1984 Honda 125cc Aero 2 stroke find

[litninrod]

OK so it's not a 50cc Spree or Elite but it's still a Honda scoot

I didn't even know Honda made a 125cc 2 stroke - I've found that the 1984 Aero was the only year they did.

I saw this on Craigslist..ad said it had spark and compression but wouldn't start. He also said he had a few spare parts off another Aero 125.

So I went and picked it up for $150. And the spare parts turned out to be about 2/3 of a spare scoot - frame, forks and front wheel, engine, seat, gas tank, speedometer, seat (ripped though) and some miscellaneous. Good deal right?

I got it home and charged the battery and checked for spark - very strong. I took the carb off and soaked it and cleaned it up. Cleaned the air filter and put it all together.

Cranked and sounded like it was trying to start but not quite.

Ran a compression test and found 40psi. Uh oh! 28 year old scoot with an engine size only made one year (US...4 years Europe) I knew rings would be hard to come by.

On a whim I went by my local Honda dealer that has been in town like 40 years. To my shock, they had a set of NOS rings back in the archive parts bin!

Came home and took off the top end and the piston was horribly grooved and had a chip at the top. Thankfully I had that spare engine, and the piston/cylinder were fine.

So I cleaned it up, put on the new rings and reassembled. Now I have 150psi compression and the rings haven't even had a chance to seat yet. (factory specs new was 171 psi, so I feel pretty good)

Cranked it, fired up and after blowing out the cobwebs and a little carb adjusting, it purrs like a kitten and screams like a hawk.
That $150 investment is looking REAL good now!

I'll be ready to test ride tomorrow.

I should probably post this part in for sale/wanted, but if someone has the cowl that goes below the front of the seat I could use a better one. This one has been carved up I think so someone could access the plug without removing it.

Oh if anyone has one of these and needs some of those spare parts I listed, I'll let em go cheap to anyone on this site.

[Bear45-70]

Nice find and a great price!

One of the few things I don't have spare is the center engine cover, sorry.

I would recommend you replace the fuel and vacuum lines. 12 year old lines do not react well to today's acidic gas. I prefer using clear lines, then you can see what is going on inside them.

[zuphilius]

Nice find!

Listen to the Bear, he's our Aero guru, though he may get grumpy at times.

Careful with the new rings, break them in before doing too much ripping'.

[eliteguy50]

Did you cross hatch the 'new' cylinder?

[Bear45-70]

Did you cross hatch the 'new' cylinder?

He only got new rings, no cylinder, but yes he should have honed the cylinder or the rings will have trouble seating or never will.

[motormike]

Fantabulous score !!!!...next thing you will want to do is something like this
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

[allisswell]

My buddy just picked one of these up for $100. I have no idea of its running condition but it is complete. Will post back here once he brings it over for me to work on. What top speed should I look for? Are these really quick out the box?

[eliteguy50]

54mph top speed. Quicker than a 50 about the same as the nh80 until the granny starts working then it pulls away.

[litninrod]

I always replace fuel and vacuum lines too when I fix up an old scoot - especially the Chinese ones. I like clear too, Bear, because I can see if it's getting gas.

@Eliteguy - The cylinder and piston were used off a different engine, and no I didn't cross hatch. (I assume that means hone it but I never heard that term) I just put in new rings and reassembled.

Took it out for a quick test. Turned right at the end of my street and opened it up. 0-60 in about 50 yards on a 10 degree uphill grade. I think it had more in it but the speedometer won't go much higher than that anyway.

I read somewhere that the speedometer on the 125 could be off by as much as 10mph, so that 60mph might actually only be 50mph? Can anyone confirm or deny that rumor?

@zuphilius - how long is a break in for new rings?

[eliteguy50]

The manual says 600 miles for a new engine. I was taught that cross hatching is even lighter than cylinder honing but they might be the same.

[Bear45-70]

..............................@Eliteguy - The cylinder and piston were used off a different engine, and no I didn't cross hatch. (I assume that means hone it but I never heard that term) I just put in new rings and reassembled...............................

Wrong way to do it. Any time you install new rings you have to hone (that term has been in use since before I was born in he 40's. Cross hatch is the design you end up with on the cylinder walls from honing) the cylinder or the new rings have less than half a chance of ever seating properly.

[litninrod]

Thanks Bear, good to know for future reference.

Are the speedometers accurate on your 125s? I've read that they can be off by 10mph

[eliteguy50]

Mine was 2 mph off the one time I checked it against a gps at top speed.

[Bear45-70]

Thanks Bear, good to know for future reference.

Are the speedometers accurate on your 125s? I've read that they can be off by 10mph

3 mph is the worst any of mine is off. 10 is pretty much unheard of.

[litninrod]

Thanks to you both for the replies.