CT90 top-end rebuild - completed!

Here's the bike as it looked back in July (just unloaded off the
truck):

http://www.otherpower.com/images/scimages/236/ct90_2.jpg

I decided that it would make a good paddock bike for my 10-year-old
niece (she's a bit too tall for the "family minibike"). About $250
later it has:

* A functioning front brake;
* A functioning ignition system[1];
* A cleaned-out carburettor;
* A new piston, rings, and 0.5mm overbored cylinder;
* A sidestand.

I had a bit of e-bay luck on some CT90 parts in Wagga which my uncle
collected for me, $18 bought the correct seat[2], exhaust heat shield,
front mudguard, spare forks[3], spare fuel tank, and centrestand. I've
got a CT90 wreck at Tarago that still has a brake pedal and rod
attached.

It was interesting to learn that the fork oil seals can be bought from
a bearing shop for $1.50 each, if you know the numbers for them.

Amazingly it started on the first kick after reassembly. It runs in a
very smoke-free manner until the exhaust pipe gets hot, which is full
of oily muck due to being run with a broken compression ring and
worn-out oil scraper ring[4] for Quite Some Time. The exhaust port was
about 25% smaller than it should have been, due to a thick layer of
oily, sooty goo.

And yes Pat, as a matter of fact I *DID* check the bolts on the
camshaft *VERY* carefully!


BTH
[1] I recycled the old ignition coil & condenser from my truck, and a
suitable 6V battery for $14 from Jaycar.
[2] It has the narrow seat of the first k0 model, where it should have
the current CT110 wide one.
[3] In case the fork sliders on it are too rusty to fit new seals to.
[4] The "wear limit" for the piston ring end gaps is 0.5mm, the
unbroken ones were about 5mm.

 

Bastard!!

 

When I see her tomorrow, I'll tell my mum that you said that.

Boy oh boy, are YOU gonna be in trouble! >:-D


BTH

 

Heheh. You may very well be surprised, BT!