MOPED ARMY

Definitely open the intake port up to match your intake manifold. Then tune.

because of the machine shop bit, check your piston to make sure it is clearing the intake and exhaust ports correctly, if not correct it with gaskets.

for jetting, do plug chops and rejet accordingly. you may just be running too lean or too rich and thats whats causing your problems.

you don't have to open the intake if you open the exhaust, but like tim said, you really should.

are you running a 15mm intake? if not you arent using all that carb's potential. youre not going to see great performance improvements runnning a 15mm carb into a 12mm intake then a 12mm intake port.

I believe I have the 15 mm intake. I have the engine on the bike, then bought a parts engine. I did all the machine work to the cylinder I pulled off the parts engine so I wouldn't screw anything up too bad. The intake on the orriginal has a much wider opening and exits to the side of the engine, where the parts bike has a manifold on it with a much smaller diamiter opening, and it exits to the front of the bike. The inside diamiter is different on the two of them, but the outside is the same, and the carb fits nicely on both.

I don't think I changed how the piston clears the ports becasue I took all the extra material off the top of the cylinder, so the piston never reaches the area i modified.

I'll open both ports up, see how it works, then maybe move those ports down and up respectively. Thanks!

Its a air pump. The ore in the more out.

if you are just widening you aren't messing with port timing just port area- do 2mm on each side. if you want to mess with port timing lower your intake window by 1mm and raise your exhaust window by 1mm. as long as your porting is consistant between the intake and exhaust (lower intake/raise exhaust) then you are golden.

for the 15mm carb i would put a decent puch pipe on that mounted on the other side versus a crappy biturbo. and yeah make sure that intake is 15 cause if it is not then all your efforts are wasted. good luck.

60? 68? Seriously? I am running a 15.15 and a Mamba and I run a 59 jet. I might need to be a little higher, but if it was super lean I'd have seized already. I haven't done a real plug chop with a fresh plug, but a I got a nice brown coating last I checked. I max out around 33-34 and have way better acceleration than stock. Quinton I think you need a lower jet, I was doing a 56 when I had a 15.15 and a stock exhaust, I don't know what effect your drilling will have on the situation.