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Thread: Polini, Briggs and 447

  1. #11
    Diamond geezer 500 Club
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    Polini, Briggs and 447

    And to me the scent of a 2 stroke is such a nice thing...each to there own I suppose.

  2. #12

    Polini, Briggs and 447

    I'm thinking of the polini for the Dragonfly. Cruising at 37mph it presumably won't be an awful lot worse than the Bailey which is 3 litres per hour but working at 75% throttle to manintain height. The polini should allow a very short take-off run, and should take just a couple of minutes to get up through a hole in clouds
    Mike

  3. #13
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    Polini, Briggs and 447

    Nick, indeed, I've assumed there must be people that like the smell of petrol and oil. Clearly an acquired taste!

    And not what I think of when I read "When once you have tasted flight..." :-)

    Mike

  4. #14
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    Polini, Briggs and 447

    peter.finlay@nov.com[/U]

    [3]Cheers,[/3]

    [3]Pete[/3]

  5. #15
    Diamond geezer Banned500 Club
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    Polini, Briggs and 447

    That sounds encouraging, it seems that with the latest model they are trying to address the carb problem, friends in the paramotoring world seem to rate the Polini. Is the new carb adaptable to your engine?

    The combination of lightness, smoothness and power could make it ideal for SSDR use

    Ginge

  6. #16

    Polini, Briggs and 447

    Its the same carb. Jetting may be different though. I believe its set up quite rich to help cooling on the 200.

  7. #17
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    Polini, Briggs and 447

    Hi Guys,
    The Polini can come with two carb types, the conventional PKW carb or a Walbro, Iím not sure what carb goes with what engine capacity, but my Thor 200 has the PKW carb.
    Paul, you are correct in saying it comes from the factory set rich, so rich it will hardly run. The EGTís show this well. I have dropped the idle jet right down to a 35 and it still starts first time with little or no choke, Iíve just ordered a 30 along with some smaller main jets so should get better fuel economy and an EGT around 580 Ė 620 across the range. Still have a very small hot spot mid range-ish, this may need a slightly different needle profile or different slide cutaway to cure, but itís me just being anal! Ben will confirm this attribute!! The needle is set to its second from the top slot & I should be able to drop the needle right down, but only once I have cured the afore mentioned hot spot.
    The Thor 200ís manufactured before March of this year have got a factory mod sent out that lowers the compression & alters the reed valve movement to help address some of the ďpiston melting problemsĒ that some of these engines have had. The newer ones have this mod done to them. These problems have mostly been in the paramotoring world, but in a lot of these cases its guys who have altered the carb settings and not had an EGT fitted to see whatís going on in the engine. Iím sure this might not be the case with them all, so I apologise now if I have upset any of our paramotoring friends who might read this.
    Working with Pat Gardner, who also has the same engine in his Dragonfly, we have had identical EGT & general running results from adjustments made which confirms a good manufacturing consistency, well done Polini!
    I think we are now close to getting the carburetion perfect; I am now going to start playing with Lord engine mounts to make an already very smooth running engine silky smooth to the point where you will hardly feel it running, as Ben said, ďanal!Ē But thatís what I love about SSDR, you can tinker to your heartís content and as Iíve just bought a lathe & milling machine, I have to do something with them!

  8. #18
    Diamond geezer Banned500 Club
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    Polini, Briggs and 447

    Ah that may explain my misunderstanding, the engines that I saw were equiped with the Walbro carb, this was giving mid range problems. One guy was experimenting with a Bing which he claimed was looking promising.

    Ginge

  9. #19

    Polini, Briggs and 447

    The three 200's we have on Dragons all have the float bowl PKW carb and ditto the 250 we are fitting. Looking at the website it seems the Walbro is an option on the 200 - but listed as though the standard supply is the PKW. Standard on the smaller engines though.

    My laymans thoughts are that diaphram carbs like the walbro are OK on smaller engines, but show their weakness on larger engines and arent as accurate at mixture settings and dont have the adjustabilty for optimum setup across a range of RPM and loadings.. - good for flying upside down though...

    Paul

  10. #20
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    Polini, Briggs and 447

    Paul

    " - good for flying upside down though..."

    You have just reminded me why I have a Tillotson on my NMZ201:-)

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