Splitting cases on yx140

[ash.onmtb]

I've got a mates PP140 sitting in the shed waiting for some surgery, and I guess I probably should get started.

We suspect that second gear has died a sorry death and so I figure that it needs to be replaced.

My question is basically, is there a video that someone has done to show how to split the cases, and what specialty tools are required where? I can get the magneto off, but what else needs doing?

I've had the cases opened, but couldnt be bothered/get into the gearbox, as I didn't need to at the time I had it open. Now I do need it open, so I should learn how.

any and all help, links or videos will help this process be more painless would be appreciated!!

Cheers,

 

[motorman]

This should get you on the right path mate:

http://www.miniriders.com.au/mini-tutorials-how-s/24595-tear-down-bike-parts-completly.html

The last couple of pages go through splitting the cases.

 

[bulldog93]

You need your stator puller and a clutch/oil slinger socket too. Both can be found on DHZ website:
Tools & Other - DHZ Mini Moto

 

[ash.onmtb]

so I just had a bit of a whoopsie - the phillips head star selector bolt/screw just stripped its head... Anyone got any suggestions to get it out, and secondly, its not reverse threaded is it? I was thinking an ezy-out might have to be the only way, but Idon't have one. Or maybe filing a slot into it, but I really need more 'grip' than that would offer...

Thoughts?

 

[mattbombers]

nar mate its not reverse thread, you make be able to use an impact driver if there is a little bit of the slits left?

 

[ash.onmtb]

it was the impactor that stripped it..

I'll see if I can get my hands on some 'regrip' - kinda like PVA and sand, it makes whats left of the head a lot grippier...

I was so close to getting the thing apart Its never easy...

 

[mattbombers]

hmmmm, try getting a punch and smacking it in the center of the bolt head? you dont want to hit it too hard tho, may damage other parts on the selector. that re-grip sounds like the way tho.

 

[The_GDFP]

Some body been in there before? I've never seen the star held on with just a Phillip's head. Been a 10mm-headed 6mm bolt in all the ones I split (a few Lifan's with Allen-head, thanks for the reminder). Can't get crisp Vice-Grips on the round head? Left-hand drill bit might be the quickest. Welding an old extension to it is tricky work, another idea.

 

[mattbombers]

iv seen em with Allen key heads and the 10mm headed ones, but not the Philips... but in saying that only pulled half a dozen apart

 

[MiniFighter]

Needle nose vice grips maybe?

How about a pic mate?

 

[sean01]

if we talking about the same thing, you dont actually need to take that off..

but anyways another trick is to put a can of wd40 in the freezer for 20minutes and then quickly spray the bolt.. it will shrink it just enough to loosen it.. (good old james AKA dvdrip trick)

and it must be something else we have different over here... all yx engines over here have a star screw holding the shift star cover on..well all that iv worked on anyways....

 

[The_GDFP]

LOL. I stand corrected. Did a half-dozen Honda bottom ends that day, got confused. Leave it in. Loctited and a bear to remove. No need, unless it's broke a pin any way. Gotta stop putting that stuff in my morning coffee...

 

[ash.onmtb]

righto, so we had a bit of a win - a few hard whacks on the screwdriver shocked the screw enough and it came out, so thats a win...

Which let me split the cases, which was great.

On the down side, I found nothing wrong in there..... No teeth, no metal looking beaten up, no metal filings in the oil, nothing that looked or sounded like the amount of descruction that you could hear outside the engine.

Clutch worked fine

Everything else worked fine, just second gear was a box of marbles...

So, experts, what should I be looking for. I REALLY don't want to work out how to put the thing back together until I've found what was wrong. The *only* think that I found that I didn't expect was a washer sitting down amongst the gears. I don't know if it fell off something whislt I was splitting the cases or it was left in there since new, but it isn't all torn up so I don't think its been through the box.

I've never pulled an engine this far down, so I'm kinda guessing here. I'm keen to pull the thing totally to bits but I don't think I could get it all back together without a *lot* of help from here

Cheers for any thoughts or checks I can make

 

[The_GDFP]

Real common for a washer to stick to the bearing and slide off the shaft, then slip loose as you lift the case past the end of the shaft. See if it fits either shaft. Look close at the shift forks, engagement dogs on the sides of the gears. The bolt on the other end of the drum was snug, right?

 

[ash.onmtb]

So what we're saying is pull the thing absolutly to bits? I can't see any damage as is, so I think the forks, dogs and gears all need to come apart. Whhich bolt do you refer to, I haven't found anything loose so far, but its not completely totally apart so I may have missed it so far...

Where/ what else else should I look for?

Thanks.

 

[sean01]

above the front sprocket, there is a rubber bung and behind it is a bolt.. this holds the shift drum in place..

yep you'll need to remove the gearbox out of the cases to inspect everything..
but make sure you take note of the shims, if you fudge them up you'll be worse off then where you are now..

shift forks, gear dogs are what to looks for.

maybe when you pull it out shoot some pics up..

 

[ash.onmtb]

I've (exective decision) decided that old mates getting a new engine.

Found a lifan 140 on DHZ for 379 - that seems to be about where the market is at. Anyone go any other suggestions of places to purchase etc? Located melbs, needing replacment for blown YX140 into pitpro.


thanks,

 

[ash.onmtb]

I've (exective decision) decided that old mates getting a new engine.

Found a lifan 140 on DHZ for 379 - that seems to be about where the market is at. Anyone go any other suggestions of places to purchase etc? Located melbs, needing replacment for blown YX140 into pitpro.


thanks,

 

[ash.onmtb]

so I got to tinkering with that engine again, as its apart on my bench still and found perhaps a few things...

Firstly the shift drum, on which the shift forks ride, seems to have some weirdness going on.. Whats with the casting? It seems like they just cast it rough enough, with some holes in it, and then machined it down to round. But there is barely any strength left in the thing, barely any material thickness...!? Does that look normal to you??

Secondly inside on of the cases, against the outer wall, there are two cirlcular rub marks. Like a shaft has travelled too far and rubbed on the casing. Again, is that normal. You can see them pretty easy.

Finally, it looks like there is a fine metalic dust throughout the engine, almost like somethings been very finely machined for a period of time. I would not think that its normal, making the oil quite dark with almost a soot like quality to it.

Thoughts?

 

[themountain]

which wear marks?? There where the gear drum sits???