paddle height walbro

John Brittain · Joined: 08 Aug 2001 Posts: 5 Location: silsden england

What effect does raising/lowering the paddle have on engine performance

Pete Muller · Posted: Thu Aug 09, 2001 7:13 am Post subject: paddle height walbro

Do you mean the fulcrum arm?

If so, you can find a brief explantion here.

Pete

John Brittain · Joined: 08 Aug 2001 Posts: 5 Location: silsden england

Cheers pete , however I would like to know the effect on the engines performance when raising or lowering the 'fulcrum lever'

Pete Muller · Posted: Thu Aug 09, 2001 10:02 pm Post subject: paddle height walbro

There is no simple answer, sorry.

If you are in the range I mentioned in that article (~.040 - .060 below the top of the gasket), you will notice that the high speed jet will probably need to be leaned a bit as you raise the arm. The converse holds true too, of course.

There is a point when the arm gets too low where all of a sudden the engine will not have enough fuel through peak torque... almost regardless of where you set the jet.

There is also a point when the arm is too high where it's very difficult to get the engine lean enough on top end... almost regardless of where you set the jet.

Of course all of this is also dependent on what type of exhaust pipe, the gear ratio, etc. etc.

Marshall Martin · Posted: Sat Aug 11, 2001 4:40 am Post subject: paddle height walbro

Pete

With the change in the diaphragm, which does not require the fork to hook on the the diaphragm, is there any change to this procedure?

Jimmy Moore · Joined: 26 Jul 2001 Posts: 664

Pete, I run Yamaha 4H can on a short sprint track. I set my "paddle" at .035 to .040 without the gasket. If I want to get your numbers I just add .032 for the gasket then, I've been setting it at .067 to .072 which is a bit leaner than your settings. Even so, my carb seems to run wet. My needles work best set at 1/8 H, 1 1/2 L. I don't understand how people run the high at 1/4 and the low needle at 2 1/2 turns. Is their pop off real high? I know the OEM paddle spring sets the pop off way up there. I set mine at 10 1/2 psi. Am I missing something?