First job was a new battery mount. the original was well, non existant, so i fabricated this one up from some 3mm aluminium and an old gudgeon pin i had laying about that was conviniently sized. Just a simple clamp arrangement bolted down with 2x M6 bolts to keep the battery in place stopping it from falling into the frame rails and shorting out. TRUST ME you dont want one of these things to short out.
Steering bearings were equally non existant as well. half the balls were missing in the lower one and none were in the top bearing.. a brand new set of quality bmx bike ones (they are interchangeable) courtesy of blackmans bicycles with some heavy duty grease made the steering smooth as.
The setup was further modified by using a large m8 bolt that passed through both the triple trees and clamped them both together with a custom made aluminium boss kept things spaced apart properly. Definitely solid!
With that sorted a good thrashing was in order. the bike went fairly good considering its so heavy and the engine is so small. The jetting was well off however as you had to slowly wind the throttle on to prevent it cutting out, no doubt because of the filthy state of the carb that had been run with no air filter.
As it turned out when i pulled it apart to clean it, the atomizer tube was crushed by the main jet being screwed in way too far under serious force and all the atomizer holes squashed closed. The carbs being so cheap (less then 30 dollars with postage) i just bought a whole new one plus a foam air filter. If you run them without a filter there is a risk small particles can flow into the tiny idle passages and so forth and you will be trying to chase down the problem forever. at this cost it was sensible to just replace the whole thing.
Jetting was pretty good from stock. a quick adjustment of idle speed and the air screw (that meters the idle mixture) and it took off well from a stand still, however at mid to full throttle it would die. Dropping the needle clip one position to richen the mixture fixed that issue. The bike now ran great along with a new NGK spark plug.
Plenty of fun to ride around because the riding position is much more akin to a full size bike then a mini moto and dragging the knee about in the car park is pretty easy, even if the bike is horribly unstable and prone to tank slappers. definitely installing some kind of steering damper!! For a 50cc 4 stroke it definitely has a fair bit of low down torque and revs out well. the biggest let down is the lack of any gearbox so the top speed is pretty slow. in the region of 50kmh.
Last job done on the bike was to add a head/valve breather. They are supposed to help relieve the head of built up pressure (allowing it to pick up revs quicker and lengthen the life of the top end parts) as its argued the crankcase breather is insufficient. Now there is a lot of debate as to whether these actually provide a difference. The general consensus being that on large capacity high revving engines they do but are hardly worth the effort on low power and capacity motors. I figured it was only a 5 minute job so here's mine!
Personally i felt no difference to performance and no real flow out of the breather, but you dont know if you dont try!
Next up is a new muffler a bit of work on the dash board + rewiring plus some fairing modifications in the future.
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