Losing power

[tbarn917]

Hey everyone I have been looking around the forum as a guest for a while and finding some pretty good advice about my scoot. I have 50cc 1E40QMB 2-Stroke and I am having a problem with power.

Long story (scroll down for short story)

Bought the scooter for $250 from my friend who graduated and it ran well when I bought it. After about a month it went from a top speed of about 47-48 to 44-45 but I didn't really know too much about the engine so there wasnt much I could do. Then it rained one day when I was at class and when I left I made it to about 50yds to a stop light before it wouldn't go past 20mph. I assumed it was water in the tank so I drained the gas, changed the filter and I cleaned the carb to see if anything was going wrong in there. After that it was running at about 40 mph but would lose a lot of power on even slight uphill climbs. This worked for about a month before it would top at 20 again.

Short Story

Now the scoot is messing with me. Sometimes it will start and run at about 30mph and I can feel getting little bursts of power but it gains no speed. sometimes it wont get past walking speed to 8mph.

I've been messing with the petcock to see if that was my issue but gas seems to be flowing well and clean. I rode it today for about 45 mins and it ran better than it ever has since I had it. I went to lunch (with my truck) came home to see if it was still running well and I got less than a mile away before it wouldn't go past 20 then took it into the parking lot and it wouldnt get past walking speed. it sat for about 30 mins while I got my truck and brought it home. I went upstairs to get my tools came down and fired it up and it ran fine.

I dont know why it is so hit and miss on when it works any ideas would help. Sorry for the long post.

Barnes

[vvtr]

whats the mileage on it mate???
might just be time for a top end rebuild.
thats the thing with little 2 strokes.... they spend 90% of their life at full throttle, max rpm and they do need regular rebuilds.

seems you got it cheap enough so it owes you nothing

new plug, clean air filter, piston & rings, job done.
could also be the exhaust is gummed up with oily carbon residue.
old trick used to be bung the end up with a wine cork and leave it soaking overnight filled with caustic soda.
before doing this, check the exhaust is not made of ally lol or it will dissolve it!

[tbarn917]

Not sure the mileage. It had one of those digital gauges that crapped out ofter being cracked and rained on so I bought a used analog gauge that reads different mileage. But it is a 2007 that has been used to go back and forth to campus and then some for the last 5 years. I know that I had it pegged every time I've been on it and if I know my friend he was doing the same. I recently changed the plug but ill look into the air filter and top end. I have soaked the exhaust before so Ill do that again as well.

Is that typical then its time for a rebuild that it would go in and out of power like that? I am still fairly new with engines and I thought that once that time came it would run like crap all the time. It used to run well for the first 5 mins or so then when it warmed up it would die out so I assumed the petcock want getting fuel to the bowl and after burning the gas in the carb it was starving. But I'm starting to rule out the petcock. Thanks for the help!

[kek64]

I had a problem similar to that a while back. If it has a choke on it, I believe its getting more gas untill the engine warms up, then it backs off to normal range. Could be your jets are too small for the carb. I'd ask your friend if he was having the same issue. You could try uping the size on the main jet, don't mess with the pilot jet (as i'm told). Also check that the float in the carb is working properly. No sticking or anything that would impede its function. I run some fuel injector cleaner, like my car. Seems to keep my carb clean without any wear on parts that I can see. That might help in the long run.
My next scooter is going to be fuel injected so I don't have to deal with carbs. It is quite the pain in the ass

[90GTVert]

:welcome3:

Mine always seem to steadily or suddenly decline when the cylinders are getting worn, not on and off. With 5 years of riding though, it wouldn't hurt to do a compression test or have a look in there. In fact if you haven't done much other than repairs, now would be a good time to start going over a lot of things. The CVT is likely dirty and could have flat spotted rollers, worn belt, etc.... Here's a list of some maintenance issues to check over. Not saying that these would be the problem, just some stuff to consider taking care of if you wish to keep riding the scooter for a while.

49ccscoot.proboards.com/index.cgi?board=basicstuff&action=display&thread=344


If you haven't done it already this go-round, clean the carb thoroughly. I've had an issue in the past with a hose that was deteriorating and periodically getting little bits of it in the carb. They'd move around and issues would come and go, so inspect your fuel lines. If they're as old as the scoot, I'd just replace them to be on the safe side. Same for vac hoses. Check the auto-enricher and tune as was mentioned.

It doesn't sound like an ign issue, but I feel it never hurts to have a look at electrical connections when a problem is intermittent. Coil connections, make sure the plug wire and cap are secure, stator and CDI connections.

[jmkjr72]

i would clean the carb and air filter
run a compresion test any thing less then 100 is rebuild time
and also pop open the the cvt check the rollers
replace the contra and cleand and regrease the torque driver

[jmkjr72]

the fact that you mentioned the hill is why i would look into the cvt and contra spring

[tango]

I have a question: Does it usually misbehave when it rains? My 90cc would give me a hard time when it rained and I rode through any water. Turns out my spark plug kept getting wet, shorting out the ignition. But when it did so it did so with misfiring, certainly not as smooth as with bad mixture or choked air intake.

[marieaa]

Not sure its age, I have a Suzuki 1999, with 35,235 km on it, My problem for awhile was it would turn over but not start, I tap the carb and it runs great now, I use good gas and fuel injector cleaner, Best little scooter on the road, I just love it, Also have a new Saga, 4 stroke, has not got the power the 2 stroke has, on hills,

[Deleted]

marieaa

:welcome3:

[marieaa]

Thank you for the welcome,

Attachments:

[2strokd]

Nice. Looks like a lil Yamaha Jog . Great scoots!