SX/SXi/SXi Pro help will not crank

[kass727]

whats a leak down test? also with a two stroke engine what lubricates the crank shaft? does the oil from the fuel travel that far down? i know in a 4 stroke the piston rings prevent oil form going up into the cylinders above the pistons, so wouldn't they also keep the oil above the cylinders in a two stroke?

 

[ger87410]

whats a leak down test? also with a two stroke engine what lubricates the crank shaft? does the oil from the fuel travel that far down? i know in a 4 stroke the piston rings prevent oil form going up into the cylinders above the pistons, so wouldn't they also keep the oil above the cylinders in a two stroke?

The oil/fuel is drawn into the pistons through the crank. (Very basically)

A leak down test, basically, is sealing up the intake and exhaust port and pressurizing the case to check for leaks.

 

[kass727]

all right great diagram it made the whole thing a lot clearer as to how the two cycle works. are there any parts i have to worry about specific torque when i reassemble the engine? if so does any one have the specifications?

 

[ger87410]

U got a 750?? Get a manual. All the specs are in there. If not, try to get it off someone on here. Don't over torque the head nuts.
I coulda helped you if you had an old 650. :smile:

After you're done with assembly, it'd probably be a good idea to check ignition timing.

 

[kass727]

yea i went to the local book store they had to order it for me so hopefully it will be here in a few days. I'm sorry but i don't understand what you mean by ignition timing?, how do you set timing on an engine that doesn't have valves or or a balancer for that matter? what is there to advance or retard. again sorry i know some of question may seem simplistic i'm just not use to playing with 2 strokes, i have only worked on cars before.

 

[ger87410]

U have a lot to learn, grasshopper. :jester:

The ignition timing is, of course, electrical in nature. All old jetskis have stators. Most of the new 2-stroke engines too, but not sure. That stator acts like an alternator. It has 2 coils. 1 coil is for the battery and 1 for the spark. The flywheel spinning around the stator is what generates the current. That stator can be rotated slightly counterclockwise/clockwise to adjust when the pickup on the stator triggers the spark. Or, the ignition timing.

If you're only rebuilding the topend, chances are you won't have to mess with it nor will it get knocked off. It's just a good idea to check, IMO.

 

[kass727]

thanks i tore the whole thing down and every thing came apart including the crank case, so i have to get the book and see what the proper alignment for the stator is, there are a few marks on the free wheel and on on the stator so i assume that when first piston is at TDC the hashes should line up but ill be sure to double check before i reassemble. In any case, how would i be able to check if the timing is correct after its all together?

 

[ger87410]

The book won't tell you.

You're stuck fixing the timing. The instructions in my book were in the maintenance section and not listed in the appendix or glossary.

Find TDC in piston 1 with the flywheel on. There should be a mark, or a 'T' on the top of the flywheel now. Secure a pointing device to the case that points to that mark. Hook the timing light as per manufacturer instructions. Test it. The light should flash the instant the pointer passes over the mark on the flywheel.

EDIT: Turning the stator clockwise is retarding.

 

[kass727]

OK if when i took off the stator, i did not touch or alter its positioning at all, the ignition timing shouldn't be off by too much correct?

 

[kass727]

FYI: i came across a .pdf version of the owners manual for the 750 sx and sxi if any one wants a copy pm me with your email nd ill gladly email it to you. or you can dl it from this link http://www.mediafire.com/?elnywpenkxm hope it helps some one else as much as it has helped me, enjoy

 

[Cannibal]

Wait, you guys are talking about a stator plate, like on a 650? Now I'm pretty new to the 750's, but isn't the stator fixed on the front cover along with the ignition pickup? Isn't the ignition a Hall sensor and is non-adjustable unless you buy the advancing plate?

 

[kass727]

yea thats what it looks like, its seems to be mounted pretty securely but i cant say i really tried adjusting it but looking at it now it doesn't seem to be adjustable. does this mean that i do not have to worry about the ignition timing? Is there a such thing as self timing?

 

[kass727]

if anyone is actually following my thread, i finished cleaning up the engine casings, every thing is rust free and pretty much ready to be re assembled. the only thing i have not done yet is hone the cylinder walls, i cleaned them up as much as possible with steal wool but figure ill just hone them quick the night before i am ready to put it all together other wise they will just haze over in a couple of days if they go with out being covered in some sort of oil. to bad i took for ever to decide on pistons and gaskets which i should have by the middle of next week.(went with wiseco forged pistons, kept the bore size stock tho :-/) but at least it leaves me a with a few days to paint her up real nice. will post pics later tonight.

 

[KAWI4ME4NOW]

so wait ur ski was locked up but ur cylinders are ok to go wit standard? still doesnt make sense to me and i tear down and rebiuld and install power plants for all different kinds of skis from 9 -5 every day

 

[Bren]

i dont understand either, if ur pistons were siezed to ur bore, u wld have to bore it out a size wouldnt u? thus getting oem size pistons wwould be too small...?

 

[kass727]

idk how to really explain, the pistons were not seized to the cylinder walls, i do not fully understand how my self, but some how the under side of the pistons were seized up ware they connect to the piston rods and were not able to pivot on the rods what so ever thus the crank could not turn.

b/c with out being able to pivot on the rods, the piston is not able to move up and down in a straight cylinder.