Stuck flywheel

[Sketchy]

Anyone have a suggestion as to how to get a stuck flywheel off a 250 engine?  I've tried a gear puller with no luck. Thanks 

[Mech]

I use a puller and give them a tap with a hammer.. but if you aren't used to doing things like that it's probably best to buy a custom puller for that job.. They can be had for as little as twenty bucks.. and last forever.. Google flywheel puller and your bike brand.

Are you sure you need the flywheel off ?

[Sketchy]

Looks like it, I found a green/red wire from the stator going behind the flywheel cover and it is severed,  not enough behind the cover to splice.   I'll try to post a pic if it will help 

[Mech]

no, I just thought you may be wanting to look in there when it wasn't really necessary.. which happens quite often.

[Sketchy]

Looks like it, I found a green/red wire from the stator going behind the flywheel cover and it is severed,  not enough behind the cover to splice.   I'll try to post a pic 

It's a project my neighbor gave me,  I replaced the ignition coils,  cdi,  regulator to finally get the plugs to spark. but they only sparked for a second when cranking then quit so I'm thinking of replacing the stator when I saw the g/red wire.

[Mech]

Yeah I saw your other posts.. I think you'd get more responses, in future,  if you say what make, model and year.

[Sketchy]

It's Chinese, long chang, 2001 I think,  250cc.  Here's a couple pics if anyone has any ideas as to what my next step would be. 

[Mech]

Put your puller on, wind it up fairly tight.. Then use an eight ounce engineers hammer(engineers hammer !), and give the bolt on the puller a sharp hit. It would pay to be holding the flywheel away from the engine as much as possible.  Not a really hard hit, just swing the hammer a short way, but fast, and let it bounce back away from the puller. Depending on the end of of the shaft, and the end of your puller, it might be best to have the nut on the crank bolt..

That works on most bits of machinery, but some of those cheap import jobs these days are made really really badly, and it is possible that something could get bust.. I'd imagine there are fine threads on or in the outer end of that flywheel. If you measure the diameter of the threads, and using metric bolts to check what pitch the threads are, you can probably buy a puller made for a jap bike. The thread diameter has to be measured to what the outside diameter of the threads are. They will be metric, probably in whole mm. If you have a vernier caliper it will be easy. If not, you might be able to use something like a pair of scissors as a gauge, then apply it to a ruler.

Edited August 16, 2022 by Mech

[Sketchy]

I have the hammer,  and calipers,  hopefully I have enough patience to get it off.  Thanks for the advice,  I'll update tomorrow after I play with it some more 

[Mech]

Did you get what I meant about the hammer hit ?

If we want to move a tight shaft in a hole, we use a big hammer and hit hard, and don't let it bounce.. That has a lot of drive to it... and could bend your crank..  Just a short sharp hit, that bounces the hammer back away.. That's what you want.

[Sketchy]

Got it, thanks again.  Here's a pic of the flywheel and puller. 

[Mech]

Good. Try and hold the flywheel firmly away from the engine when you hit it, even the tiny amount of play in the bearings will help prevent the bearings getting impacted when you hit the puller..

And that's a big puller, it can likely pull with ten tons or more. Don't over tighten it or it may bend that flywheel. The shockwave from the hammer is what's going to loosen the flywheel on the tapered shaft..

Edited August 16, 2022 by Mech

[Sketchy]

Flywheel still not moving,  maybe it's time for plan B.  The green/red wire that is severed goes to the ignition.  My question is the end behind the plate goes into the case to where?

[Sketchy]

Pics added for previous post

[Sketchy]

[davefrombc]

Is that a center saver under the tip of the puller rod?  It looks like if there is, it appears slightly off center / too  large for the shaft and catching on the clutch preventing the clutch from  moving out when  I  blow up the picture.

[Sketchy]

I thought the same thing last night,  so this morning I found a bolt the same size and used the puller on it to no avail.  I'm not sure what to do next.   The only reason I pulled the cover off is the red/green wire was caught behind the cover.  

[Mech]

I'd have thought that all the stator part of ignition system would be in that outer case, with the windings in it. Are you sure those cut wires aren't for a neutral switch ?

And those windings, some look like they have been hot, and some not..

[Sketchy]

Not sure about neutral switch,  I trace the green/red wire to the ignition switch. Here's a better picture of the stator. 

[Sketchy]

The green/red wire is no longer plugged into wherever it went, 

[Mech]

Ok, those copper coils will be for battery charging, the two covered ones will be for the cdi charging, and that black box is the trigger coil..  Betcha..

The battery coils will have a low impedence/resistance reading, the two will have higher resistance, and the trigger.. it will have a higher resistance still,..

Pretty sure those cut wires will be neutral light..

[Mech]

I don't suppose you have a wiring diagram..  It's just possible those wires might go to a neutral switch, that effects the ignition..  Some small two-strokes start up with rev limiters for safety reasons, till they are in gear. If it has a centrifugal clutch, that would be a possibility..

[Sketchy]

Manual clutch,  just for giggles I put everything back together and hit the start button and got no spark,  

[Sketchy]

I checked resistance of the 3 yellow stator wires,  1-2, 2-3, 1-3 , all show about the same ohms 

Assuming the loose green/red wire (the pic of it on my knee)  is a neutral switch,  how do I get to where it plugs in?  Maybe pull covers off the other side?

[Mech]

But now diagram huh...

Well check for continuity/resistance from the cdi, down to the various windings in the stator. Each wire at the cdi will either have a there and a return wire from the stator, or just one that goes to earth. Just check there is continuity with your ohm meter to start, don't worry about the exact readings..

Then try the same process to trace the wires to the key switch and kill switch..  Try and make a wiring diagram.. Just draw where each wire goes as you check it's continuity. Some wires might go to the switches and to the cdi or stator.. Draw switches as boxes till we figure whether they are meant to be open or closed for run. Draw the stator real basic and don't worry about what set of wires is inside, just where the wires run on the bike.

We can probably make a wiring diagram..  Or a whole new loom if need be.

To test those broken wires on the motor, put it in gear and use the ohm gauge on the bits of wire you can see to check if they are earthed or connected or open circuit. Then put it in neutral and repeat the process.

[Mech]

Is the cdi original ? Or aftermarket ?

It could be that you need to reverse the charging wires to the cdi, or reverse the trigger wires to the cdi, if it's not an original cdi unit. Some(lots) cdi need to have the ac going into them the right way. They may need to have a positive first wave, or a negative first wave of charging, to set them up to be triggered.. The trigger probably only works with the right trigger voltage, positive or negative, and rising or falling.. You could just try swapping things and trying.

[Sketchy]

its a new cdi.  After replacing both coils, new plugs, new cdi, new regulator I finally got spark, but only for a second and then it quit sparking.  I did this numerous times and each time it only sparked for a second and then quit.  That was before I saw the cut wire.  I'll trace the wires and make note of their resistance and try your suggestions.  One step forward and two steps back on this project.  Good thing I'm retired and have the time and patience for this ordeal.  Thanks for all the help.

[Mech]

That one spark and then quit could be because the ac that's charging the cdi is not in the right phasing with the trigger coil.. The way the cdi charges up is often important. Some of the electronics(in the cdi) count the number of pulses of charge before they will allow a trigger event. They sometimes need two positive pulses say, with a negative pulse between, but if the ac windings are back to front they can get two negative pulses and one positive.. something like that, or backwards from that.

[Sketchy]

Found out the green/red wire is neutral switch by bypassing it.  This gave me spark but only for a second then stops.  If I shut off key and turn back on it once again sparks for a second then quits.  I'm checking wiring today to see if I can get it to spark consistently 

[nicktribz]

TORCH and retry with hammer help