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Thread: ESE's works engine tuner

  1. #31
    Join Date
    18th May 2007 - 20:23
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    RG50 and 76 Suzuki GP125 Buckets
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    Auckland
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    Quote Originally Posted by F5 Dave View Post
    The correct compression ratio is the one that best matches the bike, there are other compromises that in isolation may appear best, stinger size (or steep baffle), general pipe, ignition, head shape to name a few.

    Primary compression is another compromise & which way it is approached has different benefits, the Honda or the Yamaha route (some way back) was high crankcase compression for more pumping efficiency (the crankcase is afterall just a pump) or more volume & let the pipe do the work.

    Yes! I agree its the compression ratio that best matches the bike thats needed, and its the Black-Art fitting it in with all the other compromises.

    It could be said the "Black-Art" is the tuner who compromises best, wins!

    From what I've read. The high crankcase compression bikes have high but peaky power and the more volume & let the pipe do the work bikes have lower but wider power bands.

    My bike is of the " more volume & let the pipe do the work" approach/compromise for the gear box it has and Kart tracks.

    After Taupo and when we have got it going properly we are thinking of taking it to a Pukekohe Track Day. Ride in the slow novice class and see if we can crack 100MPH.

    If we can pull that off, the plan is to then fit a fairing and run it in the GP125 class with the aim of a fast start and coming around mid field on the first lap. I know I can make real fast starts and wouldn't that give them the shits. A bucket running mid pack (at least for the first lap), once would be enough twice would be excellent.

    Should be fun.

    Does any one have times and top speeds for the GP125 class, especially mid field times/speeds?


  2. #32
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    29th September 2003 - 20:48
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    2008 DRZ400E & 1983 CB152T
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    FYI: RS125's running leaded have head cc of anywhere from 10.6cc to 9.8cc. Although to go that low you need some super duper $8 a litre race gas. For avgas the optimal is about 10.6-10.5cc.

    Ignition curve is here

    Quote Originally Posted by TZ350 View Post
    Does any one have times and top speeds for the GP125 class, especially mid field times/speeds?
    Top speed at puke earlier this year for me on datalogger was 215kph, fastest lap 1:05. Standing lap 1:10.

    Sorry to tell you but you'd be left for dead even off the start. I can do 0-100 in 3.9s and even if you did make it onto the back straight leading you'd be dead last before the kink. Good luck though

  3. #33
    Join Date
    18th May 2007 - 20:23
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    RG50 and 76 Suzuki GP125 Buckets
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    Auckland
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    I enjoyed reading your Bucket race report http://www.kirkpritchard.com/extras/2008_report7.php

    Thanks for the info, ignition map and encouragement.

    I had the idea that mid field Honda RS125's did about 110mph.

    I did try a while ago and managed mid field from the start to about 1/3 down the back straight then the engine shit itself. Had't up jetted from Mt Wellington. The fast bucket start helped in cutting through the traffic around the s'es to the back straight as typically the mid fielders were waiting for a clear run before getting into it.

    Later, did manage to get it to survive lap after lap but top speed was a little less than 100MPh.

    Lap times, 1:27 to 1:32

    Yes it could just be a small boys dream and a step to far.

    Might have to settle for just cracking the Ton and a sub 1:20 lap time if thats possible.

    But for the moment any more info on the GP125 class especially mid field would be appreciated.


  4. #34
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    8th April 2005 - 23:14
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    Joe2 the ALMIGHTY
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    Christchurch
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    exciting project... i am enjoying the reading and information you have provided... thanks!

  5. #35
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    29th September 2003 - 20:48
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    Quote Originally Posted by TZ350 View Post
    But for the moment any more info on the GP125 class especially mid field would be appreciated.
    Ask away, but mid field isn't really applicable at puke. In march top 10 were separated by around 1-1.5s and all very much of a muchness. Then the slowest 2 or 3 back markers doing approx 1:10s laps. Even the slowest modern 125 will do 190kph at Puke. For me I am hitting 200kph at all tracks in NZ bar Manfeild. However my old 91 RS did only about 182 give or take. I could still manage 1:10s at puke on that though.

  6. #36
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    18th May 2007 - 20:23
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    Thanks for the reality check. I know how fast 1:05 and 1:10 is.

    Looks like the after Taupo aim, is cracking the Ton and/or sub 1:20 and embarising a few novic big bike riders on a Track Day in 09.


  7. #37
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    23rd January 2004 - 12:00
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    Are you still running a 24mm carb on the GP125?

  8. #38
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    18th May 2007 - 20:23
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    .

    Yes 24mm carb. They say a rotary valve engine with its asymmetrical and longer timing sucks more through a 24 than a piston porter does. I hope this is true.

    There may not be much benifit in going to a bigger carb as we can get to the thermal limit of the air cooled 125 engine with a 24mm carb.

    .


  9. #39
    Join Date
    2nd September 2005 - 17:48
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    '08 zx6r, GP125, '76 T140V
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    Whenuapai
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    tell you what robert, i dunno how you've managed this while fixing my bike too!! this thread's given me a headache lol.. came 7 out of 22 bikes in 6 hr mopedathon today
    Sorry Officer - I wasn't speeding, i was qualifying...

  10. #40
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    18th May 2007 - 20:23
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    Had your bike running today it's going great. I am ashamed to say the problem with it was all my own fault and pretty much what you predicted. Glad to hear you survived today.


  11. #41
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    18th May 2007 - 20:23
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    .

    Thomas and I have been working on a programmable ignition, its actually three kits from J-Car. Programmable Ignition Kit, Coil Driver Kit and Hand Controller Kit for setting the parameters.

    The ignition works by seeing a trigger point calculates the rev’s and waits 360 degrees plus or minus the advance/retard programmed into the parameters table by the hand controller. Then triggers the CDI.

    We have run this on a bike already but found a problem with the signal coming from the trigger.

    The problem is the trigger output is a full 360-degree sign wave and the trigger point varies as the rev’s go up. At first it’s very retarded then briefly correct then over advances.

    Its all to do with the fact that the triggering takes place at a set voltage and as the rev’s go up the amplitude of the sign wave goes up triggering the ignition sooner and sooner.

    I have drawn a picture to show how this happens. If any one has a circuit idea that triggers at a constant point like where the sign wave changes sign in the middle. I would be very interested. Can anyone help me?

    Another solution might be to have a small trigger coil on the outside of the flywheel that gives a short blip then the trigger point can’t wander to far.

    Any input would be welcome.

    When we ran it, it was soggy to start (to retarded) then as the rev’s picked up it began to backfire as the over advanced ignition tried to spin the running motor backwards and the flywheel key sharing off probably saved the engine.

    The plan is to insert the programmable ignition between the original stator and CDI box in such a way as to be able to quickly un-plug it if it becomes problematic and be able to quickly revert to the standard system.


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  12. #42
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    2nd September 2005 - 17:48
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    Quote Originally Posted by TZ350 View Post
    Had your bike running today it's going great. I am ashamed to say the problem with it was all my own fault and pretty much what you predicted. Glad to hear you survived today, was it the 6 hour race?
    I only just survived to be honest, had a pretty bad crash at the 1 hr mark, which we lost 5laps on rebuilding the foot peg, re fueling and swapping riders.
    banged my knee up and scuffed my leathers, and put a little scratch on my lid lol. i hit a tyre at about 40k's, bounched about 1.2m in the air then hit the track. i won a box of red bull for best crash.
    I love endurance racing!!
    sorry for the thread hijack!
    Last edited by CM2005; 30th November 2008 at 08:22. Reason: spelling
    Sorry Officer - I wasn't speeding, i was qualifying...

  13. #43
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    12th February 2004 - 10:29
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    bucket FZR/MB100
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    I'd be going optical for the trigger. The LED/Trigger devices are cheap and then all you need is a chopper disc, easy. See this link for the sort of thing i'm thinking of. http://www.meccanisms.com/modules/xf...p?articleid=21

  14. #44
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    20th November 2002 - 11:00
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    This is great info... I'm looking at the ignition system on my F6 and wondering what to do.

  15. #45
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    29th September 2003 - 20:48
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    Yes, very interesting. Any chance you can let us know how you made the ignition?

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