hi i'm paul brodie we're in my shop here welcome it's a friendly place mitch behind the camera
i'll do the fabricating i'll talk to you about what's going on
so today we're gonna do engine mods that's what i call it on the cub motor this is a cub motor
if the engine is in the frame you can work on a multitude of things you can work on the clutch
electrical inside the case the cams the gearbox but if you want to change the sprocket which is
the counter shaft sprocket you have to you have to take the motor out of the flame frame and split
the case which is a pain now i don't know how often you have to change the sprocket but i've got
three sprockets i got a 17 18 and a 19 and i don't know which one i really want i'm thinking the 18
so we're gonna make a door here there's going to be a plate which bolts on here
we're going to make a hole with a hole saw and then while the engine's still in the frame i can
change sprockets i don't have enough room here in the metal to put a 19 through there because
this sprocket has to go through there i've got little allen screws the hole on the plate
that's gonna be the plate there i found a piece of aluminum i've got a little oil seal
i wanted to show you this i've been working on the transmission a little bit i've got a bushing here
this is where the oil seal goes it goes over top like that that seals the case this oil seal goes
into that one-quarter inch aluminum plate and so i had to take out out the old old bushing
so there's the old bushing i had to make up what i call a driver it's the right size
and then i use the arbor press and i pressed out the old bushing made a new bushing then i honed it
so that's all taken care of so what we're doing today goes over over the bushing so we're going
to go to the mill this first part happens in the mill and then the second part making the plate
i've got a drawing i got this from uh a guy that i'll be messaging he's in australia his name is
steve burns he's got four cubs he says that he doesn't ride much anymore but he used to ride
back in 1989 he set a guinness record for the fastest wheelie in the world 150 miles an hour
well that record stood for a little while in 1999 it was surpassed or maybe earlier
and the new record is 192 miles an hour can you imagine doing 192 miles an hour on your back wheel
that's amazing that's scary so we're going to go over to the mill set this up
and i'll show you what's going on we're going to bolt the case down this is the right side case
i've got i've got the clamps all ready to go and then we're going to take a dial indicator
and we're going to dial up to the surface here where the oil seal fits in
and then once once that's done then we bolt this case on top using these existing screws or bolt
holes that's when we bore so that we know that our bore here is perfectly concentric with this
bearing and the oil seal here so there's a little bit going on there i've got one bolt right here
and then i need to hold it somewhere else so i'm going to hold it at the back here
where there's a mount and i put this under here and that fits pretty well like that
i got a gap here because it it's a cars thing it's not perfect but i've got a a feeler gauge and this
is 18 thou and that happens to fit quite nicely like that so that's when i put this up and hold it
down like that so i'll put a little bit of thought into this it's not just happening right now
well it is happening right now but there was a bit of thought that went into it so holding it
in two spots i don't i don't want to just hold it in one spot because
it can move so it's always good to have have two spots minimum to hold something down like this
i've got my fancy little one here it's in tenths of a thou so from here to here
like from the zero to the one that's only one thou so this thing is really really sensitive
so this needle has to go to see that needle it's got to be moved to thou it's got to
go down to the one there so we'll see which way we're going okay there we go
moved it a little bit lock the table
and the other side was at once so it's out one quarter of one thou which is
almost nothing so there we're gonna that's our center right there zero zero
i've got my soft hammer here this is soft rubber so i can hit on aluminum not not cause any damage
and that looks like it's seated there's the line i don't see any gap
i've got my four special bolts bs c i think i think it's bsc with a 55 degree thread angle
all right so first we'll use the hole saw
we're through so we're going to swap this out for
a boring bar now and we have a size so that the sprocket fits through
oh
well i have to hold it it's got some vibration it's got a ring to it
i thought i bought it way too big but can you see how there's a little bit of movement there
probably five tenths out and then the sprocket goes through so that's what i wanted
so now i gotta face this here it goes out to right there i'm going to show you the allen screw that
we're going to use here there's very small four mil allen screws can you see how there's not a
lot of space there but that does that that'll go like that that's going to go right like that
and i'm going to have six of them all around there so what i need to do is i need to face this now
so i i think what i'm going to do i'm going to put it on a really slow speed
i'm going to bring the boring bar down and then i'm i'm not going to use the feed
in the quill i'm going to raise up the table because that's going to be more more secure
we'll get a little bit more speed going okay so that's about 160 rpm
so i'm gonna i'm gonna raise up the table slowly slowly slowly
and hopefully it all goes well
this is the part i was most concerned about
hear it
and i might need to hold it so it doesn't ring
so we're watching that bit right there it's not cleaned up yet
okay okay do you see here it was the last area to clean up can you see there's a little bit
there that didn't quite clean up in machine shop terms that's known as a as a witness mark
if a customer comes into a shop and tells you to take off the least amount possible
you want to leave a a little witness mark so the customer knows that you did what you were told
so that's what i learned back when i was a kid off to high school witness mark
so it ended up exactly on size that's a bonus so we need to make this 3.05
or something like that so it fits in there and the od of the plate we want to make is going to be
3.560 that looks good
kind of a round circle let's go make it really round
there you go it's right on it's on zero that's good so what i do you have to make
sure this is clean i put this in like that i'm pressing this piece against the chuck
and then this finger is pressing whatever i want against this piece so i tighten it up
it's not that tight right now let's just see if it spins true
okay so can you see how it's got a wobble to it so this is this is where the technique comes in
so there see how there's a gap i don't have this super tight right now
see that go in and i pull it out
do the next one okay okay so that one's tight that one's fine and this one here
is not fine so it needs to come out a little bit i'm going to open up the chuck just a touch it's a
little too tight so if you go around and you get these all the same then it's going to run true
okay so i think that's pretty good
oh this one's a little loose
okay so now i make the chuck tight so i'm just holding on with one
one jaw one one one two i think i don't know the proper name someone's going to tell me
there's going to be a comment i know it so now we'll start it up and let's see if it runs true
okay so now we can we can bore out the middle and we have to make a couple steps
ah
um
let's take it off and let's see if it fits into the case oh look at that it it's a nice fit
how's that that's a good fit we had it in the chuck this way we need to flip it around then we
have to bore here for the little oil seal that's what we've got to do now so we're getting close
okay so it's one thou over but that's okay so that's where the oil seal is going to sit right
in there so it's a see that it's a little bit of a press fit it doesn't want to go in there right now
i thought we were going to have time to make the holes in here and attach it to the case but we are
running a bit short of time but what i want to see now is how this all all fits together if how the
height is of this and the oil seal because the oil seal has to go on that bronze bushing right there
so why don't we put this together just loosely you can see how it all
fits there's the sprocket going on there's an oil seal that goes in there those are on their way
i want to know if the height is good
so
so that guy goes over there and
so the oil seal goes in this way like that because it has to stop the oil from going from the case
outside
it kind of looks like this is too thick it needs to be a little bit thinner there so
i'm not sure about that this here this is this is where the clutch goes
so if i take off the case we can see how we can see how close the taper is getting to that
bronze bushing there i was told this is a fiddly thing to do so let's take this off
so there's a little bit of well after you talk down the nut it's going to go onto the taper a
little bit more so there's not really a whole lot more so what i need to do is to this is too thick
so what i need to do is to go into the lathe make up a an arbor a spigot this has to be
a little bit thinner here where my nail is so that the seal can go down just a little bit more so
i have a little bit of work to do and then i also have to make sure that i got room in between
in between the clutch and this as well so engine modifications not always simple but effective
i have a little work to do thanks for watching thanks for hanging out in the shop here
we hope you enjoyed what we do here and mitch and i like coffee if you buy us some
coffee would be much appreciated and see you next week next time