Changing the oil input on a Spree.

Bear45-70 · Post by **Bear45-70** » Thu Sep 11, 2008 6:19 pm

Has anyone tried putting the oil from the pump into a "t" in the gas line before the carb, instead of using the nipple on the intake port? Would probably need to jet up one size but it would give you a better oil distribution.

Kenny_McCormic · Post by **Kenny_McCormic** » Thu Sep 11, 2008 7:16 pm

How would it give better distribution? I think a high speed flow of gas and air blends the oil in pretty good.

devenex · Post by **devenex** » Thu Sep 11, 2008 9:21 pm

were you thinking of doing this with a se50 intake installed?

Bear45-70 · Post by **Bear45-70** » Thu Sep 11, 2008 11:26 pm

devenex wrote:were you thinking of doing this with a se50 intake installed?

The SB50 intake and yes. Every carbed outboard I every saw was oil into the fuel line before the carb.

To answer kenny's question; being sucked thru the venturi section of the carb would give a more even oil distribution than just being dumped into the intake manifold.

mousewheels · Post by **mousewheels** » Thu Sep 11, 2008 11:39 pm

Sounds good from the distribution end just like you say.

What do you think about from the failure side? -
Failure condition:
Leaking petcock valve, oil tank level lower than level of gas tank.

Could (over time) gas force a reverse flow up the oil tube & though the pump? That would create a starved oil condition until run long enough to refill the tubing.

Bear45-70 · Post by **Bear45-70** » Thu Sep 11, 2008 11:50 pm

mousewheels wrote:Sounds good from the distribution end just like you say.

What do you think about from the failure side? -
Failure condition:
Leaking petcock valve, oil tank level lower than level of gas tank.

Could (over time) gas force a reverse flow up the oil tube & though the pump? That would create a starved oil condition until run long enough to refill the tubing.

If you tapped into the gas line an inch or so from the carb for the oil inlet and with the oil pump acting as a one way valve for the oil tank and the vacuum petcock would stop anything trying to get into the gas tank. I just don't see how the oil and gas tanks would ever "see" each other directly enough to be a problem regardless of their respective levels. Besides

mousewheels · Post by **mousewheels** » Thu Sep 11, 2008 11:54 pm

Bear,
Yeah, I'm just trying to rationalize why Honda chose the path they did, when you basically showed there's a better path. IDK if the oil pump can hold off the gas or not, it's just a what if scenario....

Do the outboard oil pumps have any reverse flow check valves built in?

devenex · Post by **devenex** » Fri Sep 12, 2008 12:12 am

Bear45-70 wrote:The SB50 intake and yes. Every carbed outboard I every saw was oil into the fuel line before the carb.

My mistake with the model letters

If you do change the intake, please be sure to post what your results were. I'm pretty curious about this (almost) bolt-on upgrade.

Bear45-70 · Post by **Bear45-70** » Fri Sep 12, 2008 12:23 am

mousewheels wrote:Bear,
Yeah, I'm just trying to rationalize why Honda chose the path they did, when you basically showed there's a better path. IDK if the oil pump can hold off the gas or not, it's just a what if scenario....

Do the outboard oil pumps have any reverse flow check valves built in?

The pump doesn't have to hold off the gas. The vacuum petcock will shut off the fuel flow when you shut the motor off. On the O/B's there is nothing except the oil pump between the oil tank and the fuel line. The only time you see a problem with the oil migrating up the fuel line away from the carb is when there is a bad fuel pump which allows the pressure to bleed off toward the pump rather than toward the carb when the engine is off.

PimpinSpree · Post by **PimpinSpree** » Fri Sep 12, 2008 12:41 am

sounds like a tremendous waste of time and effort. if it aint broken don't fix it

if it worked like you hope it does, it would work SLIGHTLY better than stock. If it works out like the many other possibilities it may be disastrous

Bear45-70 · Post by **Bear45-70** » Fri Sep 12, 2008 1:13 am

PimpinSpree wrote:sounds like a tremendous waste of time and effort. if it aint broken don't fix it

if it worked like you hope it does, it would work SLIGHTLY better than stock. If it works out like the many other possibilities it may be disastrous

How would it end up being a disaster? Specifics please. If one does the SB50 intake mod then you don't have a second nipple in the intake and this fixes that problem for you. Plus how is better oil distribution a disaster? Waste of effort, I don't know what you call effort but this ain't it? I can do this mod in way less than 5 minutes and the cost of a Tee, a cap for the manifold nipple and a few tie straps.

Post by **noiseguy** » Fri Sep 12, 2008 10:12 am

It seems like this would work; my concern is why Honda didn't do this in the first place, it would have been less expensive. I'm asking around on this.

Bear45-70 · Post by **Bear45-70** » Fri Sep 12, 2008 10:45 am

noiseguy wrote:It seems like this would work; my concern is why Honda didn't do this in the first place, it would have been less expensive. I'm asking around on this.

I've seen engineers do some pretty stupid things over the years. I worked for a few years in the expermental department at Beechcraft Airplane factory and sometimes the engineers would suggest stuff that would make the airplane unflyable. Theory only works well sometimes and at others gets you in trouble sometimes. Besides that, it appears at least from what I've read here, that Honda went to injecting the oil into the carb on the SB50 engines.

Post by **noiseguy** » Fri Sep 12, 2008 4:06 pm

The injection point move to the carb, true, but it's essentially the same way of putting in oil, after the venturi.

DJPhatman · Post by **DJPhatman** » Fri Sep 12, 2008 5:23 pm

It may have been to prevent oil build-up on the float, giving it more weight. that would keep the needle open too long and cause leaking. IIRC, aren't most outboards using a diaphragm in the carb?