Soft seize again

[vernw3]

After messing up my bbk by seizing it I  decided to just buy a cheap 50cc kit but this one also seized 

I don't know anything about engines so I followed a guide on how to install it. it seemed to work fine for 15 min then it locked up for a sec. I assumed it was a jet problem with the bbk but the new one is the default 50cc and it still locked up.

I have no idea what to do next 

[pinkscoot]

The main reason that an engine seizes is heat. The cylinder and piston swell and there is no room for the piston to move. Heat can be caused by not enough lubrication, not enough fuel in the mix or no cooling shrouds. Are you premixing or using the auto lube pump? Are the cooling shrouds in place? What size jets have you tried? Pictures would be great.

[PIG]

Probably an air leak that caused it to lean out. You need to pressure test it and check for leaks. There’s lots of write ups on it here.

['O'Verse]

Everything Pinkscoot said is correct. Heat could also be from an air leak. If your having problems like that it's always good to preform a pressure test. You can make your own for under $15 from most hardware stores like Home Depot. What you experienced was a hard seize. When the metal expands from heat it has nowhere to go except inside your cylinder and cases where your crank is. That's what's causing it to lock up. There's probably piston, cylinder wall, or cir clips, jamming up your crank. Not allowing it to rotate freely. Sometimes if your lucky some chunks of material will blow out your exhaust. Once you pull the cylinder off you can get a better idea of how much material your missing. If there's any material inside or around the crank the best option would be to split the cases. Check your crank and bearings for damage. Also buy a temp gauge. Great for tuning and a you'll have a better chance at possibly preventing any future seizes. Also read up on heat cycles. 👍

[ryan_ott]

Some of the cheap cylinders have very loose ring to ring groove clearance. As the saying goes you get what you pay for. Tell us about your setup: carb, jetting, airbox, exhaust, premix or auto lube - is it primed and we can help from there. Also cylinder prep is very important.

[vernw3]

OK I did a leak down test and the cylinder where it meets the engine has an air leak at the top the gasket looks fine

also the cylinder and piston look in fine shape does not look like much damage was done to them

[pinkscoot]

Some of those cheap kits don't have very good engineering and will not mate up to the cases well. Look at where its leaking and see what's causing it. On any build a leak down test is a must before you start it.

[ThaiGyro]

Learn to become Burt Munro. Expect that nothing is straight, just because you coughed a nut for it. Get EVERYTHING near perfect before assembly.

If you are new at this...simply ask and study. Tuning, no leaks, cleaning, proper combining of working parts.

Ohh, if you do not know who Burt Monro is...you need to learn. Cut off your right nut and piss on the lemon tree.

['O'Verse]

Jun 9, 2019 22:09:59 GMT -5 vernw3 said:

OK I did a leak down test and the cylinder where it meets the engine has an air leak at the top the gasket looks fine

also the cylinder and piston look in fine shape does not look like much damage was done to them

If the cylinder and piston looks ok. Slap it back together using some good gas and oil resistant silicone around your base gasket. If you just recently replaced your gaskets. You can reuse them. If you need a little reassurance around your head gasket area I'd go with copper gasket spray. Let everything cure after you've torqued the cylinder and head down. Re pressure test. If it passes 6psi for 10mins. Think about going pre mix. You could fix all the air leaks in the world and still have a lubrication problem. Plus after seizing your bore a little extra oil mixed in with the gas won't hurt. And check your jetting via your plug.