Chinese engine failure after 1300 miles - Tried troubleshooting root cause unknown -

Discussion in '2-Stroke Engines' started by djsalto, Oct 28, 2010.

  1. djsalto

    djsalto New Member

    Hi guys, I am little concerned about what happened to my first 65cc chinese motor. I use it to do 15miles/day and the engine started to lean out...
    I noticed that by the way it started to work after riding for a half an hour.... it started to loose power and Im very concerned about what could fail.

    After this the engine won´t started again, started to troubleshoot:

    -Checked spark plug (spark ok) but it was dry (ngk b6hs)

    -Tried a new one just in case: nothing happened

    -Took out carburetor cleaned it up and tested again -> nothing

    -Tried with a spare carburetor and then improved very little: Spark plug was wet, but engine was still not starting giving a few plops and i needed to rev. up the motor by pedal...

    -Gaskets in good shape....

    -Noticed loss of copression but it still was having some (compared it with a brand new motor)

    -Also i supose by loss of compression: If i put my hand over intake port (tapping ig) and I move the motor no notice of suction as the newer engine

    -After all this: Took the cilinder out: Saw rings in good shape, cilinder with a few deposits of carbon and piston with nice build up of carbon at the top but saw that it was very brown on the sides (don´t know if this was normal)

    I have used 50cc / litter all the time. But i like to go fast. so the engine was hardly used. I am concerned of this because there not was any noise that could aware me of an engine failure.


    Sorry if the photos are not so well. tooked with a cellphone

    At this moment I count with new cylinder/gaskets/piston/rings in order to restore it's compression but I did't found any clue with my little knowledge about 2 stroke motors...
    Last edited: Oct 28, 2010

  2. hurricane

    hurricane Member

    I have a very similar situation. I have a little over 600 miles on my engine and also your engine symptoms sound the same as mine.

    On mine , I have grown tired of trouble shooting it and am just going to purchase another kit to replace the worn out one. My guess is these engines can only last so long and as they are reasonably priced there is more reason to replace them than to continue on trying to find the problem.

    Sense you have 1300 miles on yours and I have 600 miles on mine, what more can you expect from a 2 stroke engine ?
  3. Al.Fisherman

    Al.Fisherman Active Member

    I had a compression issue on the first of 5 engines I have bought. That issue was caused by something besides the engine itself, I won't go into that now. But, I don't care how fast you peddle you just won't get it started. With that said, I towed my son on it with my bike. Sure enough it would start but as soon as he stopped the engine would quit, unless that was that he held almost full throttle. These engines don't have that much of a compression ratio to start with, so a small percentage drop will make more of a difference then you could imagine.
    To me, by the looks of your photos you have a compression problem, and you can't usually tell by just looking at a cylinder/rings/piston if there is a problem until the problem is so far gone it's very obvious. How do you really tell if ring tension is gone...not by looking by the average person.
    Last edited: Oct 28, 2010
  4. djsalto

    djsalto New Member

    That sounds logical to me.
    Now I´m being realized that not all engines are being manufactured with same materials, as far as could see on this forum the engines that for example someones bought from grubee engines are more durable than theese chinese "generic" ones.
  5. machiasmort

    machiasmort Active Member

    You could always try removing the gaskets if you have enough clearance (this will up the compression). That's if your willing to throw in the towel anway. Try contacting the vendor, new rings are cheap!
  6. philski

    philski New Member

    HI, you have run it a bit hot, ie: the glazed bore, you really should get a new piston, small end bearings, gudgeon pin and rings. The soot on the piston is blow down. the localized brown coloration could be the start bearing failure. You can get away with a hone and new rings. But that piston is not 100%. The bottom ring i can see the locating tab? is it sticking at all? i should not be able to see one end of the ring? the only time i ever see them, is if the ring is stuck.

    Because there are so many manufacturing differences in the motors it would be a good idea to get a complete piston and cylinder or get a micrometer, measure your piston and get that exact size off a supplier. The whole she-bang is on ebay for about $30 plus postage. so its not too expensive to get going again.

    All is not lost either. If you want to go fast, While you have it apart now is a perfect time to remove any casting slags from your transfer passages etc. Get quality bearings that are within spec, and balance it if possible

    If your running a bit hot you can adjust / retard your timing a few degrees with your magneto stator coil. Move the coil end downwards /anticlockwise to retard the ignition timing, raise your carburetor needle a notch or 2, or get a bigger jet, more fuel will cool it down considerably. A higher octane fuel will also help. and check for any air leaks..

    Or buy a new motor? perhaps it would work out cheaper and you would have some spare parts left over
  7. Al.Fisherman

    Al.Fisherman Active Member

    Wasn't sure what engine to get at first...bought the cheapest one I could find, I switched suppliers on the rest due to supplier warranty (dead coil within 3 days). I'm happy with all of them.

    I won't buy ANYTHING from "luckyearlybird" ever, ever...I'll do without first.
  8. HeadSmess

    HeadSmess Well-Known Member

    you mentioned theres no "suck" when you cover the inlet manifold...

    two strokes have TWO compression cycles... crankcase and combustion chamber.

    me thinks you maaaaaay have a cruddy crank seal... rubber seals. on the shaft itself.

    this "dying off after half hour" seems normal... mines always doing, time, temp, humidity...grrr!

    mine also has 4500km on it before it died, turned out to be the top ring disintergrated, bottom ring stuck tight. ports smashed, bore gouged... it was running enough to get me home like that though... and it was cus of me fiddling... :)

    in other words...youd actually be AMAZED at how bad a cylinder can get and still run...

    meh. buy a new one :) cheap n easy :)
  9. Old Bob

    Old Bob Member

    cylinder is shot, you are missing chrome all over the place
  10. machiasmort

    machiasmort Active Member

    I've got to agree w/ Bob upon further inspection. That's a sleeved cyclinder! Might run w/new rings and stuff for a while, but not for life expected out of new motor for sure!

    Sorry I didn't notice earlier, Good eye for an old Guy!
  11. djsalto

    djsalto New Member

    photos taken from cylinder show buildups of something that seems to be carbon, if I rasp it with a screwdriver i can see that there is still polished chrome under it, but correct me if im wrong Im not skilled on this matter... trying to learn reading...
  12. chrisnbush

    chrisnbush Member

    Just some thoughts -

    I started losing power at 2500 miles on my first DAX. I pulled the piston, and the lower bearings were failing - the connecting rod wobbled quite a bit on the lower bearing.

    Any of these motors I have pulled, the piston is always pretty loosey goosey on the top bearings, even on a new engine. You might want to take the pin out of the piston (remove clip on side) and check pin - is their a groove worn in it ? Are the bearings missing a roller ?

    My first motor lost power at higher speeds , and I learned about the intake gasket. It must be air tight, these things will suck air like crazy. I have extras, but have had real good luck with one on my current motor (DAX) that I made out of a margarine box (that waxed cardboard) - I learned this from a post.

    I have 3400 logged miles on my current DAX. I have never run it at full throttle though, and pretty much always pull the clutch and coast down hills - even small ones. My crusing speed is like 23 miles per hour. I got a 44 tooth sprocket, and use 20:1 oil that I get at Walmart by the gallon. This is my transportation, so I go easy on it.

    Not that I don't want to go fast, but if you wind these things up going DOWN hill you are asking for trouble.

    I am thinking your bearings are going, wiggle the connecting rod, should be tight and check the top ones. By the way, you can go to a chainsaw store and get Stihl 028 wrist pin bearings, these are supposed to work as upper bearing replacements - I have never had occassion to try them, but I bought them and they fit.


    1st engine I got 1500 miles, from LFM or some vendor like that - top bearings went and motor locked up
    2nd engine from DAX, blew up (top bearings again) after 400 miles, DAX sent me replacement under warranty
    3rd engine (DAX replacement) got 2500 miles (still running but big loss in power, bottom bearings going)
    4th engine used from eBay for 60 bucks was real weak, I think the kid screwed up the ports with a dremel and wanted to unload it - I trashed it.
    5th and current engine 3400 miles - seems to be running strong - a small loss in compression maybe over time, but not much. I put on an angle fire head for more juice.

    I could rebuild the current one maybe, but the "aint broke don't fix it" applies to me

    Your pics seem to indicate more wear on your motor than I would expect with that few miles. So again, I suspect the bearings.

    Last edited: Nov 2, 2010
  13. djsalto

    djsalto New Member

    Now engine is working and on break-in just replaced cylinder, piston and rings (with upper connecting rod)

    engine is running ok, just little worried because i hear a noise like a bell i think maybe a bad bearing but on the bigger end of the connecting rod.


    Thanks all of you guys for your help
    Last edited: Nov 2, 2010
  14. beentryin

    beentryin Member

    mines start to rev high when i goose the throttle itll take a min to idle back air leaks at carb,but i think its sucking air somewere,who knows ill drive it till it wont run then try to fix it
  15. A_FITZ

    A_FITZ Member

    well god ****.. , you guys are only getting about 600-3000 miles out of these things?

    And went through 5 engines already?

    ****!!! :90:

    So if each engine is $100, after $1500, you could only get about 15000 miles if each engine got 1000 miles a piece?

    WTF! :ack2:

    I mean ****. So thats the life expectancy of these things......, ****.

    Im now thinking about selling mine now when I fix it up.
  16. HeadSmess

    HeadSmess Well-Known Member

    :whistling: that was a highly articulate outburst! though also ignorant:thinking:
  17. chrisnbush

    chrisnbush Member

    Well, you have to think a little about the value of the motors. The total MONEY I spent on motors since the fall for 2007 is 120 x 2 (two new kits), 100 (one replacement motor), 60 (I used motor I wanted to play with) = $400 total cost.

    I got a total of 7800 miles on motors (see above). I have a jeep that gets 20 miles per gallon, if I had driven that (my only other ride) would have used 7800/20=390 gallons of gas. At $2.80 per gallon (it has been much higher than that since 07) that is $1092 dollars. I get 80+ MPG on my bike (LOTS of hills), since the gas mileage is 4x better, that would be 1092/4 = $273. SO my savings taking my bike (I commute 30 miles a day) has been 1092-273 = $819.

    So $819 gas savings - $400 equipment cost = $419 profit. I have certainly spent that on parts, mirrors, oil to mix with gas (Walmart cheapo 2 cycle in quantity) BUT think of the savings for brakes, tires, etc. on the Jeep. I can't replace the tires on the Jeep for less than $400 and that is for the 2 year wear max life tires ! And oil changes, etc.

    I have another 4 cycle bike that I have used since 08, got over 3000 on it - probably have just about paid for it at this point.

    The reasons I am moving away from 2 cycle is, kind of strangely as I have done so much work on them and have gotten them to be pretty reliable for me, is the oil mix (!). I work in an office, and the extra oil (in the gas) makes the engine dirty quickly, frame, tires, etc. Every time I touch the dang thing I ruin another shirt or pair of pants. Also, my feeling at this point is that the Hua Sheng motor is going to get more miles on it than your average 2 stroke motor. Since I commute a reasonable distance, I think I am going to save even more with the 4 stroke.

    I have a Titan motor now on a moondog, center mounted, using the Grubee 4g transmission (the one with the freewheel). Have about 400 now on this situation, this is the Titan motor that I have over 3000 miles on. I hear that the freewheel can be a problem, might consider replacing it with a fixed sprocket, until then I will get and keep a spare with me. Not quite as much speed as the 2 stroke, but pretty good torque (have it geared low). Better for my purposes - I am going for the best value. I drive the thing much of the winter time.

    As I read a lot on this and other forums, its all about what you like and what you are trying to accomplish. The other thing is how much I enjoy riding my motorized bike. I love it - it is different than a motorcycle (had a number over the years), just great !

    Enjoy the ride, and remember how much you enjoy it when you are working thru technical problems. It gets better (at least it has for me)

    :) :)