy blue Z1 Super Six, taking its total mileage up to 1100 miles. I’m really pleased how well it’s been running, but I noticed that the rev-counter was a bit erratic and would wander 1000rpm either side of a given reading.
The painted parts and quality reading.
When I made the bike I had adapted the rev-counter to electronic operation using the electronic internals from a Koso rev counter in the original Z1 casing, so I wondered if I had calibrated it correctly. The voltage displayed on my ‘in dash’ digital voltmeter would vary from 12.5v to 15.1v depending on rpm. If I flashed the headlight while riding at a constant speed I noticed the rev-counter drop around 1000rpm! By turning on the headlight the voltage dropped from 15.1v to 13.5v. It
would seem that the regulator wasn’t working to control the voltage to keep it below 14.7v.
When I got home I checked my original Kawasaki service manual and was surprised to see the regulator was actually within spec and 15.1v was a normal condition when riding at speed with lights off. This explains why the old-style lead acid batteries would sometimes boil the electrolyte, spitting it out the vent pipe, especially on the two-stroke triples, where the acid would dissolve the chrome plating off of the exhaust pipes!
I needed to control the voltage below 14.7v for my modern rev-counter to work properly so I decided to upgrade the charging system with a modern threephase rectifier/regulator from a Suzuki SV650 with three yellow AC wires and red +ve and black earth wires. These are available online for around £20 and are easy to fit. The Z1 is fitted with a selenium plate rectifier behind the side-panel and
separate voltage regulator under the battery box and, once removed, the Suzuki SV650 regulator fits perfectly on the original mounting holes under the battery box, but it does require longer M6 bolts. I then cut off the connectors and extended the wires so that they would reach up to the row of electric connectors behind the side-panel. I reused the white connector from the old selenium plate rectifier by sliding out the three pins, cutting off the old yellow wires and soldering on the three yellow wires from the new combined rectifier/regulator.
With the connector pins replaced, the white connector could be reconnected in its original position. The red wire was cut to length and fitted with a new single bullet connector, and then connected to the twin white wire connector that is connected to the battery +ve lead. Finally the black wire was connected to a suitable earth. I haven’t had a chance test the new regulator but will let you know how it performs next time.
On one of my rides I bumped into fellow CMM contributor Chris Moss at the top of Combe Gibbet on a gravel track; he was with a few big KTM adventure bike riders on a demo ride. We had a natter about the bikes and I was surprised to hear the weight of my Super Six was similar to the big KTMS!
A few days later I had a call from my friend Neil to say that the tank and panels for my Z1B Super Six were painted and ready to pick up so I eagerly drove up to his workshop to collect them. Neil had done a great job as usual, painting on the stripes so they were undetectable when you run your finger over them, and the candy red metallic glistened in the spring sun.
I fitted the rear fin, first assembling the four two-piece rubber grommets, pressing them through the plastic fin and securing in place with four M6 screws. The side-panel badges were then pressed into three holes in the side panel and secured in place with three press-on spring clips. I fitted the new petrol cap and tap, then fitted the two Kawasaki badges on to the petrol tank and fitted it on to the bike, carefully sliding it on to the two front mounting rubbers and pressing down into place. I had bought a new replica Uk-style seat from Phil at Z Power (01942 262864) and it fitted just perfect, and after adjusting the locking plunger it snapped shut with a nice firm click.
The four header pipes have just arrived back from chrome plating at ACF Howell’s (01922 649992) so once they’re fitted I can start the engine for the first time. More on this next month.