Think I've already heat seized new engine??

[ITZRIL3Y]

Hi so I've built and rode one of these engines before but was used before so never had to break in seized after a while so I bought a brand new 80cc china engine from Amazon built and runs
But having slight issues it will kick instantly and run great until the engine starts to hault when trying to pick up speed then will eventually die but then kicks up right back into action to repeat same process again I've never had to break in an engine before so not sure if this is normal but from previous experience it feels like it's heat seized I have rode twice since building maybe about 5 miles max am I being stupid what should I be doing different to break in have I already ruined my bike?

 

[ImpulseRocket]

If I had to guess, you either have an air leak making it lean or the carb is tuned lean. A lean tune will heat the piston up faster than the cylinder and cause it to soft seize. It sits, disperses the heat and cools off, and thus frees up. You start it again, and repeat.

 

[Gordy]

Re torque the head bolts before you get too far. But I second IR's opinion. I soft seized my chainsaw because it was running lean. It's a cheap saw so I don't really care lol, but it was running lean

 

[ITZRIL3Y]

Ah ok thank you thought this might be the case I had seized my last engine up as I didn't realise the idle screw had fallen out and currently running this engine without an idle screw because I had to strip parts etc will this be the problem also is there any reversing a soft seize

 

[ITZRIL3Y]

I also have substituted the idle screw for a normal screw just to temporarily stop any air leak but I'm guessing this is not ideal for the engine at all as I'm pretty sure it seized up my bike last time

 

[Gordy]

Ah ok thank you thought this might be the case I had seized my last engine up as I didn't realise the idle screw had fallen out and currently running this engine without an idle screw because I had to strip parts etc will this be the problem also is there any reversing a soft seize

Pour marvels mystery oil down the spark pug hole amd let it soak. If it's a 2 piece pull the head off and use a chunk of wood against the piston and tap it down woth a hammer. Gently, not super hard, you don't want to snap rings or score the walls any more.

If its a single piece still pour marvels down it, but rock the bike back and fourth until it pops free.


The bike shouldn't idle without an idle screw. Check for aor leaks all around the base gasket, intake, carb, and case gasket woth a spray bottle of water. If the engine stalls you've found an air leak.

 

[ITZRIL3Y]

Thank you well I've heard about the oil but the bike isn't stuck it will start and run evertime but when getting up to higher speeds the engine will halt jerk and die but then can be started again easily I just don't know what is causing the problem

 

[ITZRIL3Y]

Thank you well I've heard about the oil but the bike isn't stuck it will start and run evertime but when getting up to higher speeds the engine will halt jerk and die but then can be started again easily I just don't know what is causing the problem

Almost feels like when you seized Ur motorbike at a certain speed evertime u get up to that speed it will stop until u let out the throttle
Even though today is the first run of the bike and I am breaking it in

 

[ITZRIL3Y]

Almost feels like when you seized Ur motorbike at a certain speed evertime u get up to that speed it will stop until u let out the throttle
Even though today is the first run of the bike and I am breaking it in

Also could be 4-stroking but I am very new to this and not sure how to tell for sure

 

[robe]

Also could be 4-stroking but I am very new to this and not sure how to tell for sure

Check the spark plug. Dark is rich, light is lean, tan is perfect. What fuel oil mix are you using? Don't be afraid to use at least 25:1 at the beginning.
The first one I made the mistake of running 40:1. Bad idea. It would heat up pretty fast. I changed that to 30:1 on the good advice from this site and really should have used even more oil.