Rear-Wheel Socket / Drive Chain Misaligned

Discussion in 'Frame Mounted Engines' started by BirthNight, Mar 8, 2009.

  1. BirthNight

    BirthNight Member

    Hey guys, I meant sprocket not "socket" in the title :(

    I'm about 75% finished with the installation of my 66cc HT 2 stroke ( I just ran into my first major problem - the drive-chain seems to not fit correctly with the rear wheel sprocket. It is a 44 tooth 9-hole sprocket and it is a "415" chain (not sure what that means). Anyway, this is the chain and sprocket that came in the kit so I don't know why its not fitting. The chain will sit on the sprocket and turn a few rotations but then it wants to jump off. After closer examination I saw that I cannot wrap the drive-chain completely around the rear-wheel sprocket. For example, on the pedal chain, if I give it slack, it will wrap perfectly (360 degrees) around the socket. ---When I try to do this with the engine side, the drive-chain will wrap around about 3/4 of the way and then the teeth wind up getting misaligned and hitting the portion where the links connect (not the space where the sprocket tooth should be...) The drive-chain will, however, wrap 360 degrees perfectly around the little clutch sprocket. So this leads me to believe that I just have a faulty rear-wheel sprocket.

    Oh also, should the little clutch sprocket be able to free-wheel? It's really tight and I cannot turn it by hand, I have to use a screwdriver to get it to move...

    Any help would be GREATLY appreciated!
    Last edited: Mar 8, 2009

  2. dougsr.874

    dougsr.874 Active Member

    It sounds like your rear wheel is not aligned properly with the engine sprocket. Loosen the rear wheel axle and make sure both sprockets are in line....You can not turn the engine sprocket unless the clutch is disengaged..the best way I've found to turn the engine sprocket is to remove the sparkplug and use a socket wrench on the sprocket.
  3. biken stins

    biken stins Member

    zip tie clutch handle closed, remove plug. most kits come with a plug wrench. it is the 2 1/2 inch tube.The ends are six sided,four small holes in the sides. The small end will fit the nut. The small holes on sides hold/ use a leverage bar (not included ) to turn the tube. Don't use sharp objects as it may slip. You need to line up the sprockets. This sometimes is done using washers placed behind the sprocket. If your chain has slack use the tension bar to correct. Line the pully on it with the bottom of rear sproket. Go SLOW so nothing gets stuck at either end. When posting you might wait for a response or do some searching of the site. For the most part there is more than one way to do anything. You don't know if it is right for you untill you try. Just my thought on the matter. Good luck. Hang in there it is worth it.
  4. Mountainman

    Mountainman Active Member

    you state that you may have a faulty rear sproket
    I have read around here regarding fileing said sprokets out a little
    is this what you need to do -- not sure -- careful

    once it's done -- it's done

    ride the motor bike thing
  5. BirthNight

    BirthNight Member


    Good thinking mountainman - However, the chain and sprocket become so misaligned about 3/4 of the way around that I don't even think filing would help... :( I guess I'll try taking the bike into a local lawnmower repairman and see if he can figure it out... As of now, I don't even know what kind of replacement sprocket I would need to order. :confused:
  6. biken stins

    biken stins Member

    You say out of line do you mean warped ? If so get it on something flat and strike it with a hammer (flaten it ) wear goggles.Work it from center out as it is worked around. If you have money for shop repair,save it . Get a #41 chain and 36 tooth sprocket. Would get a #41 chain any way master links are every where. Some one said it was the size used for garage door openers but havent checked. Hang in there !
  7. cooltoy

    cooltoy Member

    Some kit sellers recommend doing what Mountainman suggested, it will allow the chain to sit lower on the teeth. I think I read that the chrome plating makes it to thick. It would be interesting to see a pic though. You also asked about the front sprocket, it is hard to turn and should only turn with the clutch pulled in, otherwise you are trying to turn the engine over.
  8. spad4me

    spad4me Member

    Have someone hold the bike up.
    First loosen the wheel nuts.
    Evenly pull on the wheel engine drive train side until the chain is tight and the wheel is centered in the rear wheelstays.
    Tighten the nuts.
    Visually check that the rear wheel is centered in the rear wheel supports.
    Using a small piece of wire twisted around a rear wheel support with one end almost touching the rear driven 44 tooth sprocket slowly spin the wear wheel.rotate the wheel.
    With the rear wheel correctly installed the pointer will indicate how much out of true your rear sprocket is .
  9. Mountainman

    Mountainman Active Member

    side to side or up and down ???

    I guess we should get this out of the way

    is it out of line side to side or up and down

    each to be dealed with in a different way

    as we ride the motor bike thing
  10. BirthNight

    BirthNight Member


    When I begin to lay the drive-chain onto the rear-wheel sprocket, it fits as it should. I continue laying the chain on/around the sprocket and about 1/2 to 3/4 of the way around, the teeth become misaligned with the chain. The teeth begin to want to set at the point which connects the links together (sort of hitting the pin in the middle you know) instead of the little spaces where they should go. There is no way around this. I cannot position it any differently to fix this. The sprocket's teeth and the spaces on the chain where those teeth should be eventually become "out of sync". That might be a better way to phrase it.

    I hope this helps explain what is going on. Unfortunately I cannot take a picture - I live in Los Angeles and the bike is with my Dad in another city (where we are building it). I might be able to get him to take a picture for me.
  11. Youngbird

    Youngbird Member

    Sounds like the sprocket needs to be aligned with the wheel/hub....trued as it were.
  12. graucho

    graucho Active Member

    Humm, when you gave your last explanation I visioned you having the wrong chain for the sprocket? It sounded like you were saying, as you wrap it around the sprocket, the links-spacing gets off. Like you have a #Size T8F or #35 trying to wrap around a #41 sprocket.

    If the sprocket isnt warped, and the tire is evenly spaced between the frame you may have recived the wrong chain? Do you have a tractor supply or a impliment co. by you? It may be a good idea to upgrade your chain anyways to a #41 (same as #410 _ 16.00 for 10 ft piece at tractor supply) graucho
    Last edited: Mar 9, 2009
  13. BirthNight

    BirthNight Member

    Hmm - good information graucho -

    I was originally thinking it was the rear-wheel sprocket because the chain won't fit correctly around it - but it will fit correctly around the clutch-sprocket (maybe this is just because the clutch sprocket is so small and most chains probably would fit around it?

    As far as I can tell, the sprocket is not warped and the tire is evenly spaced between the frame (I double and triple checked). I don't know guys, :( thanks for all the help and good information - I think I might just have to take this to a mechanic of some sort.

    I just hope I can ride soon :helmet: that's all I hope.
  14. Mountainman

    Mountainman Active Member

    got you Birthnight -- as you roll the sproket onto the chain seems not to fit

    I haven't ran into that problem -- but have read somewhere
    where someone files the teeth on the sproket just a little so as to fit
    if a sproket had a few defects that could be seen with the eye
    I would have no problem with the filing -- but if defects can't be seen -- CAREFUL

    before trying this I think you should call the place where you got your MB set up
    tell them what's not fitting right -- see what they have to say

    ride the motor bike thing
  15. BirthNight

    BirthNight Member

    Ok - just want to clear this up (BECAUSE I"M SO EXCITED)!
  16. gubba

    gubba New Member

    chain misalingment

    i had the saame problem....
    you need to take a good metal file and 'dress' both sides of each tooth on the sprocket.
    the end of each tooth is flat, file away some of the chrome plating on each side of the teeth. you don't file away enough to make the teeth sharp.

    the chain is not seating all the way into the teeth. this takes up a little room on each link and it wont go all the way around.
    i have helped install about ten of these kits here in florida, i've had to do this with each one.

    by the way the 415 chain, master links and extra links are readily available at

    stay dry

    Last edited: Mar 22, 2009
  17. BirthNight

    BirthNight Member

    Wow - you must be psychic gubba - took my bike out for the first test ride and got her going for about 30 seconds - was LOVING it! getting my first taste of MBing.......then i lose power - look down and the chain is broken and all twisted up around the rear wheel sprocket.... :icon_cry:

    Oh well... I'm going to order a new chain immediately and it will give me a chance to go ahead and order an extra spark plug and CDI unit for later when they inevitably break too. Thanks for the info!
  18. Alaskavan

    Alaskavan Guest

    I think Mountain had it right in his first response. Also, I've heard that the chains that come with the kits aren't of the highest quality.
    Last edited by a moderator: Mar 22, 2009
  19. BirthNight

    BirthNight Member

    yeah i definitely think MountainMan is right - My bike is from like 1975 - an old Raleigh racer. I don't really think the HT guys had a 40 year old bike in mind when they built the engine....but I'm going to make it work. I'll have to fiddle with the rear wheel alignment like MM said...and also re-work the chain-tensioner pulley. The top metal corner of the chain-tensioner was in the way when i tried to put it on the first so I'm going to have to take a hammer to it and bend it slightly. Lots of warp adjusting needed for these HT least on older bikes with thinner frames. Anyway - - I'm going to order all this stuff from bikeberry probably and give it another go next weekend... Thanks for all of you're help guys!!!