DD2 Throttle response?

Brian Degulis · Posted: Mon Nov 05, 2012 8:08 pm Post subject: DD2 Throttle response?

Hello All. I have a 2011 DD2 with around 10 hours on it. When I accelerate at around 7500 RPM I get rough spot. It's not bogging it's more like 4 cycling as in to rich. Up to 7500 it's smooth and above 7500 it's smooth. The power valve has been cleaned belows and spring changed. I believe the power valve is set correctly and opening at 7500 RPM adjustment one way or the other and the problem gets worse. The echaust mat is new air filter is clean and main jetting is correct right around 172 or depending on conditions. The plug looks just right. I've tried diffrent needle positions and that effects top end but no effect @ 7500.

There are 2 things I haven't tried. The low speed mixture screw and the pilot jet. The pilot is the standard 60 it hasn't been changed. I'm thinking try a 55 pilot? Any other ideas?

Thanks

Brian

Brian

Eric Alexander · Joined: 19 Jun 2011 Posts: 121

7500 rpm is a big red flag for the RAVE valve so I'd keep digging in that direction. I've had the loctite (used to secure the blade to the shaft) get into the hole on the mounting bracket and bind the valve just enough to make it stick slightly. The motor would run rough at 7500 until the valve would unbind and kick open.

With the cover and spring removed - and the valve still on the motor - make sure the valve moves freely. It should have a bit of wiggle play from side to side. If you experience any binding, rotate the valve (using a nut driver on the bellows bell) slightly in each direction - making sure the blade is not hanging up in the slot.

If you're still experiencing binding, remove the valve and check its function off the motor. If the valve binds or has any rough spot, you can disassemble the valve and use a chainsaw blade sharpening file to gentle clean the hole in the mounting flange. At the same time, inspect the shaft for excess Loctite. Clean and sand any rough spots on the shaft.

Hope that helps and good luck.

Brian Degulis · Posted: Tue Nov 06, 2012 8:01 am Post subject:

I'm with you Eric but the valve is perfect really perfect. It's clean moves freely new bellows proper dimensions gasket in correctly. Plus with the adjustment a few clicks in either direction the problem changes a little and gets worse. So as much as I agree it's classic power valve at that RPM I have to move on.

Brian

David Struve · Posted: Wed Nov 14, 2012 8:57 pm Post subject:

Make sure you dont have the choke engaged. I've forgotten to flip it down a few times, and hit a rough spot around that rpm.

Also are you sure your jetting is right at 172, not sure where you are located but im using 188 on mine currently.

Brian Degulis · Posted: Wed Nov 14, 2012 10:09 pm Post subject:

I switched from the standard 60 pilot jet to a 55 that cleared it right up.

Brian