Discussion in '4-Stroke Engines' started by El Sid, Nov 2, 2014.

  1. El Sid

    El Sid Member

    I'm pretty sure its ok if i use the word retard in this respect. I am asking anyone if they can tell me how to retard my timing to get maximum head pressure at proper RPM. Or direct me to a video anything that could get me the info I need. Came up empty on you tube.:-/


  2. butre

    butre Well-Known Member

    buy a jaguar cdi
    Fabian and El Sid like this.
  3. El Sid

    El Sid Member

    where should i look to find this Jaguar CDI?
  4. El Sid

    El Sid Member

    damn looks like its for a 2 stroke. I'm running a funky little 2.5hp 4 stroke chinese something 'er other.
  5. dirtwarrior

    dirtwarrior Member

    Great question
  6. HeadSmess

    HeadSmess Well-Known Member

    more than likely a lifan or huasheng...

    go get chainsaw file. or dremel.

    remove magneto/coil, taking note which way engine spins.

    file slots longer in required direction.

    voila :)

    or get some funky "eccentric" studs machined up...

    learn how the cdi units work, and make one, or gut one from a pitbike and modify...

    sure you wanna retard rather than advance? got a timing light and checked what its timed at already? done any work, like exhaust, ports, or reprofiling cams? bogging up the head to raise compression? figured out what the minimum octane it needs to make max power?

    if you subscribe to the theory that more octane instantly equals more power...go do some research ;)
  7. El Sid

    El Sid Member

    Thanks. Have been doing research which this is a part of. Lots of helpful people here. I Learned of "the loss of power" from this forum. I read that factory will set timing so head pressure maxes or before proper rpm is reached. And timing should be retarded. Thus the reason for my "retarded" thread. Everything I can learn will help. I am assuming i will know what "slots" you are mentioning when I take the magneto and coil off. Thanks again.
  8. El Sid

    El Sid Member

    maximum RPM/speed

    How to maximize RPM/speed

    Both the 48cc and 66cc (80cc) engine have around 141 degrees exhaust port open duration which is enough for a maximum RPM of 7000. But these engines only turn up to 5500. Why?
    1) ignition timing is too advanced at high RPM. This basically serves as an RPM limiter. Some motocross bikes with digital CDIs stop retarding the timing at about 500 RPM before the max RPM the engineers want the engine to turn at. This causes the timing to be too advanced which causes the peak cylinder pressure to occur too early to do much good at contributing to engine torque.

    (This is what I read to make me wanna ask how to retard my timing, El)
  9. El Sid

    El Sid Member

    Does a jaguar cdi work for 4 strokes?
  10. butre

    butre Well-Known Member

    it would work but it wouldn't be ideal. there's plenty of info on the internet for rolling your own cdi
  11. keatonx

    keatonx Member

    That info you referenced is talking about a 2 stroke, that naturally requires timing retard at high rpm (and in this case, the CDI isn't giving it). Yours is a 4 stroke that likes timing advance at high rpm. There probably isn't anything too wrong with your stock timing (not to say that it can't be further refined, but styll)
  12. keatonx

    keatonx Member

    My guess is that if anything, you'd want to advance the timing
  13. HeadSmess

    HeadSmess Well-Known Member

    complete concurrence... dont get the requirements of two and four strokes mixed up...and ignore most of that drivel dragged in by a certain cat. close examination reveals several flaws here and there...

    fourstrokes...ive always found ignition on any engine to be pretty irrelevant. yes, you can go too far both ways...advancing will reduce power, and make things hot...retard will reduce power but the thing will always start... but usually the factory is pretty spot on, even after doing major surgery elsewhere...which is a definite must on a four stroke!

    it does help to get it in the right spot but its usually fixed for a reason... these days of CDI, nobody has to remove and readjust points... the manufacturer has spent the money on research and development...

    not saying what engine it is, i can only assume that its a standard industrial engine...meaning, more than likely, a single lobe cam operating both valves.shame. not much you can do to the profile to improve it. can experiment, but each change affects both valves, and the curves they follow are NOT symmetrical! need a lab for conclusive results. old briggs and stratton, and other similar engines have separate cams...which can be modified :)

    cam design is complex and theres things like "j3rk" and "float" and g-forces and strength versus load versus wear/life type things to consider... not for the ametuer to go making new cams! some engines, the parts are out there... most arent!

    ports... removing manifolds will usually expose nasty casting flash, brutal square and right angled airways, gaskets that arent cut properly, the works... the smoother, and curvier the ports are, the better airflow will be, the better performance will be.

    you can use jbweld/epoxy in the intake port to make it pretty... bigger is not always better!

    exhausts... theres an ideal length pipe for any rpm with a given set of cams.

    carb... most industrial carbs are junk...

    slots...yep, should be obvious enough... the ones that the bolts go through to attach the thing to the cylinder...assuming its a cylinder mounted coil... move in direction of crank rotation is retard, against rotation is advance;)
  14. KCvale

    KCvale Motorized Bicycle Vendor

    NO! And it was incredibly ignorant to even be talking about 2-stroke CDI's in the 4-stroke forum to begin with.

    If you have the HS 49cc 4-stroke get yourself an NGK 7544 (CR7HIX) Iridium spark plug, that alone will be something you imminently feel, pull of the stock box exhaust and throw a real tailpipe on, heck even a 2-stroke non-epa goes right on, and boost it some more.

    Start with the cheap easy stuff to let it run and you'll see the timing is just dandy ;-}
  15. darwin

    darwin Well-Known Member

    OK I cannot let this go. Why is a spark from an Iridium plug more effective then from a platinum plug? Gotta hear this. Platinum gives more durability.
  16. El Sid

    El Sid Member

    thanks guys. Good info. In my research I have learned the lower the number on a plug the hotter. Now I need to look for iridium and platinum. I'll try them both, what the hell. I did get another pipe and broke the governor of the carb. lm looking at opening the case and taking the governor out there as well.

    Check out my latest in my project. and please feel free to advise. Especially if something rubs you wrong.

    Apollo creedo take 2:
  17. El Sid

    El Sid Member

    One quick question, Valve gap, 0.003 for both intake and exhaust?
  18. Robot

    Robot New Member

    I don't know what you expect to gain on a $95.00 2 stroke but if that's what you are working with then you will get more accurate timing with pure silver brushes or coil portion of the ignition I'm not sure which it is but likely spark is advance via tin or copper once establish MMMMMK ?and plug wire on this engine or any working with a magneto type ignition the rpm range is limited for more than one basic reason.
  19. KCvale

    KCvale Motorized Bicycle Vendor

    Q. What makes Iridium better?
    A. Until recently, platinum was considered the best material to use on the top of an electrode because of its durability. However, Iridium is 6 times harder, 8 times stronger, and has a melting point 1200 degrees higher than platinum. Put that into a harsh environment such as an engine piston chamber, and you have a spark plug that can resist wear much better than platinum. Additionally, the DENSO Iridium Power alloy is so durable; it allowed our engineers to produce the world?s smallest center electrode (.4mm) which reduces the voltage requirements, concentrating its sparking power. Also, its smaller size, combined with the tapered U-Groove ground electrode, allows more room for the flame kernel to develop and produce a more efficient combustion.

    I use them in every 2-stroke build because I can actually feel the difference and there is no manual gapping, they come pre-gapped with a cardboard cylinder over the end you slide off when installing

    The end is a touch longer than stock so a slight compression gain I assume, but it's a nice big spark I like as I also re-wire every Magneto to CDI build with excellent wire so every iota of the ignition can muster makes a nice big concentrated spark.

    You don't have to 'let it go' Darwin, it's like $8 to feel for yourself.
  20. HeadSmess

    HeadSmess Well-Known Member

    do you ever talk sense, mmmmmmkay?

    where exactly, are the silver brushes?

    tin? wtf are you on? because ive its ever prescribed to me, im not taking it!

    rhenium...why dont they use rhenium?

    never tested it it out, but in theory, an engine will run on methanol with a platinum plug...without the spark.