crankshaft damage...options?

[antirealm]

After getting some advice from here I bought one of those emergency impact wrenches. Yayy now I can get that nut off with ease. Concerned about getting the right torque when its back on though.. but anyway here is my problem:

My splines are nice and damaged. They were bad when I first got the scoot but now they may be even worse. Photo attached. I really want to avoid replacing the crank if I can. Any advice on what my options are? Or is it over and I just need to come to terms with it?

By the way, is the variator nut some special nut or is it just replaceable with one I might find at a hardware store?

Thanks.

Attachments:

[antirealm]

another angle photo

Attachments:

[90GTVert]

I think your best option is to replace the crank, anything else is just a bandaid. You can file buggered up splines, but yours looks like the splines are worn away in one spot and worn down just past that. You could try to set the variator up so that the key locks into place on the portion of the crank before the damage, but it's far enough back that you'd probably have to shorten the drive boss and it would take off really bad from the belt being squeezed high in the variator. I don't really think that's a great idea, but I suppose you could try it if you're hellbent on keeping the crank. You'd have to run enough washers on the outside too so that the nut could actually hold the fan on tight. I'd suggest kick start in an emergency only if you set it up that way, since it would have to be on the bad bit.

The variator nut is nothing really special, but it may be hard to find in a local hardware store. Yours looks like 12mm. I think the thread pitch is 1.25, so M12 x 1.25. Might need to get a half nut. I usually just pick up nuts from kaseaparts.com, the 90cc parts sections should have the larger style crank stuff.

[antirealm]

Thanks for the advice. If I do go ahead with that, I have a few questions. One is which crank should I need as I've read there are different types, full circle etc? I believe this one is 16mm 15 splines 21mm boss and 12mm wrist pin.

And two, I'm guessing I should replace other serviceable parts inside while I'm there, I have no clue on what they are. Scooter has done over 11,000km = 6,835 miles. Engine is 1E40QMB.

Parts are fairly hard to find or expensive down here in Australia, gotta get em all shipped from Taiwan or USA.

Thanks again.

[90GTVert]

You can get a stock replacement crank. I'd go with something aftermarket that's cheap. You can get a Naraku crank for just a little more than a stock Chinese crank, and they are better quality. Whatever you get, just look for the 12mm wrist pin and 16mm splines. Here are a couple of Naraku cranks. One is the cheapest, standard model. The next is a stuffer to increase primary compression and it includes bearings already installed to make life a little easier. I'd go with the 2nd if it were mine. A stock crank usually ends up being around $100, but it's worth the extra for quality IMO. There are brands other than Naraku BTW, I've owned one and other members have used them and we've all been happy and the prices are pretty good.

www.racingplanetusa.com/crankshaft-naraku-keeway-china-2stroke-p-21407-1.html?cPath=2948_2952_2992&sessID=f521fc3649cc22851b98957284c08915

www.racingplanetusa.com/crankshaft-naraku-racing-keeway-china-2stroke-p-21415-1.html?cPath=2948_2952_2992&sessID=f521fc3649cc22851b98957284c08915


You will need to replace crank seals (one on each side) and you will need a head gasket, base gasket, reed/intake gaskets (2). You'll also need a sealer to seal the cases, something like ThreeBond or Permatex Ultra Gray. You should inspect your cylinder and piston as well and see if they need attention.

With that many miles, I'd suggest a full CVT inspection. Change your gear oil while you're at it.

[antirealm]

thanks man. i'll check back as soon as i got all the parts and what not. do they happen to have a kit for all these gaskets available? hmm what do you think about a variator that has no key but the teeth part of the assembly?

[antirealm]

oh, and btw. where can i find a crankcase splitter and the correct flywheel puller?

[90GTVert]

I've seen the variator fixed halves with teeth built in, but never used one. I'd think the standard key would be a little tougher. Not sure.

RacingPlanet, PFS , and ScrappyDog all sell gasket kits I believe. It won't include the seals though.

[Aaron420e]

Dec 10, 2012 11:45:05 GMT -5 antirealm said:

thanks man. i'll check back as soon as i got all the parts and what not. do they happen to have a kit for all these gaskets available? hmm what do you think about a variator that has no key but the teeth part of the assembly?

I have the Naraku with no star washer. The Naraku HS vario. No probs for me. Seems to be much stronger than the washer as it is 10x as thick as the star washer.

Your splines have to be good though or it won't go on.

[2strokd]

Or even come back off