Wow - what difference a little oil makes

[Whit]

Many moons ago Debbie informed me that I should oil my slip on air filters. Well I finally got around to it this weekend and the poor power at low RPMs went away. The bike now has good power at low RPMs but after about 30 miles it started to run poor. Looked at plugs and they looked fouled. Replaced them and now it runs better than ever. I still may be too oil rich as I left a smoke screen that almost stopped traffic when I left the neighbourhood. I may look at fiddling with my oil pump settings this weekend. I know Allan has indicated in the past that the original oil settings can be cranked back today with modern oils, its just a little scary to reduce oil output. ///Pat

[Suzsmokeyallan]

Pat that was a Buffalo i was referring to, for a Titan the Titan gurus will have to step up and give their opinion on the exact setting they are using.

[tz375]

Oiling foam and pleated paper filters is necessary to get fine dust to stick to the filter oil. if it's done right, pod filters should still flow slightly better than stock filters and motors typically run slightly lean c/w stock.

Too much oil and air flow is partially restricted and teh bike runs rich. The symptoms described tend to indicate a bike that is running rich and sounds like the filters may have too much oil on them.

I'd focus on getting the jetting and filter combo spot on first.

The next question is whether or not the oil supply can be cut back with modern oils and the jury is still out on that one. More oil seals the rings better and makes more power. Less oil = less smoke in theory, but less power (not more) and am motor that tends to run hotter.

Manufacturers tend to be slightly conservative with their settings and if you are nor riding across any deserts, you can probably cut back the pump slightly.

[H2RICK]

Whit, there is NO hard and fast rule about cutting back your oil pump output because every bike is that little bit different and every combination of local gasoline and brand of injector oil is also different....soooo.....
What I do is set the pump to the stock settings as a starting point and then reduce the output in small increments by adjusting the pump cable adjuster in the lean direction by ONE-HALF a turn of the adjuster for each test/trial run. Take the bike for a good thrash and then check the plugs. Still too rich (which it probably will be, depending on which oil you're using) ??? Then lean out the pump another HALF TURN on the adjuster. Keep doing this until you're happy with the plug readings in ALL throttle settings.
Caution: For this method to be successful, you must make sure that your air filters aren't over-oiled, your timing is as close to perfect as you can get, you have NEW plugs installed with correct gaps (at the start of the process) and you MUST use the SAME injector oil AND same gasoline throughout the whole series of tests.
Yes, the whole thing is tedious and time consuming.....but it's cheaper than ventilated pistons and scored barrels, IMO.

[Suzsmokeyallan]

Richard

More oil seals the rings better and makes more power

This is true in a real world scenario but can also lead to gumming of the rings in the grooves which causes poor sealing and sticking rings.
Remember this is not a race motor, only a stock road motor which will not be revving at high rpms constantly to clean away the excess oil.

Suzuki had the bikes at around 20:1 as a stock setting back in the day, but a 32:1 ratio is more suited with the newer oils.

Rick your method is tedious,,,,BUT,,,, its the best way to get the setting as close to perfect as possible. The thing is you are then bound to use that brand of oil for the sake of maintaining that type of plug reading with the grade of gas you're also using factors in as well.

[tz375]

More oil does not lead to gummed rings or poor sealing. Within reason, the opposite occurs. Cleaner rings, less blowby and more power and better economy - albeit at the cost of maybe some smoke.

Why are people so obsessed with using less oil (apart from cost & pollution that is)? I have yet to see a definitive study that shows less oil improves anything.

[Suzsmokeyallan]

Richard I'm sure you have your reasons, so can you shed the light on this simple scenario that goes against what you are saying.
A 32cc two stroke piston port engine fitted to a grass trimmer is brand new and run on a 20:1 ratio. After about three months of use the muffler is clogged, the compression is weak due to sticking rings, and the combustion chamber and exhaust port is choked with carbon.
The engine is pulled down and all the parts are cleaned of the oily carbon buildup and then run on a 50:1 ratio.
Here we are now about 5 years later and there is no oily buildup and hardly any carbon anywhere in the engine.
Nothing was changed in the overhaul the same parts were cleaned up and reused.

[tz375]

Allan,

One could speculate, but I have no knowledge of your garden implement on which to base a hypothesis.

I could, however, probably point you to a couple of studies conducted by people far more qualified than I as to why in general, and within reason, more oil makes more power and leads to a cleaner engine in motorcycles.

If that weedwacker worked better with a different ratio and you are happy with it, then I'm happy for you. Was it oil quality, operating temperature, loads, run cycles? Who knows.

Maybe 20:1 was just all wrong for that motor and was an excessively conservative number from the factory.

BTW, what is the average oil:fuel ratio on a GT750 that you would like us to compare that number to? I'd venture to suggest that a GT at 1/3 throttle and modest cruising RPMs is probably around or greater than the garden tool.

[Buffalo-guy]

Just to shed a little personal light on this debate, my experience with my stock 72 buffalo is somewhat interesting. I compute mileage in imperial MPG, based on 160 ounces, I average about 55 MPG at cruising speed (say 60- 70 mph). I use Amsoil HP injector oil at 32 oz, and get at least 700 miles per quart. When you do the simple math, that comes out to about 63.6 to one ratio. At cold start up there is a light haze visible, and at cruising speed, there is none. This setup seems to work, and the numbers make sense to me. I suspect that If I was to use the throttle more, the numbers would go down, but this is somewhat indicative of the average. It would be interesting to see the consumption numbers of CCI Allen, the Marathon Man, to get some alternate numbers to play with. Food for thought. Cheers.
Fred

[Suzsmokeyallan]

Ok Richard lets bring this right into the Suzuki arena then and forget what ive seen repeatidly in grass trimmers and other small sized general purpose engines.
An RM 125 was run with an even richer oil mix at 16:1 and the results were not impressive. This mixture damaged a left crank main journal where the main bearing sits by allowing it to spin on the bearing, the engine also sounded noisy mechanically in the bore and smoked a lot obviously.
It was a new crank that got damaged and on new bearings too, and yes the fit was to spec before it was assembled.
ANOTHER new crank and new bearings were fitted and the engine run on a 32:1 with nothing more than a main jet change and pilot setting revision.
The top end was left as it was to see how it would sound with a changed mixture ratio, instantly the whole engine had more power was mechanically silent in the bore and lower end obviously, and smoked less with less carbon buildup etc.
The engine had no further issues and the left journal stayed tight with the correct interference fit of the bearing to journal.
I'm not claiming i have all the answers on this topic but i know what ive seen repeatidly and in this case and many others, adding more oil has not shown me any benefits.
Using more oil has actually caused me money and unecessary repair work, so to these plain facts i base my findings.
32:1 seems to be the most common ratio in use today and most manufacturers recommend it.
Lets agree to this,,,, you like more oil and i use less,, hey it works for me with no ill effects.
I'd like to hear again from Iron Butt Allen as hes got over 100.000 miles of proof on a few Buffalos hes owned.

[tz375]

Allan,
How do you believe that oil managed to damage main bearings. That is preposterous.

Let's keep this to GT's shall we.

So using your logic that 32:1 is the new magic number, we should all increase our GT oil pumps to pump more oil to get them up to 32:1 instead of say the 64:1 that Fred calculated. Yes?

Or are you suggesting we should all change our other premix bikes to 64:1?

Of course both are a little silly, so let's get back to basics.

The answer I came up with for a GT is to use a modern oil at the stock settings. For a racer 30/32:1 is probably fine without the pump, and with modified main bearings.

Could you get away with less oil? Probably? Would that leave as much margin of error? No. Can you save some operating expenses by running less oil? Absolutely? Will it bite you in the long run? Perhaps.

For most of us, oil consumption is a very small part of our annual motorcycle expenses and saving half a bottle a year is probably not a major issue either way.

So we absolutely agree that you want people to reduce the already meager oil consumption (Fred's 64:1) and take that risk, and I consider it to be folly.

What people chose to do is up to them, but seriously when will the myth of high fuel:oil ratios ever die? It's about as relevant as Big Foot or the Loch Ness Monster. At least the latter I could believe in and so far they have been unable to prove that it does not exist.

[Suzsmokeyallan]

Richard I'm hoping you are aware that the more oil you add into a PRE-MIXED ratio is actually going to a leaner mixture. This situation creates added heat within the parts that causes expansion of a greater value than their designed operating parameters.
If you wish to run more oil in a premix only engine you have to go to larger jetting sizes to allow the higher content oil in the fuel to pass freely through the carb orifices.
You would know this simply by the fact of jetting changes are needed to smaller sizes as you reduce the ratio of oil in an engine using premix.
Since engines running on a premix ratio such as off-road motorcycles, they are jetted for a factory set mixture ratio. Stepping out side of this requires average to massive carb rejetting changes.

A system such as the CCI type is not a fixed premix ratio so falls under a slightly different heading. As you know its a variable delivered metered mixture since the pumps delivery is not constant.
As Fred pointed out hes technically measured 64:1 at cruising conditions, which happens to be in the very minimal delivery slope on the oil pump output of bikes such as the GT750.
This condition he references to would relate to riding on a level road in high gear, at minimal engine load and throttle position
This however does not compute as a static figure since it changes with throttle and pump output position, and as you know, the delivery figures do change gradually until the pump reaches full output delivery.
Again Fred stated it as correctly where there's a slight haze at start up till the residual oil in the lower crankcase clears up once the engine warms. At cruising you should not see any visible smoke, but with a high gear roll on, some slight visible smoke output should be constantly seen.
The back of the baffles on Freds GT750 are just like those on my stock 76 Buffalo, slightly damp but not wet, with no splatter around the pipes or on the bike.
Its possible to get the plugs to burn with a medium tan colour on the centre insulator with a slightly darker brown around the edge of the plugs earth.
I know the 16:1 ratio damaged that engine, the reason being the fact the leaner mixture and hotter running temps created by it allowed the bearing to spin on the shaft journal, the right side couldnt do it as it runs in the gearbox oil.
Remember the carb jetting was still stock and designed for a 20:1 ratio using the older dino oil, and not a 16:1 ratio.
I never said 32:1 is a new magic number, I merely stated that 32:1 seems to be the industry standard, something that was not very common 20 plus years ago.
The issue here being raised is nothing to do with saving CCI oil or its cost, its to do with getting as clean a burn in the combustion chamber as possible under all road going conditions and nothing more.
If you just crank up the pump you will smoke up the place, add carbon to your engine and actually lose performance by fouling plugs clogging up your baffles etc.

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