Kymco People 50 2 T

[catsailor]

Hi,
I bought a 2001 people 50 2 stroke about a month ago. While riding to work at 50+ mph my engine died on me. Thought I might have blown head gasket, so I ordered a new gasket set and piston set from scooter assasins on ebay. Today I started to take her apart to be ready when the parts come in. Once I was able to get to the engine, I noticed that the jug and head said AIRSAL on them:



I am assuming that the PO installed a big bore kit. Once I got it apart, this is what I saw on the piston:





The first thing I noticed on the piston, is that there is only one ring. Seems kind of strange. i also noticed the burned out pinhole, and the one ring that there is, is now "welded" to the piston at the pinhole. I measured the piston across the bottom end and it measured 48mm. I believe that is the right place to measure it. The stock piston is 39mm. A huge difference!

I had the Taz kit on my Spree, and had to put a little extra oil in each tank of gas because the pump on the spree did not add enough for the extra displacement. Am i assuming correctly that i should have been doing the same thing here? What should I do to replace this, as well as make sure that it does not happen again? You guys have been the best so far with your advice. Although I am no longer a spree owner (should have kept it), i appreciate your valuable input. Thanks a million in advance.
Todd

[motormike]

If your bore is honeable, buy a 48 jug and keep your cc's.....and like you mentioned, adjust oil/fuel ratio by supplementing.......check jet / compare to specs / adjust if needed by usual methods...plug inspection, CHT, etc....oh yeah,.....send those parts back

[catsailor]

plug looked a little lean. will have to dig into carb tomorrow to check jetting. there have been no mods to the air intake box, or filter. can hone the inside of the jug. it is almost flawless. I wish i knew this was done when I bought it. I boug from a girl who was 2nd owner. It had too much zip for her and she wiped out on the first day she owned it. That was the last time she rode the bike. Has so much power i had to lean forward as to not wheelie. thanks motor mike.

[catsailor]

any ideas on the 1 ring piston? should I try and find the same to replace, or should I go with a 2 ring? Any ideas on where to buy?

[motormike]

Awwww, poor widdle girly-girl...............the cheapest way to by a bike........first day wrecker......

[motormike]

I'm not too sure about the one ring,....I've seen it mentioned here....maybe common in 2T world......a little shopping will tell.....someone more knowledgeable will key-up........rock-on

[catsailor]

Thanks Mike, I got a Great deal on a first day wrecker, and talked another $150 of the price because the mirror she landed on was loose (tightend with a 13 mm wrench in about 3 seconds) Thanks for your help. Waiting for Bear, Baka, Wheelman, or Tjamz to chime in. Those guys are a wealth of Knowlege. Also, Taz, got anything in your store that I can fix this with. It may be a 47 mm kit vs the 48 mm kit that my 47 year old eyes are reading on the metric ruler.

[Bear45-70]

Several of my race motors came with 1 ring per piston. They worked fine and lived long but I never used less than 25 to 1 oil mix either. Clean any aluminum in the bore out and hone it. Get a piston, 1 or 2 ring is OK. Then go for it.

[catsailor]

thanks bear. what do you think could be the cause? was I assuming correctly with the lack of oil? Do all bbks require that you run extra oil in the gas?

[Bear45-70]

Looks oil related to me. You need to run 70 to 1 in the tank along with the oil pump.

[Wheelman-111]

Greetings:

I haven't read much here about Airsal, so I suspect not many have tried the Honda kits they make.

Single-ring pistons are indeed the norm for racing engines, where performance is prized over durability. Not saying Airsal's don't last, I just don't know about 'em and a single-ring suggests their philosophy and intent.

That said, if the PO was clueless and didn't know enough to pre-mix, or the second owner failed to add oil, a broken-in bore might survive a while under-oiled. But the first WOT run on a mis-jetted day would produce the results you see. Were both wrist pin circlips in situ?

In addition to cleaning out the bore, I'd split the cases and check and wash the bearings very carefully. No sense re-doing a top end only to have the bottom let go. Carefully assess the lower con-rod bearing too.

[catsailor]

Wheelman, I woke up in the middle of the night thinking the same thing about splitting the case and cleaning. Not much metal scrapped off of the piston, but there is enough for me to worry. This is a big drag. I wish I had known there was a bbk installed on bike. still would have bought it, but would have added the oil to my fuel as I did my spree.

[bakaracer]

you got 2 things going on there. 1 is it was running lean. that splatter marks and pin holes is the sign of a lean condition. 2 the seize marked piston is not enough oil.. you can find replacement pistons for that airsal kit online for your bike. get the same make piston as this kit was setup to run that piston for a reason. that airsal kit is aluminum so its nickel plated. use your nail to see if there is any lines in the wall. if they are you need to determain how deep they are and if it can be honed just a little. if not that kit is toast or unless you know someone that can renickel plate it for you after you rebore it. if you run a new piston on a bore with seize lines in it, your just wasting your money and time and risk more damage to the motor itself for a possible worst seize.

[catsailor]

The entire bbk is toast. There are a few nicks inside of the jug, so after honing it would need to be replated. The PO did not do anything with the carb after the bbk install. I talked with one of the the suppliers of this kit (moped hospital www.mhr-usa.com). He said that with the Kymco, you cannot properly re-jet the carb for this kit. You have to upsize the carb itself. This was not done. Any of the options that I have at this point are going to be CO$TLY!!! I think that the most economical for me is going to be bringing it back to stock. I already had ordered the stock piston, rings, and gaskets from Scooter Assasins prior to taking apart and realizing the PO had done the big bore. I need to get my hands on a stock jug and head, as well as carb jet (not sure if PO tried to drill out existing jet). Thanks for everyones help on this one. It sucks, but I guess its all part of it. Will keep you posted as the parts start to come in on the slow boat from taiwan

[Wheelman-111]

Greetings:

Agreed with what's been said above with one minor correction:

A Nickel-Silicon bore is just about impossible to hone. The material is harder than the stuff on the hone. It can be bored, but the Nikasil is even hard on carbide tools. Once bored, the soft fast-wearing aluminum is exposed and the jugs will cost well-nigh $100 to re-plate as Baka said.

I've seen Airsal kits online for relatively cheap, but not many here -if ANY - have offered an account of their performance.