Carby Newbie doubts and help with carb tunning

Discussion in '2-Stroke Engines' started by Padovani, Oct 19, 2011.

  1. Padovani

    Padovani New Member

    Hi to all

    I´m experiencing some situations and I decided to ask some help.

    I´m still breaking in my engine (Grubee 58 cc Gen-IIa). It probably has 15 km (10 miles) on it. I´ve changed (since first start) the stock air filter by a hi flow from SBP.

    First issue: Don´t need to pull the choke when starting. In fact, when I pull it on, it gets very hard to start. The only time that I used a little of the choke was on a cold night. Is it normal or something in carb tuning could be wrong?

    Second: After starting the engine, i´ve noticed that I can´t throttle the bike more than 20%, because if I do, it starts "failing" and looses power, especially in uphills. In fact, in this situation, I have to reduce a little the throttle and the bike stabilizes, and slowly and gradualy it gains some speed. When the engine warms up, the problem decreases on straights but keeps happening on uphills. Pulling the choke increases the problem.

    So the problem is from mid to full throttle.

    I disconected throttle cable and I changed the "c" clip to the intermediary position (3rd position, middle position). Innitialy, it was set on the 2nd position (one step leaner). I Made that change because of the failed choke test on uphills, but didn´t notice any acceptable result.

    To finish, I didn´t make the spark plug test because kill switch isn´t connected, because of the problems other users posted in starting.

    Any help?
    Last edited: Oct 19, 2011

  2. wan37

    wan37 Member

    Hey there padovani
    Try this if its a cns carb pulling the little hose on the side that goes back to the air filter it should be on the right side,but that's not a right fix but it can make a difference try that on a short ride .Let us know. Then tell what kind of carb it is or show some pics.Some one on here might help you if you state what carb.
  3. richirich1113

    richirich1113 Member

    my first motor was the 58cc. if i remember correctly i think i had the same problem. if you only have 10 miles on it, it is not broke in yet. it took at 4 tanks before i started getting good power from it. also what oil ratio are you running? it instruction say 16:1 but at that i had oil leaking everywhere so i went to 24:1 on my seconed tank and was much better. at the 4th tank at 32:1 the motor now had great power. That motor is reall y tight brand new. make sure to use a gooid ngk plug and check the mixture patient , it took at least 6 tanks before i could say it started running at its best.
  4. lazydog

    lazydog Member

    That's what chokes are for, cold weather starting. You shouldn't need to choke if the weather is nice.

    The carb isn't tuned right, you said you raised the C-clip sounds like it's running lean. So at higher speeds there's just not enough fuel.

    Really until the motor breaks in, it will be hard to tune. Also it will most likely change a little after break in anyways.
  5. bideronit13

    bideronit13 Member

    Ngk B5hs
    Some find it hard to find the plug but SBP carries it.
    Last edited: Oct 20, 2011
  6. Padovani

    Padovani New Member

    About the spark plug, somebody can tell if the ngk b5hs is different from the bp5hs? The only difference I found was the electrode space. It increases from 0,6 mm to 0,7 mm...

    This bp5hs probably is very easy to find here, because it is the same used on the old volkswagen beattle, so much common in Brazil...
  7. lazydog

    lazydog Member

    I put one in today (bp5hs) runs fine if thats what your wanting to know. Looks like the head sits a little deeper in the cylinder not sure really. Works great tho. should be safe to use.
  8. Padovani

    Padovani New Member

    I´m not 100% sure, but it´s probably a NT carb
  9. Padovani

    Padovani New Member

    Yes, I´m running 16:1 but don´t had any oil leaking yet. The only place I´ve noticed a little oil accumulated was on the base of spark plug when I removed it, but I just put a bit more torque on it and that was solved!

    So, I´ll wait a few more mileage and will let you know latter!
  10. wan37

    wan37 Member

    Well some one in here knows more about the nt carbs then me since I only have had a cns carb and I guess I was one of the lucky ones with it and a float adjustment was all needed to fix it and check the jets a clean them out.But for someone to help you they really need to know what carb it is.
  11. wan37

    wan37 Member

    The reason I'm saying you need to know what carb it is because grubee has the cns carbs on alot of the newer kits.
  12. Padovani

    Padovani New Member

    I just want to make some updates:

    Today, based on information from you friends, I found and changed the spark plug for b5hs, and put some more mileage on the bike. As this spark plug has a couple of thread wires more then the stock one, I ended up putting an extra washer to avoid the risk of hiting the piston. I can say that now I´m starting to have fun.

    Apparently the engine is showing signs of breaking in - not so much in max speed but in the way it is facing uphills. Even the sound of the engine is changing. I also noticed that with the changing of the spark plug, the engine became more predictable, both in starting and in riding. It is also working a little cooler I think.

    With the exception of the leaked oil I found when arrived (I must have put too much oil in the crankcase before mounting it on the bike, and now I believe that with rotation and heat engine is starting to throw it out), I'm much more satisfied with the result.

    Thank you so much to all the advices!
  13. HeadSmess

    HeadSmess Well-Known Member

    bpr5(6,7...)hs is prefferred ;)

    if the bp is easy to find, use it :) why freak around looking for something specific (but not necessarily the best) when the closest alternative is right there at hand?

    a b5hs wont touch the piston, unless something is very very wrong....

    a bp5hs wont touch piston either.

    a bp5Es will!

    mmmmm, vw bugs! i so i dont want one actually... horrible sounding things! but they do go...and go...and go....and go... and after ten years in ice....still go... sand, ice, whatever...still goes... except my last bosses old one... it was a bit sad :(