The jetting that has worked best for me......is a #150 main and #50 or #52.5 pilot jet....and 3 washers on the slide needle.  (My personal bike wanted just 2 washers on the needle.....with 3 it had a lean surge at low throttle settings).  I was using the stock air cleaner.....maybe you need bigger jets with other filters (not sure).

This jetting worked well for me with both the stock piston/cylinder/cam, and also when I went to the 95mm Wiseco and a performance cam.

A #155 main seems a bit big to me.

You can buy the proper jets from Lancer on this site.

Or you can go to JetsRUs if you know what to buy.  (You can compare shape/size to what you currently have).

Moarpower wrote on 05/09/23 at 19:50:36:


No washer on the needle?  Are you still using the stock white spacer?  The needle jet circuit is too lean with the stock sized white spacer.....cutting it down or using 3 washers gets the mid range mixture to be richer.

The pilot jet is easy to size correctly.  Warm the bike up completely, drop the idle down to around 800rpm while holding the bike vertical (so the exhaust cam lobe still gets oil).  Then adjust the idle fuel mixture screw for the smoothest idle.  If you can turn the screw out more than 3 turns and the engine won't get rich...the jet is too small.  If you can turn the screw all the way in and the engine doesn't die....the jet is too big.  You want a jet size that allows the screw to be 1.5 - 2.5 turns out from being lightly seated.

NOTE:  You need to drop the idle rpm down to adjust the fuel mixture screw so that only the idle circuit is providing the fuel.  With the engine up at the normal idle of 1,100 rpm the slide is beginning to lift and some fuel is flowing out the jet needle.  Dropping the idle speed and adjusting the needle should take less than a minute once you get used to doing it.