Tuning the Ace 125

I had an interesting talk with a bike shop guy regarding the Ace tuning.
It went something like this.

Keihin Deni cp26 carburetor
“Changing the pilot and main jets is not the answer to improve performance, it’s the midrange that needs sorting and all it needs is an O-ring under the needle jet clip where it attaches in the slide.”

Has this been brought up on this forum?

Anybody done this or know what’s involved?

Not looked but does this mean the needle jet is not notched and therefore cannot be raised.

Also.
“To retain the air box but remove the OE foam filter and replace it with some gauze/mesh.” Reason being the foam is not engine filter quality apparently.

Something else for you tuners to think about.
8)

There's a gauze mesh in the standard air box plus the foam filter.
Just checked on my needle, No notches.

Cheers for info

Gunny

Hi Lance, I tried a KnN air filter on my Ace and it wasn't happy even with re-jetting. So what I've done is use a Malossi foam filter that I had for an other bike, and cut around the STD foam. Ace breaths OK now. Not looked into raising needle by way of a 'o' ring though.
Cheers, Tad.

@Lance,

I've managed to fit a thin washer under the needle jet. But there is very little room. The needle is held in its place by some small springs. It's hard to raise the needle any further without taking away some material from the plastic holder where the needle sits in.
I recommend you make a home made tool to remove the needle jet because the plastic holder is fragile. I used a small aluminium pipe and cut one end in the shape of a castle nut with three spikes (I'll add a picture)

It did make a difference in performance with the washer in place. I think it should be raised some more. I just haven't figured out yet how to raise it further without the risk of breaking anything.

@Tad,
I had the same problem with a K&N style air filter. The correct size filter has a very narrow hole in the rubber ring. This opening is smaller than the carb opening. A modified 50mm air filter worked better because the opening to the carb allowed a better air flow(see picture). But now I use a velocity stack(see picture), even better air flow (but more risk of damage)


greetings