problems of a throttle and others

Discussion in '2-Stroke Engines' started by dadesign, Jul 16, 2010.

  1. dadesign

    dadesign New Member

    this is my first build and i am happy with it but i am having problems with the twist throttle.

    i have a black horse engine. mounted to a huffy mtn bike(very tight fit)

    i have the engine running and breaking it in. at first I could not get the engine to turn over because the kill switch seems to be hindering it so i removed it fromt he circut. now the main problem is the throttle.

    it is essential non working. I twist and it seems to pull but doesn't do anything. at the time I am riding it I have to adjust the speed adjusting the lever on the carborator. you can imagine while moving this to be a very dangerous practice. since it is a simple pull action device, i cant seem to figure out why it is not working. i will tell you that once i get the carb set in the sweet spot, it seems to climb in acceleration. i turn it back down as to not affect the break in period. still on the first tank of gas.

    i assume the throttle is to work much like a motorcycle throttle.

    i have searched on here for a week but cant quite find a simialr answer.

    the throttle is in there meaning the wire is atached but it seems to really not move. once i take it apart, it seems to move but the cable inside the sheth seems to do very little. when i twist it nothing happenes. it seems the cable is pulling as the cable gets tuant. but unsure. i was thinking the cable might be too long for the application. but unsure if that is it to shorten it.

    i have been working on this bike fro three weeks, and last weekend getting it running after a lot of effort

    i am close to a daily rider(and only means of transport) i know it is goign to be something simple too. personally i would like a lever you pul to adjust the speed but that is just me.

    thanks for the help in advance

  2. Al.Fisherman

    Al.Fisherman Active Member

    1) Check to make sure the cable/housing is not in a bind.
    2) Remove the top screw cap to the carburetor and twist throttle handle
    A) if it is still hard, trouble either in the handle or cable
    B) if it is easy to twist, replace the piston making sure that it goes in the beveled side aligns with the idle screw (on left side of carb). Back out idle screw first. There is a pin in the throat (you can look and see) and has to be aligned with the cable cut away on the piston.
    3) Remove piston and make sure that it slides up and down in the slide hole easily.
    A) slides easily replace the cap but don't over tighten.
    B) does not slide..determine if top of slide is squeezed in, determine which one binds the piston or carb.
    4) Don't over tighten cap as this will/can crush the top of the piston tube in.
  3. motorpsycho

    motorpsycho Active Member

    it sounds like the slide inside the carb (the peice inside that the throttle cable connects to) is in wrong.
    the slide should have a long slot in the side of it, and there should be a pin inside the carb body. make sure that the slot is aligned with the pin. some slides will have 2 slots, a short one and a long one. if yours has 2 slots, make sure you line the long slot up with the pin. the short slot is used for the idle screw on the side of the carb.
    you will have to unscrew the top cap on the carb to pull the slide out of it. there will be a spring on top of the slide to help the throttle close back to the idle position, this spring should not come off because the cable should run through the middle of it. unscrew the top cap and pull it out. the entire slide assemble should come out as one peice. (cable, cap, spring, slide and needle)
    did you assemble the carb. or did the carb come with the cable already installed?
    I am not familair with the black horse it a 2 stroke or a 4 stroke?
    but, all motorcycle style carbs have the same design as far as how the slide and throttle work. the slide should go into the carb nice and smooth with little to no resistance when you put it in. if you find that the slide is aligned with the pin correctly, it is possible that the carb body or the slide is slightly out of round. this will cause the slide to bind up and not move.
    when you put the slide into the carb, leave the cap off and try to move the slide up & down with your fingers. it should move easily with a small amount of resistance because it is a precise fit between the slide and the carb body.
    Last edited: Jul 17, 2010
  4. dadesign

    dadesign New Member

    yep. i had the thing in backwards. I didnt even see the smaller slot on it before. now it twists good but cant get it start after it sitting for a few days. thing i will have to check the idle screw next.

    the choke lever or what ever that is called on the right side of the carb, i have had to move that up an down to find the spot to turn it over and that is where i have been adjusting it at. i am guessing this is one of the places that needs some adjusting to do

    but it was something simple like that. at least that is taken care of now

    i am working on the starting problem now. i have had a problem before with the kill switch so that is the next question. the kill switch, i can choke the engine to stop if needed but the kill switch would make it a lot easier too. i took it out of the circuit because i read sometimes that can be the problem with it starting

    so next question is where should the lever be to start it.. full open like ona lawnmower?
  5. motorpsycho

    motorpsycho Active Member

    with the choke (lever on the right side), you should not have to adjust it at all. it's either open (lever in the down position) or closed (lever in the up position. this is how it is on my carb anyway).
    if you take your air filter off, you will be able to see the choke plate move open and closed when you move the lever up & down.
    the only time you should need the choke is on "cold" starting. so, you flip the lever up (choke closed), start the engine, and then flip the lever down.(choke open) the engine should start right up with the choke closed, and then it will run a little rough until you open the choke back up. when you close the choke, the fuel/air mixture is reduced to a very rich mixture. there will be a lot more gas than air, which makes for easier starting. but once the engine is running, there will not be enough air for it to run good, or even stay runnning for very long.
    the possible reason why it's so hard to start right now, is that the cylinder could be flooded, or you have an electrical issue.
    have you checked for good spark at the spark plug?
    did your engine kit come with the cheap push together connectors on the wires?.
    if it did, do yourself a favor and cut those connectors off, and solder the wires together in place of the connectors. then wrap each wire with heat shrink tubing or electrical tape at the least. if one of those connectors is loose, or touching anything, your engine will not run. does your engine have the white wire with nothing connected to it?
    if it does, make sure that the end of the wire is cut off, and taped so no bare wire can touch anything.
  6. dadesign

    dadesign New Member

    i got it to turn over an the throttle works great. accelerates the way it should too. i am happy

    so I should have the choke all the way closed then..hmm and then leave it all the way open when riding. I will take it out again and try that. full choke.

    will see what happens..

    any ideas on the kill switch. now that it runs and has a varible speed on it I can see where i might just not need it.

    i have the white wire and I will cap it. i already cut and connected the wires together.
  7. Al.Fisherman

    Al.Fisherman Active Member

    Use choke to start if need ..Up position. After engine warms up take choke off... Down position. Also you can just come to a stop, let the clutch out, hold brake if necessary and this will kill the engine.

    And yes the choke can be put in different positions from full off to full on.
  8. motorpsycho

    motorpsycho Active Member

    but if you do that after the engine is warmed up, it will run terrible (unless you have an air leak). close the choke ALL THE WAY to start when it's "cold" open the choke ALL THE WAY once the engine is running.
    the only time i can think of that you would need to use 1/2 choke or 3/4 choke is on an extremely cold winter day. you could close the choke all the way, get the engine running, and then move the choke lever so the choke is only 1/2 or 3/4 closed to help keep the engine running until it warms up.
    In the summer time here, (90 + degrees F. / high humidity) i never need to use my choke ever. my engine starts right up without ever using the choke.
  9. dadesign

    dadesign New Member

    seems mine will start at half choke, and it seems if i put it on closed or open all the way. it wont turn over or stay running.. I am thinking i have a air leak so the next thing i need is a sealer around the carb intake. i have seen some fuel leak and read it is a big part of the problem as far as how the engine is running.

    at the moment, it is bogged down and sputters. working on it today. each step i learn more about them so soon i will be able to keep it running for a long time

    still the engine is being broken in.. doing it by the book.
  10. Al.Fisherman

    Al.Fisherman Active Member

    I don't...I was stating ..upon start up you don't always need FULL choke. In fact sometimes FULL choke on start up is too much. After my first start up for the day I don't have to touch the choke at all.
  11. dadesign

    dadesign New Member

    something is again amiss(no pun)

    after getting the bike to run some with the throttle working now(still no kill switch)

    now it runs ok, not smoothly but every now and then it misfires, or backfires i guess. but I see a puff of smoke and I swear it comes out of the engine head. I read about not having tighten heads. I know it will not do over about 7 mph. i figured maybe it is not tightend down. i thoguth i i did but who knows. I am goign out to try to tighten it down some (not too much from what I understand)

    any other ideas if that turns out to not be it
  12. Al.Fisherman

    Al.Fisherman Active Member

    I tell everybody, if you have OEM studs and nuts, replace them...Cylinder head nuts (8mm) torque to 150 to 200 INCH POUNDS...leaking head gasket is part or all of your trouble, but that is wher I would start.

    Read this thread....
  13. dadesign

    dadesign New Member

    I believe

    I have fixed the problems.

    i got some gasket material and started to replace the gaskets. I found out the top head gasket is metal, but didnt check the bottom one. as I found out that there was NO intake carb gasket at all. This could have been the misfiring and cloud I kept seeing from that area. I also changed the plug from the OEM to an autolite 425 (as no NKG was available) and tightened down the head, I found the back a bit loose.

    So now, it is a bit "Chuggy" when it starts but once it turns over and I can adjust the carb to full open, then it seems to work as it should

    I found out that when i took the plug out it was black meaning it was running rich so i adjusted the c carb needle pin(not sure if that was the name) and it runs better now.

    this was major as when i change the plug I have to take the whole engine loose as there is about 1/8 inch clearance between the plug and the top bar. I did adjust it a bit so it cants to the left a bit more and I can change it easier...still I am worried how the chain sits. it was already loose on the bike. I will work on something better for that. still have to put the chain guard back on there now.

    any final thoughts on what I could do more to improve? i am on my second tank of gas now. i guess it is still in break in period, still cant resist taking it up in speed.