Zongshen 250cc sprag clutch sticky & slipping, adjust or replace?

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RangaBlitzFanga

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So an update regarding the E-start thread. Turns out the starter motor and sprag clutch are operating correctly, however it's getting jammed and slipping at the same time. If I turn the engine by hand a few times it frees up (takes a lot of force as the sprag clutch is 'sticking' the opposite way and trying to turn the starter motor as well, until I spin it a bit and it frees up)

After it frees up I can engage the e-start and it'll turn the engine briefly (not even 1 full rotation) then slips again

So the question I have is can the sprag clutch be cleaned/adjusted? I've smashed the engine case 3 times now, so there's a very high probability that some crud has got stuck somewhere it shouldn't be
Oh and getting the flywheel off to get to the sprag clutch, is there any way without a special flywheel puller? Do I just need to somehow jam the flywheel to prevent it moving, then take off the middle nut?
Pic:
2r1zo9d.jpg


Failing that, is it a replaceable part? I can't seem to find anything on ebay, so if anyone has a link to a 250cc zongshen vertical engine sprag clutch i'd be grateful :thumbup:
 
Yup thats the one, also found one here http://www.ebay.com.au/itm/Zongshen...orcycle_Parts_Accessories&hash=item25742aeda0 which is a bit cheaper
Once I get the flywheel off i'll try cleaning out all the clutch bearings and stretching the springs a bit to get a bit more tension on them

Next question is getting the damn thing off. I can't seem to budge the centre nut on the flywheel (can't stop the motor from moving enough, even with it in 5th gear and jamming the rear brake on). Is it a standard bolt that you need to turn counter clockwise? or am I doing it all wrong. There's a notch in the flywheel as shown in the link you provided

Before I start swinging with hammers and jamming the rear wheel further i'd like to make sure i'm doing it right
 
Well from what I can see going off a general 200cc china engine manual, it appears it just screws off (please correct me if i'm wrong)
So I have the brake locked on, as well as jammed a large screwdriver between the swingarm and rear wheel to stop it moving. Took to it with a 1 metre breaker bar, flapping hell still won't budge, causes the clutch to start slipping!

Unless someone can confirm how to get it off, i'm not gonna proceed any further
 
you can use the leather strap type oil filter removers to hold the flywheel too.
do you have a rattle gun?


does the centre boss of the flywheel have a thread on the outside ?
if it does,you will still need a flywheel puller to remove the flywheel off the crank though.
that bolt tightens the hub of the flywheel onto a taper, so it gets tight.
26mm puller- http://www.ebay.com.au/itm/FLYWHEEL..._Parts_Accessories&hash=item1c279b0078&_uhb=1
28mm puller- http://www.ebay.com.au/itm/FLYWHEEL..._Parts_Accessories&hash=item2eb8bdc4d0&_uhb=1
 
Last edited:
Ok giant breaker breaker bar and steel mallet knocked the centre bolt loose
Now to get the flywheel off... Looks like I need a puller but of a different sort.
The centre bolt screws down into a thread which sits about an inch below the surface. There's a thread on the flywheel itself however above that. So It looks like I need a bolt-in-a-bolt type flywheel puller, rather than a bolt-in-a-nut

I'm going to try some methods to get it off, mainly leverage while gently tapping the centre bolt while its half screwed in. If I bugger the flywheel so be it i'll order a new one along with a new sprag clutch
 
Good luck with it, don't tap the crank too much, or you will end up with a bit of axial play in the crank ( tapping knocks the opp side crank bearing in a little inwards).I didn't bother getting a puller when I swapped a 90cc motor from leccy start to regular kick start stator setup, got it off but then realised I had about 10thou (.25 mm)axial movement in the bottom end now, luckily I had a taki axial shim set with a .20mm shim in it, even so the gasket cost and the effort involved weren't worth the 20 bucks a cheap puller costs
 
Well i've already taken to it, hopefully havn't damaged the crank. Anyway the DIY method didn't work
Turns out the outer thread on a chain breaker is the exact size, so that screws into the flywheel itself just fine. Went to the hardware store and bought a longer bolt to go right through the middle and push it free. The bolt itself is no good, it threads into the chain breaker bolt. But the thread on the end is the same size but different pitch to the centre bolt I removed. If I tightened that one down it would start screwing in and bust the thread. So I dropped a washer in the hole to make the end a bit bigger than the thread and prevent it from screwing in

So I took to it with the massive breaker bar, turned a bit but wasn't loosening so I took it out. It has pushed and stretched the (fairly thick) washer into a cylinder! hasn't damaged the thread, but this **n flywheel is not budging. Surely it can't be on that tight???
Am I missing something? is there something else that might be holding it in place?

edit: for clarification and to make sure i'm doing the right thing
Big chain breaker bolt screws in and threads into the flywheel. Bolt goes through the middle and pushes on the crank. This 'should' force the flywheel outwards away from the crank correct?
All i've done is remove the centre bolt, there's 3 little hex bolts but I believe they don't need to be removed and come off as a single unit yes?
 
so neither of the pullers i linked will work for you then?
 
Ive got the screw on type and pull hammer type pullers and I have had some only budge after a heap of tries, the screw in type can also flair the end on the crank requiring grinding down if its tight and the flywheel isn't budging.
 
so they can be stupid tight? to the point where you almost need a sledge hammer on the breaker bar to get them to move?
I think i've got this one to budge about half a millimetre so far
 
RangaBlitzFanga said:
so they can be stupid tight? to the point where you almost need a sledge hammer on the breaker bar to get them to move?
I think i've got this one to budge about half a millimetre so far
Click to expand...
how long is your breaker bar? also to get the correct jerk on the nut maybe put a screwdriver in the clutch side primary gear? otherwise your wheel and tranny take up the jerking action
 
^^ if you ever need to put something inbetween gears, jamb a rag in there.
it will lock it up easi;y and safely.
if you're using a screwdriver to jamb the gears, you could end up in tears
 
i've given up. My breaker bar is 1m long, even smacking at it with a 1.5kg steel mallet didn't do anything except absolutely destroy anything i'm using as a spacer. Steel nuts crumble like flour
Don't have a heat gun so tried boiling water to heat it, that didn't work
Tried tapping several screwdrivers between it and the ring gear, just marked up the gear

The damn thing isn't budging. So i'm gonna put it all back together and pray I havn't damaged the crank, there's no force on this planet strong enough to shift that damn flywheel
 
anyone of your mates have a rattle gun? it may make all your troubles go away
 
if not buy a new nut and smash the old one off or cut it with a dremel, once you remove its tension on the thread it should be able to be spun off by hand
 
Nah guys I got the centre bolt off, but I can't seperate the flywheel from the crank. I don't know if a rattle gun would solve it. Was thinking of buying one but cheapest is about $200, way too much for a once-off sort of job. Not often do I need to do this, and the breaker bar has worked for everything so far

The weak point is getting something between the flywheel and the crank. If I simply thread a bolt through my puller then it will start screwing into the crank (pointless, and it'll bugger the thread) so I need to place something between the bolt and the crank. No matter what I use it gets totalled. I'd need something very thin and VERY strong to have enough strength to seperate them
 
heat up around the inside of the flywheel before you go to pull it, also have you got a large spare bolt (off a car or somthing strong) cut a triangle of scrap steel and drill holes in it then thread one for the large bolt in the center and use it to pull it off?
 
Well I started the bike up and it ran fine, no obvious increase in vibration or noise so the crankshaft is fine, thankfully

But since I didn't put the side cover gasket back on properly I needed to pull it off again so figure i'd have another crack at it, here's some new pics

Here's the culprit

2cdk.jpg


Here's the makeshift puller, outer piece is from a chain breaker and threads perfectly into the flywheel

zu2g.jpg


But as you can see from photo 1, if I use the above puller as-is it's going to start threading into the crankshaft instead of pushing them apart. So I need something to sit between the 2 to stop it trying to thread in, well this is what happens

a892.jpg


And by the way, that centre bolt is slightly bent from the force being exerted

I'm posting this to see if i'm being a retard and forgetting something? I.e. those 3 hex bolts are they holding the flywheel in place?
 
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