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Thread: Single spark 1400 motor is now running...

  1. #1
    apriliaforum expert pete roper's Avatar
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    Single spark 1400 motor is now running...

    Took longer than expected and was a fair bit more complicated than we thought it might be. Should be ready for mapping next week if all goes according to plan. It's in Mark's Griso so it's all set up for logging purposes. Let the fun commence!

    Pete
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  2. #2
    apriliaforum expert bloodnutt's Avatar
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    Awesome Pete.
    As they say in drag racing "Ya can't beat cubes".
    Got any pics ?
    Do not go gentle into that good night,

    Rage, rage against the dying of the light.

  3. #3
    apriliaforum Junkie
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    What makes it "single spark?"

    As in, not multi spark?
    Last edited by Chris Wilson; 11-20-2017 at 01:47 PM.

  4. #4
    apriliaforum expert pete roper's Avatar
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    Cali motor runs twin plugs Chris. The 1200's only run one.
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  5. #5
    apriliaforum Junkie
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    My standard 1200 heads have twin plugs.

  6. #6
    apriliaforum expert pete roper's Avatar
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    I thought you had a Bellagio?
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  7. #7
    apriliaforum Junkie
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    Quote Originally Posted by pete roper View Post
    I thought you had a Bellagio?
    I do, and when I bought it, it was advertised as having 1200 heads and barrels with an 850 crank.
    If it doesn't then I want my money back!

    Back on topic, why delete one plug per head?

  8. #8
    apriliaforum expert pete roper's Avatar
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    They didn't, one was added for the 1400.
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  9. #9
    Honest always, feared often Micah / AF1 Racing's Avatar
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    Twin plugs in a 4 valve head with one located centrally are completely non beneficial for anything other than cleaning up a tiny fraction of emissions bs. Think about it, 4 valve head, plug located in center...flame front effectively reaches extent of travel in same amount of time no matter since the second plug located next to the cylinder wall. Keep us posted...maybe with some pics too? So this is a 1400cc Griso conversion, sounds very cool!
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
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  10. #10
    apriliaforum expert pete roper's Avatar
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    Yup, I'm not going to give too much away because there has been a history of my generosity being exploited by assholes but I'll copy you in on a run down of the details I'm preparing for some mates. Just let it be said its a long way from being a simple drop in big pistons job.

    Pete
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  11. #11
    Honest always, feared often Micah / AF1 Racing's Avatar
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    Cool. I have no intention of copying your work Pete, it is just a fascinating project to me. I get it though, I have seen pics and posts using wither my words or photos distributed all over the net to make other people money or give them credibility.
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
    AF1 Racing
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  12. #12
    apriliaforum Junkie
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    Ok, I see what you are getting at now Pete.

    I was under the initial impression that the Cali had multi-spark technology (firing the same plug multiple times during that stroke).

    Anyway, having a central plug and an offset plug in the same head can be of benefit if the intake charge is directed towards the average centre between those plugs and not the geometric centre of the head volume. In other words the intake charge is deliberately directed towards the outside of the head by virtue of the curved manifold creating a horizontal swirl.

  13. #13
    apriliaforum expert pete roper's Avatar
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    That old chestnut!

    Nah. With a 2V Hemi head combustion chamber there are benefits as, especially in high compression engines the poor old flame front has to traverse an alp of alloy which takes an age so having flame propagation on two fronts can be handy. With a modern combustion chamber with four valves and a compact pent roof combustion chamber with a narrow included valve angle an extra plug will do very little.

    I was told by a Piaggio suit that the reason they stuck an extra plug in the Cali 14 was to combat 'Surging' at idle and low RPM. I now think that this was simply the usual Piaggio suit mouth-flap as the single spark 1400 betrays no such conditions. While there may be a very minor benefit as Micah mentions to combatting end gas issues and maybe reducing oxides of nitrogen I actually think that the main reason they twin plugged it, (The second plug only fires at lower rpm.) was to make the wretched engine shake at idle so it would bounce around in its rubber mounts 'Like a Harley'! Which is pretty damn sad but it would fit right in with Piaggio 'Groupthink'.

    As it is the main challenges to the Guzzi design, in both 1200 and 1400 forms is not the number or location of the plugs but the fact that it combines that very nice, modern, combustion chamber with a side draft intake and exhaust set up. Combine this with the weirdly long duration and overlap and you end up with a motor that is to be honest, pretty lousy in terms of volumetric efficiency and why if tuning via specified AFR's conventional wisdom has to be thrown out the window due to charge transition issues! If you want an 8V Guzzi to run like a sack of shit and drink fuel all you need to do is stick a short, open pipe on it and rev the tits off it.

    pete
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  14. #14
    apriliaforum expert pete roper's Avatar
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    Well, it went home today. Map development will now commence but we went out for a 100km flog yesterday and nothing leaked, fell off or blew up! Then we adjourned to the Royal for a celebratory ale!

    The 1400 with my 'Tree Frog' behind it and Michael's blackie in the background.



    First impressions running a barely modified 1200 Hi-Pipe map are favourable!

    Pete
    Professional Goat Burster.

  15. #15
    apriliaforum expert rdbandkab's Avatar
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    Awesome! Makes one think of the possibilities... Breva 1400?
    02 aprilia Futura
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