loose black line, fall, engine noise

[william13]

Look at the engine case . It will have an ID plate stamped into it in the middle of the cvt case, bottom. If it is QMB_M 139 or any thing close to that they are the exact same engine. If yours is a ky or ka or anything like that you can swap the cvt covers, and all else is the same. I forget what the Kymco engine codes are but I think you get it. By the way I wasn't meaning to imply the place you are dealing w/ is a "used car lot" or a evil /mechanic?. Just meant shiming is sort'a Rigging.

I know you were not implying anything...I just took the opportunity to plug the guy because he did not run from the situation.

Could I suppose weld/re-shape the bad spot? Maybe even use a square dowel like a "key". Better than shimming cause the belt will be skewed,

This is my fear:  skewing:  is this a given or a possible?  Welding was discussed but there was concern the plate might not be 100% even or balanced.  are you suggesting we take the stripped part of the shaft which now looks like a round dowel and file it to be square and then make the hole in the face plate square and weld it?
and wear/perform poorly. JMHO

[zombie]

[Areomyst]

Sorry for the extra big pic on page 2 - I wanted to show the "zoomed in" version.

~Josh

[zombie]

I saw J's post before yours showed The cowboys are for Josh's post about run out. Also, No I meant more like a slot cut length wise along the shaft, and the inside of the drive face. Like a boat prop/shaft or such. A 5x5mm Key would work. Didn't suggest it as a good idea, just better than shimming.

[zombie]

It was VERY dramatic  .

[william13]

Yes, the Kymco engine is by far better.  The parts look the same in many cases between the Kymco and the China engines, but believe me, they are VERY different.  

Point well taken

Shimming the variator out will indeed cause the belt to run at a slant.

I do not like this slant business.  I will speak to kymco again about this


 The misalignment isn't the end of the world, the CVT will still work, but if it was my own new scooter, I wouldn't really want to settle with having a goobered crankshaft and a belt that's misaligned.  I used to work for a Kymco dealership.  The quality, longevity, parts support, and value pricing is what ultimately led me to buying a Kymco.  

Since then, I've rebuilt a LOT of Kymco engines, but not one of those rebuilds was due to KYMCO's quality...  Most often, it was due to negligence.  

I take really good care of the bike with periodic check ups

I intend no disrespect towards any involved parties, but I've got to be blunt.  If you did not loosen that variator nut at any point in the bike's life, then there is absolutely no reason that you should be having to deal with this.  

That was the first question the Kymco man asked. Did I mod it.  The answer is a big no. I did not mod this nor did anyone else ever.

The crankshaft should be replaced to perform the repair correctly.  In the service manual for that bike it clearly states that the runout limit for the crankshaft is .10mm.  That is about as much play as the thickness of a piece of notebook paper.  If .10mm is unacceptable, then why is this:

I am not sure I understand the line "runout limit for the crankshaft is .1 mm.  What is the runout limit?

[Areomyst]

So I'm a cowboy huh?  Cool.  

I didn't really wanna press the issue, but the 50cc scooters do come with a restricted drive boss...  What does the current drive boss look like?  How fast did the scooter go from the showroom?  They come in the crate from Kymco restricted to about 32 MPH.

That is, unless they started shipping them unrestricted...

~Josh

[Areomyst]

Runout limit is how far "out of round" or "off center" your crank can be.  It does not have to do with the damage on the crankshaft, I was (albeit dramatically) trying to make a point.

I shouldn't get so worked up about it.  I'm sure they're all trying to do what they can to help you, I just don't feel like some shims and a couple of minimum parts is enough.

~Josh

[william13]

Runout limit is how far "out of round" or "off center" your crank can be.  It does not have to do with the damage on the crankshaft, I was (albeit dramatically) trying to make a point.

Is my crank changing positions?  I thought just the plate was being shifted out

I shouldn't get so worked up about it.  I'm sure they're all trying to do what they can to help you, I just don't feel like some shims and a couple of minimum parts is enough.

~Josh

[Areomyst]

Nah, the crank doesn't change positions.  The runout is honestly not a concern in this situation.  My point, is that Kymco has some pretty good/tight tolerances that they hold their product to, and I feel like we can officially say that your crankshaft is "out of factory tolerance", because a factory crank sure doesn't look like that.

All the best,

~Josh

[zombie]

http://www.neiu.edu/~rerebecc/blackholes/facts.html

[william13]

so I am in a black hole, unexplored territory!  yup I is!

[Areomyst]

William,

I have started uploading photos showing a crankshaft replacement on an engine very similar to yours.  My intention is to write a "how to" article, which I will post here on Kymcoforum when I'm done with it, but for now I'm just uploading all the photos before I go to bed... It's late, and I've got lots of work to get done tomorrow so it'll be an early day.

At any rate, if you're interested in seeing the photos, check them out here:
http://scooterinvasion.net/forum/viewtopic.php?p=33463#33463

Please keep us posted on the bike, and on Kymco's response.  I hope that the problem gets taken care of one way or the other.

Best,

~Josh

[william13]

These are great photos:  I know the proper fix is what you say.  I contacted kymco again and asked them to consider giving me a "factory spec" repair.  My contact is Joe V.P. of operations.  He really seems like a stand up person.  I sent him my concerns (or should I say the forum participants concerns) about the proposed repair.  He is running those by the tech department.  I will let you know how it goes.  One local shop said they could split a motor and replace a crankshaft if 4 hours time.  Does this sound possible with all the know how and correct tools?  By the way the parts I will be needing  are 1) crankshaft 2) drive plate 3) pinion starter 4) gasket

bill

[Areomyst]

These are great photos:  I know the proper fix is what you say.  I contacted kymco again and asked them to consider giving me a "factory spec" repair.  My contact is Joe V.P. of operations.  He really seems like a stand up person.  I sent him my concerns (or should I say the forum participants concerns) about the proposed repair.  He is running those by the tech department.  I will let you know how it goes.  One local shop said they could split a motor and replace a crankshaft if 4 hours time.  Does this sound possible with all the know how and correct tools?  By the way the parts I will be needing  are 1) crankshaft 2) drive plate 3) pinion starter 4) gasket

bill

Sounds good!  4 hours with the engine in the bike, or just bringing the engine in by itself?  That doesn't sound bad to be honest either way.

You'll need the crankshaft, crankshaft seals, engine gasket set, drive face, starter bendix, and for good measure, you may want to get a new belt. 

The problem when an issue goes "public" like this, is that you get a lot of different opinions.  Take for instance, oil.  If I ask 10 different people which oil they use, I'm probably going to get 10 different answers.  I think your case is pretty cut and dry though, as far as what needs to be done, and you seem to be on the same page.  I'll be surprised if Kymco's tech department comes back on a different page, but hey, they're the ones (hopefully) providing the warranty repair so the ball stops with them, unless you pursue the job on your own.

If they fix the bike with shims, be sure to ask how that will affect your existing warranty, and if the repair is guaranteed at all.

~Josh