I'm having a jetting problem with my 98 evo. It has Hillside stage 2 heads, woods 8 cam, Dyna 2000 ignition module on curve 3 and a Mikuni hsr42 with 165 main, 20 pilot and the stock needle in the middle position and the accel pump is set out of the box. It starts easily and warms up quick, runs real good and seems to be getting pretty good mpg ( I'm only on my second tank full with 250 miles on it ). When I roll on the throttle easy it takes off great but when I wack it open from say around 50 mph in 4th gear it stumbles for a second or two then clears up and goes like hell. Before I start tearing into the carb I wanted to get some opinions from you guys on here. BTW the spark plugs look good and are not sooty, kind of a gray color. Thank guys.

 

Not sure what exhaust your running.. or breather.. adjust the air adjustment screw.. when hot,try small increments.

 

Sorry about that, I got a rb racing pro stock 2-1, big sucker intake and the air screw is approx. 1 1/2 turns out. It idles good just stumbles when the throttle is wacked open as I stated above, thanks.

 

try adjusting the accel pump.

Bob
1997 Heritage

 

Should I increase the pump shot or back it off?

 

get the tuning manual and the section on accell pump


Bob
1997 Heritage

 

I have the tuning manual and it doesn't go over specific symptoms.

 

Try increase first..

 

Adjust the pump cam so that there is basically no gap between it and the rod. Make sure it's squirting gas to around 3/4 throttle, by adjusting the little screw by the top cover. Also make sure it's squirting in the center of the manifold.

 

I switched my dyna 2000 to curve 2 and gave it 2 turns more accel pump shot, seems to have cleared the problem up. Thanks guys.