Looking for information about the use of alkyl nitrates I have found the following link

www.patentstorm.us/patents/5782937.html

"Gasoline compositions containing ignition improvers" .
I have copied the following fragments:

SUMMARY OF THE INVENTION .
It has been discovered that the use of organic nitrogen-containing compounds selected from organic nitrates and/or organic nitro compounds, in gasoline, at specific treat rates, results in improved ignition properties and therefore benefits fuel economy, cold start ignition, lean burn, and emissions. Improved ignition properties are evidenced by the reduction or complete elimination of engine misfires. The addition of organic nitrogen containing compounds typically thought of as cetane improvers to gasoline appears counterintuitive. Since additives which increase the cetane number of diesel fuels are known to be pro-knock agents when added to gasoline, the discovery that the addition of an organic nitrate compound or an organic nitro compound to gasoline, at specific treat rates, will not negatively affect fuel octane and at the same time will improve the ignition properties of the fuel is surprising. The present invention includes fuel compositions comprising a major amount of hydrocarbons in the gasoline boiling range with which has been blended from about 1 to about 1000 ppm of at least one organic nitrogen-containing compound selected from the group consisting of organic nitrates, organic nitro compounds and mixtures thereof. Further, the present invention includes a method for improving the ignition properties of a spark-ignition internal combustion engine Another embodiment of the present invention is directed to a method for reducing misfires in spark-ignition internal combustion engines, In another embodiment of the present invention, the nitrogen-containing compounds are added to fuels containing a major amount of a hydrocarbon in the gasoline boiling range, in order to improve cycle-to-cycle variation. Cycle-to-cycle variations occur as a result of uneven combustion, either among cylinders, or for consecutive cycles for a single cylinder. The fuel compositions of the present invention promote a more even combustion and thereby can reduce the cycle-to-cycle variation. The gasolines utilized in the practice of this invention can be traditional blends or mixtures of hydrocarbons in the gasoline boiling range, or they can contain oxygenated blending components such as alcohols and/or ethers having suitable boiling temperatures and appropriate fuel solubility, such as methanol, ethanol, methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and mixed oxygen-containing products formed by "oxygenating" gasolines and/or olefinic hydrocarbons falling in the gasoline boiling range....

Therefore the alkyl nitrates ( that are using like cetane improvers in diesel engine) improves ignition, reduce cycle to cycle variation, and reduce misfires in a spark ignition internal combustion engine in the range of 1 to 1000 ppm. (1000 ppm = 0.1%)

Looking for the meaning of misfires a have found ther following from others links:

From:

http://www.autotap.com/articles/Anal..._Misfires.html "ANALYZING

IGNITION MISFIRES"
... No engine fires every cylinder 100% of the time. Misfires can occur at idle, when the engine is pulling hard under load, at high rpm and during throttle transitions as the air/fuel mixture changes. A few misfires are to be expected under these conditions, and should cause no major performance problems or significant increase in emissions. But if the misfires get out of hand and occur too often, they can make the engine idle or run rough, stumble when accelerating, waste gas and fail an emissions test....

And from other link:

www-chaos.engr.utk.edu/pap/crg-pre57.pdf
"Observing and modeling nonlinear dynamics in an internal combustion engines"

In real engines, not all the gases during are expelled during the exhaust process. The residual fractions which includes combustions products and tipically some unreacted fuel and air, is a function of engine design. Residual fraction is affected by several design parameters, one of the most important being valve overlap, the brief period that the intake valve is open before exhaust valve close. Valve overlap is generally helpful at higher engines speeds in producing power but al lower, near idle speeds tends to degradate combustion (ie increases cyclic variability = CV)...... The course of each combustion even can by followed by monitoring the internal cylinder pressure versus crank angle, as despicted in fig 1. As energy is released during combustion, cylinder presure excceds that wich occurs without combustion, thereby producing usefull work. CV causes non repeating preasure traces during successive engine cycles. The region in fig 1 in which the pressure traces diverge is the combustion region. In some cycles combustion is incomplete, leaving residual unburned fuel. In other cycles, excess energy is produced from combustion are undesirable because they produce alternating pulse of fuel and nitrogen oxides in the exhaust and a feeling of "roughness" to the driver.


Therefore alkyl nitrates due to that are ignition improvers, avoids the incomplete combustion, leaving less unburned fuel for the subsequent cycle, reducing cyclic variability and then avoid erratic idle or run rough, stumble when accelerating, waste gas and fail an emissions test.

These articles are referred to 4 stroks spark ignition engine. In 2 stroke glow engine appear in stronger way the mixing of fresh fuel with unburned fuel and combustion residues due to the operation simplicity of 2 stroke engine ( you can put your hand near the exhaust), and the chemical action of alkyl nitrates ( in the range of 1 to 1000 ppm), increasing the ignition speed without negatively affect to fuel octane, must not be affected by the kind of engine.

From:
http://www.freepatentsonline.com/4457763.html
Diesel fuel cetane improver:
...The amount of cetane improver added depends on the type of fuel being used, the initial cetane value, and the amount of cetane number increase desired. Alcohol fuels such as methanol, ethanol, isopropanol, isobutanol, hexanol, and the like, have very low cetane values and large amounts of cetane improvers are required. A useful range in which to operate is about 5-25 weight percent cetane improver.....

5-25 weight precent is to much than the range that it is used in spark engines
(1 to 1000 ppm) 1000 ppm = 0.1%
Due to that it is not expective a negative effect on the octane of methyl alcohol that on the other hand , has an octane of 105 (very hight)

This mechanism could explain the inclusion in the first link that you have enclosed
http://www.turbofast.com.au/racefuel.html
of nitrobencene like ignition accelerator

This could explain the effect that we feel that happens since more than 3 month ago with the use at 0.1 % of methyl nitrate and or amyl nitrate in the fuel. (improving in running, start easy and acceleration)