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UK Karting - Tech Talk: Preparation & Jetting of the Rotax Max Carburettor Tech Tips & Information The Preparation and Jetting of the Rotax Carburettor The Preparation and Jetting of the Rotax Carburettor by John Savage The Rotax Power Valve (PV) All PV systems vary the duration of the exhaust port open time, which gives the engine usable low end power combined with excellent top end power. This is of course the reason why most gearbox karts blank off their PV's, as with the use of a gearbox the engine will always be in the rev range of the open PV position.

Sep 13, 2016 The Rotax MAX Jetting Guide App is designed to assist users with. App as well as setting up the carburetor can be found. Too rich Main jet.

The PV in the Rotax Max effectively operates in 2 positions - closed and open. When the PV is closed, the engine produces good low speed torque/power curves that drop off rapidly just above 7500rpm. When the PV is open, the engine produces good high speed torque/power curves that drop off rapidly just below 7500rpm.

So in simple terms if you want to use your engine at 7500rpm and below then the PV must be closed and conversely if you want good torque and power above 7500rpm then the PV must be open. However it must be remembered that adjusting the PV spring pressure by turning the red knob (2) spring pressure adjuster on top of the PV cover does not alter the torque/power curves, it simply alters the engine speed at which the PV changes position, thus switching between the curves. If the adjuster (2) is set too far out, the spring compression force will be low and the valve will open at too low an engine speed, giving a torque/power dip below 7500rpm.

Similarly, if the adjuster (2) is set too far in, the spring compression force will be too great giving a torque/power dip above 7500rpm. See page 98 of the Rotax Max Operators manual.

When the PV is adjusted correctly the change over between the two torque/power curves should be seamless as this setting will give the overall best performance. If you have adjusted your PV to a position were you are able to notice a dramatic change in the torque/power curve then this adjustment is wrong and you will need to re-adjust your PV spring pressure, to a position where the change is hardly noticeable to the driver. The most common symptoms which may cause poor performance from the PV are: • Lack of bottom end power: Either the valve is stuck open, or the spring is too short or soft for the setting you are using. Check for correct operation, or screw the adjuster in to adjust the revs at which the PV opens.

Incorrect driver technique can also cause a 'BOG' see below. • Lack of top end power: The bellows are leaking, the valve is stuck closed, or the adjuster (2) is screwed too far in.

If your engine has been popping, check that the bellows (6) has not blown off the piston (5). Contoh Internet Software. The sudden rise in exhaust pressure caused by the popping (exploding of unburned fuel in the pipe) may be sufficient to blow the bellows (6) off. Which will cause the power valve not to open fully and will result in loss of top end performance, however the new green bellows (6) are not prone to this problem. Never be temped to stretch the PV springs (4), always screw the adjuster in or out to change the revs at which the PV opens and closes. If you stretch the spring (4) it changes the spring characteristics, then you are only guessing. The PV spring adjustment can cause big losses of power if not set correctly. Clean the PV blade (15) after every race to ensure that it always moves freely in its slot, always checking for correct alignment of the PV sealing gasket (10).