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HOW TO FIX BROKEN PIT BIKE ENGINE TOP END lifan 125CC

This video is for anyone interested in taking apart a pit bike lifan engine and doing a top end rebuild by themselves.

Hey guys in this next batch of videos here we’re going to see above doing up let’s pit bike god as a stomp 125 proper pet back leg one of the bauer versions but the engine is totally fried we’ve got the carb off taking this off i’m gonna bout to pull the head off it and find out what’s the matter with it see what the damage is yeah the guy had that said that just

Started making a hell of a racket and then it completely failed in power and since then i had no compression i can get it to work it’s no spark a don’t know lots of issues with it it’s a complete pile of junk just now and we’re going to rebuild the top end so if you’re interested in finding out how to do the top end i’m just the way here undo the four bolts the

Front of the engine undo the side casing off the side undo the cam just the camco of the sprocket and save the little chain on you undo that and then slip the head off and then we’ll see what the cylinder head looks like and see what the damage is now go for no guys be back shortly okay my guys well wait till you see this we have one head bolt completely sheared

Completely off peston alright see it so i’ll smash the way along here although the edge feels a bit sharp doesn’t feel like it’s taken too much over the edge but totally fried there was no gasket on the base gasket no gasket in between the bottle and the cylinder had ice on the head is chewed up of the bottle this is the bottle that came off and the bottle looks

Quite good sadly no big deep scores but yeah it’s been bothering about now something wrong yeah we is gonna rebuild this top end i’m gonna get into the house cuz it’s freezing cold we’ll have a look at the top end and see how the valves and everything’s doing yeah it’s missing a site casing on this as well magneto i think steer bike brake doesn’t work front brake

Lever is snapped bike isn’t pieces over here these bolts just keep spinning and they won’t come out hey there’s zero engine a engine oil and save the more and the shocks when i push down the shops are taking a long time to come back up so you could generally say the whole bike is ruptured we’ll see how we can get it back together anyway let’s go have a look at

This head and see what the damage is boksoon right guys well we’re going to take a look at the pit bike cylinder head this is from the one to five stomp put bike and as we check it underneath i’ve sanded this up this was completely damaged and when i look at it closely you can see there was a screw right one about inside this head that completely destroyed it and

It’s bent valves and i even have the valves sitting here this was the culprit i don’t know if you can tell but it’s got a serious warble going on you can see the marks and the shaft where it was rubbing in the valve guide pa it went so far didn’t was seat properly it was pretty much stuck but yeah damaged valve would you have been a screw bouncing about and seat

So know that we have that damaged i’ve went ahead and sanded all down careful not the sound do an edge there but just sounded only inside have i ordered another set of valves and ordered the wrong set because i was just jumping ahead thinking i’ll get new ones anyway and tonto sniper the right head but in the pack that i got i got a twenty three mil one so 20 ml

And 23 mil but the park i ordered was 23 millimeter and 27 so the twenty sevens huge so the only way i actually ended up using over there well i’m gonna use as the 23 millimeter ryan new so this is going to fit i have lined them up so first i’m going to show you how to take apart at head so this is the side that your time and we would be on and you want to take the

Top cap off it’s going to be off because this is how you’d get the thing off in the first place this side you have this one here with the bolt all through this middle part here takes the cap off it in the side then you’ve got these two here or either screws or the inlets for your oil cooler this will come off as well now once you take these off i’ll show you in a

Moment how to take apart of the other parts in a second hey guys so just to show you when you’re pulling this thing apart hey i’ve got mine apartments i’d just never it’s just to show you this cap here would come off and of course you would see like if topic valves and stuff it up in here there’s a little site case here that comes off this is usually where like

Your oil cooler with the touch or just some bolts just to keep it on now you get something thin you can put up here and pull the little pegs out the taffet’s you just slot it and pull the side this one comes out a bit easier the screwdriver let’s disable knocked it because we’re recording at the moment of course but yeah you get the idea you just put something in

Get a hold of the bhushan swings are the only which is good and you have these caps on the side also still undo as well now then save the actual head we can put and tie our cam over the top of it no your valves i’m sure you just know the valves come through your engine side like this they come up out of this valve stem seal up here are your springs no double line –

Got one inside the other thin one and a bigger one and they’ll slop down over the top of your valve stem and then you’ll have a collet here let’s call it slides over the top of the spring gate like that and you have two little half collars now these drop and say here perfectly just two of them and they bite in at the top of the there’s a groove in the top of the

Valve show you that see how pure the edge of it bites in this when the springs under fill’ compression its underlord no you need a special tool to take these off and put them back on especially put them back on i came across a tool having a shared a really old metal tube tool is used for taking spark plugs however think it was a fiat pin was a 16 mil of think so

Yeah it’s just a chip so if you ask me maybe even bike seat pole maybe an old set of straight handlebars but i just place that over the top of the valve stem surely over the top and press down the valve was coming up with the balkman pressing down so i just sat two bits of board down left the space in the middle and just place it over the top and forced it down

Jiggled it a couple of times until i heard the call it’s come loose slipped off now this engine had mag a bent hop valve nag a bent up so replacement valve was needed now already got a set valves no one who’s gonna have to do the engine job and got valves way too big but the size that i have that replaces the buckled one is okay but as you can tell by the sheer

State of the cylinder head that’s totally destroyed but i’ve sanded it down so smooth and i’m actually going to sand down the absolute busted piston that’s on the bike just now i’m going to shove it all back together just to show i can get it all working again while it’s totally malda part but we will be upgrading and be doing a full engine rebuild anyway so we’ll

Get a whole new head and piston get a whole world of stuff but it’s just to show you how to take this off your bike pull it apart in every piece it’s not that complicated the bits are there they can only all go in one way there’s nothing to really get lost about but anyway that’s been pulling it apart now as soon as we get the bits bit so coming in the mail and

I’ll keep updating this run lessers for however long it takes or however many videos it’s going to take be over a few weeks maybe it will rebuild the bike get it going get everything working but yeah it’s just to see if we can get a totally smashed up angeles of absolutely no use running again everybody else would call this engine dead but i’ll bet a million bucks

It’s going to run again so yeah got some gaskets in order the order the gasket kit and a fill loom kit which it’s got a new coil cdi kill switch a couple of sets of the loom wires well that’s not the ht lead so it all helps if you started from scratch one the wiring have been used some of the connectors were rusty the coil just wasn’t connecting to the wires it

Was totally bust up so we’ll see but for just now we’re going to have to rebuild the fill top end so as soon as i can get some bits in what my waiting for i’m waiting for one of the big stretch bolts up here and set and nuts for the top i don’t have any of the screws for the side case and so i’m gonna have to make some some m5 bolts i think yeah i think that m5

So i’ll chop down a few m5 bolts get them in there make sure they’re not obstructing anything inside and yeah it should be ready to rebuild again if it runs it might even just pull it straight back off and port the life out of it but yeah you’ll see he’ll work anyway guys that’s it for just now and a lot day as soon as we’re getting a little bit more progress and thanks for watching bye

Transcribed from video
HOW TO FIX BROKEN PIT BIKE ENGINE TOP END lifan 125CC By Oracle’s Cave