Aero 125 help

[Bear45-70]

Hello jwhite2: I sent you a pm...I've got the original carb set-up complete...

I keep forgetting that you replaced yours.

[jwhite2]

Thanks for the quick replies guys.

The head was dinged up just like the piston. Little gashed spots and nail holes. May just grab one off of ebay unless someone here has a decent one.

Question about the crank. Cleaned out the variator today and noticed that at certain points the crank tends to stick a little, to the point that I could not turn it by hand. Had to use a ratchet on the flywheel to get it to turn. (At least I think its the flywheel. The one before you get to the variator.)
What would cause that?

Was happy to see a belt in very good shape. I am hoping once the carb and top end stuff gets sorted out then we may be good to go!

Thanks

-J

[Bear45-70]

The magnet in the flywheel not wanting go past the stator or trash in the crankcase bearings.

[jwhite2]

Trash in the bearings sounds worse than the magnet. Should I tear into that part of the engine or wait and see if it affects anything?

Thanks

-J

[Bear45-70]

Trash in the bearings sounds worse than the magnet. Should I tear into that part of the engine or wait and see if it affects anything?

Thanks

-J

Remove the flywheel and see if the problem goes away before tearing the motor apart.

[jwhite2]

How do you remove the flywheel without the "rotor puller" that the manual mentions? Looked around for some advice on this and couldn't find anything. Can you still even buy that tool?

Thanks

-J

[noiseguy]

You probably can use a steering wheel puller to remove that part.

Before this, grab crank end and push up-down and fore-aft. There should be no play or ticking.

Rotate crank. The crank magnet feels like a magnet pulling and pushing together. Crud in bearing will feel and sound different... more like crud.

Given piston failure, chance that there is stuff that fell into the bottom end. Fill and dump bottom end with 2-stroke gas and see what drops out of the crankcase. Try this first if bottom is crunchy before tearing apart bottom end. Bearings and seals are generic machine parts... they will be available but the procedure to tear down a bottom end is complex and requires a couple special tools.

This is not a 4-stroke. The head is simple and just needs to have a flat sealing surface. Use 220 grit or curved file to dress down pits in combustion chamber on head. Avoid damaging sealing surface by taping it off if needed. Parts for this particular model are not easy to find, typically, so reuse what you can.

[jwhite2]

The crank will rotate ok and I can feel what I would say is a magnetic pull as it goes around. Then it gets stuck as it rotates. Probably something in there. I will try dumping 2-stroke gas through it and see what comes out.

The crank does have a fair amount of play from left to right across the engine. Not sure how much this hurts performance or function.

Thanks for the heads up on the steering wheel puller. Oreilys had no idea what a roto puller was.

The head is really damaged. If I could figure out how to put pictures on here I would show you. Maybe I need to do that and you guys can evaluate what is worth reusing. The piston is shot either way so I am going to need a new piston and cylinder bore.

Thanks

-J

[noiseguy]

Engine should not have play across the axis of the crank either, but this should have shown up in fore aft or lateral play. Sounds like you will need new crank bearings and seals as well.

Post a pic of the head when you get a chance.

[jwhite2]

You can see pics of the head and piston here.
http://www.flickr.com/photos/11395472@N ... hotostream
http://www.flickr.com/photos/11395472@N ... hotostream

I also added pics of the cylinder. Does it look bad? The ports are chipped a little but I am hoping the bore fixes that. Is that to much to be fixed?

Pretty bad. What are new bearings and seals going to cost? This is getting more complicated the more I dig in. Im at $200 right now and I haven't spent a dime. Not sure if I want to now.

Thanks

-J

[motormike]

...I might be questioning further investment in this one, myself....IMHO
Hate to say that, really. Still, the cost of repairs ultimately determines how much it is worth. You've got to be asking how much is it worth when finished. IDK,...maybe $1,000 realistically...LMK if you're gonna need some stuff....

[Bear45-70]

That head is junk, do NOT use it.

[noiseguy]

How much it will cost depends on whether you do it yourself or hire it out. If the bottom end is really toast then you've crossed the line from simple to complex. It's not so much the parts as the tools. The bearings and seals, probably $50-$60? Tools to get into it though will run $120. Add to that piston and bore work. Cheap way out would be to find someone that has these tools locally and can lend a hand.

The bore looks fine. That will hone out.

The piston's pretty bad. BTW, were the rings broken / bits missing? B/c that's definitely damage from a piece of ring bashing around inside. I'm betting you have a few more pieces in the bottom end.

I disagree with Bear on the head. You can fix that. Just a question of whether you want to spend your time fixing it, or getting a good used one. Besides removing the impact marks (which would be best done with a dremel at this point), the sealing surface will need to be re-faced. You can do that with a chunk of 1/4 glass with 220 grit wet sandpaper plastered down to it.

[Bear45-70]

How much it will cost depends on whether you do it yourself or hire it out. If the bottom end is really toast then you've crossed the line from simple to complex. It's not so much the parts as the tools. The bearings and seals, probably $50-$60? Tools to get into it though will run $120. Add to that piston and bore work. Cheap way out would be to find someone that has these tools locally and can lend a hand.

The bore looks fine. That will hone out.

The piston's pretty bad. BTW, were the rings broken / bits missing? B/c that's definitely damage from a piece of ring bashing around inside. I'm betting you have a few more pieces in the bottom end.

I disagree with Bear on the head. You can fix that. Just a question of whether you want to spend your time fixing it, or getting a good used one. Besides removing the impact marks (which would be best done with a dremel at this point), the sealing surface will need to be re-faced. You can do that with a chunk of 1/4 glass with 220 grit wet sandpaper plastered down to it.

If he grinds out the head until all the dings are gone, then he will have to have the head cut or lose compression and how much it needs cutting will be determined by how much material is removed, now he is into measuring head volume. One * of a lot quicker and easier to replace it.

[noiseguy]

Yeah, he'll lose some material and thus compression. Somehow, I don't think this guy's trying to build a race bike. So if final compression is 5% off... I don't think it's going to matter. And like you said, compression is recoverable by decking the head.

That said, heads are typically one of the easier parts to find, and sure enough there are a few on Ebay, starting at $20.