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1:11 YZ250F 2019-2023 Full Motor Rebuild (Part 1). Engine locked up on this Yamaha. — Transcript

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0:01welcome back to the shop this is Joey's
0:032022 YZ 250f he told me the motor locked
0:07up so let's
0:09check on the left side of the motor here
0:11I'm going to remove this little cover
0:13and that's going to give us access to
0:15the bolt that holds the flywheel on the
0:18crank and then we can suspend the motor
0:21by
0:23hand sometimes them can be on there
0:25pretty
0:26tight let's get that off of there all
0:29right
0:30now I'm going to put a 17 mm right here
0:33on the nut for the uh flywheel I'm going
0:37to spin the motor I'm going to attempt
0:39to spin the motor counterclockwise cuz
0:41that's the direction that it spins when
0:43the bike is running so let's see how it
0:47feels and the fuel pump turned on
0:49anytime the motor spins and the uh
0:51stator senses motor spinning it will
0:53turn on the fuel pump so far it's
0:57spinning well
1:01huh okay it feels funny I can tell you
1:04that there's something about it doesn't
1:05feel right right
1:10here
1:12H it's definitely not locked up he said
1:16it did lock up but it was in the air and
1:19when he landed it slid the rear wheel so
1:22maybe if it did lock up whatever was
1:24causing it to lock up it broke through
1:28and uh so we do have a
1:30problem hm yeah I believe we do have a
1:33problem cuz even though I feel it feels
1:35funny right here watch you'll hear it
1:37it's like snaps through something
1:39there's no
1:41compression want to spin it quick so
1:44we're going to have to open her up let
1:46me start by getting the seat off of her
1:49and disconnect the negative on the
1:51battery the ground cuz as you heard
1:52every time I spun the motor it would
1:54light up the fuel pump so this will
1:57eliminate that from happening also um if
2:00someone was to accidentally bump that
2:02start uh the starter button while we
2:04have this motor apart things can get
2:06nasty so it's just good to go ahead and
2:09disconnect that and make sure that don't
2:11happen after I disconnect it what I'm
2:12going to do is hit the start button real
2:14quick you'll hear a slight
2:16little sometimes and that's just going
2:18to uh kill the last little bit of power
2:20that's in the uh little condenser on the
2:22bike let's see there it is you heard
2:24that click now it won't click anymore so
2:25we've drained all the power out of it
2:28all right let me get the tank off
2:40I want to get the tank off real quick
2:41pop the valve cover off let's just see
2:44you know I've heard of these things
2:45breaking timing chain now I will
2:48honestly say I haven't seen one break
2:51myself nor have I uh do I know anyone
2:54who has personally had it happen to them
2:57it's just something that it's like a
3:00something that's going around I'm not
3:01going to say it's a rumor it could be
3:02true but I don't I haven't seen one but
3:05let's see what we got here but before I
3:07move the valve cover let me go ahead and
3:08get the shrouds off and stuff get that
3:10out of the way so I can get a better
3:11view with the camera in there and you
3:13can see what's going on plus I already
3:15know we're going to have to dig in this
3:16motor that stuff's going to have to come
3:17off
3:19anyway all
3:22right that little safety thing right
3:25here now normally I would just go ahead
3:28and already removed this whole airbox
3:30and stuff it does make getting the valve
3:32cover off a little easier however the
3:35owner of this bike is real Curious just
3:37the time he chain broke or if it dropped
3:39the valve so before I even pull off that
3:43just so I can give him a quick notice of
3:45what happen I'm just going to yank the
3:46valve cover off it's going to be a
3:48tighter tighter fit to get it out of
3:51here because I still do have all that
3:53stuff on but you know we'll get it
3:58out let see here all right let get a
4:14flathead pull the fuel line up here a
4:17little bit definitely a tight fit to get
4:20it out like
4:24this but we got it
4:26out
4:28oh got guys I think it dropped the
4:31intake
4:34valve oh
4:37boy yes sir she dropped intake valve
4:41timing Chain's good so there we go
4:44there all right let me figure out how I
4:47can get you up in here and show you how
4:49I can tell that it dropped the intake
4:52valve all right these this is the intake
4:55cam right here there's one of the cam
4:57buckets you can see how it's How how
4:59high it is right there it's making
5:01contact with the cam shaft or up against
5:04it I should say over here all I see is
5:06motor oil up in here the camp bucket is
5:09down up in the hole and there's just
5:11motor oil let see if I get the light in
5:13here a little bit better for you yeah so
5:15we got a cam bucket right there up in
5:17this proper position just below the cam
5:19shaft we have a cam Bucket over here on
5:21this side remember there's two valves on
5:23the intake side that is down up in the
5:25hole that valve dropped timing chain and
5:29good shape he was concerned it could be
5:31the timing chain because again there are
5:34I guess you can say rumors going around
5:36that they break but I haven't seen one
5:38break yet maybe it does I will say if
5:41you're the type of guy that runs like
5:42kibble white valves with heavy duty
5:44valve springs it will put more stress on
5:46the timing chain and maybe them are the
5:47people that breaking it but I can tell
5:49you with the lighter weight titanium
5:50Springs I mean titanium valves with the
5:52lighter weight Springs that come in
5:54these stock I haven't seen any timey
5:56chain issues on them but this one
5:58dropped the Val so we're going to have
6:00to pull the whole cylinder head off and
6:02um let's just see what kind of damage it
6:04did I hope I hope uh the crank's still
6:08in good shape sometimes it can bend the
6:09rod when that happens as the Piston's
6:11coming back up and smashes the valve it
6:14can bend the rod um sometimes it damages
6:17the cylinder head real bad sometimes it
6:19gouges the cylinder let's open it up and
6:22see what kind of damage we have let's
6:24dig
6:25in by the way before we go any further
6:28if you're looking for a step by-step
6:29tutorial on doing a top end job on the
6:32yz250f check down in the description
6:34there'll be a link where I did a video
6:36doing just the top end job replacing the
6:39piston and that was pretty much it this
6:41one's going to be a little bit uh more
6:43involving than that we have valves to
6:45replace here um probably damaged head
6:47maybe a crank who knows we're not going
6:48to know till we get in there but if
6:49you're just looking for top end check in
6:51the description all right let's continue
6:53on we got to rip into her as you may
6:55have noticed I did not remove the tank
6:57completely all I did was just spin it
6:59around set it on the subframe there um
7:03that way I don't have to disconnect the
7:04fuel lines or anything like that but uh
7:07I'm going to go aead put a bungee cord
7:08around it so it doesn't accidentally
7:10fall off and break one of the wires or
7:13anything that'll work okay I guess I'll
7:17go ahead and get the air intake off and
7:20everything like that I'm going have to
7:21remove all this stuff right here to pull
7:23that
7:24out okay as you hear me say in pretty
7:27much all my videos you'll see me use an
7:28impact a lot during tear down but I'm
7:32real cautious where I use it during
7:34reassembly because you can strip stuff
7:36stuff out real quick and and
7:38easy okay got the CDI unbolted here let
7:42me go ahead and unbolt the uh ignition
7:45cord during disassembly this surely does
7:48speed things
7:55up all right I'm going to slide that up
7:57okay we got to disconnect the coil here
7:59we don't have to but I would like to get
8:01it out of
8:04here but I'm going to leave the CDI
8:07connected I'm not going to disconnect
8:09that sometimes does you know I mean it's
8:12not real common but sometimes you get a
8:13bad connection when you go to reconnect
8:15them just to keep things cut and dry if
8:17I can anything I can leave connected
8:19especially when they have multiple um
8:21terminals inside of here or what
8:23whatever you call them just multiple
8:24wires I like to just leave it together
8:27okay let's take out the bolts with there
8:35box oh crap I'll get
8:45that and one more right
8:53here
8:56okay okay back on this side of the bike
8:59I have to loosen up the clamp that holds
9:01the uh the the intake boot to the
9:04throttle body I'm just going to use what
9:06size is this it's a 4 mm
9:11Allen that this works good to have Allen
9:13sockets cuz it would be tough just use
9:15an allen key up in here I mean you could
9:17if you really had to but
9:20yeah okay I believe it's time to lift
9:22the intake box off of here you don't
9:24want to just yank this thing all up
9:26madly now that we have it all loose and
9:28ready to go because there is one more
9:29connection for the air intake
9:31temperature sensor right here and the
9:33wire's a little short on it right so you
9:35have to get it off the intake boot so
9:37you give a little tug but be careful
9:38with that
9:39wire there it is and now I have to reach
9:42up in here I'll show you once I get it
9:44out it doesn't give you much
9:47room this one's pretty much stuck on
9:50there pretty
9:54good let me get that loose real quick
9:58okay I think I got it loose now sorry I
9:59just paused it so I don't waste your
10:01time here there it is okay let me show
10:03you what we
10:05got see that center right here it plugs
10:08in right to this but look it doesn't
10:11have a long wire so don't go yanking
10:13this off real quick or you're going to
10:15get yourself a nice little check engine
10:16light when you put it back together if
10:18you break that
10:20wire all right we have access to this
10:23intakes open um H got some debris in
10:27there that's it's okay all this stuff's
10:28going to get cleaned out at this point I
10:30really don't care what falls in right
10:31here honestly I don't care about any
10:33dirt falling here all the stuff's
10:35getting yanked out it's going to get
10:36cleaned up before it goes back in let's
10:39go ahead and get the throttle body off
10:41I'm going to start by removing or
10:43disconnecting some of the sensors all
10:45this stuff is loaded with sand we're
10:46going to clean all these terminals too
10:48when it's time to put it back together
10:50okay got that we have a throttle
10:51position sensor over there I'll get that
10:53one a minute but let me go a get this
10:54fuel line This fuel line has a little
10:56plastic tab you slide over and that
10:58allows you you get to the two little
10:59buttons here to press it now you can
11:01press these with your
11:03finger like that like I just did but
11:06sometimes it can be a little bit tough
11:09let me show
11:10you they do sell a tool for pinching
11:14them they just call fuel line pliers or
11:18whatever but you can you can also use
11:20your fingers like I just did right
11:25here and uh I'm going to plug this let
11:27me get my plugs for that because you
11:28don't want any debris getting up into
11:30the fuel
11:35line your bike comes with this brand new
11:37if you ever wondered what this was for
11:39you'll find a little kit that comes with
11:40your bike it's for this right here and
11:43I'll put the other side right here
11:45that'll keep any debris from just uh
11:47getting in the fuel line we don't need
11:48that cuz then it'll get in the fuel
11:50injector and clog that up okay we have
11:53to go get the uh throttle position
11:55sensor disconnected we're going to leave
11:56the the uh the throttle cables connected
11:59I'll show you why in a minute cuz all
12:00we're going to do is dangle the the
12:02throttle body off to the side we're not
12:03going to remove it completely off the
12:04bike just less stuff we have to
12:06disconnect these throttle position
12:09position sensors can sometimes be a
12:10little tough you slide the little rubber
12:12cover off they can be tough because they
12:14get dirt up in them like this one has it
12:17I can tell so I can't press the button
12:20there it's just like impossible to press
12:23it so what I'm going to do is shoot air
12:24in it to clean it out that's really
12:27common on these because the way that the
12:29the sensor is kind of upside down so to
12:31say the dirt just Falls right up into
12:33the
12:36connection let's see if that
12:42helps she's still
12:51tight all right let me spray it some
12:57more
13:01I also see there's rubber right here I
13:03wonder if someone did a bad job putting
13:06this thing together at one time and got
13:08the seal on
13:13there
13:15H like I said these can be tough I can
13:18see it it's getting pressed in it's just
13:20not sliding down so I'm going take a
13:22flat head here and just kind of give it
13:24a little bit of
13:26help which that don't seem to be there
13:28it is all right you can see all the
13:30trash I don't know if you can see it in
13:31there you see all the dirt and stuff
13:33that's in there and all the dirt that's
13:34on this right here that's what happens
13:37is all that stuff just Falls in here and
13:39it just locks these things down they get
13:42really stubborn but we're going to clean
13:43all that when it's time to put it
13:44together I do need to loosen up this
13:46Allen right here for this bottom clamp
13:48on the throttle body so we can pull that
13:50off so let me go get an allen for that
13:52now this bike only has 52 hours on it
13:55and this should have never happened but
13:58every so often a valve from the factory
14:00oh someone had that on tight is a dud
14:02the valves are supposed to spin slowly
14:05as they're going up and down and that
14:06kind of keeps them from mashing the head
14:08down on the
14:09valve uh the top of the valve which I'll
14:11show you a little bit better when we get
14:12it off but uh got that loose so let's go
14:15over here but yeah so typically before
14:17they drop a valve because of this type
14:19of failure typically you're going to
14:20hear some ticking come along and uh it's
14:24going to be a little bit more ticking
14:25than what's normal for your bike and if
14:28you check your valves when you hear that
14:29ticking you would have someone would
14:31have spotted that but he didn't hear the
14:34sound he wasn't paying attention however
14:36when I'm done fixing this bike I'm going
14:37to make him listen to the bike real well
14:39and uh get to know what it sounds like
14:41in perfect condition cuz as a rider you
14:43need to be familiar with your bike so
14:45you can catch this stuff before it
14:46happens just like if you're airline
14:48pilot a jet fighter pilot whatever
14:50you're supposed to be familiar with your
14:52machine if something doesn't feel right
14:53you're supposed to kind of spot it out
14:55same thing with these right cuz I mean
14:57we're putting our life on the line when
14:58we go towards big jumps and we're
14:59jumping this thing and he this bike
15:01actually locked up on him in the air
15:03luckily he didn't go down but yeah so
15:06let's go pull that throttle body off
15:08because had he have caught that sound
15:10and brought it to me to check the valves
15:12or even check them himself they're
15:13really not that hard to
15:14check okay he would have caught this
15:17ahead of time that would saved him a lot
15:18of money and frustration and risk of
15:20getting injured all right here's your
15:21throttle body I just pulled it out you
15:23see I still have the throttle cables
15:24connected I'm just going to leave them
15:25connected I'm just going to kind of
15:26dangle It Off just like that they'll
15:29stay out of our way and we don't have to
15:31we don't have to mess with the throttle
15:32cables this way and I'll take the CDI
15:35just kind of set it somewhere over here
15:37for now there we go we still have more
15:40some more stuff we got all kinds of
15:41stuff just floating around here but
15:44okay guess the next step is getting the
15:46exhaust system off and out of the way
15:48let's do
15:57that
16:25hey look
16:27done okay got to remove these two 10 mm
16:30right here to hold the header pipe onto
16:32the cylinder I'm just going to try to
16:34use a ratchet wrinch for
16:38this yeah all right anyway like I was
16:41talking about earlier the valves are
16:43supposed to spin as they being open and
16:46closed and you know just slowly Spin and
16:48that helps uh distribute the wear and
16:50keep them from mashing down the top of
16:52the valve and I would say like one out
16:56of a thousand valves and this is just a
16:58guess right but one out of a thousand
16:59valves is a factory defect it doesn't
17:01spin so what it does is it mashes down
17:03the top of the valve to the point that
17:04it gets to the valve Keepers once it
17:06gets to the valve Keepers and it erodes
17:08them away it just drops the valve and
17:10that's what happens the valve Falls
17:11right into the cylinder gets mashed
17:13between the piston in the cylinder head
17:15and that's what causes this type of
17:17damage so my brother had that issue with
17:19the yz450 that he brought brand new in
17:21about 35 hours he started hearing a
17:23ticking pulled the valve cover and found
17:24it was doing that pulled ahead replaced
17:26that valve and he went on to put on like
17:27150 hour on that bike with no problem so
17:30again pay attention to the way your bike
17:32sounds is really important to do let me
17:33go to the other side and uh yank that
17:35header off
17:46there because if you pay attention to
17:48these the nois normal noises that your
17:51motor makes when it does finely uh make
17:53a noise that you don't
17:56recognize you'll you'll dress it you'll
17:58go digging in before the motor blows up
18:00on you okay got to drain the coolant
18:02it's going to drain it it's going to be
18:04the uh 8 mm right here has a copper
18:06washer underneath it let me get
18:07something to collect that
18:09with and I'm going to take the radiator
18:12cap and just loosen it up up here so it
18:14doesn't create a vacuum so the coolant
18:16flows out nice and
18:27easy
18:29try to catch that Whoa Don't drop too
18:33much on the
18:34floor okay now it's all drained up I'm
18:36going to go ahead and put that back in
18:38and tighten it up that way I don't
18:41forget it you can leave it out the whole
18:42job then you might forget to put it back
18:43in on the end pour the cool in it just
18:45starts pouring on the ground and I'll
18:47tighten it by hand don't want to use the
18:49end pack CU you will strip that sucker
18:51right on out all right while I'm here
18:53let me remove the rest of the stuff on
18:54this side all right so we have this
18:56sensor right here the coolant
18:58temperature put your sensor Slide the
18:59little rubber sheet up so I can press
19:01the
19:02tab there we go that one came right off
19:05that's
19:06good got the ground wire right here
19:09ground strap take that
19:16off I'll just go ahead and feed that
19:18back in the hole so I don't have to
19:21worry about where I put it later
19:24on there we go actually let me p a
19:27little bit out so I no that's the one
19:29there we
19:31go and then instead of removing this
19:33just the just the hose I'm going to take
19:36this whole coolant boss off it's going
19:38to give me a little more room when it's
19:39time to lift that head up it's going to
19:40give me room where that doesn't hit the
19:43frame these you got to kind of they can
19:45be tough to kind of Wiggle out
19:48sometimes there we go let pop that right
19:51up here somehow some
19:55way there we go you know what when I
19:59pulled that valve cover off I forgot
20:00about this you want to collect that
20:02don't lose that you need to put that
20:03back on there when it's time to put it
20:05back together okay I want to remove the
20:07cam caps and the cam shafts but before
20:09do that I have to take the tensioner out
20:11for the timing chain and that is right
20:13here so let's go ahead and do
20:16that I like to remove the uh or loosen
20:19the 10 mm up here at the end while it's
20:21still on the bike cuz that thing can be
20:23tough to remove once you have it off the
20:24motor to hold this in your hand and also
20:27loosen that up
20:29all right we got the starter wire kind
20:31of in the way here let me loosen the
20:32starter wire up a little bit oh I see
20:42okay there we go I can just loosen it
20:44and spin it like that that gets that out
20:46of my
20:49way cuz you really don't have much room
20:51to get your eight mm back in here of
20:53course there's probably easier way to do
20:55it maybe but I'll just do it like this
20:58I'm starting with the one that's further
21:00away that way once I get it Loose
21:02hopefully I can just use my
21:05finger hopefully I don't have to back it
21:07all the way out by hand like
21:10this you know what I think I'm just
21:12going to make my life easier and uh
21:16remove that starter wire all together
21:18from the starter there we go that gives
21:20me a little more room here to
21:25play let me see something here
21:29yeah looks like I'm just going to have
21:30to oh oh there I think it's finger loose
21:33now yeah it is all right that's better
21:37all right and that's why I left the one
21:40closest to me tight because
21:43uhoh now it's getting tight again anyway
21:47that that's where I left the one closest
21:48to me tight for the time being holds the
21:52tensioner down so I can get the harder
21:54one out of the way
21:57first cuz that tension is spring loaded
21:59so you'll see when I go to loosen up
22:00this side it's going to start the
22:02Spring's going to start popping it
22:05out so let me finish getting this one
22:07out and I'll be right
22:09back all right got it all right now
22:13let's get this one
22:16off
22:18actually here you
22:23go you see how it's coming out as I
22:26loosen it cuz the spring loaded that's
22:27why got the harder one out
22:33first and there we
22:35go time and chain
22:37tensioner is out of there now I'll show
22:39you when it's time to put it back
22:41together how to compress that and reset
22:43it and all that but that's later on
22:45timing chain is nice and loose we can go
22:49ahead and remove all these bolts right
22:51here there's four on this cam cap and
22:52for this cam cap and pull them cam caps
22:55out of
22:56there okay let's do do
23:23it all
23:26right now when you pick these cam caps
23:29up and off the cams you want to um as
23:33you pull them up you want to also move
23:36them to the right side of the bike not
23:38the left and not straight up either
23:40because there's a little keeper half
23:43moon shape Moon shaped keep or whatever
23:46right underneath this cap and has a
23:47tendency to fall down in the timing
23:49chain area and uh then you have to fish
23:53it out if if you're only doing a top end
23:56then you don't want to have to remove
23:57the Stater covered grab that but let's
23:58see pick it up move it to the
24:01right that one stayed on there I'll show
24:03you
24:04it that's it right there that cam caps
24:16off all right that one stayed on too
24:20good there got that
24:24one now we can pull the cams right on
24:26out of there
24:34cam number one woo that thing that valve
24:37that valve is definitely dropped
24:42bummer it's okay we'll fix her up she'll
24:45run like
24:48new all right the cams are out of there
24:51um I think now all I really have to do
24:54is take the cylinder head bolts off out
24:57but before I move the cylinder head
24:59bolts up top let me go and remve these
25:00two 10 10 mm nuts right here and then
25:04I'll get up top and move the cylinder
25:05head
25:08bolts okay I'm going to remove the
25:10cylinder head bolts
25:13now this is a 12 mm by the
25:23way just loosen them all up just a
25:25little bit first there we go
25:36all right now every one of these
25:38cylinder head bolts have a washer make
25:40sure you get that
25:45washer the ones on the left side here
25:47are more difficult I use a magnet to
25:49collect it and then I stick it in there
25:51and get the washer for it otherwise uh
25:55yeah you don't want to drop the washer
25:56down in the fly the time climing chain
25:58area and you have to go fish it
26:01out there we
26:06go okay I think it's time to pull the
26:08cylinder head up and off of
26:11there this is the interesting part
26:13because this is we're going to where
26:14we're going to see what type of damage
26:16was done by that valve dropping let's go
26:18a and pull the head
26:26off
26:45this is great everything's locking up on
26:47me
26:51here there we
26:56go
27:00all right I got one thing I have to take
27:01care of real
27:03quick there we go I forgot to actually
27:05uncp the starter wire here from where it
27:07Clips onto the back of the head and that
27:09was kind of catching up on me here but
27:11we got that out of there first thing
27:13we're going to look at before we look at
27:15the bottom side of the cylinder head is
27:17the Piston well it actually fared out
27:19pretty good actually she got one pretty
27:22good size ding here oh man but it seems
27:26like the Piston shift
27:28sideways that might indicate we might
27:30end up needing a new crank shaft dang it
27:33I can feel it this side right here look
27:37this side right here is sticking up my
27:39and this side right here is
27:41in it's lower than the than the deck and
27:45this side back here is higher so when
27:47one valve drops like that and the Piston
27:49hits it a lot of times it does shift and
27:51bend the rod uh okay well we'll know for
27:54sure when we get the cylinder off I'll
27:55have to remove that out right there to
27:58get the cylinder off but let's go look
27:59at the cylinder head real quick okay up
28:02on the healing bench I have been fli it
28:04myself I'm doing this live on camera
28:06guys I don't even know what I'm going to
28:08see when I flip this thing over I'm
28:09scared to look but here we got to do
28:13it oh man that's not good it's not good
28:16at all I can already tell you right now
28:18we're going to need a new cylinder head
28:20it
28:21completely goug the uh the
28:24valve seat there that that sucker is
28:27just wedged in there oh man this is not
28:31good at
28:33all dang it it appears it bent a exhaust
28:37valve I can see that it's bent if you
28:39see it's lift up right here but down
28:41there it's
28:42not oh man
28:46okay so yeah this is not looking good at
28:50all I can you can see let me get
28:52something to point with
28:54here I can already see right there where
28:57it damaged the uh the valve seat pretty
29:01or yeah pretty good and it broke the
29:04valve guide in there this is pretty
29:06nasty like I pointed out the exhaust
29:08valve right here is bent um oh man this
29:12is just not looking good all right let's
29:14pull that cylinder off and um let's see
29:18how the rod handled
29:20it all
29:26right
29:35bummer that's a
29:38bummer I was hoping to see a little less
29:41damage than that I mean I was you know
29:45expect how do you say expecting the
29:47worst but hoping the
29:53best okay well so far the cylinder
30:01oh there's one gouge right
30:03there yeah very small one I don't know
30:06if you can see it let me see if I can
30:07get the camera on it right there I mean
30:11technically it could probably be
30:13smoothing out and reuse but because this
30:15is a race bike we won't be reusing it
30:18we'll be getting a new
30:19one okay I got to get the Piston off of
30:24there take my time put a rag around it
30:26just cas that c clip go slinging off
30:29although I believe we're probably end up
30:31having to take the motor apart anyway so
30:33if it did go shooting down in the bottom
30:35end probably really wouldn't matter but
30:38just in
30:39case all right see if
30:45I got
30:47it all right let me go to the other side
30:50and knock the pistol
30:56p
31:17okay before I try to take measurements
31:19I'm just going to look at it from above
31:21oh yeah oh it's bent it's bent bad let
31:24me get you up in here and show you
31:26bummer
31:29all right uh let me try to get you up in
31:31here a little
31:37closer you see how this is bent it looks
31:40like it's bent that
31:43like holy cow it's bent that way don't
31:47know if you can see it in the VD camera
31:49there here let me this will help all
31:51right I'll be show you a little better
31:53this way I put the uh the wrist pin in
31:55there and and you can see how versus the
31:58crank the whole Rod the tip of the rod
32:01is bent a little bit that
32:04way so it's going to need a new crank
32:07shaft unfortunately that is a real
32:10bummer and after a little further
32:12inspection I went ahead and removed the
32:15bucket to the valve that dropped here
32:17and actually the top of the valve is
32:19just fine so remember earlier I was
32:20saying that they can Mash these down to
32:22the point they lose their Keepers well I
32:24was wrong in this case that's not what
32:26happened here um looking at the Piston
32:30here obviously you can see the big
32:32damage right here but if I look closely
32:35right here I can see a little swirl Mark
32:38right there where the valve made slight
32:40contact with the with the um piston
32:43before it broke and also right over here
32:46too I can see where it made contact
32:48before it broke
32:51so two things happened either something
32:54got into the intake and lodged the valvo
32:57open but he has a good filter on it and
33:00I don't think that's the case but I I've
33:02seen that happen before where something
33:04got in here and lodged the valve open
33:06and it wasn't able to close and the
33:08Piston hit it and it bent it and broke
33:10it off and then we get this damage
33:13another other times that I see this
33:15happen is when people way over rev their
33:18bike um and you can't do it by the
33:20throttle it's more like it's more like
33:22you're in fifth gear hauling but you
33:25downshift the second gear and just let
33:27the clutch out meaning the motor spun
33:30faster than what it's capable of
33:31spinning on its own because it does have
33:33a rev limiter so if you down shift too
33:35many times you let the clutch out and it
33:36spins higher than it than it ever was
33:38meant to spin the valve can float
33:41meaning the spring is not strong enough
33:42to close the valve fast enough at that
33:45speed and so it didn't close in time as
33:47the Piston was coming up and boom it
33:49makes contact with it and it breaks it
33:52so I'm guessing one of two of them
33:54things happen there now what bent that
33:56on still confused it could be debris
33:59from this when it was breaking got
34:01caught up in here let me look up in the
34:03exhaust Port see what we got yeah I
34:05don't see anything in
34:08there
34:15uh just expecting a little bit it
34:18doesn't
34:21look yeah you can see right here the
34:24line going around where the Piston made
34:27contact I mean the valve made contact on
34:29this side before it broke so well
34:31whatever broke it I guess it really
34:33doesn't matter at this point we just got
34:34to fix it and this is going to be a lot
34:37of
34:37parts and of course now I have another
34:40question that arises in my head
34:43here when the intake valve makes contact
34:46with the Piston sometimes it has a
34:48tendency to shift the gear on the cam
34:52shaft here this gear is just press
34:54fitted onto the cam shaft right and but
34:58if there's enough
35:00um there's enough torque applied on this
35:03and
35:06if hard to
35:09explain if as it's spinning the cam the
35:12cam gets lock shut from trying to smash
35:14it about in the Piston it can actually
35:16spin that gear on the cam shaft and
35:18that's going to knock out your cam
35:19timeing now because now when you go to
35:21line up the dots when we go to put the
35:22motor back together you'll line it up
35:24but then the bike ain't going to run
35:25right because the cam timing will be off
35:28or it'll run poorly or it won't run at
35:34all so if it was my bike honestly I
35:37would just get a new intake intake cam
35:39anytime
35:41uh anytime a valve hits I I that that's
35:45usually what I practice but I'll ask him
35:47what he wants to do all I'm doing right
35:49now is looking at it it doesn't look
35:51like it shifted right so I lined up the
35:53dots as as if we were I got this dot
35:56right here lined end up with the uh
35:57mating surface for the valve cover and
35:59the two dots up there I got this dot
36:02right here lined two dots up there and
36:03then I'm going to spin it down and look
36:05at the cam I mean at the loes the loes
36:06are pointed up and at angle I'm going to
36:09say that this one didn't shift I'm going
36:10to say this one's good so he might be
36:13okay and um again if it was my bike I
36:17would probably do it just for good
36:18measure or at least compare it to
36:20another um intake cam shaft and make
36:22sure the loobe is in the same place and
36:24hasn't moved a good good practice if you
36:26have your bike apart take a uh just
36:29grabe a line going right across here so
36:31if you ever do have this type of failure
36:33you'll be able to look at your cam sha
36:34and them two lines don't line up then
36:36you know uhoh we got a problem um I've
36:38also seen pro circuit actually put a dab
36:40of weld on each side to guarantee it
36:42doesn't shift or move you know but all
36:45really all you got to do is just grab a
36:46mark on it and um that way if if this
36:49type of failure ever happens to you
36:51you'll be able to know if the cam Shi it
36:54the cam gear shied or not this one is
36:56looking like it's good and the cam
36:57blob's looking in good shape so it'll
37:00probably be okay to reuse it but I'll
37:01still run it by them again if it was my
37:03bike just for a piece of mine if I
37:05didn't have another cam shaft just like
37:06it to compare it to I would just replace
37:09it
37:11honestly so yeah this could be a pretty
37:14expensive repair let's go take a look so
37:16we're looking at a spark plug timing
37:19chain gasket another gasket gasket a
37:21piston assembly crankshaft assembly
37:24crank Baron cylinder cylinder ahead uh
37:28head gasket cylinder base gasket two
37:31intake valves two exhaust valves I'm
37:33going to go ahe replace the intake valve
37:35springs just to be safe you're looking
37:37at
37:39$2,254 worth of parts and that's before
37:42tax but before we order all them Parts
37:44he told me to hold off for the time
37:46being cuz we he might be purchasing this
37:49kit that I get us the cylinder head new
37:51cam shafts but it's a gytr kit it'll get
37:54bring it'll come with the Piston all the
37:56gas to get you see all the stuff right
37:57here CDI uh bump up the performance
38:00obviously it's more money obviously too
38:04but he told me hold off so I don't know
38:05which route this is going to go yet so
38:08stay tuned for part two of this video
38:10where we pull that bottom end out uh
38:12replace the crankshaft put it all back
38:15together and most likely that video put
38:17the motor back in and start her up for
38:18the first time so stay tuned for that I
38:22will put a link in the description to
38:24part two of this video there'll also be
38:25a little thing probably over here or
38:27over here at the end of the video let
38:28you know where part two is at when we
38:29get there but um yeah if you go down in
38:33the description it says coming soon just
38:35check back later soon as the part two is
38:37available I will update it with a link
38:39down into there this weekend I will be
38:42riding um Dade City motorcross but I'm
38:44actually going to take out the YZ 252
38:46stroke not the 125 this week most likely
38:50Dade City Motocross hope all you guys
38:52have a good weekend riding stay tuned
38:54for part two of this video also coming
38:56up here shortly most likely this week
38:59KTM 450 SXF top end rebuild with the
39:04timing chain and also a
39:07CRF250R top end rebuild coming this week
39:10catch you guys next time

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