Updated info when using a ROV with MPI drain mod

Update for Yamaha/MPI turbocharged snowmobiles when using a Roll Over Valve kit

After the MPI air/oil separator drain modification is performed and you are using a Roll Over Valve kit, the ROV shut off valve will need to be relocated in order for the Quick Prime feature to function correctly.

When the MPI/Yamaha drain modification is performed it changes the breather air flow direction. In stock form a majority of the breather air flow escapes out through the outlet (front) port of the separator where the ROV is normally mounted.

After the separator drain is relocated to the engine mag case cover, the majority of breather air flow is now cycling back through the engine.

The Quick Prime system uses this air flow to build pressure within the oil tank and pressure feed oil to the oil pump pick up port.
After the separator drain modification has been performed. Simply move the ROV valve from the front (outlet) fitting on the separator tank, to in-line between the oil tank and separator box.

By relocating the valve after the MPI mod, this will allow the Quick Prime system to build pressure and operate as designed! Attached are a couple of diagrams that I drew up to show breather air flow. The Red arrows indicate high air flow rate, while the Blue arrows show low air flow rate or oil drain back.

Bill

turbo800 said:

How about some pics instead of schematics???

Click to expand...

I hope to have some pics soon. My computer that I use for photo processing crashed :frusty:. and it has put me behind on a few things.

Bill

Pics!

On Yamaha/MPI turbo Vipers with the separator drain update, the ROV valve is relocated over to the right side.
To install it, remove the 16" hose that is clamped to the aluminum down tube that connects to the top of the oil tank.
Cut approx. 7/8" off of the 16" cross-over hose. The hose is then clamped to the plastic fitting on the valve and the previously attached hose (in the green square) on the valve is connected to the aluminum tube.
Angle the valve up into the cowling hole (red square), this helps keep the valve cool as shown in the pic.
Secure the harness and cross-over hose to the frame as shown at the Red arrows and your good to go!
I will be adding pics to the web site as well:thumb:

Bill