Ethanol Gas

[HarleyCreation]

Originally posted by T. Cotten
Additives may sooth a symptom, but if a motor is over-heating, the cause is most likely a mechanical problem that cannot be fixed out of a bottle.

....Cotten
(Exception: military leg guards are a non-mechanical cause of overheating. I guess so is two adults, two children, and full camping gear load on a sidecar facing a 40 mph headwind on the Interstate. )

Flatheads seem to have special problems in that they seem to locally overheat around the exhaust valve area and such "hot-spots" can result in piston failure. Like you say, bolting on a sidecar, two-up, wind- or leg-shield, and a lean mix adds to the problem. No oil on top running thru the head makes matters worse.

Not to say that flatheads aren't nice motors. Easy to start. Simple. And like Uke said: "Mighty looking like a locomotive!"

[HarleyCreation]

Re: Re: Ethanol Gas

Originally posted by AFJ


This [adding oil to gas] was a reccomendation when some of these [side-valve] engines were new and it appears that modern gasolines may have even less lubricity, in part due to the alcohol content.

AFJ

AFJ (or other forum members):

Can you document an early rider's handbook or other literature source that recommends using an oil-gas mixture in the side-valve/flathead engine?

It's a small point, but important as it may demonstrate that there was an admitted weakness in the flathead engine when they were new and the current standard motor of 2 U.S. manufacturers.

That may become significant, perhaps, if a guy were going to write a 70th anniversary 61/74 OHV story......

[Kojack]

One thing I remember reading a few years ago stated that adding more oil to a two stroke mix has the effect of leaning the mixture. Two stroke racers found this out the hard way after seizing pistons and adding more oil thinking that would solve the problem. The leaner mixture made the pistons seize even more quickly. I don't remember the exact reasoning but it had something to do with the less combustable oil taking the place of more combustable gasoline.

[HarleyCreation]

Originally posted by Kojack
One thing I remember reading a few years ago stated that adding more oil to a two stroke mix has the effect of leaning the mixture. Two stroke racers found this out the hard way after seizing pistons and adding more oil thinking that would solve the problem. The leaner mixture made the pistons seize even more quickly. I don't remember the exact reasoning but it had something to do with the less combustable oil taking the place of more combustable gasoline.

That is a HUGE point of argument and controversy on the chainsaw forum between 2 schools of thinking: one that believes a little more oil in the gas mix is better for the motor and another school that thinks less oil is better.

(More being in excess of the normal 50:1 factory spec ratio and less being the standard factory 50:1 ratio).

They go back and forth, back and forth, and neither side can convince the other who is correct.

There is no doubt that the fresh incoming gas charge has cooling effect upon the combustion chamber and esp. on the top of the piston. Some feel that more oil in the gas detracts from that cooling effect. Others feel the extra lubricity of more oil is worth it.

On the 4-stroke flathead it seems possible that oil in the gas might give the top ring and the valves & guides added lubrication where it is most needed.

Going by memory here, but I think the steel strut in the Harley-Davidson piston was originally intended to help stop piston failure in the old side-valve engine.

[servicardenise]

ethanol/additives

The last time I rebuilt my 45 it had small areas on the valves with deposit on them. It looked similar to arc marks, I was using some well known fuel additive. I speculate that the additive might have been the cause. Has anyone ever seen something similar to this? Regards, Denise

[Kojack]

"On the 4-stroke flathead it seems possible that oil in the gas might give the top ring and the valves & guides added lubrication where it is most needed."


The bad thing about top oil is that it contributes to extra carbon build up. That in itself was recognized as a cause of overheating and burned valves on the old flatheads. Owners manuals routinely mentioned engine dissassembly for carbon removal or de-coking. The old Indian 741 manual mentions a bunch of possible causes for overheating and burned and sticky valves but they don't recommend adding top oil. I agree with Cotton that intake leaks probably cause more overheating problems than anything else.

[HarleyCreation]

Originally posted by Kojack
"On the 4-stroke flathead it seems possible that oil in the gas might give the top ring and the valves & guides added lubrication where it is most needed."


The bad thing about top oil is that it contributes to extra carbon build up. That in itself was recognized as a cause of overheating and burned valves on the old flatheads. Owners manuals routinely mentioned engine dissassembly for carbon removal or de-coking. The old Indian 741 manual mentions a bunch of possible causes for overheating and burned and sticky valves but they don't recommend adding top oil. I agree with Cotton that intake leaks probably cause more overheating problems than anything else.

Yeah, intake leaks and a lean mixture. That is also a huge bug-a-boo in the chainsaw realm. I fried one chainsaw that way myself. No motorcycle engine that I know of altho I've broke a few.

Modern 2-stroke oils (esp. synthetics) claim to be low ash and create few combustion chamber deposits and are also low smoke. They do seem to be very clean burning. But any kind of top-end oil that would leave deposits in the engine would be a bad thing.

[HarleyCreation]

Re: ethanol/additives

Originally posted by servicardenise
The last time I rebuilt my 45 it had small areas on the valves with deposit on them. It looked similar to arc marks, I was using some well known fuel additive. I speculate that the additive might have been the cause. Has anyone ever seen something similar to this? Regards, Denise

Usually a motor with miles on it will have some crud/deposits you have to clean out. But as others have stated, fuel additives may increase them.

BTW: from one Servi-Car owner to another: Welcome to the Forum!

[T. Cotten]

Pitting upon the valve faces and seats is quite common even in OHV's when temperatures get elevated to near what Flatties consider optimum.
Indeed, it is "arcing" of a sort, in that the valve and seat are momentarily welding to each other at that spot.

This seems to occur to the greatest degree with valves of certain stainless steels: The nickel in them has great affinity for the castiron seats.
And often the valveguides as well, which naturally go first.

It seems unlikely that any additive would aggravate it, nor any that would prevent it, although tetraethyl lead was supposed to do just that, by insulating the metals from each other, but still allowing heat transfer.

....Cotten

[Paps]

Cotten....your nickel comment is especially true. Why else would nickel rod be used to weld up iron castings ? Because it bonds to it so well. Paps

[swall]

No conection to the use of nickel rod (Ni-rod 55, Ni-rod 99)for welding cast iron and stainless valves sticking to iron valve seats. Ni-rod works because the nickel content prevents the formation of carbides when the molten cast iron weld solidifies. Also prevents cracking of the weld deposit and heat affected zone. Valves momentarily sticking to seats is due to adhesive wear, a form of solid state (no melting) microscopic welding that occurs under intense heat and contact pressure.Adhesive wear is also known as galling. Prevention of adhesive wear between the valve and the seat requires proper selection of the valve alloy and seat alloy. Fuel type is also a consideration. Valve and seat combinations that work well for unleaded fuels do not necessarily work well for leaded fuels.

[HarleyCreation]

You guys are getting into areas way beyond my expertise, but I still find it interesting.

Seems like whenever you stray inside the combustion chamber and start discussing fuels, oils, and the (dubious) merits of additives in relation to engine failure controversy reigns.

[servicardenise]

Harley Creation, Thanks for the welcome, It is rather cumulous to me as well. I don't want to go there due to the lack of combustion knowledge and regarding the use of additives. BTW rocks, nice folks I hit the Western PA trike in at Kane, PA. Denise

[T. Cotten]

Swall!

I appreciate the insights! So it is still a welding of sorts, and still dependent upon alloys.
Is SS valve/softiron guide galling considered induction welding as well?

And HarleyCreation wrote:
"Flatheads seem to have special problems in that they seem to locally overheat around the exhaust valve area and such "hot-spots" can result in piston failure."

Indeed Flatties run at a much higher optimum temperature than OHVs, and distortions of the bore and valveseats are much greater. This gives the hardware a harsh environment and narrower window of survival, yet the machines proved incredibly durable and long-lived when all is in order.
So for a hot spot to destruct a piston, or even accellerate wear, something had to go wrong to spike the temperatures.

Personally, I am still at a loss to explain why even when all is in perfect order, the front "runs hotter" than the rear.


...Cotten

[swall]

T.Cotten--no such process I am aware of called "induction welding". There is, however, induction brazing where an induction coil is used to heat the parts and allow the braze filler to melt. Perhaps you were thinking of induction hardening, used by the automakers to harden cast iron valve seats for use with unleaded gas. Now more about wear--despite the 70 or so years of metallurgical research on this subject, selection of metals for wear situations is still a trial and error process. There is no magic formula to predict what will work and what won't. With valve guides, the coefficients of expansion and the thermal conductivities of the metals used need to be considered. If a valve stem expands relative to the guide I.D. it could be that the stem is momentarily siezing in the guide due to a loss of clearance.Loss of clearance could also prevent oil from getting to the guide I.D. Was there a specific problem you had? Maybe the bulletin board needs to have a "cylinder head" forum?