Stock Oil Pump Delivery Ratio

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Trafficjamz
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Re: Stock Oil Pump Delivery Ratio

Post by Trafficjamz » Mon Apr 30, 2012 9:04 pm

JJ Joseph wrote: 2-strokers arguing that the oil pump is irrelevant are ignoring developments in 2-stroke technology. The oil pump was developed by Yamaha to overcome a major defect in 2-strokes: premix 2-strokes are dirty and unreliable. With premix methods, your engine will be either over-oiled or under-oiled with the same mix. When your engine is under-oiled during closed throttle ops (high-speed, downhill) you will cook the moving parts. If you are over-oiling during acceleration, your engine will accumulate excessive carbon deposits. Accumulated carbon increases wear in the engine and decreases performance. Many racers don't worry about carbon because they run at continuous wide-open throttle & don't mind rebuilding their engines. The people on this forum aren't racers. They're low-budget performance enthusiasts who mostly don't know how to do a 2-stroke rebuild. The oil pumps were added by clever Yamaha & Honda engineers for one reason: increased engine life & reliability. The difference in reliability was so huge that most "premix" bikes like Bultaco & Montesa went out of business after Yamaha (and Honda) introduced oil injection. If you figure you know more than Honda, Yamaha, Suzuki, Hirth, Rotax, BRP, and the aircraft engine builders that insist on oil pumps for reliable engine operation, there's not a lot the rest of us can do to save you from self-destruction. As has been said before, you must have more "dollars than sense".

The oil pump was added for convenience only, and it works well at 50cc.

anything over 70cc needs more oil than the stock pump can provide.

When the throttle is closed, oil gas mix still flows through the bigger aftermarket pilot jet.

JJ has the stock carb on his "90cc" setup.

Is the stock carb the best for BBK's too ? :crazy:
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Re: Stock Oil Pump Delivery Ratio

Post by evilone » Mon Apr 30, 2012 9:32 pm

:crazy: JJ loves his oil pumps.
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Re: Stock Oil Pump Delivery Ratio

Post by Bear45-70 » Mon Apr 30, 2012 9:55 pm

JJ Joseph wrote:
Bear45-70 wrote:You trying to teach me about 2 stroke technology changes is like a 2 year old trying to teach grandpa.
There's no point. You're still a bit too young & belligerent. Not ready to learn anything useful. Now where's that nice snapshot that I had stashed away . . . Oh, here it is again:
I have children older than you, so don't ever call me young. Oh and I have forgotten more about two strokes than you will ever know.
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Re: Stock Oil Pump Delivery Ratio

Post by JJ Joseph » Mon Apr 30, 2012 11:39 pm

Bear45-70 wrote:I have children older than you, so don't ever call me young. Oh and I have forgotten more about two strokes than you will ever know.
Well, I'm over 70 so you must be a real toothless old fogey if your kids are older than me! No wonder you have so much trouble remembering stuff!

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Re: Stock Oil Pump Delivery Ratio

Post by Bear45-70 » Mon Apr 30, 2012 11:58 pm

You can claim any age, without outside support of your claim, aren't gonna buy it. But if you were 70 you would be smarter than you obviously are.
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Stock Oil Pump Delivery Ratio

Post by Madman » Tue May 01, 2012 4:00 am

Let me have a go, please. Stock oil pump stock engine! Simple

Larger engine requires more oil!

So per mix can control oil mix very easily.

So if my premixed Honda cr80 when I was a kid had a pre mix system why would that hurt my 80cc scooter, same principle!

And oil pumps are throttle controlled so they would have the same issue down hill as you say (jj says) unless you run throttle wide open down hill!!
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Re: Stock Oil Pump Delivery Ratio

Post by zadman2012 » Wed Jun 27, 2012 7:15 pm

Wow! what a thread! Ahem...
Soooo, if'n I were to ditch the pump on my aero80, and did 40:1, by what measure should I rejet? If I had a #90 with injection, do I go 95 or so for premix? Thanks.
I am looking to do intake and exhaust mods only... Bigger piston, maybe after the cylinder ovals... :)

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Re: Stock Oil Pump Delivery Ratio

Post by Rogerio » Tue Oct 30, 2012 5:22 pm

Just measured my pump (not throttle controled) flow ratio: 60 ml oil for 1,9 l fuel = 1/31,6 or 3,1% as we used to say here in Europe :thumbwink:

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Re: Stock Oil Pump Delivery Ratio

Post by JJ Joseph » Wed Oct 31, 2012 1:19 pm

Wheelman-111 wrote:If you plan to mod the scooter with a big-bore kit, pipe, etc., then a thicker premix ratio of something like 32:1 is the norm.
You don't need to increase the oil ratio just because you're running a BBK. The stock oil pump does the job nicely with even the 85cc (50mm bore) kits. Where you need more oil is when running high RPM mods. A BBK running at 9,000rpm doesn't need more than 50:1, but running at 12,000rpm (because of bigger carb and tuned exhaust) needs WAY more oil (30:1 is suggested by others). A regular street-type BBK will run for years with 50:1 premix or with the stock oil pump. Scooters are just the same as 2-stroke dirt-bike racers when it comes to oiling. The gas:oil ratio needed depends on the RPM you're running at, not on the size of your piston.

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Re: Stock Oil Pump Delivery Ratio

Post by 7m-iata » Sun Nov 04, 2012 8:10 pm

JJ Joseph wrote:
Wheelman-111 wrote:If you plan to mod the scooter with a big-bore kit, pipe, etc., then a thicker premix ratio of something like 32:1 is the norm.
You don't need to increase the oil ratio just because you're running a BBK. The stock oil pump does the job nicely with even the 85cc (50mm bore) kits. Where you need more oil is when running high RPM mods. A BBK running at 9,000rpm doesn't need more than 50:1, but running at 12,000rpm (because of bigger carb and tuned exhaust) needs WAY more oil (30:1 is suggested by others). A regular street-type BBK will run for years with 50:1 premix or with the stock oil pump. Scooters are just the same as 2-stroke dirt-bike racers when it comes to oiling. The gas:oil ratio needed depends on the RPM you're running at, not on the size of your piston.
This seems all fine and dandy, but what I've noticed everyone seeming to forget to mention is that when you upjet your carb to allow for more fuel you aren't adding more oil. So in essence the pump being able to deliver 50:1 mix from the stock pump on a stock jet is not able to deliver the same mix on a jet large enough to supply a 85cc BBK is now at around 75:1 or possibly even leaner. Am I the only one seeing this or am I wrong? I actually don't have much 2T background I've just done 4T fuel injection and turbos not 2T so this is al new to me, but common sense tells me that without modding the injection pump an equal amount to the jet you are in sense running leaner oil mixture even by just a little bit?!?

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Re: Stock Oil Pump Delivery Ratio

Post by JJ Joseph » Mon Nov 05, 2012 2:54 am

7m-iata wrote:. . . common sense tells me that without modding the injection pump an equal amount to the jet you are in sense running leaner oil mixture even by just a little bit?!?
Yes, but hardly enough to notice at normal engine speeds. Where you'll get into a whole heap of trouble is increasing the WOT rpm. Then the cylinder gets so hot that the normal oil ratio can't keep up. The piston will melt. At normal cruising speeds (less than 9,000rpm) you don't need to muck with the oil pump. Get a CHT gauge (not a bad idea anyway) if you're still worried about it.

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Re: Stock Oil Pump Delivery Ratio

Post by 7m-iata » Mon Nov 05, 2012 6:43 pm

I premix anyway I've had an oil pump fail with no warning on a stock cyl and sieze my engine, although I've always over revved my engines which probably plays a role in it. What rpm is s stock sa50 af05e turning at 50mph?

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Re: Stock Oil Pump Delivery Ratio

Post by paulpauly7 » Mon Nov 05, 2012 8:54 pm

around 11000rpm with the 12:1 gearing found in most afo5es
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Re: Stock Oil Pump Delivery Ratio

Post by JJ Joseph » Mon Nov 05, 2012 9:25 pm

7m-iata wrote:What rpm is s stock sa50 af05e turning at 50mph?
I be surprised if an sa50 could come anywhere near 50mph on flat ground! On the flat, a stock sa50 won't turn more than 8,000 rpm, even with a tailwind. paulpauly7's guess of 11,000rpm sounds about right to me, if you were on a long downhill with a strong tailwind. Even then, I don't think you could hit 50mph.

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Re: Stock Oil Pump Delivery Ratio

Post by paulpauly7 » Tue Nov 06, 2012 12:37 am

my malossi 47mm afo5e does 11150rpm at 52 mph with 12:1 gears its a heavly ported block and cylinder
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8.44 to 1
Michelin s1
71.3mph
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