Engine is mostly new, definitely under 100 miles and when I looked at the cylinder when I got it, it was clean. Used 30:1 (or about 1.2 fl Oz to 1 gallon) on a pretty hot day around the 90s, it has a performance head aswell and when it started having issues I was going the fastest it can go downhill. When I slowed down to turn around instead of pretty much having a humming noise till it got up to speed it would instead sound like it was firing every few cycles, enough to get a little bit of speed but practically half it should've been and definitely noticeable in the sound difference. Unsure what exactly is the issue as it's not blown but it's not acting right at all. When I hold the clutch down to rev it it's also fine so it's only under load. Hopefully it's not something to do with the gears or flywheel
66/80cc unable to rev high under load
- Thread starter Skullcmd
- Start date
1st off...1.2 ounces per gallon is NOT a 30:1 ratio...See chart below.
30:1 ratio would have been 4.3 ounces.
That is still wrong though as you should have been doing the first 200 miles breakin using a 20:1 ratio which would have been 6.4 ounces and only after breakin is over would you ever go no lower in oil amount than a 32:1 ratio which would be 4 ounces per gallon of gasoline.
This is bad news all around...Trying to go as fast as you can go downhill with too little oil to lubricate and keep things cool in summer heat trying to go as fast as you can is a recipe for complete and total failure with these motors.
You also NEVER do engine braking especially going down hill with a two stroke motor unless you want to destroy it.
If I were you, I would junk it and start all over again and asking advice from forum members every step of the way to try to save you from yourself and destroying your motors.
I should've done more research on the oil to gas ratio, I was able to take the head off and there is a lot of sludge in it, another thing to note is when I was unscrewing one of the head bolts, the entire rod unscrewed, before unscrewing the head I let it cool down and tried to ride it again, it was mostly the same as before but i was almost able to hear the correct sound I guess, high speed low throttle also cars back with the correct sound as well (I have no idea what to call it)
To be honest with you, you have done everything wrong as possible already for its first 100 miles and I am sure it has been overheated as well at this point...I think it is going to be just one continuous problem after another and you will be throwing good money after bad and still be out a motor at the end of it all.
I would be buying a new motor and start from scratch all over again.
There are many long time seasoned builders of these machines right here on the forums that will happily assist and help you not only choose a good motor, but also how to build and break it in properly step by step.
We even have tutorials to share with you as well.
I'm straight broke right now so that's not possible, I just bought this bike and I'd liek to fix it or at least know which parts to replace than buying a brand new one for 250 or about a quarter of what I payed the bike for
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I'm going to try to replace the piston rings, the bore for the piston still feels smooth and there'd minimal iron shavings on the head, just gonna hope its a compression issue
Chainlube
Well-Known Member
That doesn't look too bad, a little dirty, that's all. Can you take the piston off the rod? Do that and wash it off and inspect it for any flaws. Rinse the engine case out with clean gas and put it all back together.
I know it's a pain to take it off the bike right now, but it has to be done for you to save it and your money.
Happy riding.
Yeah I'll do that tommorow, also plan on still replacing the rings
Chainlube
Well-Known Member
Those look fine from here, save your money for some more oil.
