I've just purchased a 77 O'Day 25 tall rig with the Vire 7 gas engine...even came with original manuals and documentation that it was rebuilt in 98. I've searched the boards for info and have found a lot but I'm curious about your opinion on oil mixture. The original manual suggests 32:1 for breaking in a new engine then shift to 50:1 There is a note in the log from a previous owner mentioning 4oz/gal....unfortunately the most recent owner has passed away and the seller(a relative) has no idea what was used last. What have you found to be the best mix for your engine? Thanks for your advice.
Vire 7 gas/oil mix
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Mixture and a Tip
I owned a Vire 7 for seven years and always used 50:1 mixture using regular self mixing 2 cycle outboard motor oil or that used in motorcycles and scooters. If yours has not yet been run in after rebuild then 32:1 would be a kindness.
Tip:- The manual advises to set the mixture by closing the throttle against the stop screw and adjusting the idle mixture screw for maximum rpm and then backing off the throttle stop and repeating the process until it idles nicely.
Once the idle is set then one engages forward gear, goes to full throttle and adjusts the main jet mixture screw for maximum rpm.
I found that when I went back to idle, normally just as I was approaching the dock, and then engaged reverse and opened the throttle again to stop the boat, the engine often used to cut out and refuse to start again. Hair raising and very embarrassing whilst heading down a blind alley!
I diagnosed this as being too lean at idle to allow the engine to accelerate under load. The remedy is to unscrew the idle mixture screw one full turn and adjust the throttle stop to maintain best idle speed. This means it runs slightly rich at idle but this does no harm anyway.
I owned a Vire 7 for seven years and always used 50:1 mixture using regular self mixing 2 cycle outboard motor oil or that used in motorcycles and scooters. If yours has not yet been run in after rebuild then 32:1 would be a kindness.
Tip:- The manual advises to set the mixture by closing the throttle against the stop screw and adjusting the idle mixture screw for maximum rpm and then backing off the throttle stop and repeating the process until it idles nicely.
Once the idle is set then one engages forward gear, goes to full throttle and adjusts the main jet mixture screw for maximum rpm.
I found that when I went back to idle, normally just as I was approaching the dock, and then engaged reverse and opened the throttle again to stop the boat, the engine often used to cut out and refuse to start again. Hair raising and very embarrassing whilst heading down a blind alley!
I diagnosed this as being too lean at idle to allow the engine to accelerate under load. The remedy is to unscrew the idle mixture screw one full turn and adjust the throttle stop to maintain best idle speed. This means it runs slightly rich at idle but this does no harm anyway.
Re: Mixture and a Tip
Thanks for the info....very helpful. In your locale what did you do to winterize the VIRE? And when winterizing, if done, did you drain the fuel tank, keep it full, or neither?
Thanks for the info....very helpful. In your locale what did you do to winterize the VIRE? And when winterizing, if done, did you drain the fuel tank, keep it full, or neither?
Hi STX,
In our locality I lifted out for the winter and did nothing to winterize the engine. I don't recall if there was a drain cock on the engine but, if there was, I would simply have opened it.
BTW winters are mild in Southern England. Only rarely do we see -5°C (41°F) and then only briefly overnight.
Now, with a Hunter + Yanmar, I remain afloat all winter and again do no winterization of anything
In our locality I lifted out for the winter and did nothing to winterize the engine. I don't recall if there was a drain cock on the engine but, if there was, I would simply have opened it.
BTW winters are mild in Southern England. Only rarely do we see -5°C (41°F) and then only briefly overnight.
Now, with a Hunter + Yanmar, I remain afloat all winter and again do no winterization of anything
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