more 250sx questions

[skidoo99]

hey all, ive got a spare motor for my sx since the one i had was busted. i was swapping the top ends and noticed something between the motors. with both heads and right cases off, one motors crank will spin freely both ways and the other (new motor) only spins one way. which is correct?? the motor i am replacing is the one where the crank spins both ways. sick of having problems with this bike and i just wanna ride!!!

[dougspcs]

I theory a four stroke engine should spin in either direction..but with this particular arrangement not sure. The transmission and clutching may not allow this..maybe that is what is broken in your 'bad' engine..

On the bench your should be able to compression test and check the shifting of the 'new' engine. Have you done so??

Just drop it in and try it!! Won't take you but an hour..

[Dirtcrasher]

The SX has 2 one way clutches.

The correct way they work; The engine grabs at the centrifugal clutch and freewheels the opposing way and grabs at the flywheel and freewheels the other way.

[skidoo99]

131157131158

well the motor i got to replace mine was an 87 and i knew it needed a new top end and was supposedly in good shape lower end wise. at least thats what he told me and he has been quite reliable. this is where im at and am getting ready to swap parts.

[skidoo99]

so it should spin both ways, when turned one way it should spin the centri clutch and the other way should just free spin alone

[tri again]

so it should spin both ways, when turned one way it should spin the centri clutch and the other way should just free spin alone

Man, I wish I could tell you.

What if I try to roll an sx back and forth in neutral and see if it rolls freely both ways.

hang on a sec.

Silly me, of course they roll for and aft, that's how we load them

Ok, now in first gear, it will not roll foreward...well maybe it would if I pushed hard enough to
turn the engine against compression.
again, in first gear, it will roll backwards fairly easily but not as easy as neutral.

In first gear again, pulling backwards, it rolls easily but it sounds like it spinning a whole bunch of stuff
inside the gearbox, doesn't seem to have any engine resistance.

Now this is ME pulling an the grab bar with the tires on the ground.
Lord knows what the conversion of torque would feel like if you're just trying to turn the driveshaft by hand.


is that the kinda info you were looking for?
I'll be back in a couple hrs and check on ya.

[skidoo99]

haha thats a great way to look at it. duhh, all i needed was a lightbulb. thanks