49cc ignition problems

[mtrammel9122]

I was driving down the road and lost power. It didn't die, but kind of bogged down a bit. I pulled into a gas station and when I tried to start it up again, it wouldn't catch. The starter is working and I can hear it turn over, but sounds like no fire. Changed the plug and cleaned the carb. I'm not much of a mechanic, so what should I check next? Btw, no problems with it before this. Nothing reoccurring that would seem connected. Please help. It's my only ride.

[scooterpimp]

I gotta ask did kill switch get bumped off?

[mtrammel9122]

No. Not unless it is a short. I did check that. Thanks tho.

[90GTVert]

Check for spark.

49ccscoot.proboards.com/post/8057/thread

[mtrammel9122]

Checked that too. It is sparking.

[Sir Scoots-A-Lot]

have you ever had any issues starting it before? Like did it always start instantly first try or was it on the first try after 5 seconds or on the 2nd or 3rd try? Do you know which jets you have in? are all your electrical connections 100% sound and is your battery highly charged?

also by loosing power you meant just bogging down right--you didn't lose electrical power?  was it bogging down under what conditions --- just acceleration?  or were you holding the same speed doing fine then it started bogging down? did the bogging go away if you backed off the throttle? or did it still feel like it would stall after you pulled over and were idling?

I know you probably don't want to write a novel but if you are still having issues and need this fixed as your primary transportation, then any little details may help us diagnose the problem, especially since we are trying to do so online. If you can easily post a short video, preferably with someone else holding the camera so they can show exactly what you are doing and capture the sound it is making that MIGHT help. Is your scooter making the usual sound it makes when it was starting? Have you recently made any changes at all to your scooter before this problem occurring? How did your carb and plug look when changing/cleaning them? carb really dirty? plug brown or black, or wet with gas or wet with oil?

Are you holding the brake while trying to start/ is yours a model that only starts while holding the brake? have you tried the kickstarter/ if you do try the kickstarter don't go crazy hitting it really hard many times if it wont start as that will break the kickstart just like holding down the electric start for too long and too many times in a row will break that too. 

try to make 100% sure you are getting gas after cleaning the carb too. I know it sounds silly but the carbs are very touchy and just from taking them apart and putting them back together without really doing anything I have seen them both flood and not get gas as well as I have seen large a air bubble get stuck in my clear gas filter after a carb cleaning and the air bubble was about 1/4-1/3 the size of my little filter and didnt go away during operation but only by flicking/shaking the filter and squeezing the line just below the filter many times. I was having issues at the same time the air bubble was there but not sure if they caused problems or made problems worse.

[Sir Scoots-A-Lot]

Someone recently suggested to me that if I was 100% sure I was getting spark, had a fully charged battery, was getting fuel and it felt like it had compression by slowly turning over the engine either with the kickstarter or a socket wrench on the flywheel then maybe try disconnecting the air filter from the carburetor and spraying a quick shot of starter fluid for a second or two into the carb then try starting. if that doesnt work you can try holding the throttle open while spraying the starter fluid to make sure it goes directly to your intake then try quickly starting it. starter fluid usually doesnt fix your issues but it could be a temporary fix and save some serious strain on your starter.

Also have you ever adjusted your intake and exhaust valves on your cylinder head under the valve cover?? if yes, how many miles ago? if no, how many miles have you rode without adjusting them? Mine both went a couple thousandths of an inch loose within a roughly estimated 1500-3500 miles 

good luck and let us know how it goes.

[ratdog]

Miss adjusted valves would make it loose power but once it cooled down all would be good again.

I know I’m famous for overreacting ( someone told me that) but it sounds a whole lot like you seized the engine, but your momentum broke it loose again. So my guess is that you don’t have enough compression to run the motor now. Did you look at your plug to see if there were any bits on it?

Might be fun to take a close up pic of the tip and post it

about the valves, I was thinking about valves that were too tight.  If the valves are too tight, when the engine gets hot they have no slack at all and start leaking.  Buy when the engine cools down, the engine can start and run (until it gets hot again). Loose valve adjustment will mostly just make the engine louder.  As in a loud clicking sound.  Power will be down a bit, but no real damage.

[Sir Scoots-A-Lot]

Oct 13, 2018 19:05:04 GMT -5 ratdog said:

Miss adjusted valves would make it loose power but once it cooled down all would be good again.

I know I’m famous for overreacting ( someone told me that) but it sounds a whole lot like you seized the engine, but your momentum broke it loose again. So my guess is that you don’t have enough compression to run the motor now. Did you look at your plug to see if there were any bits on it?

Might be fun to take a close up pic of the tip and post it

with the misadjusted valve theory I'm not sure about the loss of power part but I know people have said bad valve adjustment can cause starting issues and I think that has been my experience as well.

This thread sounds a bit like my problems Ratdog, one of the reasons I replied to try and help. In my case I did see some stuff on the spark plug, a little junk on the tip as well as dirty wet stuff that could be metallic shavings mixed with gas or oil my spark plug threads still not sure if it is from seizing my engine but eventually got it to run for a bit and still need to look into everything more to see if my engine can still run at normal capacity or if it needs to be rebuilt to run normally at normal top speeds for long trips etc. I think you may be onto something Ratdog, by asking for the OP to check his spark plug tip for junk such as oil and mettalic bits/shavings 

If my engine has been wearing out and seized then i was able to still get quite a bit of use out of it after my problems reared their ugly heads although I have continuosly had starting issues, sometimes really bad, sometimes not so bad, intermittent bogging/power loss also.

It would be great if you had a compression tester to test for this theory (I wish I had one!) as it only takes five or ten mins to unplug HT plug wire, swap out the spark plug for the compression tester and give it a try. I think even a partially siezed engine would be significantly down on compression from stock numbers, probably down under 150psi, even if it still was able to run

[ratdog]

If an engine had 150 psi, it would start and run OK. When an engine seizes and then releases, it normally takes out the rings. At that point the compression will drop well below 100.

I rebuild a lot of “lawn art”. That’s bikes that have sat for a good deal of time. One trick I use is to squirt some heavy oil (like 20w50) straight down the cylinder. ( remove the plug and shoot it into the cylinder) then squirt a bit of starter fluid in the carb. Often this will get it to fire and a great cloud of blue smoke. To me that sz “overbore”. Of course on these little guys, that’s a BBK.

[mtrammel9122]

So, after looking at it some more, I think the motor may have seized. I tried the kick start to check for compression, and it seems to stick when it tries to wind back. Would that be right? If so, would that mean a new motor?

[jackrides]

A seized 2T is fairly easy to fix, 4T more work. Upon disassembly, if the piston sides are totally dry of oil, you have to find out why. What kind of motor? Water or air cooled?

[Sir Scoots-A-Lot]

Oct 15, 2018 9:15:23 GMT -5 mtrammel9122 said:

So, after looking at it some more, I think the motor may have seized. I tried the kick start to check for compression, and it seems to stick when it tries to wind back. Would that be right? If so, would that mean a new motor?

that could just be a problem with your kickstarter assembly....what I was asking you to check is slowly push down on the kickstarter to see if the engine moves freely. if it is fully seized then the engine shouldnt move at all--or be extremely difficult to move at all or very hard to get it started moving because it will be stuck. Have you used the kickstarter before to start it so you know about what it should feel like? Under normal conditions the kickstarter does take some force to move at all and even more of a hard fast kick to start the bike. If you slowly shift your weight onto your foot with it on the kickstarter it should go down unless maybe if you are very light under 125 or so

If it moves like normal when you push down the kickstarter the engine should move freely but not too easily because force is required not only to turn the engine parts but also to compress the air/gas mixture in the combustion chamber. if the engine is not fully or partially seized and the cylinder walls are still smooth but has significant compression loss then the engine may be a lot easier to turn over with the kickstarter.

So you said the kickstarter feels funny on the way back up? that doesn't sound like it has anything to do with the engine. How did the kickstarter feel on the way down?

If you are unsure if there is a problem with your kickstarter, you could try turning your engine over by putting a socket wrench on the flywheel, which is where the fan spins next to your oil filler, and try turning the engine over by spinning the fly wheel with the socket wrench. My flywheel I believe I use a 13mm socket on although it may be a 12mm. Turn the socket about a quarter turn at a time it should go either direction lefty loosey or righty tighty--doesnt matter which way it should turn and you should feel some points you get to the engine will spin easier than at other points as the engine goes from bottom dead center BDC to Top Dead Center TDC and goes thru all the different strokes of intake, compression, combustion/power, exhaust. You might even be able to "feel" or hear the engine breathing. 

So I would test the flywheel and see how that goes. If the kickstarter feels normal on the way down, your engine is probably not fully seized at least, but doesnt tell you much more unless you use the kickstarter wnough to know how it should feel. If the kickstarter is only having trouble on the way back up then you might have a problem with kickstarter in which case you should try not to use the kickstarter until you look at it

[Sir Scoots-A-Lot]

what state are you located in? Im in CT if you are around me I would look at it for you, I am no expert but I know a thing or two. If you don't feel confident checking things on the scooter maybe try to find a friend maybe another member on here to take a look at it for you. If you check the flywheel and the engine seems to turn like it should then I would suggest checking your valve adjustment if you havent done that in the last 1,000 or 2,000 miles. I also suggest you take Ratdog's suggestion and check the end of your sparkplug first to see if there are little mettalic pieces on it or on the old plug you just changed if you still have it. If something happened to your engine like the cylinder walls or piston or piston rings were scraped then bits of that would often be seen on the tip of your spark plug

[Sir Scoots-A-Lot]

If your starter sounds like it is turning the engine but the engine isnt "catching" meaning it isnt starting the combustion process then I suspect your engine isn't fully seized and you will most likely be able to turn it over with the kickstarter or with the flywheel. Sometimes the engine can do what I have people call a "soft seize" which happens to different degrees of severity when your piston rings basically get caught on a rough spot on the cylinder momentarily so instead of moving smoothly with proper oil lube protecting the moving parts the piston rings and/or piston itself scrape the cylinder wall and you can either lose one or more piston rings entirely or just scrape up the cylinder wall or the piston or piston rings or a combination of all 3 may become damaged, warped. This causes a power loss and can cause some oil to leak past the piston rings and somewhat a compression loss because everything will not be sealed as well anymore now that the rings/piston/cylinder walls are damaged or missing and it can be a minor thing and get worse or be a major problem from the start. This condition can happen when your engine gets too hot an/or runs too low on oil which causes all the metal parts to expand as they heat up and when they expand the piston and rings are too tight up against the cylinder wall and they scrape each other which can cause a power loss like you mentioned. In a "full seize" situation the piston would become fully stuck in the cylinder and the engine would not turn at all until the piston gets freed and if that happened while driving the engine would stop 100% although you would keep rolling forward. It is hard to say for sure if a soft seize is what is happeneing with your scooter without looking at it 

From what you described with the power loss I am going to guess you either have a soft seize, and/or a valve adjustment issue and/or your carburetor is jetted incorrectly or otherwise is malfunctioning by becoming clogged. It is difficult to diagnose over the internet and without pictures or videos ....so someone seeing it in person who knows what they are doing is best but if you want the wise people on here to help you and for me to help you too then please post as much info as you can