Jetting up

[dune19670]

Following up on my post, honda xl125rc lacking power.
Im wondering if increasing the main jet size would help.
The carb has the standard 102 main jet at the moment, but the bike has a micron and a k&n,
So my question is, how much bigger do i go !??
Anyone had any experiance doing this,.
Thanks Steve

[dune19670]

well ive just ordered a selection of main jets, as follows
115
125
135
145
i will see if any of these help ????

[scrog10]

Its a case of getting the mixture correct. Main jet only affect the top end performance. the pilot jet and needle jet control the bottom and mid range.
You will have to make sure your bike is not running lean as this will cause engine damage. When you do a plug check kill the engine while its in the upper rev range because letting the bike idle will give you a false reading from the pilot jet. Its also easier to read the colour on an older plug as the deposits have something to stick to. As I'm sure you know the plug should be a light tan colour when the bike is at normal operating temp, (off choke).

[fuelpumP]

imo these smooth all around bikes can't be pushed harder than factory horse power. imagine 10 horse running in ur engine but you want 15 horse. 125 cc is even too small piston size for long time usage. If you don't care that will engine components wear faster you can try anything. and there is no water cooling in ur bike I guess. take it easy with ur bike or go exchange with exc ktm or like that