Inline Oiler for small 2 stroke

[mitch184]

First, did yamaha ever make a small inline oiler similar to the OMC Accu Mix or Mercury Autoblend?

Reason being, picked up a small Yamaha 8hp 2 stroke for an auxiliary motor and I would really like to run it off the main (unmixed) tank.

I found a great deal on an unused OMC Accumix 100:1 unit. I search around and couldn't find a yamaha version that was ever produced. The smallest Precision Blend seemed to be a 50hp.

Anyone ever installed one of these oilers in front of a Yamaha 2 stroke?

Thanks
Sean

[boscoe99]

Yamaha did not and does not offer an external system ala the OMC system.

I have never used one but see no reason why the OMC system would not work with a Yamaha. As long as oil gets mixed with the gasoline the motor will not know nor care how it got there.

Is the motor rated for 100:1? I believe there is an Accu mix system that is rated at 50:1, if that is what is needed for your specific model. Some Yams are 50:1 and some are 100:1.

Yamaha used oil injection (Precision Blend) on some 20 HP models. Ratio varies from 50:1 to 200:1.

[mitch184]

2006 Yamaha 8MSH. Everything I've read is 100:1. Unless there was a service bulletin I missed.

The OMC unit I bought is a 100:1.

Also, is the Precision blend actually a true injection or does it mix oil? As in, could it be used standalone for what I'm doing? I'd much rather have a Yamaha unit, but the convenience of the Accu Mix is tough to beat.

[boscoe99]

2006 Yamaha 8MSH. Everything I've read is 100:1. Unless there was a service bulletin I missed.

The OMC unit I bought is a 100:1.

Also, is the Precision blend actually a true injection or does it mix oil? As in, could it be used standalone for what I'm doing? I'd much rather have a Yamaha unit, but the convenience of the Accu Mix is tough to beat.

You are correct. Your model uses a 100:1 ratio of gasoline to oil.

With Precision Blend there are two means of automatically adding oil to the motor. One way is to pump oil into what is called a vapor separator tank which is filled with gasoline. Kind of an automatic premix system if you will. Used on two stroke EFI engines. The other way (more common) is for oil to be pumped to just behind either the carburetors or throttle bodies where the oil gets picked up by the air flow and taken into the motor. End result is the same.

The accumix system might be analogous to the Yamaha system where oil is pumped to a VST.

[mitch184]

Thanks for the confirmation on the ratio.

On the smaller OMC engines, it states that sometimes a larger fuel pump is needed. If this is the case on this 8hp, is there an optional fuel pump at all?

I haven't seen a part number for one anywhere and the fuel pump part number for the 8MSH is used on everything from a 6hp to a 15hp.

[boscoe99]

Thanks for the confirmation on the ratio.

On the smaller OMC engines, it states that sometimes a larger fuel pump is needed. If this is the case on this 8hp, is there an optional fuel pump at all?

I haven't seen a part number for one anywhere and the fuel pump part number for the 8MSH is used on everything from a 6hp to a 15hp.

Yamaha's use just one size fuel pump for a particular model. What is specified for the 8 HP model is all that is available. Given that the same pump is used on both a 8 HP model and a 15 HP model one might surmise that the pump is a bit over sized for the 8 HP model.

I suspect that the accumix system increases the restriction to fuel flow which might be the reason for a larger pump being needed in some cases. What you can do is to plumb a vacuum gauge into the fuel system to see what the vacuum is at wide open throttle without the accumix system being installed and then with the system installed. If the change is minor then you might not need a bigger pump. If the change is significant you can consider installing a low pressure electric fuel pump at the tank to help the main pump draw fuel. A bit more complicated but...

For those that are interested, I suspect this is the system the OP is considering

http://www.boats.net/parts/search/OM...UNT/parts.html

[panasonic]

Never seen one of those before.

So raw fuel goes in one of the bottom nipples and gets oil added as it passes through the pump, and back out the other nipple and on to the engine? The oil reservoir on the top?

Explain how it works will ya...

[rodbolt17]

dude
there is a reason the OMC accu blend is long gone.
same as the merc auto blend.
one OMC system actually blended the oil/gas in a 6 gallon tank. did not work well.
blew up many motors.
simply use a 3 gallon tank and mix it.
and as it is almost a blow boat motor mix it at 50/1.

[mitch184]

dude
there is a reason the OMC accu blend is long gone.
same as the merc auto blend.
one OMC system actually blended the oil/gas in a 6 gallon tank. did not work well.
blew up many motors.
simply use a 3 gallon tank and mix it.
and as it is almost a blow boat motor mix it at 50/1.

Quick question... how many motors did OMC and Mercury sell in the 30 years they used these systems? What percentage of these motors is considered "many"?

And they're gone because direct injection 2 stroke are the only 2 strokes left in the US.

Panasonic,

Basically it looks similar to a fuel/water separator. 1 line in, 1 line out. Fuel goes in, there's a valve/diaphragm that uses vacuum to pull oil into the flow. Fuel comes out "mixed".

[boscoe99]

Never seen one of those before.

So raw fuel goes in one of the bottom nipples and gets oil added as it passes through the pump, and back out the other nipple and on to the engine? The oil reservoir on the top?

Explain how it works will ya...

Yep, appears to be a siphon or jet pump type of action to draw oil from an oil hopper and intermix it with gasoline. Two configurations as near as I can tell. One embedded within a portable tank and one that is boat mounted so that oil can be added from the gasoline coming from a permanent tank. I see nothing to indicate that a pump is involved.

I got a guy that is supposed to be sending me some detailed literature on the system. When I get it I will post same.

[panasonic]

Quick question... how many motors did OMC and Mercury sell in the 30 years they used these systems? What percentage of these motors is considered "many"?

And they're gone because direct injection 2 stroke are the only 2 strokes left in the US.

Panasonic,

Basically it looks similar to a fuel/water separator. 1 line in, 1 line out. Fuel goes in, there's a valve/diaphragm that uses vacuum to pull oil into the flow. Fuel comes out "mixed".

I agree with Rodbolt on this one, mix your gas in small tank at 50:1 and you will be certain not to under oil or NO oil to your engine. I know it would be convenient to have one fuel source..

What I can tell you is I have seen many 2 strokes seize up from oil injection systems failing, whether it be a outboard, motorcycle or snowmobile. Most of the fishermen I know with 2 strokes (which they love dearly) ,some very old, have disconnected the oil injection and mix their gas for long ago...they just don't trust the oil injection on pretty much all brands of outboards.

Snowmobiles back in the late 70s 80s where notorious for oil injection systems failing and most disconnected them right away and mixed the gas. Saying that...Yamaha snowmobiles and other Japanese dirt bikes had a very good system and generally worked well....others not so much.

I believe Yamaha outboard oil injection systems have a good reliably record as well. Many on here will attest to that I think.

[panasonic]

Yep, appears to be a siphon or jet pump type of action to draw oil from an oil hopper and intermix it with gasoline. Two configurations as near as I can tell. One embedded within a portable tank and one that is boat mounted so that oil can be added from the gasoline coming from a permanent tank. I see nothing to indicate that a pump is involved.

I got a guy that is supposed to be sending me some detailed literature on the system. When I get it I will post same.

Must be some kind of siphon setup. When I think of a jet pump it would have to have a motive flow line to operate the pump, which is a fuel return line back from fuel pump to the tank or the remote unit.

[boscoe99]

[pstephens46]

Clever system. I would premix.

[mitch184]

Being it's a low rpm kicker motor, I can see the reservoir and it has a fail safe system.... I guess I'll roll and see what happens.

Hopefully there's not an "I told you so" in the future.