Oil Pump Delete Vs. OEM Oil Pump Vs. Aftermarket Oil Pump

[Drifter562]

Not sure if I have seen info yet... Yes I did see ratio's but I just wanted to point out that a lot of people suggest to delete an oil pump and run premix.
Can someone who knows point out pros and cons thank You.
I know I'm a noob but I feel like the worst thing you can do is remove the oil pump. Even if you ran a bbk the oil pump is driven by the crank so depending on how fast the crank spins is how fast the oil pumps oil correct? Correct me oh moderators/keepers of Honda Spree/Elite arcane Knowledge for that I may see the light.. Thanks guys

[Wheelman-111]

Greeting:

The Total-Loss lubrication of a 2-stroke is a dirty business. It's COMPLETELY different from a 4-stroke in which fuel in stays exclusively Topside while lubrication is limited to downstairs. (Assuming the ring seal is adequate, but that's a different story...)

In a 2-Smoke, fuel/air/oil mixture, whether pre-mixed or dribbled by a pump into the intake tract enters the engine through the crankcase. The ports exchange that mixture with the combustion chamber. A Puddle of oil condenses as the mixture evaporates, and it has to remain in the lower crankcase for the flywheels to sling around and spray the lower cylinder barrel and a Drip system to collect the excess to lube the bearings. Eventually some oil mist makes it into the combustion chamber to lean the fuel/air mixture, foul the plug and head and cake your exhaust pipe. On the plus side, it's responsible for that heavenly smell and trail of blue smoke, but it's a mess, and the reason why Civilized Society, through the EPA, increasingly eschews the whole concept of 2-strokes for any application.

But most of us don't care about Civility. In short, Dump the pump. It was configured to match the needs of a 49cc engine producing maybe 4 HP on a good day at 8000 RPM or less.

Once you install a big-block, the amount of fuel flowing through the engine overwhelms and sweeps away by solvent action the paltry emissions generated by the stock pump. That puddle will dwindle and disappear unless some oil is already in the mist generated by the carb to supplement it. This requires you to add some oil to the fuel tank, because as far as I know there's no aftermarket pump that fits the cases with an output higher enough to meet the big-block's needs.

Since you're now pre-mixing anyway, you might as well make it 32:1 (~3%, or 4 oz oil per 128 oz of gasoline) AND lose the power-robbing mechanical losses of the worm gear driving the pump from the crank. With Flash 2, I thought as you did. I kept the pump for "insurance" and added 1% (1 oz oil to 100 oz. fuel). I figured the 50% displacement increase warranted a 50% increase in oil supply. It did OK I guess, but you really can feel the power difference when the pump is deleted and a proper plug ($15 last time I checked) is inserted. Be sure to fashion some sort of mechanical retention system for the pump plug, or it can pop out with catastrophic consequences.

[MrJumps]

The smell and blue smoke is worth it. I totaly agree with wheelman though. My soree died because my oil pump became loose.

[Drifter562]

That's tru about any engine component that moves though, I understand about variables which is good thinking but i just want to know if the oil pump only delivers oil through the intake. It doesn't make sense that it would only deliver oil through the intake and not to both intake and crank as its ran off of crank. I understand it all eventually leads to crank but why wouldn't Honda also deliver oil to crank and kill two birds with one stone. Does anyone remember JJ? Him and bear would go at it over this topic.
Hahahaha thanks for the input guys ill try the pump plug and I could always switch back anyways...

[bonesv]

Hey man, I have a af16 w/new oem oil pump and add oil to tank also, and it's on a 72 bbk. Not really a big hassle to add oil when fueling. Sometimes it seems like it's burning too much oil but have not fouled any plugs yet. It's got a mild pipe/19mm stock carb/stock air box/8.44's and maybe hits 9000 rpm. I think I read on here somewhere that a higher revving motor will need more oil but I have not been racing these so I decline to comment if it's true or not. Bakaracer or 1man8 could maybe give their opinion. But, I do run a plug and pre-mix with any other bbk's with a radical pipe/carb/gears, etc.......if they exceed 9000 rpm.
It's much easier to be accurate when pre-mixing, versus the oil pump/add extra oil w/fuel.
Wheelman has a very good point and I agree with it. Too much oil is almost as bad as not enough.....
Haha, I remember JJ, haven't heard from him for quite a while......

[Rip_City_Spree]

Spend hundreds on a build to have your bike die one day because your pump stopped working or just failed to work enough to supply the proper amount of oil. Doesn't make sense remove then you know what mix your running at all times. No hoping your pump is working on your 15 plus year motor.

[MrJumps]

Yeah my oil pump didnt even fail it just vibrated loose the bolt and worked away from the motor and killed it. Trust me you wanna run premix. Its a hassle but its gonna make it even more reliable. Oil also seeps down the shaft to the crack but just enough for it to start once its running the vacume and pulses of the crank rely on the intake to spray into it. Its kinda a fool proof design but only at 50cc anything above stock and your asking for under oiled bearings at startup. The oiler dosnt spin fast enough to throw fuel in the case so what left over oil your motor relies on or death. Trust me, my dad raced built mustangs for years and new builds you always want them to have pressurised oil that has been literly over filled or you will hurn something up that first start. Its crazy the mechanics of a 2 stroke and pressure filled engines aquire to work. Its like a clock 1 secound off and time is nothing but a word with no meaning. I know

[benji]

I did a pump delete along w a variator upgrade and rejet, woke my bike up on the stock bore. I was hitting 41-42 or so. You really feel the power you get by removing it.

Btw, enriching the oil mixture effectively leans out the a/f ratio, but w oil not air. Maybe that's another reason it feels faster.

[MrJumps]

I did a pump delete along w a variator upgrade and rejet, woke my bike up on the stock bore. I was hitting 41-42 or so. You really feel the power you get by removing it.

Btw, enriching the oil mixture effectively leans out the a/f ratio, but w oil not air. Maybe that's another reason it feels faster.

I belive you are right. We need a sticky with people talking about oil pump delete

[Wheelman-111]

Greetings:

Kawasaki and perhaps Yamaha and Suzuki had autolubes when 2-strokes had their brief heyday. As the engines grew to 350, 500 and 750ccs, apparently they found it was necessary to provide plumbing to drip feed the bearings as well as a mist in the intakes for the barrels. Roller bearings impose RPM limits that pressure-fed plain inserts in 4-strokes can exceed. Suzuki water-cooled its 750. Between the EPA and the challenges and added cost of building bigger 2-strokes, even Performance King Kawasaki gave up and the result was the Z-1 900.

[benji]

I used to have a kawi 78 kx750 sr, fast bike. I wanted a z900 tho, or even a triple 750 2t.

[Drifter562]

Has anyone here ever had an oil pump fail? I mean your engine would seize or knock right? Interesting that you mentioned kawasaki wheelman as i was reading an article on premixing vs oil pump and it mentioned that there is a kawasaki engine who required the oil pump as it delivered oil to bearings and intake. That's why I was asking if honda scooter oil pumps delivered to both bearings and intake. here's the article.
http://www.thejunkmanadv.com/2-stroke-o ... stems.html

Here's another article worth a read http://www.dansmc.com/2_stroke_oilpump.htm

[Wheelman-111]

Greetings:

Nobody here hates the pump. It's fine for a stock 49cc. When you increase displacement by nearly half, there is no longer enough oil delivered, and you will seize. When pumps fail the seals start to leak and there is too much oil, usually. It won't fail mechanically because... well, it's pumping Oil, after all. But it will leak, even sitting still, leaving on startup a cloud visible from Space.

[MrJumps]

So basicly the oil pump in thery is suppost to be a seal pump ran off the crank to push oil through a line into the intake where it is atomized with air and fuel to make a fueloil mist and as the rpms vary the pump pumpes more or less oil. So if you are going down hill it still is displacing oil at the rpm the engine is running at. So by removing the pump the block is relying on the oilfuel mix from the jets. So a bigger main is needed I would say about 1 size up when you remove the pump. I would also think while the engine is chuging down hill at like 10000rpm the motor is at no throttle so your not pulling that much air but your still pulling a heaviy fuel fatio into the engine from the extra vacume added by the throttle slide being closed. So best bet if you wanna be 100% safe learn how to drive a 2 stroke by bliping the throttle on deceleration. Its better for your motor anyway it keeps the hot deposists from WOT from colling down and hardning on your cylinder and piston walls. So to be effecient on stock stay pump with 1 jet up on main, and on bbk remove the pump and buy a plug that fills in as much of the plug hole as possible and make sure it seals and run the oil ratio you need to and just go a little rich on the pilot if you do a lot of downhill driving. I think I did a good job sumerizing this? I dont know, im not an enginologist. -Jumps

[Wheelman-111]

Greetings:

There are a few mis-apprehensions in your post. The thing that pulls fuel through the jets is airflow-generated Vacuum over the jets in the narrow part of the carb throat. (Google "Venturi") When the throttle is closed, very little fuel pulls up through the Pilot circuit and none at all from the Main. Also, the pump on a throttle-controlled model like the SR and the '86-87 Aero will reduce the oil output from the pump somewhat, even if the RPMs are high as you start coast-down. I'm not sure anyone but Honda-san can say exactly how much it is reduced, but there's a cable there for a reason...

Also when you add OIL to the Fuel-Air mixture, the Air doesn't change but there's proportionately less Fuel. Less fuel = LEANER, not richer. The mixture burns hotter, maybe not a full jet size but some. If you add a LOT of oil like early Outboards running 16:1 or 20:1, the jets have to be stupid-big. Jetting is far from exact on any engine, but especially true on a 2-stroke. This is part of what makes them perform so poorly on hydrocarbon emissions testing. And why computers now basically rule the Internal Combustion world.