TS125 Low on Power

[mzeck]

My 1986 TS125 is now on the road & I've now used it a few times.
I've had it running at 60 mph down hill which I'm quite pleased with.
When picking away from junctions etc however it seems to be down on power below 3000 revs.
Above this it's fine, but it can be very slow off the mark.

It's got new points, condenser, plug & a new exhaust.

Any ideas guys?

[DAVID THOMPSON]

the MAIN thing everyone misses about a 125cc bike
is there just a mid sized moped
my rt125 4cycle with 20,000 miles on it will do 50 to 60 on a flat road
mine has had sprocket on rear changed and maxes out at 10,500 rpm and 69mph
but a very good tank of fuel is needed to get there
on a good day ..
make sure the fuel flow from the tank is good
and the air cleaner is good
recheck the timing
and if a new piston and rings it will take a bit of running to get it loose..
a poor spark at the plug will just turn any bike into a sleeping DOG
a bad tank of gas will flat kill the power
check spark plug wires at night in a very dark place and make sure there not jumping to ground

one problem with 2 strokes is some aftermarket pipes do not flow very good
as there not an exact reproduction of the original pipe

power production below 3000 rpm(udm) will be weak or poor in most cases
even when things are correct

125 cc bike performance above 50 mph is a joke....
that's the reason small bikes do not sell very well in the USA

dave

[mzeck]

Air filter now changed (I suppose the 20 year old filter on the bike was past it's best) and this has helped quite a bit. The bike reached 60mph on a long straight road today

I'm looking to get the bike running as good as it should so I've now been thinking of the fuel / air mixture.
I took the spark plug out and this seems a little sooty, but not too bad. I'm thinking that the mixture is a little rich.
To weaken the mixture slightly do I tighten or release the air screw?

[radiograf]

As the bike is so old I would reccomend checking all the carburettors settings and set them to standard. Turn the screw in until it seats then turn out the appropriate number of turns (1 to 2). This should give the standard settings, then try a plug chop. Drive the bike hard for a mile or so, kill the engine and check the plug to asses the richness. Then adjust the air screw and do another plug chop to see the effect.