Franken engine

Discussion in '2-Stroke Engines' started by Malanca, Jul 25, 2011.

  1. Malanca

    Malanca Member

    kinda like Frankenstein haha.
    so back in march or april my needle bearing inside the piston collapsed into its self and broke apart inside the resulted in horrible damage to the piston housing and pretty much the engine seized up. so that engine is sitting on the side lines and being used as a salvage engine.

    I bought a bottom half of an engine off of a site and a buddy of mine gave me a top half of a spare engine he had lying around. so i put the 2 together. everything fit in perfectly
    my main question is i wanted to test it to see if it would actually work...i tried checking for a spark by walking with the bike but the back tire just freezes up// what would cause this?
    also i dont know if its relevant but i did adjust the clutch plate. i did notice my clutch handle is a tad bit harder to work. maybe too tight?

    i'm a paranoid person so...
    my worry is are these 2 parts not compatible??
    or since theres no gas or oil maybe it needs it in order to move the piston? any help or advice would be greatly appreciated.

  2. motorpsycho

    motorpsycho Active Member

    umm, you need some weight on the rear tire to turn it, even with the spark plug removed. the best way to do it is to get the rear wheel up off the ground and turn it by hand. squirt some 2 stroke oil down into the cylinder to help lubricate the rings. When you assembled it did you assemble it dry or did you lube up everything?
    as long as the piston and rings fit into the cylinder and are not bound up it might be ok.
    the other thing to watch out for is piston to head clearance. If the cylinder you used is shorter than the cylinder that came off of the engine, the pistoon could be going up too high and hitting the head.

    if the clutch handle is too tight or too hard to pull you may have it adjusted too much. you want to have some free play in the clutch cable and the clutch handle should be pretty easy to pull in.
  3. Malanca

    Malanca Member

    THANKS!..i kinda forgot to mention my chain from the engine isnt actually all that tight still needs a bit of tension so thats something i'll add.

    when i inserted everything it was dry. i'm hoping that isnt going to delay me or set me back. it went in smoothly the O rings weren't any trouble i aligned them with that little mark.

    the whole clearance thing..i havent checked and it didnt even occur to me so i'll be sure to check that as well.

    with adjusting the clutch...thats done with the cable on the clutch arm? right now i have alot of excess wire on the arm...maybe giving some back?

    thanks motorpsycho
  4. motorpsycho

    motorpsycho Active Member

    you can either adjust the clutch by the cable and arm, or by adjusting the flower nut on the clutch itself.
    the easiest way is by the cable, but sometimes it won't give you enough and you can really fine tune the clutch adjustment with the flower nut.
    It's all trial and error.
  5. Malanca

    Malanca Member

    Thanks/ i've done adjusting thru the flower bolt but i wasnt sure if that was the right thing to do or if it would damage the pads or plate in the long run/ i'm going to attempt all that was listed.
  6. Malanca

    Malanca Member

    My piston was all the way up when i took off the head pretty much touching the headcase. i have one of those slant spark pugs.. it slid all the way down smoothly.
  7. Malanca

    Malanca Member

    the past few days i've been doing a little here and there..
    bottom line is got the bike running for a block but it was only going at 5mph or around there it was pretty slow. (I HAVE NO IDEA WHY ANY INPUT ON THIS?)
    few times before that it would stutter a bit like it would wanna turn on but after a few seconds it would just die out.

    the whole cylinder to piston size wasn't cooperating because i forgot to put on those metal gaskets right before the head. so i added 2 extra homemade ones and thats when it started to run for the distance of the block like i mentioned earlier..

    after that it just died out slowly and it wouldnt turn on anymore after that.
    an uncle of mine told me its most likely the timing.
    I have checked for spark (got a small orange one) the bottom half is a brand new engine so i doubt its the magneto or the CDI since its emitting spark.

    any input / suggestions / ideas how to get my bike back and running.

    i will post pics later on. my bike is a little modified with a strange new expansion chamber (i havent been able to test it out yet! :/ )
    and i got a seat post that leans pretty low ;)
  8. Big Red

    Big Red Active Member


    Hey Malanca, Red here again.
    First, Only ONE head gasket goes on between the cylinder and the head. Two could make THAT your weak connection. MOST, (not ALL,) chinese engines have pretty close to the same spec's so you should have the clearance you need for the piston. Check it by pulling the plug and turning the engine over SLOWLY. If it turns easily then the only difference after that will be the spark plug clearance. Put in the plug and turn it over ONCE, SLOWLY, as gentle as possible. If it stops, DON'T force it. Check the plug to see if the electrode is bent. If it is you just might have the wrong size cylinder. I doubt you will have this problem, BUT, like I said, don't force anything. It sounds to me like you lost compression due to a blown head gasket. as it got worse you lost power and got slower and slower as the gasket blew out more and more. If your bike is a little loud you might not have heard the TISH-TISH-TISH sound of a blown head gasket.
    Timing is factory set and it's almost impossible to mess it up. Everything concerning the timing is "keyed" to fit and to go together one way only. I'm sure your uncle is a real good guy and a great 4-stroke mechanic. But it's likely not the timing.
    Try a NEW head gasket or if you have some copper cote(spelling?) that will also help seal the head gasket. Make sure the head itself is flat. You can check it by getting some emory cloth and a small sheet of glass. Run the head's sealing surface gently on the cloth while laying flat on the glass. You'll be able to see if the surface is flat just by looking to see if the emory cloth "missed" any part of the surface. If it did, Keeping it as flat as possible, Keep going untill it all looks the same. Some guys tell me they do this anyway just to mill the head for higher compression. I don't bother with things like that normally. IF IT WORKS, DON'T FIX IT!!!
    If none of this helps, get back here and we'll all do our best to get you on the road again.
    Big Red.
  9. Big Red

    Big Red Active Member


    By "O rings" I think you mean the piston rings. And yeah, if you take it slow they slip in pretty easily. Motorpsycho is right, You NEVER want to run anything dry. a little light oil down the plug hole will do the trick.
    If your chain is loose it could be binding in the engine case. A loose chain will bunch up inside the drive gear case and things will come to a stop in a big hurry. A friend of mine put a hole in his case this way. So keep that chain adjusted properly.
    I also want to ad that if you were running with more than one head gasket, then you are in reality giving it more cylinder space and that in turn will give you LESS compression when the piston is at T.D.C. (top dead center). So like I said, Only one head gasket.
    Big Red.
    Last edited: Aug 8, 2011
  10. Malanca

    Malanca Member

    Thanks a lot Big Red once again!

    i wont be near my bike till the end of the week. but i am going to take all your advice and try to work it all into my mess. i'll have an update by friday or so to see how everything works out.

    I added the extra head gaskets because i was paranoid thinking that the piston was actually hitting the plug. when i had 4 it ran at the low speed. when there was 3, it didnt want to start up. maybe it was gas too because i put a little bit in i'm also going to try to put in a good amount..since it was a brand new engine and never had gas in it.

  11. Big Red

    Big Red Active Member

    Four head gaskets = low compression = 5mph.
  12. HeadSmess

    HeadSmess Well-Known Member

    i think i can see your problem... exact condition of the cylinder bore?

    the rings arent seating/contacting the cylinder wall evenly. usually happens after taking them off and then putting the top at the bottom and bottom at top...

    cylinders warped, and once again, rings just arent sealing. hand in hand with above at times :)

    chromeplating has gone. usually results in an engine that starts nice, runs great then carks it...til it cools down the starts great, runs fine then carks it til it cools down ad nauseum... until final complete death.

    head gaskets make a squeaking sound usually... depending on size of the leak. or you can feel the leak :)

    im finding my slant plug head leaks on the plug side, no matter what i do...

    i recently just ran a 3.2 mm head gasket, with little or no noticeable difference in performance, even with a dirty great pipe on it... now on a 1.6.

    the engine came with two fitted :eek: about 1mm? 0.7 after squashdown..

    oh. last and least! bottom cylinder gasket is very important :) got one? a new intact one with nice flat mating surfaces? thats around the right way? :p
    Last edited: Aug 10, 2011
  13. Malanca

    Malanca Member

    I've come to the conclusion (or just stupidly guessing) that my cylinder isnt matching up to the correct size in height. (something motorpsycho said from the start)

    Big Red i took all but one gasket off..and when attempting to see if it would turn over. it would just lock i went back to the 4 gaskets and when attempting it would turn over. :confused:

    i got the engine off thatsdax or something like that...when talking to the them over the phone they said it may or may not fit with whatever parts i have.

    HEADSMESS: The cylinder is perfectly fine on the inside. the piston rings are brand new and are the correct size. there are brand new gaskets on all parts of the bottom engine. the only ones that were hand made out of gasket paper and sealant were the ones for the head.

    (some minor details that i never put into this thread but happened)
    1. i didnt have a muffler the whole time when attempting this, but today i put on my expansion. i didnt see a difference or think it would because i ran a previous bike with no exhaust for a few months.
    2. it appears my gas isnt flowing from the tank thru the gas hose?
    I have a clear gas tube and only half the hose has gas and i have a full tank...but when i remove the hose the tank begins to release gas.
    3. I have 2 heads...ones a normal one where the plug sits straight up and the 2nd is a slant one...the slant one belongs to the cylinder thats on...but i have the straight one on it as of now because it seemed it had more room. (mistake using that one??)
    4. would the throttle have anything to do with this? i've adjusted the screw on the carb as well as the IDLE screw.

    any last minute things anyone would like to put in before i decide to order this top half from the site i got the bottom engine from.
    I'm going to post pics in about an hour
  14. Malanca

    Malanca Member

    <a href=";current=DSC_0073.jpg" target="_blank"><img src="" border="0" alt="Photobucket"></a>

    <a href=";current=DSC_0076.jpg" target="_blank"><img src="" border="0" alt="Photobucket"></a>

    <a href=";current=DSC_0078-1.jpg" target="_blank"><img src="" border="0" alt="Photobucket"></a>
  15. Big Red

    Big Red Active Member


    Hey Malanca,
    I don't know if anyone asked this yet? Are you SURE that you have the correct spark plug? If it reaches too far into the cylinder it will contact the top of the piston. Next time you pull the head look to see if the plug extends very far below the head dome. Will it turn over without the spark plug in it?
    Just something to look at before you order a new cylinder.
    Also, make sure ALL gaskets are the correct gaskets. A homemade gasket will not have the same thickness of the factory gasket. The clearence on these engines are very closley set, so don't mess around with homemade stuff. The entire gasket set is only about $10.00. Heck, I'll mail a used head gasket to you just to use for mock up. It would at least be very close to what the clearence should be. If I have a new one, (I'll check tomorrow) I'll just give it to you. You can't really just "make" a head gasket out of "stuff".
    Anyway, you didn't say if the engine would turn over WITHOUT the spark plug in. So I'm real curious to know about that. Go back to one head gasket, the correct one, and leave the plug out, see what happens. Checking that you have the right spark plug is free. A "cheap" cylinder is about $25.00 + shipping.
    Big Red.
    .P.S. Looks like air in the gas line is normal. Trust me, It fills the carb bowl just fine.
    Last edited: Aug 12, 2011
  16. Malanca

    Malanca Member

    yes its a new spark brand i've always used, but i also had one of the spare ones that comes with the kit..(brand new too) tested it on it as well..
    even used a new CDI

    spark plug to dome..theres still some clearance between that and the piston.
    I can load a pic of it.

    Engine wont turn over with the plug in it. ( i havent really payed attention if the piston moves, the bike either just freezes up in its tracks when i walk with it) or if i ride it and try to turn it on the bike starts to lose momentum when the clutch is engaged.
    with out the plug. all i can hear is the piston move up and down. i would walk with the bike and the clutch engaged. (dont know if thats the proper way to turning over and engine with the plug off. ) i would use that trick to kill some gas when the engine overfloods.

    thanks for the gasket offer. i just got a set in the mail today i pre ordered it a week ago incase it would be the problem. much thanks Big Red

    it just stumps me that i had it almost running at a low speed and i'm no where near that now.
  17. Big Red

    Big Red Active Member


    Looks like yer gonna order the new jug. When you get it in measure both, old and new, to see the difference. If there is it would be something new I have learned. I REALLY thought the chinese factorys went off the same specs when making these engines. Then the only difference would be quality control. Quality, in a chinese engine? Thats almost a joke that ain't really funny.
    I think once you get the spacing problem solved you'll be OK. Let us know how it works out. Like I said before, Too much space between the top of the piston and the cylinder dome = low compression = 5mph. Too little space = hitting the head (or plug) with the piston or TOO MUCH COMPRESSION and risking blowing the head off the engine, Blowing a head gasket or stripping out the head bolts. Keep in touch. We're not giving up on this yet.
    Big Red.
  18. Malanca

    Malanca Member

    I dont blame ya I thought the exact same thing when I ordered it. I kept thinking yeah yeah yeah its gonna fit they're all the same. the guy in the phone told me it was a D-model engine. and said there was a different kind as well...i thought he was talking about the kind with the pull start.

    but yes i will let everyone know about the sizes when i get to order it