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what type of fuel black devil


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What compression ratio is the BD? Does a high comp ratio justify the use of a higher octane fuel? I remember reading an article by an X-oil distributor who said low compression ratio motors use regular gas best and a high ratio can use - yep, a higher octane gas (which actually retards the spark?).

I use regular in me Solo 210 and high test in the Parajet - 2% TTS works well for this lad, I just multiply 10 liters by 2% and add 200ml to the applicable compression ratio of the day.


Marko D.

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Hi Marko,

I was told by the Manufactuer of my ParaMotor, which has a JPX Italia Corsair M25Y Black Devil 172.5cc 2-stroke (wow thats a mouthful) to use Super Unleaded, as it gives a bit more power at the high end. I have been running it that way since new.

This is also now confirmed by the UK importer (ConAir Sports Ltd) and is also in the manual.



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Yes Mike, the muscle cars of the 60's and 70's had high compression ratios like upwards of 10:1 and 11:1 and these too worked better with higher octane fuel. But to use high-test in motors with 8:1 is redundant and possibly counter-productive. Having said that, your motor is of the higher ratio if I remember correctly (she's all going fuzzy with age). The motor manufacturer, like you say, will yield the very bestest advice on octane grade and oil mix - at least that's who I go with.

Power Up

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thanks for help and disscussion so far. the manual for my cors air M 25 Y black devil describes the fuel in a number of ways as:

premium petrol 98 octane

97 octane gasoline

4 star (super) fuel

my question is this;

is this just American for normal unleaded petrol

their are two choices at my petrol station unleaded and super unleaded

which should i choose? Also, if either is ok, is there an advantage for using the more expensive super unleaded and what would that be?

thanks for help


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