Motorized bike, question about 48cc and 80cc 2 stroke

[FurryOnTheInside]

So is the 40mm truly 80? I've read that they can be 70 and 72 too

pi*r^2*h=v
3.142 * (2.35*2.35) * 3.8 = 65.93
3.142 * (2.35*2.35) * 4.0 = 69.40

The 72cc and 79cc are wider bore cylinders and pistons that will fit on the 69cc engine. Little bit more expensive than the 48cc cylinder that you need for the engine you have.

 

[crassius]

since it is usual to round up with motors, I call those two 66 & 70

 

[Vikingimike01]

Thanks guys. Last question. You've been very helpful so far

This are some pictures of my cylinder:

Cylinder 3.jpg

• Vikingimike01
• Jul 10, 2018

Cylinder 2.jpg

• Vikingimike01
• Jul 10, 2018

Cylinder 1.jpg

• Vikingimike01
• Jul 10, 2018

I also have lots of blow by, and lots of brown burn marks on my piston. So what could have caused this? I need a final answer. The ratio should have been right, it wasn't lean nor rich, it was running 16:1 first 3 tanks, fourth tank 32:1, Arol 2T motor oil, 95 gold fuel (That is the lowest we have here)

Was running with muffler off (I won't do it again, I know it's bad for the engine.)

What was the issue?

 

[crassius]

hard to guess, but I've never seen one that bad and also have not seen one after running with no muffler - might be a link between the two

 

[FurryOnTheInside]

There may be more than one issue, of course. Yes the exhaust is necessary not optional, crap thrown up from the front tyre probably got into the cylinder and abraded it.. but that doesn't mean that there weren't also other problems.

The cylinder plating might have been defective from the start. There could have been a chip in the plating or a bubble which could tear, leave an edge that catches the rings, and then the rest of the plating is more easily scraped off by the rings.

It is possible there was debris inside the cylinder.
I got a new engine and took you head off and could see chips of metal resting right in the edge of the piston. This, if not removed, would have caused damage to the plating as soon as the engine was started. I was lucky, the previous owner had installed the kit but hadn't attempted to start it.

It is possible there was debris inside the crankcase which may or may not have started the damage to the plating in the cylinder.

There is surely plenty of debris in the crankcase now. You should rinse it out really well with gasoline, and blow it out with compressed air if you have it.

 

[FNTPuck]

When you say no muffler, do you mean a straight pipe without a baffle/muffler or literally nothing bolted to the head??? If a straight pipe I doubt it would have caused that unless it was a tiny little 4" pipe hanging off.

If you mean no exhaust pipe/header at all (like an open exhaust port) it will definitely ruin a motor. On a 4stroke you will burn valves, on a 2stroke it is even worse since you will destroy your cylinder by ingesting debris while also burning your piston from a severe lean condition as the motor inhales unmetered air between strokes...I would imagine that would be especially harmful on these cheap chrome plated chinese cylinders.

 

[Vikingimike01]

The exhaust was on, just the baffle/muffler part that needs 1 bolt, and has a long pipe that goes into a hole in the exhaust was off.
Also if I want to rinse it, do I have to get it off from the bike frame? And do I rinse it with pure gasoline, or the premixed one for the engine? Or does that not matter? Thanks!

 

[petey59]

Hello forum!

I have a question. I bought a 2 stroke engine kit. The upper engine wall got damaged, and the chrome plating flaked off (Almost all of it) ( I was riding 4 gas tanks without the muffler on, could this be the reason? Since it could suck cold air in the hot engine? ) and I have to get a new one. Now the current one is 48cc. If I buy the 80cc version of the gaskets, head, cylinder, and piston, could I bolt them on my 48cc? I have the NT carburetor.

It costs less to buy the new parts (Even if I want to upgrade to 80cc) than to buy a new engine here. And both the 48cc and the 80cc parts cost the same.

Thanks in advance!

I brought a 2stroke engine and put it on my bike I never got the engine running went to get gas and peddling my bike got pulled over and given A citation to court cause I need a license and tag for me to operate motor bike

 

[DAMIEN1307]

I brought a 2stroke engine and put it on my bike I never got the engine running went to get gas and peddling my bike got pulled over and given A citation to court cause I need a license and tag for me to operate motor bike

First off...Welcome to the forums,

I should mention to you that this post should, by all rights, be posted under "Other Topics" or if questions of law, there is a category here in the forums as this is not a question about a 2 stroke engine kit, but rather a statement of an incident referring to a citation and a court date.

Is there something that your trying to ask about but just do not know or realise how to ask ???Let us know about this and questions you may have about your situation in the "Other Topics" category that you will find on the forums sub-headings...DAMIEN

Ps...Are you old enough to be a licensed driver or you never had one, or lic is suspended or revoked etc.??? what state is this ???