What to expect in my new (used) 2007 race spec lifan?

[BMX_on_ST3R01DS]

Hi all,
im new to the forum so bare with me!
I currently ride a stock thumpstar 125 (worst bike on the planet) which I paid $70 for off a work mate, so i can't complain!:banana:

Anyways, I just bought a race spec Lifan 125; specs are as followes:
- 150cc piston
- 140cc head
- smaller, lighter flywheel
- bigger cam
- bored out intake
- ported exhaust
- and a few new and trick bits and pieces.

It just had a service and rebuild so im not doing too bad for 500 bucks! :first:
Anyway, being a 16 year old, very noobish young gun new to the REAL side of the pitbike sport, what can i expect from my new bike as apose to my current stock thumpy??

Thanks all

P.S. ill post a photo of the Lifan with the thread.

 

[my67xr]

Welcome to Miniriders,

make sure you drop in and say hello in our Introduce Yourself thread too.

with your new engine, let us know what the engine model number is.
it's stamped into the engine case below the sprocket, the top line eg 1P54FMI

do you know what size piston it has now, a 55.5/56 mm ?
what brand/grind cam is the race cam ?
and you mentioned the ported exhaust, so do you mean that the head is ported ?

yeah, post up some pics


cheers, craig

 

[BMX_on_ST3R01DS]

I'm not sure of the in-depth specs just yet, i'll get back to you on that one. Im just curious as to what improvements those modifications make to the bike?

 

[my67xr]

a bigger cam will draw in a bit more fuel and hopefully make a bit more power over the standard one.
(some are worse)
they move the power up more in the rev range, so if your old engine used to start pulling hard at 5000 rpm, the new cam might start pulling at 7000 rpm.
usually you'll need to upgrade the valve springs (stronger) too to help stop valve bounce at higher rpms

porting helps the air/fuel mixtures get in and out the engine quicker and more efficiently

a bigger piston/bore will increase the engines' capacity, a 125cc might go out to a 138cc or around that
so bigger engine cc's usually = more power

the head change may have upsized the inlet and exhaust valve's
so more fuel/air can get in and out again

a lighter flywheel will help the engine to rev a bit quicker, hopefully it's not an inner rotor kit, a lot of those are unreliable
and some can fall apart and damage the engine at the same time
the downside of a smaller flywheel is you will lose a bit of engine braking.
this will be noticed when you change down gears as you want to slow down, a smaller flywheel wont slow you as much.