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  1. John Murray

    Cb450/500t track bike

    14v - 16v can give more spark energy with an inductive ignition, but as mentioned before inductive isn't the best choice if battery life is important. CD isn't normally fussy about supply voltage as it steps the primary voltage up to 400v or so anyway. I run Turnigys on a Bultaco.
  2. John Murray

    Cb450/500t track bike

    Interesting thread. The secret to getting good battery life out of a total loss system is to use a CD ignition rather than inductive. I've run both types and the CD runs much longer. A CD ignition will only draw a fraction of the current of an inductive ignition of a similar energy level - you...
  3. John Murray

    Texas Two Step Taco

    I've seen some engines using variations of the variable length chamber - mainly karts and outboards. Which kinda makes sense with applications like these that lack a sufficient spread of gear ratios, or any at all. It's not something I'd want to do unless there were no better alternatives. It...
  4. John Murray

    Texas Two Step Taco

    Alex demonstrates how to launch. Bill is smiling and gracious. You're a lucky man, Pat.
  5. John Murray

    Texas Two Step Taco

    You gotta let the Busa guys win one occasionally, it's good for their self-esteem..
  6. John Murray

    Texas Two Step Taco

    I think I'm almost as thrilled as you are with the performance Pat :D I'm sure there's more in it, enough to get you well into the sevens at least. Keep in mind that a dyno tune will only get you into the ballpark, and it's a pretty big ballpark at that. I'd plan on making quite a few runs at...
  7. John Murray

    Texas Two Step Taco

    Good to see the clutch held up. I wouldn't worry too much about the grey sludge, it's normal for an all-steel clutch and doesn't seem to hurt anything. If the current setup is working I'd stick with it for the time being rather than introduce a new unknown. Finish tuning first.
  8. John Murray

    Texas Two Step Taco

    Don't be surprised if you find it wants more jet at the track than it does on the dyno.
  9. John Murray

    Texas Two Step Taco

    Some good numbers there - I'd better start work on the 2021 NFI Racing T-shirt design...
  10. John Murray

    Texas Two Step Taco

    No, the BMW is irrelevant to the N/A Bul engine.
  11. John Murray

    Texas Two Step Taco

    Teazer said this earlier: Bill is correct that lambda results can be misleading. As John points out, give the motor what it wants for max power and keep that record as a baseline. Lambda isn't actually what is read by the O2 sensor. It supposedly measures unburned oxygen, so a high O2 number...
  12. John Murray

    Texas Two Step Taco

    No, I use Shell M with methanol and also with gas. I was using an ester with the air cooled engine on gas but had piston scuffing issues because the rear (thrust) wall consisted mainly of intake port. Switching to the castor blend eliminated the scuffing completely and gave a small hp increase...
  13. John Murray

    Texas Two Step Taco

    https://www.eshifterkart.com/Elf-HTX-909-Kart-Racing-Oil-1-ltr-HTX909.htm https://www.accelerationkarting.com/ElfHTX909Oil There may be other suppliers closer to you.
  14. John Murray

    Texas Two Step Taco

    Not too bad here, only 34C. My son was working in Cobar that day where it hit 47C.
  15. John Murray

    Texas Two Step Taco

    I dunno Teaz, I live in Orange NSW where the winters are long and frosty and sometimes snowy. Overnight temps below freezing aren't unusual. On the positive side the summers are bearable. I follow a particular forum purely because two guys, Frits Overmars and Jan Thiel, also go there. These...
  16. John Murray

    Texas Two Step Taco

    Ignore the a/f readings, they are often inconsistent and misleading with a two stroke, the only thing that matters is that torque gauge. Trying to make sense of them will just waste your time. Because the dyno loads the engine so lightly you'll probably find you need to go richer at the track...
  17. John Murray

    Texas Two Step Taco

    He's out riding and going fast because he doesn't have to troubleshoot unnecessary doodads. How long have I been saying ditch the damn Zeel? So far it's done nothing but waste time - how many hours have been spent on it? 20? More? This build has been going on for months and still no result. It...
  18. John Murray

    Texas Two Step Taco

    I haven't used a Bultaco kill switch for maybe 40 years or more, they were pretty poor quality. If there is any doubt about the switch just swap it out. Looking at the wiring diagram for the Pingel air shifter it appears to be set up for an inductive ignition system. It might work with a CDI...
  19. John Murray

    Texas Two Step Taco

    That's normal - there's insufficient load. Wouldn't it make sense to make a run or two with a conventional shift lever and the air-shifter disabled if there's any doubt over whether it's working properly? You seem to be continually distracted by peripherals... I'd be focusing on tuning the...
  20. John Murray

    Texas Two Step Taco

    Sounds good, a good burnout would purge any fuel from the crankcase and get enough warmth into the engine to provide clean running.
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