40cc 2-stroke scooter

[burnout]

I'm planning on buying a used scooter from a friend soon (Mosquito Tiger)

Has a 40cc engine. He is the second owner. I was there when he bought it and cleaned it up a bit, and did some regular maintenance.
He used it regularly for about 3 months, and it has been sitting for a year now in his backyard. (Inside a plastic outdoor-box though.) I made sure it got the correct oil mixture all the time too.

My question: Whats a good way to clean out these things? I'm thinking of taking the engine off, and pouring some MMO in the plug hole to let soak for 8 hours. New plug, and I'm gonna clean out the carb real good.

How often would a scooter engine need rebuilding? I've been reading now that people replace pistons and bearings more frequently, but those have been on motocross bikes. This is a little scooter, so I'm assuming this probably won't be needed. Scooter is approx. 4-5 years old. Original owner seemed to take care of well.

PS: I have a bottle of mx2t all ready for it

 

[wileyE]

For sure dump out the old gas in it and start with fresh mix. Probably a good idea to clean the carb but if it starts, idles, runs out, fine your probably good to go.
I've seen MMO in the fuel slowly clean carbon off twostroke pistons after many treated tanks of fuel were run. A quicker way if you think you have an issue is the aerosal outboard engine cleaner/decarbon products that you spray in the warmed up running motor. You can also do a piston soak through the plug hole with it, much more effective than the mmo for this IMO.,
rings/piston? you can always pull the head and measure the ring gap if you know the specs, and visually inspect the piston through the intake and exhaust ports, compression check it? but heck if it runs out good maybe just ride it!

 

[burnout]

I've heard that berryman's B-12 is the strongest stuff you can buy. (or one of the strongest)

Think a soak with that could do some good?

If no soak, i'll just remove the head and use solvent to liquefy some of the carbon on the piston, etc..

Any other insight guys?

 

[GreeCguy]

The B-12 Chemtool is some really strong stuff. Used some this past Saturday to clean the carb on my mower. Sprayed the carb, some dripped onto the mower deck, and within seconds, it blistered the paint on the deck. Not that I care about the paint on the mower, (it was dumpster diving find). But I sure wouldn't spray it liberally around anything I did care about.

 

[burnout]

Also:

My ryobi string trimmer calls for a 32:1 mix, of which I have on hand. I don't want to have to get another gascan for this scooter. The scooter calls for a 25:1 mix. That seems like overkill to me. On MX2T, I'm assuming a 32:1 mix should be perfectly fine, correct? I want to run one ratio for all my 2-strokes.

EDIT: If I take a picture of the carb, could you guys tell me how to tune it? (I believe theres two set-screws for mixture)

[ May 04, 2005, 03:55 PM: Message edited by: burnout ]

 

[blano]

If its says 25:1 use 25:1. A 40cc aircooled engine hauling a full size human around in a full traction environment is very hard ooooon any motor.

 

[burnout]

Alright, I figured that this type of motor gets more abuse than say, a weedwacker motor. Running the weedwacker at 25:1 couldn't cause any harm I assume though, right? MAYBE some smoke?

 

[MN Driver]

I have a gas scooter too. A goped with a 22.5hp engine. A little bit smaller but basically the same concept. I would run the scooter at its recommended ratio of 25:1. These usually get long-term WOT, which can get things very hot for that little air cooled engine, I wouldn't skimp on the ratio, the weedwacker won't care if you have a 25:1 ratio in it, but too little oil in the scooter and your scooter's engine will seize and if its a direct drive like mine, you would be flat on your face.


On a personal note I wont clean a carb with any strong solvents because of past experiences with it hardening the rubber diaphragm and stiffening the thin plastic valves inside. It caused me to do a rebuild and when I pulled the metering diaphragm out it was pretty rigid. Your mileage may vary but generally if I need to clean a small engine carb out with carb cleaner or a solvent, I usually consider picking up a rebuild kit so I can replace the 'soft parts' inside after I spray carb cleaner through the various tunnels inside. After looking at a carb I can't see how any spray chemicals could clean out the inside of a carb without going inside and doing it, but usually the gaskets need replacement when you pull it apart hence the rebuild kit. I say if its not broke, don't fix it. Try adjusting the carb on it, there are plenty of scooter sites on the web that can help you, www.gopednation.com is one dedicated to the goped brand but there is some carb tuning advice there. I personally figured it out myself and later found information on the web on how its done. Just make sure that the carb is set 1/8 richer(counter-clockwise) than whatever setting gives you maximum rpm or it could run too lean and seize.

 

[burnout]

Got some new gas today, put in ~5.5oz of MX2T, which equates to probably a 24:1 or so.

Rebuilt the entire thing from scratch in 1.5 days. Phew, my hands are torn up

Started it and had it idle for a bit, didn't run too well because of all the carbon in the combustion chamber I suspected. Sure enough, I pulled the plug and peered in, and there were flakes just peeling off of the piston. Right now its soaking in MMO. It'll be fun to see how much smoke comes out tomorrow morning when I start it

 

[burnout]

Well, started it up today after putting anew plug in and scavenging out all the MMO I could.

WOW, smoked out my entire block with this thing. The smoke was white, and very dense, barely even moved once it came out the exhaust pipe!

Once the MMO burned off, the scooter barely smoked at all thanks to the MX2T. /happy

 

[Shannow]

I've a book "2 stroke performance tuning", by A.G. Bell (different guy I think).

His theory on oil mixture in 2 strokes gelled with my thinking.

Oil is a hydrocarbon, and burns. A residual provides that last poofteenth of protection.

He showed some dyno figures on go-kart engines, showing that richer oil mixes produced more power, up to the point that the exhaust pipe started to get "wet".

(I'm sure that if you were playing with compression as well as oil ratio, the results would be messier.)

 

[burnout]

Phew! I got bored within the last week and changed the piston rings and head gasket. Compression is WAY better; I can tell just from pulling the string. Haven't started yet though, the carb needs a new barrel valve. (aka throttle)

Scraped a lot of carbon off the top of the piston, and cleaned out the ports and combustion chamber. I'm betting i'll feel a decent increase in power.

 

[burnout]

Also, what octane gas should I be using?

Most scooter stores/websites i've been to say to use around 92+, but don't say why. It varies at every site I look at. I currently have 87 octane, and while I have no complaints, I'm left wondering if it COULD be better . Is there a high possibility of detonation in 2-strokes because they get so hot? I could imagine that at full throttle for 1min, it could easily get so hot in there that it would preignite.

Thoughts?

 

[wileyE]

As little fuel as they consume I'd run the premium, but it's probably fine on the 87 though.

Deto will show as peppering or sandblast look around the outer part of the piston crown. Sometimes you can see specs of alum on the plug.

Your correct, the longer the pull at wfo the more likely it is to deto.

 

[burnout]

Woooeee!

Started the scooter up today after making some final adjustments.... My oh my.. What a difference piston rings can make.

The only thing the last two owners knew to do was to mix the gas and the oil. Had no idea how to maintain it right. Probably went WOT for long periods and never let it warm up properly.

This thing is bordering on unsafe its so fast!

 

[MN Driver]

From everything that I have read, the higher octane recommendation is because it is supposed to run cooler than a lower octane gas in these smaller engines.

I don't know if that is the real reason they recommend it or not, but I run 92 in mine. I doubt it has much to do with performance because I feel no difference.

You are right, letting it warm up for about a minute is important. The rings will make a big difference but since it's a 2-stroke, I wouldn't expect the performance to last forever, the rings don't really break in as they do with a 4-stroke, they just seem to wear out.

Going WOT is pretty much standard with these scooters however, I'm not sure how fast yours is but most of the scooters go around 20mph so people usually are at WOT most of the time.

 

[burnout]

This one is spec'd brand new to hit 30, but I know enough to only do WOT bursts for maybe 5 seconds, if that.

 

[car54]

I like raising dead topics, so here goes..

I have a 2000 Honda Elite with 10,500 miles.. run on dino until 2200 miles when I bought it from a huge company auction.. I ran Amsoil S2000 for awhile, then switched to Redline two stroke Race oil for the smell alone.. (didnt like smelling like two stroke after a ride to work, and the redline has a slightly sweeter smell)

I immediately modified the scooter when I bought it (carb, expansion pipe, trans mods).. it now tops out at 45mph and depending on how I tune the transmission, it revs out good on the high end (screaming like a dirtbike)

My gps shows most of my trips average 29-32mph.. thats roughly 400 hours on the engine, with most of the cruising done at WOT. I always run it wide open, and I never warm it up. still making good compression, and no corrosion from what I can see.. (I havent torn the engine down, or replaced the spark plug.. just removed it for the 10,000 mile compression check) I have the injection pump set very lean, and run about 14 gallons of gas to 16 ounces of oil. (stock it runs alot more oil, but it does not know I modified the carb for more gas/air, so it happily squirts away at its lowest ratio..)

My experience proves to me that these scooter engines are quite possibly the most durable two stroke engines on the planet.. I run hard with a fully exposed to the rear tire's dust K&N filter, little to no oil (no smoke at all), no tune-ups, and hours of Wide Open Throttle in temps from below freezing to 100F heat. The stock engine is also putting out much more power than it was designed for..

 

[Steve128]

Car54, great post. Love reading how members do imprompto "tests" of their vehicles and share the results. So 400 hours at 30 mph ave. gives you 12k on the abused scooter.

Not sure why the lean ratio though?

First thing I noticed was you were wearing a helmet, for a scooter rider BRAVO.

 

[car54]

I run low oil because the redline is expensive (~$5 per 16oz after shipping) and I put alot of miles on the scooter and cannot justify saving money on fuel only to dump it in the tank in the form of oil..

It runs great with the current settings, so why change anything? Nothing is wearing out and I paid less than $200 for the scooter (It belonged to kozmo.com, an internet based delivery company that went under. Me and a friend bought 21 of them at the asset auction)

If the test proves that my oil ratios are too lean and ruins somthing, I'd toss it and buy a new one.


I have faith in Redline two stroke even after reading about all the corrosion issues on this board. Those stories made me think about changing, but my personal experience proves the oil works fine in my application, and if at some point in my "test" I am proven otherwise, I will dump the Honda and buy a new aprilia SR50. Until then, I will continue commuting at 65MPG while screaming thru the traffic and accidents that makes most folks commutes into ****.