A smoother rpm range?

Discussion in '2-Stroke Engines' started by boogerballs, Feb 21, 2009.

  1. boogerballs

    boogerballs Member

    Why does the HT type engine have such a tiny power band?

    Mine runs very rough from idle all the way up to around 3000 rpm then just a little bit better (not good or smooth) up till around 5000rpm where for a miraculaous moment I actually hear the motor smooth out and create some torque, Unfortunately, this is very short-lived beacuse it starts to run rough again at around 5800-6000rpm until it tops out at around 6200-6300rpm.

    Is there anything that anyone has come up with to improve this performance? I have had a few two-stroke motorcycles and they each seemed to have at the very least, SMOOTH power all the way through the rpm range. They had the normal power boost at their rpm sweet spot, but they performed smoothly throughout.

    What's up?
     

  2. cooltoy

    cooltoy Member

    Could it be an air leak at the carb and when you hit that power band you love so much, the air fuel ratio is just right? Do you stall out right away when you give it choke?
     
  3. boogerballs

    boogerballs Member

    No, I've checked for an air leak at the carb and there isn't any.
     
  4. bluegoatwoods

    bluegoatwoods Well-Known Member

    Could it also be that your engine isn't broken in yet?

    I've broken in two now. the first one smoothed out pretty early in the game.
    the second one needed at least a couple of gallons of fuel run through it before it smoothed out. I was even beginning to worry about it a bit. then suddenly everything was fine.
     
  5. boogerballs

    boogerballs Member

    After yesterday I have about 250-275 miles on it. When do you consider it "broken in"?

    By the way I'm at 385 ft above sea-level if that makes any difference.
     
  6. bluegoatwoods

    bluegoatwoods Well-Known Member

    That would be about 2 gal of fuel. If it doesn't smooth out soon, then I'd guess that break-in is not the issue.
     
  7. cooltoy

    cooltoy Member

    if it was me, I would get a new plug, check my wiring connections, including the spark plug wire and ride the bike while playing with the choke to see if a richer or leaner mixture helps. You never did say if it stalls out with choke on or not.
    You may also want to play with the clip on the needle seeing as you mention the sea-level thing. There are lots of threads on that around here. I still think you need to figure out your rich/lean mixture first but I guess trying two different settings would not be a big deal.
     
  8. rearengine

    rearengine New Member

    You want to be careful .. These little 2 strokers run & sound the best just before Seize up. From my old Go Kart days.. Bill
     
    Last edited: Feb 21, 2009
  9. boogerballs

    boogerballs Member

    I'll go ahead and do that and see what happens. Hope I can do it before it rains... thankx
     
  10. boogerballs

    boogerballs Member

    If that's true I guess I should feel confident that my motor will NEVER seize!:cool:
     
  11. boogerballs

    boogerballs Member

    Checked all my electrical connections, changed the plug and once it was warmed up I put the choke on at idle. It didn't do anything. But when I gave it some throttle, it died.

    Then I changed the needle setting to one notch richer (3rd notch down rather than 2nd notch). That just seemed to kind of bog down the power. No improvement in smoothness noted.

    I need to try out the leaner setting next, but the rain is threatening and I've still got a few items on my honey-do list.
     
  12. cooltoy

    cooltoy Member

    I think you should spray some carb cleaner around the carb area to see if it speeds up as you spray. The choke should have flooded and killed the engine. I could be wrong but it may have a small leak. Do you have a fuel filter?
     
  13. boogerballs

    boogerballs Member

    I have checked for an air leak at the carb and everything is fine. When I was on the second notch and I put on the choke I needed to blip the throttle for it to die. Same when I went one notch richer (3rd needle notch).

    I just tested it on the top needle notch and was surprised that ir an noticeably smoother. I don't know that it halped any with the top end but definitely was a bit smoother low to mid range. Oh, and when I put the choke on, it just died.

    Jeff
     
  14. cooltoy

    cooltoy Member

    That sounds better, I'm going to assume you have good gas with the proper mixture so let's just hope that you are on the right track and that things will improve with your next tank of gas.
    Good luck!
     
  15. boogerballs

    boogerballs Member

    Yes, good, fresh gas with a 32 to 1 mix of caster based synthetic go kart racing oil (Blendzall).

    Do you think it safe to stay at the top needle notch? Safe in terms of not running it too lean?
     
  16. cooltoy

    cooltoy Member

    Well, I guess you could say that it is not running too lean if it's running right. I also think that from the sounds of things, you seem to be at one with your little baby so I think you will be fine. I'd love to get some of that oil but I've never seen it around here.
    I can still remember that smell from my dirt bike days in the 70s.
    Steve
     
  17. boogerballs

    boogerballs Member

    Yep, when I first got the motor installed I used some synthetic two-stroke oil recommended by my friend who recently set the world land speed record for a 50cc motorcycle (144.966mph). It worked well but the smell was just that crummy burning oil smell. When that same friend bought a 49cc motor kit himself and set up an old schwinn and we went riding together, I rode behind him and got a whiff of his exhaust. Wow, Talk about bringing back memories! That was my last ride with non-caster based oil.

    I guess I'm pretty much an old-timer, although I don't think myself one. I used to road race motorcycles back in the 70's. There's just something about that caster smell...
     
  18. boogerballs

    boogerballs Member

    My friend's first recommendation for what type of oil to use was before he got his own kit. Once he got his kit engine, first thing he did was pull off the top end and check things out. He was amased at how loose everything was. He was used to his little Aprilia 50cc engine and how precision it was. He decided to run caster was defineitely for the smell and that caster based oils tend to lubricate better in the hot spots in a two-stroke, or so he said.

    By the way, his little 50cc streamliner that set the world record at Bonneville produces 20+hp at 14,500rpm with 6psi of boost. He runs with a tiny turbocharger on his 2-stroke 50cc.
     
  19. cooltoy

    cooltoy Member

    We were just kids back then on our little mini bikes, I had what I think was the worst bike ever built, an Orange Italian made Bombardier. I was so stupid because my Dad was willing to spend the $300 to buy me a bike and I chose this over a Honda mini trail because it was a bigger bike. The thing fell apart every time you drove it. I also learned about using front brakes going down hill very fast. My handlebars, levers and gas tank were bent the first day and I may have cried that day walking it home all bent out of shape.
    Back then there used to be these European men who would show up at our trails with their CZ motocross bikes and they would fly by us on one wheel and that sexy smell .
    Now you have me on a mission, I guess I could order some online.
    By the way, there are those that say you should not use it on a new engine because it leaves a ceramic coating, ( I think that's what it was called).
     
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