1991 Johnson 90horse VRO2 system.

[mtblackdog]

My question on the oil injection system for this motor is, how do I know what mix the system is running, in the manual it says that during breakin and "high performance" operation that it should be run at 50:1, I just inherited this boat and it has less than 50 hours of operation, I know from earlier conversations with guys on this board that at that time period Johnson was experimenting with 100:1 ratios and then later learned it wasnt such a good idea. So I guess I need to know what the ration it is running on now? Thanks again for the help.

 

[bb_ed]

Re: 1991 Johnson 90horse VRO2 system.

Your Variable Ratio Oiling pump feeds the engine more oil as its RPM increase. For break-in purposes you can pre-mix oil in your tank. Use a 100:1 ratio. For "high performance" (like racing) you should probably disconnect the oil side of the pump and run 50:1 pre-mix in your tank. The factory service manual will show you how to block it off. VROs came with a yellow plug clipped to the oil line near the pump that can be used for this purpose.

 

[MCM]

Re: 1991 Johnson 90horse VRO2 system.

oops

 

[MCM]

Re: 1991 Johnson 90horse VRO2 system.

Fuel/oil mix ratio should be 50:1, you are correct about OMC reversing the 100:1 reccomendation for the motors. During breakin or high performance operation you may want to increase that although I'm not sure what the reccomended amount be.

 

[bb_ed]

Re: 1991 Johnson 90horse VRO2 system.

MCM, did I oops something?

 

[DHPMARINE]

Re: 1991 Johnson 90horse VRO2 system.

VRO's did mix at low ratios at low rpms.But they increased the ratio at higher rpms.Basically the size of the diaphrams inside the pump,and the rpms.<br /><br />Small OMC motors (Johnson/Evinrudes) had decals advising 100:1.They later rethought this because if the motor sat too long,it did not have enough oil inside it.<br /><br />DHP

 

[MCM]

Re: 1991 Johnson 90horse VRO2 system.

I'm not sure, it looked like you advised using 100:1 for normal operation. Which may be what the manual originaly reccomended. Omc found out later that it was a little too optimistic with that 100:1 mix reccomendation.

 

[seahorse5]

Re: 1991 Johnson 90horse VRO2 system.

Years back when OMC recommended 100:1 ratios, it was only for the small hp motors.<br /><br />For the true "VRO" information and troubleshooting, go to:<br /><br /> http://continuouswave.com/whaler/reference/VRO.html

 

[bb_ed]

Re: 1991 Johnson 90horse VRO2 system.

I suppose I should have used two paragraphs to prevent the confusion. <br /><br />After rebuilds I would fast idle VRO motors for an hour on really oil rich pre-mix (50 or less to one) out of the shop fuel tank. That, plus the oil from the VRO made it pretty oil-rich. I would then add oil to the boat tank before delivering it. I tried for approx 100:1 so at idle the engine would be seeing about 50:1. Who knows what at higher RPM. I found that some folks complained (loudly) about poor idling if I spiked it more than 100:1.<br /><br />As far as the mix for racing, if it's a stock motor with standard tuning, 50:1 with the oil hose blocked off should be OK. I heard this from a few guys who ran in stock classes at the drags. It's the same mix you would use to get home if the oil section of your VRO failed. For real "high performance" apps I wouldn't know what to recommend. That stuff is usually TOP SECRET anyway.

 

[bb_ed]

Re: 1991 Johnson 90horse VRO2 system.

Seahorse, that article has all the good stuff. Mtblackdog, check out the article. <br /><br />It was not my intention to recommend running a 90 horse on 100:1. I re-read my post and don't believe it says that but apparently that's the idea that comes across.

 

[mtblackdog]

Re: 1991 Johnson 90horse VRO2 system.

Good Article! Thanks<br />Jamie