Wow - what difference a little oil makes

[h2okettle]

I have put a 158K miles on my buffalos in 5 years.. Mine is a 74 L model with stock jetting.... At 84K miles I did a rebuild on one, but it was a crank seal that finally went. When I pulled it down the bearings, pistons and rings were still in perfect condition... My oil pump setting is as far leaned out as the rod will allow.. It hits the back of the case. My spark plugs are a nice tan color. I get close to 900 miles to a quart of Suzuki CCI oil. The bike does smoke a little when first cranked, but clean as a 4 stroke after its warmed up.. I have over 114K miles on it now. In my (unprofessional) opinion the factory setting is overkill.. In the beginning (stock setting) my pipes would drip oil out the back.. This was my reason to lean it back.. It has worked very well and I have not had any engine problems.

Allen....... GT rideaholic

[tz375]

Allen,
Thanks for some real world experience to think about.

Allan,
Good point about pre-mix jetting. Sounds like you're saying that the reason those main bearings failed wasn't the amount of oil but was the fact that it was jetted too lean on stock settings

That's always a possibility.

Let's explore that "massive jetting change" you mentioned. So let's say my TZ250 was supposed to run at say 25:1 and I changed it to 30:1. Which is a pretty big change. Ignoring the fact that competition motorcycles are typically jetted way safe (rich) for a moment, at 25:1, for every liter of fuel) mixture, 1/25 (4%) is oil and 96% is gas.

At the new ratio of 30:1, the oil is reduced to 1in 30 or 3.33% and fuel is the remaining 96.667%.

That's a change of 1.667 percentage points, or 1.75%. Now let's say for simplicity sake that I was running a 200cc/minute main jet. I would have to adjust it for the extra 1.667% of gas which is more or less a jet change of 3.5 from 200 to 196.5. So maybe I'd leave it at 200 and maybe I'd try a 195. In reality, I can't jet that close to perfect, so I would probably leave it alone.

Now let's try changing from say 32:1 to say 50:1. that's a change of about 2% in fueling or 1 jet size. not "massive" at all.

Yes you are right that when experimenting with changes in oils and fuels and ratios, one must be aware of the related effects, but it is a second order effect.

As for 50:1 or 32:1 being a "standard", I don't think there is an industry standard, though it is possible that some manufacturers are using the same numbers now. TZ and RS race bikes are still around 32 to 1, but they have not been manufactured since 2003/2009. There are so few bikes that use pre-mix today that it's a largely irrelevant concept unfortunately.

If we wanted to define a standard for modern bikes, it's possible to study all of the bikes around and categorize them and average out the oil:fuel ratios. I'd be surprised if they all came out at 32 or 50:1 but that's fine if they do. They are modern bikes made with modern machine tools. We're dealing with almost 30 year old dinosaurs. Unfortunately such a study wouldn't get much data we could extrapolate to a street GT.

Some people ride hard and some ride smart. Some have well set up bikes and some don't. Some jet close to the edge and run lots of advance and use low octane gas. Others set timing sensibly, jet safe etc.

Some are geared high and load their motor, and others let them spin at higher revs and lower loads.

Iron Butt Allen rides huge distances and manages to run a lower pump setting that stock. Some people like "good" oil and some of use whatever is on the shelf.

As for reading plugs, let's take that one up as a different subject. Plug reading has to the next most misunderstood issue with two strokes.

And back to the original post........There is little we can extrapolate about oil:fuel ratios that has a lot of relevance to oiled air filters.

Besides, everyone else is probably getting bored with this.

[Barry S.]

I have a new aftermarket filter in my Buffalo and at first I oiled it like I did my dirtbikes, saturate it with the same sticky oil I used on dirtbikes and blot out some with paper towls. It was OK around town but when I went to the mountains and got about 3 or 4 thousand foot up it would smoke heavily and blow oil all over the pipes and the rear fender. It would leave a trail where nobody would want to ride behind me. After that I cleaned and oiled it with 2-stroke oil and backed the fuel screw out to 1/4 turn and it cleaned up considerably. I run Penzoil semi-synthetic outboard oil with the pump cut back somewhat but not bumping the back of the cover like Allen does.

[h2okettle]

My bike is usually set up for touring with the hard bags, tailbox or a fuel cell.. Plus a passenger.. My gearing is now 15/43 (stock was 15/47).... I did that gearing just before I rode to see Allan and H2Rick in Canada last August...Before that I was runing 16/43.... my bike is loaded heavily, but the engine is not really straining.. My rpm at 70mph (GPS) not speedo, since it lies... is 4K rpm.. I also live in Florida at sea level, and below sea level at high tide.. Basically no mountains.. But I did go to the highest point in Florida (345 feet)... Where I am going with this is the mountains change your lean/rich conditions with altitude.. like when I went and rode to the top of Pikes Peak in Colorado I had to use more throttle to maintain speed, so more oil was used and it did struggle going up to 14100 feet..
I also used to use Honda GN2 injector oil which ran very clean, but the downside was it is "clear".. So in the oil window in the tank you could not see it.. You had to pull the side cover to check the level.. I have no fear of damaging the engine with the lean pump setting, specially after splitting the cases when the crank seal went bad and the motor had virtually no wear... This was the first time ever the engine had work on it other than tune ups.. The compression was still 122-125 psi, the clutch plates had .003 wear as compared to brand new ones.. All this at 84K miles and loaded down most of the time.. Not sure if any of this has any meaning on what ya'll are talking about, but I am learning to type with two fingers now, and with the low numbers of posts I have I did not want to have my membership canceled due to lack of participation

Allen...... Heavy smoker........ GT brand !!

[Suzsmokeyallan]

Richard thanks for your input as always,, you do like a good banter but as you said this is not really going anywhere, so i'll leave you to your ideas and I'll stick to mine.