engine broke :(!

peppers · Oct 1, 2010

after I went though an insane registration process and spent $90 on unnecessary "moped" safety equipment my engine broke.

I was riding to the drug store and I started to hear small banging sounds on occasion then suddenly there was a louder banging sound so I stopped the bike and engine is now broke. I can no longer hear the piston moving when I move the bike forward and not hitting the clutch.

changes I resently made to my bike:
the power chain is a little tighter.

I was not as careful with my fuel mixture as I normally would have been but it was somewhere around 3 1/2 oz oil to one gallon of gas (this is also less oil than I would typically use and I'm guessing was what went wrong

) maybe slightly less oil than that but defiantly over 3.2 oz

I found that my bikes manual chain was off the wheel sprocket and kinda jammed between the frame and the sprocket at the time I stopped but did not appear to be preventing the bike wheel from moving freely although I could not say for sure.

so what is broke and how do I fix it?

I am very upset

Mac · Oct 1, 2010

Take it apart and see whats wrong. Most are fairly easy to repair, take some pictures, it will make it easier to put back together.

mapbike · Oct 1, 2010

I'm not sure what you are meaning by the term 3.2 mix or 3 1/2...?

here is a chart that might help you figure the correct mix you need, I run 40:1 in mine with full synthetic oil with no problems, many use anywhere from 25:1 all the way to 100:1 with great results so you will just have to deside which is best for you, it really depends on the quality and type of oil you use.

Chainsaw Gas Oil Fuel Mixture Chart from PROCUT Portable Sawmills

silverbear · Oct 1, 2010

How about a picture? So is it the chain off the sprocket or the motor? It wouldn't be both at the same time I would think. Follow the recommendations of the manufacturer of the oil you use. 100 parts gas to 1 part oil is only for oils designed for that. Try that ratio with another oil and goodbye motor. Or using 16 to 1 or 24 to 1 with an oil designed for 100 to 1 is also bad. It is worth paying close attention to your mix. Neglect it now becasue you don;t have the time and pay the price later plus a lot more time.
SB

peppers · Oct 1, 2010

can someone point in me the the direction of some engine disassembley instructions?

and no the chain was on right, pictures at this point would serve no purpose since there is nothing visibly wrong, I have the engine off the bike and i'm a little stuck here

FileStyle · Oct 1, 2010

take it apart now and see what went wrong. dont be scared to remove anything, it's preety straight forward! remove both intake and exhaust for starters and look inside. if you notice any part of the rings missing or deep scratch on the piston head, then remove the head and look inside there. you should see the problem, if it is a motor problem! you say the chain is correct, are you sure? the chain should never be tight!
if your rear sprocket is not true center, you will need to turn the sprocket/wheel so that it is on the high side of the wheel (torward the rear) before you adjust the tensioner. then that way your chain will never be so tight that it wants to rip off the motor! hope all info helps. you can get rebuild parts for these motors, However it might just be as easy if not easier to just buy a replacement motor for about $85.00 on ebay.

peppers · Oct 1, 2010

I am unwilling to pay another 85 dollars at this point till I fail to repair this one, its quite possible that my chain was just a little too tight and damaged something in my engine and I will corret this once I fix the engine, I cannot see anything wrong on the piston or rings but there is something that sounds broken rattleing around in there

I have been trying to get the engine apart and have been unable to take it apart.

I need to be able to get the engine apart at this point

peppers · Oct 1, 2010

I have identified the problem, it would seem the piston is seazed inside the cylinder and peace

s of it are broken off (incorrect fuel mixture is to blaim I guess), I am unsure how to get that part off though in order to replace it

peppers · Oct 1, 2010

OK I can lift up the cylinder head enough to unscrew the mounts that hold it in place but I still don't understand how to get the crank case open, once I get that far I should have no addition problem,

so how dose the crank case open?

FileStyle · Oct 1, 2010

remove the head then tap or pull jug off from case, at this point you will need to figure out if any debris fell into the bottom end and remove as best as possible, but hold the cylinder into the light and look at the walls, they should be semi smooth with no gouges at all! if so you will need to buy a new cylinder, piston head , rings , gasket, at the least!
good luck to you and Norm shows you how to disassemble a motor in the Norms How-to's.

FileStyle · Oct 1, 2010

if your willing to pull the crankcase apart, your just better off buying a new motor! you will have more money in parts and time than a new motor!

peppers · Oct 1, 2010

I was able to beat the broken Piston out with a hammer so I do not believe I will have to open the crank case assuming I am able to remove any junk that fell in there, right now I am working on figuring out separating the piston from the piston rod.

once that is done ordering a new piston and Cylinder Body+ maybe new gaskets and I should be good.

peppers · Oct 1, 2010

as you can see the piston is not in great shape but I am more curious where all these little magnetic rods that are all the same size came from, it would seem that it was not improper fuel mixture as clearly these rods are what caused the piston to get stuck, as you can see one is embedded in my cylinder, what the **** are these things and where did they come from?

mapbike · Oct 2, 2010

peppers said:
as you can see the piston is not in great shape but I am more curious where all these little magnetic rods that are all the same size came from, it would seem that it was not improper fuel mixture as clearly these rods are what caused the piston to get stuck, as you can see one is embedded in my cylinder, what the **** are these things and where did they come from?

those are needle bearings that either came from betwen the con rod and the wrist pin on piston or they are from the lower con bearing between it and the cranshaft journal, if you dont have a puller for removing the small gear on the clutch side of engine and the sprocket on the other side I say get one and pull the case apart to check that crankshaft needle bearing, you can buy a new engine for what it will cost you to rebuild that one as it has already been said, I know because I just finished rebuilding one lately, if you need to ride soon just order a new engine and then rebuild that one down the line when you can get the parts together and have the time. it will probrbly cost you $100.00 or so just for all the parts and shipping to do a complete rebuild and you can buy a new engine + shipping for less or the same for the all chrome engine in the second link.

motor motorized gas engine bike REPLACE 66cc engine new - eBay (item 250594522013 end time Oct-06-10 11:50:36 PDT)

80cc motor bike motorized engine REPLACE chrome slant - eBay (item 140446689423 end time Oct-28-10 12:44:49 PDT)

peppers · Oct 2, 2010

if I where to sick a new piston and cylinder on there would I be ok?

corgi1 · Oct 2, 2010

with all those rods that got loose inside the motor,,it doesn't sound very promicing,,,,, and untill you take it apart and check the other bearings in the motor for smoothe operation and no visual damage from this mishap no one can be sure

peppers · Oct 2, 2010

Well, what would a likely cause of my bearings falling apart be?

corgi1 · Oct 2, 2010

The words "Made in China" stamped in tiny letters on the inside of the bearing races instead of the outside could be one big cause,,,, little pieces of the failed bearing scaring up the surface of the other bearings ,is what you will prolly find in that motor,,, w/the bearing rod stuck in the cyl wall ,and the fancy V shaped mod missing from the piston,there has to be some debri scattered into all the tiny holes the the fuel/oil mix was susposed to go(only the mix was to go there),and the foreign pieces will eat up the crank seals,,,,,

peppers · Oct 2, 2010

humm, so nothing I could have done to prevent it?

people have bad things to say about bush bearings and insist that the needle bearing are always better but I would have gotten more life out of them than this.

corgi1 · Oct 2, 2010

you can buy a new car and a part can fail at any time in a day,month ,year(they cost more and usually are warrentied) there is no way most of us can tell the future,for the most part we can make educated guesses and we can just do the best we can to keep these things running and try to be prepaired to repair or replace them depending on the situation,they are cheap but fun,,,,I believe a 4 cycle maintained properly and not pushed to the upper limits would give a much more relaxed life span ,but the set-up is more expensive,If I need a year round performer I will go 4 cycle although at this time oil changes for me on one would be about every 5-6 days

engine broke :(!

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