VintageVmax.com

I like to know how things work, probably like many on this site. I have often wondered how Yamaha reduced the oil flow on the updated or red dote oil pumps. I have been running the original pump and going through quarts of oil this winter. I had a spare red dot pump but found the circle the cable attaches to be froze up. Tore both pumps apart and found the change was a smaller pump plunger on the updated oil pump, as seen in the photo. Parts are interchangable between both styles of pumps so I now have a functional red dot updated pump.

i run 83 oil pump on mine and 40:1 pre-mix per updated porting in tech manual. never fouled a plug. runs great. 3:16 (YAMMIE TONY)

If you are running the stock 1983 oil pump and premixing the fuel to 40:1 your total mix has to be like 20:1 or less. Way to much oil for me.

Interesting.....I know on some Yamaha oil pumps there is a way of calibration by adding shims(?) and also, changing gears ? back in the day I sent my Vmax 600 pump to Bender for an update to reduce oil consumption.

IN 1984 WHEN YAMAHA CAME OUT WITH PORTING UPDATE, THIS WAS RELEASED THROUGH A TECH BULLETIN. I MYSELF WORKED WITH JEFF FORNIER HERE AND DID THIS TO MY 1983. IN THE TECH MANUAL , YAMAHA STATES TO USE A 1983 PUMP ON THE 84-87 VMAX. THEY ALSO STATE TO TO USE 40:1 / 50:1 PRE-MIX NOT FOR PISTON FAILURE BUT EXTRA LUBE FOR CRANKSHAFT. I ONLY DID THIS PER UPDATE. 3:16 (YAMMIE TONY)