so why do engines blow up I got that question recently so I figured I'd cover
the topic of why engines blow up on motorcycles and what you could do to
prevent it from happening so technically engines don't really blow
up but there's many different types of an engine failure the most drastic and
most damaging type of failure is a connecting rod going through the cases
and that pretty much destroys the whole engine and is a really really cost to
repair and another common failure is a valve snapping or bending and then we
have an engine overheating warping things blow and head gasket there's many
different things that can happen when an engine overheats and then another type
of failure is a crankshaft main bearing or rod bearing going out that's pretty
common on a four-stroke and then a piston or blowing hole through a piston
and then a piston scraping the cylinder up so ruins the cylinder bore and so
those are the most common engine failures you'll see on a motorcycle here
I've got a couple examples of what happens when an engine blows up the
first piston here is from a CR f250 so the broad broke right in half here
piston hit the head hit the valves snap the valves off and the connecting rod
went through the cases and destroy the cases so on this engine we had a
busted-up cases broken crank or broken rod damaged piston damaged cylinder
damaged head broken valves so pretty much the entire engine was garbage on it
except for the transmission and clutch so this engine actually blew up on me
this was probably six or seven years ago there was actually a video over on the
channel of when this engine blew up a helmet cam video and so if you want to
hear what that sounds like I'll put the link up in the corner of the screen
to that video so I'm not sure exactly how that happened sometimes it's hard to
figure out exactly why an engine fails like that but this is probably the most
drastic engine or most damaging engine failure you'll see and then next up this
is from a klx 125 I bought this bike all blown up and so
the valve snapped off and lodged into the piston I made a big hole in the
piston no idea why that happened probably just the kid running it into
the ground what not this stuff happens so that's what it looks like when a
valve breaks and this is from a zero 50 so it's actually a big bore piston and
the rod just straight up snapped in half and you actually bent actually bent
pretty good too so similar to the CRF 250 but I don't think the rod went
through the cases on this engine so not quite as much damage and I'll actually
put a picture up on the screen right now of a 2003 Sierra 450 piston so this bike
was already blown up when I bought it pretty similar to the CRF 250 so it
broke the rod broke a bail damaged a head cracked the cylinder broad went
through the cases pretty much destroyed the entire engine so pretty crappy deal
so now you know what it looks like when an engine goes bang bang now let's
discuss what you can do to prevent that from happening
first up it's kind of a given change your oil your engine oil is obviously
what lubricates the engine so you got to change it out before it gets dirty and
breaks down you leave it in there it's not gonna do you any favors for
preserving your engine life now for this bike it's a two-stroke so the engine oil
is mixed with the gas so no need to change that out and for the gear oil I
changed out about every four to five rides using this Maxima MTL of your oil
and for a four-stroke I would go every four to five rides on the engine and
gear oil - if you do only trail riding you can get away with less frequency for
a gear oil this is a great one to go with if your engine has a split
transmission and engine oil side and for a four-stroke engine oil maxima has a
couple different flavors of that I've had really good luck with Maxima over
the years so that is what I would recommend and a couple more
considerations with oil is you want to watch your links in time to time check
your oil level everyday before we go out and ride and then obviously when you
change out your oil change out your oil filter as well if your bike
and then check your oil and oil filter for signs of copper aluminum steel brass
any type of metal shavings in there obviously that's an indicator of
somewhere going on and that needs to be looked into and this one's pretty
obvious as well clean your air filter your air filter is the only barrier from
dirt entering your engine and obviously dirt inside your engine is gonna wear
things out pretty quickly so I prefer to clean my air filter after every single
ride unless I pull it out and there's not a speck of dirt on it so a good
percentage of engine failures are the result of a cooling issue so that could
be from coolant be a too low having a bad quality coolant having a coolant
leak or some sort of issue with the cooling system so obviously you want to
make sure your radiators are topped off full of fluid and then as far as the
coolant itself this is what I use here inch nice really good stuff been using
it for probably 10 years now and I'll have the link to where you can buy it
down below and as far as having a coolant leak it's pretty easy to check
around the water pump cover for leaks check around the radiators all the
corners and the radiator hoses as well and many times on the bottom of water
pump cover there's gonna be a bleed hole and when your water pump seals go bad
you'll notice coolant dripping out of that hole and obviously that will need
some attention and other issues with the cooling system could be your radiators
being blocked all the fins you know caked with mud or all the
little fins here bent over and another culprit could be the head gasket so you
might want to check into that if you're noticing some cool loss or some steam
coming out the exhaust now another thing to check out is your spark plug that
will indicate whether you're too rich or too lean with your filled mixture more
importantly to lean if you're way too lean with your mixture that like to
create an excessive heat inside the engine and blow a hole in your piston
fry things inside of there and ruin your rod bearings so I did a whole video on
how to read a spark plug and I'll link that video right up here in the corner
of the screen and a big big thing with any engine whether you have a two-stroke
or four-stroke is to warm it up properly you don't let it warm up that'll create
excessive wear inside the engine and could lead to a cold seizure so
basically inside the engine you have pieces that are made of aluminum steel
maybe other materials as well like copper or brass and all of these
materials heat up at a different rate so say you have an aluminum piston and a
steel cylinder aluminum heats up at a faster rate and so if you let that
piston warm up too quick all of a sudden it expands you know it
gets hotter it expands and before you know it it's too big that cylinder and
that'll lead to a cold seizure so just a small example of how not warming up your
engine properly could lead to some damage so basically how you warm up your
bike is you're gonna start it up and let it idle or give it a very little
throttle for a minute or two maybe even longer if it's colder outside and then
slowly bring up a temperature through a little bit more load on the engine and
more rpm so whether the engine is idling or you're out riding you constantly want
to be listening for noises coming from the engine if you hear something and it
starts to get louder and louder or more frequent that's obviously an indicator
or something and you should probably stop and check it out and also while
you're out riding you wanna be feeling how the engine is responding to throttle
or braking it's not accelerating as quickly as it should or you let off the
throttle it's really dragging feels like the brakes are being applied then
obviously that's a really good indicator that something's wrong with the engine
and you need to stop and take a look at it and actually this happened to my
buddy Jeff with the CRF d50 we are riding along and the engine was draining
so much that it locked up the rear wheel killed the engine and so we pulled out
the oil filter and it was just full of copper shavings really nasty and not
indicated the crankshaft rod bearing went out so I'll actually put up that
video right up here in the corner for you guys to go check out now to get
technical and exactly how an engine blows up that could happen in a variety
of ways so the first thing I touched on was a broad snapping so like those two
Pistons I showed you with half a rod hanging off of them that could happen
from just years of fatigue and abuse so if you're not keeping up on your oil
changes the engines getting too hot and just Oh
time those rods weaken especially with heat and over-revving and eventually
it'll just snap so definitely keep up on your oil changes keep up on your coolant
make sure it's not overheating and those rods just wear out over time too and the
second issue I touched on was a bell snapping or bending and most commonly
that happens from an engine when out of time so say if the timing chain jumps
off or jumps a tooth that will create contact between that valve and the
piston and once that bends or snaps off you're in for a whole lot of carnage and
another way that can happen too is an over-rev or the valves floating so if
you have valve springs that are too light for your application or too light
for the camshaft you're running the valves can float and your piston will
make contact with those valves and like I said that's not a good thing to happen
and another issue I discussed was blowing a hole through a piston or
seizing a piston inside of a cylinder so most frequently that happens from lack
of oil or lack of oil changes or excessive heat within the engine so that
could be from cool and being too low or having a coolant leak or if your fuel
mixture is to leave and one more thing I was talking about earlier is your crank
bearings going out so the bearing that wears that most frequently is the rod
bearing so that would be the bigger bearing on the bottom of the connecting
rod and that wears out pretty similarly to that of the piston so from excessive
heat lack of oil or lack of oil maintenance and same thing for the crank
main bearings as well so keep up on your oil changes make sure your oil is always
topped off same thing with your coolant and check around your engine and cooling
system for leaks as well and one last thing you can do to prevent your engine
from blow it up is to fix things before they break completely if you notice your
bike is lower compression it's smoking making a noise or a rattle or it's
leaking something fix those before they become a bigger issue and that will save
you a lot of money down the road and repair costs I really hope this video
answers some of your questions and if
you enjoyed it please hit the subscribe
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so I know you guys really want to see the cr250 build but I'm still waiting on
a few essential pieces in the engine so that's kind of holding everything up at
the moment keep in mind these bills do not happen overnight there's a lot of
moving pieces to make it come together but trust me if I had everything I would
put it together right this second but I promise you as soon as those parts come
in I'll have some epic videos roll on your way so stay tuned for that and in
the meantime let me know down in the comments section what kind of videos you
like to see alright guys thanks for watching and keep apprised