Does this cylinder look ok

[Pothole]

Guys, having sorted the Electric start on my Daughters 2011 jog 50cc when it tries to turn over it sounds like a bag of bolts. New battery new starter and starter relay. Fired up first time but doesn’t fire up any more. Pulled the cylinder head off this afternoon to inspect. It’s all smooth no scoring from what I can feel. Does it look ok to you lot
https://imagizer.imageshack.com/v2/150x100q70/924/fsEwl4.jpg

[MCN]

Looks like there is/are a broken piston ring/s. The bore surface appearance should be uniform.

You will have to dig deeper.

New rings and a rub around with some wet and dry will possibly rectify the bore finish.

The bore needs to have a surface that has micro-grooves in it.
The grooves hold oil to help lubricate the piston.
When the grooves are worn off the engine will burn more oil.

There is a precise angle for the grooves that are produced by controlling the rotational speed and feed of a hone tool.

But you can phaph a good enough effect using a drilling machine, A brush handle, a bunch of rags wrapped in wet and dry or emery cloth tape.

Maybe 200 grit or 180 grit.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[Pothole]

So the fact this feels smooth by finger its no ok is that what we are saying

[Nobby the Bastard]

It looks scored. That'll require reboring or a replacement cylinder.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Pothole]

So now the heads off and the piston at the lowest point will the cylinder just pulled off?

[Easy-X]

[Pete.]

That cylinder has had it. The piston will need changing too so buy a pair, and new gaskets.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[A100man]

The marks must mean something even if it's not scored enough to catch a nail. I'd take the cylinder off too so we can view the piston. BUT that isn't what is making ists oiund like a 'bag of bolts' so I suspect something else is at fault.
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Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[stinkwheel]

I think that barrel needs to be pulled so you can inspect the piston and see if there is any play on the big end or small end. Piston has definately been rubbing on the bore.

Also worth checking for vertical play on the main bearings.

If we're placing bets, I'd guess repeated partial seizures and a fucked small end.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[A100man]

[Pothole]

Cheers guys, ended up ordering a 70cc upgrade kit with new choke so hopefully will resolve everything

[Pothole]

Ok I have installed the 70cc upgrade kit which came with a new carb as well. It still won’t start! Turns over far better then before however it just not firing. With the new carb there seems to be no feed of fuel to the carb. If I put the old carb on there’s a feed but neither of them fire the dam thing up!!

[Easy-X]

Sorry, how are you figuring out one has a feed and the other not, wet plug? Will the bike go with a little Ez-Start?

If the carb is just part of a cheap Chinese kit you'll want to pop the float bowl off and check the float can move up and down freely. The thing's probably spent most its life jiggled about in air freight
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Pothole]

Because I have a clear online fuel filter. On the new carb nothing is moving through the filter on the old carb you can see the fuel moving

[Easy-X]

[WD Forte]

it has vac operated fuel tap so check the new carb is actually actuating the actuator.

If it aint, no juice

Is the new one a £178 ( Fowlers prices ) pukka Yamaha one or a chinese substitute?
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bikers smell of wee

[Pete.]

[Pothole]

[Robby]

Do the carbs look identical externally?

If so, the next one is probably a cheap copy of the original, with different jetting and needle height. I would transfer the needle and jets from the new carb to the old. That way you have a known working carb, with the right jetting.

The problem with the new carb is probably the float valve. It isn't a great sign, suggests poor machining.

[Pothole]

No this one looks different. The original had and inlet and outlet for the coolant which I believe is for the choke. The new one doesn’t
Checked the float and it’s moving freely

[A100man]

[B1N]

This might sound like a stupid question but is there any oil in the two stroke oil tank?