Motorized bicycle making funny sounds. Best heard at 0:19 - 0:30. Sounds like it runs fine at times and other times it sounds like a lawnmower farting. Bike is on the second tank of the break in cycle. 1st tank was mixed at 16:1 as per the instruction manual and this tank is mixed at 20:1. Made the higher mix as I thought 16:1 might have been too much oil but it didn't solve the noise. Spark plug is a nice brown tan so the fuel air mixture should be good. This is my 3rd motor and the other 2 never made this sound. Lost on this. Any ideas? Video can be seen at - https://www.youtube.com/watch?v=NB6H_p7MssQ
Can anyone identify the strange sound my bike is making?
- Thread starter HarleyXLH666
- Start date
That's called 4-stroking. Is the engine @ operating temp? Try leaning out your mixture. Also keep in mind that your rings haven't seated yet, so you're probably getting some blow-by. Also, break-in @ 25:1....then use 40+:1.
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OUCH the manual told me 16:1 for break in :S Next one will be 25:1.
For operating temps, I store the bike inside the house and it does it even at start up when I bring it outside but for this video I was pedaling for a while then started it and was going uphill and I really noticed the sound so I went back down the hill and started the camera and went back up. Its still kind winter here so for THIS video I would have to say that no it was not at operating temperature. Outside temp was about +6c.
It was probably running for about 2-3 minutes before I started recording.
"4-stroking" I guess if it has a name I can't be the only one who has experienced this though my concern is my 1st 2 motors never did this but they were local bought. This one here is a Zoom bicycle from ebay delivered from Canada.
How long does it typically take to get the rings seated?
Tnx for the quick reply as well
Edit: As for leaning the mixture the choke was all the way in the down position. Does that mean I need to adjust the c-clip on the needle inside the carb?
For operating temps, I store the bike inside the house and it does it even at start up when I bring it outside but for this video I was pedaling for a while then started it and was going uphill and I really noticed the sound so I went back down the hill and started the camera and went back up. Its still kind winter here so for THIS video I would have to say that no it was not at operating temperature. Outside temp was about +6c.
It was probably running for about 2-3 minutes before I started recording.
"4-stroking" I guess if it has a name I can't be the only one who has experienced this though my concern is my 1st 2 motors never did this but they were local bought. This one here is a Zoom bicycle from ebay delivered from Canada.
How long does it typically take to get the rings seated?
Tnx for the quick reply as well
Edit: As for leaning the mixture the choke was all the way in the down position. Does that mean I need to adjust the c-clip on the needle inside the carb?
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Yeah, there's a school of thought about the Chinese manual, and the quality of North American fuel products: Chinese petroleum products suck, so they use more oil. It's generally accepted that we can use 87 octane mixed with standard 2-cycle oil @ 25:1 for break-in. This may also reduce your 4-stroking right off. I'm running 45:1 on a broken-in 66cc, and it'll 4-stroke as much as yours until it reaches operating temperature. I'll ride it gently for a few minutes...like 1/2-mile, and it'll start purring. As for the choke, I assume you have an NT carb. My experience is, choke should be on (lever up) only when you need it. Once it turns over or starts, you can put it all the way off (lever down).
As for the rings seating themselves, that can take a few hundred miles; you should notice the engine performance improving over time...compression increased, as will power.
C-clip:
away from carb = lean (restricts jet)
towards carb = rich (opens jet)
As for the rings seating themselves, that can take a few hundred miles; you should notice the engine performance improving over time...compression increased, as will power.
C-clip:
away from carb = lean (restricts jet)
towards carb = rich (opens jet)
For your reference, here's a recent ride...it was the first ride of the day, and it was about 32F. You can hear classic 4-stroking from 3:00 to 4:00 as the top-end heats up, then it goes into smooth 2-stroking.
http://www.youtube.com/watch?v=_Wb08gpTWdU
http://www.youtube.com/watch?v=_Wb08gpTWdU
Hmm not too sure about the carb. This is the engine I bought http://www.ebay.ca/itm/321052507699...sch/i.html?_from=R40&_nkw=321052507699&_rdc=1 and I can't seem to find the carb in the parts list. I'll have to take a look at it next time I go downstairs.
NOt sure about the octane # but the pumps have a bronze, silver and gold option for fuel and both times I used silver.
When I first pedal and start, since I keep the bike inside I usually start it with the choke at half to full up and drop it down right away. If I had it locked up outside for a bit I'll leave the choke about 1/2 way until it starts warming up but in general the choke is always in the lean position while riding.
So I guess from here its just a matter of tinkering and fine tuning and I now have a starting point where look. Funny thing is this is my 3rd bike motor and Ive owned motorcycles from a 77 Honda XL75 right up to 88 Harley XLH883 and have never heard of 4 stroking before and this was baffling me. Thank you for your help with this
NOt sure about the octane # but the pumps have a bronze, silver and gold option for fuel and both times I used silver.
When I first pedal and start, since I keep the bike inside I usually start it with the choke at half to full up and drop it down right away. If I had it locked up outside for a bit I'll leave the choke about 1/2 way until it starts warming up but in general the choke is always in the lean position while riding.
So I guess from here its just a matter of tinkering and fine tuning and I now have a starting point where look. Funny thing is this is my 3rd bike motor and Ive owned motorcycles from a 77 Honda XL75 right up to 88 Harley XLH883 and have never heard of 4 stroking before and this was baffling me. Thank you for your help with this
Ahh yes I can hear it switching. I'm just glad to know that this "normal" and not something wrong with my specific engine I got.
Side note: LOL @ the people at 3:02. I love the looks people give you when riding these things XD
Ahhh, yes! Poor bastards waiting for the bus. Notice the the guy with the bike? The buses have bike-racks on the front. We had a severe blizzard a few weeks back and I'd relying on using the bus (and its rack) for my return trip on this same road. When I finally went to wait at the bus-stop, the roads were really nasty, and I was surprised to find the bus STUCK on the hill the stop was on. The driver told me she'd been stuck there an hour already, and expected to be stuck there for the night. The bike, however, handled superbly, and I made it home lickety-split. In fact, I had to negotiate my way around many abandoned cars.
The buses have racks here too. I was actually wondering earlier today if buses would take these things on the front as I know they are somewhat frowned upon friom my previous bike shop and police experience in Winnipeg. Then figured why would they say anything about the little tank when the bus has 100's of time more fuel in the back.
Another thing I was concerned about is if I would be able to get across the border between Ontario to New York but I got through no problem. Then again I guess thats more the police job than CBSA. When summer comes I'm gonna tear up the dirt trails in Niagara Falls NY I just moved to Ontario from Winnipeg motorized bicycle so am still trying to figure out the legality of these things here. Some say yes and some say no but I believe that if your not being an idiot you'll be fine unless you get an officer thats having an off day. Haven't had a problem yet (knock on wood) but if I see a cruiser I still kill the engine.
Another thing I was concerned about is if I would be able to get across the border between Ontario to New York but I got through no problem. Then again I guess thats more the police job than CBSA. When summer comes I'm gonna tear up the dirt trails in Niagara Falls NY
I just moved to Ontario from Winnipeg motorized bicycle so am still trying to figure out the legality of these things here. Some say yes and some say no but I believe that if your not being an idiot you'll be fine unless you get an officer thats having an off day. Haven't had a problem yet (knock on wood) but if I see a cruiser I still kill the engine.
I live in Connecticut where motorized bicycle riding is legal if you have a driver's license. I have however been spending a good deal of time on Long Island, which is New York State. Strictly, it's motorized bicycles are not legal, but the Suffolk County cops have been super cool...no probs at all. In fact, a lot have asked me details about my build. Another great benefit: I live in Bridgeport, CT, which has ferry-service to Long Island. Normally, it's about $110 round-trip with the car. They charge like $60 RT for motorbikes and scooters. They recognize me as a walk-on though, and I pay $24 RT. I tell people I wish I'd built a motorized bicycle 30 years ago (I built my first this past Summer), I was in college in Buffalo back in the '80s and went back-and-forth to Niagra Falls (Canadian side): 18 to drink and the strip-clubs went full-nude! A motorized bicycle woulda' been handy!
Do you have a 49cc or 66cc? If it's 66cc, you may be better off with the slightly larger NT Speed carb. They're available on eBay for less than $20 delivered. Also, what's your wheel-size and your weight?
I'm not sure on the exact displacement of my motor but it was sold as an 80cc Zoom bicycle. My wheels are 26" and I am about 150.
After opening the carb I noticed in most threads I have read that the stock clip position is usually 2nd notch from the top but mine was the 3rd notch. I have moved it up to the second from the top and went around the block and its still doing it. Even though it was inside and I took it out I don't think around the block is enough to reach operating temperature as well as I have nowhere near 200 miles on it yet.
I have only went through one tank of 16:1 and am now half done my 2nd tank at 20:1. Next tank will be at 25:1 and if that doesn't help then I still have one more notch in the carb needle to try and if that doesn't work I read that alot of motors come with oversize stock jets so I may have to start downsizing on the main jet but of course thats once all the notches in the carb needle are used up.
This week is supposed to be in the + temps so it should be more pleasent riding it around for tests.
After opening the carb I noticed in most threads I have read that the stock clip position is usually 2nd notch from the top but mine was the 3rd notch. I have moved it up to the second from the top and went around the block and its still doing it. Even though it was inside and I took it out I don't think around the block is enough to reach operating temperature as well as I have nowhere near 200 miles on it yet.
I have only went through one tank of 16:1 and am now half done my 2nd tank at 20:1. Next tank will be at 25:1 and if that doesn't help then I still have one more notch in the carb needle to try and if that doesn't work I read that alot of motors come with oversize stock jets so I may have to start downsizing on the main jet but of course thats once all the notches in the carb needle are used up.
This week is supposed to be in the + temps so it should be more pleasent riding it around for tests.
For what it's worth. I have never needed to re-jet a small engine carb. That's from 100" elevation, 100 degrees, 100% humidity- to 5500' elevation, 40 degrees, 20% humidity. I know alot of guys do, and you may need to, but try it all before you do it. I usually take the breather box off, and tune it a bit, then get it right with the air filter back on.
Good luck!
Good luck!
As others said, that sound is 4-stroking, you're probably running too rich, but if it's running decent it's probably best to run through a gallon of break in fuel and get on a standard mix before you do too much tuning, cause the oil/fuel mix will effect the air/fuel mix. Better to run rich than lean any how, a lean mix can run too hot and be hard on your motor....
BTW the e clip on the needle only really effects the mix in the mid throttle region. Moving the clip away from the pointed end of the needle will let the needle seat deeper in the jet and thus lean the mid throttle mix, however, this will not lean out the mix at WOT (wide open throttle). At WOT the size of the jet, the float setting and the resistance to air flow provided by the air filter and exhaust will have the most effect on the mix.
After you have put a couple hundred miles on the motor and the rings have seated and you are running a standard fuel mix (btw, I tend to break in with a gallon of 20:1 and then switch to a standard mix of 32:1 using standard 2-stroke oil, but not the marine kind) If you are still 4 stroking at that point you should do a plug chop at WOT (warm up the motor and ride WOT, then all at once pull in the clutch, drop the throttle and kill the motor) and pedal home. After the motor is cooled pull the spark plug and inspect it. Compare the plug to the excellent chart on this page http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html to determine if you are running rich or lean at WOT. At that point you take corrective measures but rather than speculating both ways right now I will wait for you to figure out which way you need to move....
BTW the e clip on the needle only really effects the mix in the mid throttle region. Moving the clip away from the pointed end of the needle will let the needle seat deeper in the jet and thus lean the mid throttle mix, however, this will not lean out the mix at WOT (wide open throttle). At WOT the size of the jet, the float setting and the resistance to air flow provided by the air filter and exhaust will have the most effect on the mix.
After you have put a couple hundred miles on the motor and the rings have seated and you are running a standard fuel mix (btw, I tend to break in with a gallon of 20:1 and then switch to a standard mix of 32:1 using standard 2-stroke oil, but not the marine kind) If you are still 4 stroking at that point you should do a plug chop at WOT (warm up the motor and ride WOT, then all at once pull in the clutch, drop the throttle and kill the motor) and pedal home. After the motor is cooled pull the spark plug and inspect it. Compare the plug to the excellent chart on this page http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html to determine if you are running rich or lean at WOT. At that point you take corrective measures but rather than speculating both ways right now I will wait for you to figure out which way you need to move....
Yes, I agree; before you make any big changes until you're fully broken in. On a oppositely related note: I was out last-night and had to fill up my tank. It was cold...about 25F...and as usual, I added oil to my near-empty tank, then speed-pumped the gas into the tank...shoving the nozzle against the oil-puddle which does a good job of mixing it up. Well, I guess the oil was too thick at the lower temps, and after I left the gas-station, the engine started running REALLY lean...nearly running away at idle, and head-temp shooting up to 475F. Turns out a glob of oil got into the carb-bowl. I've had the opposite effect, where too much oil in the mix caused the engine to stall. This is the first time I've had a "perfect mix" for it to lean out to the point of mimicking an air-leak. The problem resolved itself after a few miles.
once the oil all gets mixed even with a little gas, it will mix more easily with more gas - if you don't carry a small empty bottle with you, you can pull an old soda can out of the trash, wash it out with a bit of gas, put in your oil, shake it good, then pour it into your tank with the gas or before the gas
all the oil in the bowl might mean some amount of straight gas at some other point
all the oil in the bowl might mean some amount of straight gas at some other point
So I had a good long run on it yesterday with the needle clipped in the 2nd position from the top. One it was running for a good while it was picking up more power and when I get to wot it would still 4 stroke for a while but then it kicks in like it should and it gets mega power. But as soon as I let off the gas and the rpms drop it starts 4 stroking again when more throttle is givin but again kicks in after a few second of wot. I only held it like that for a few seconds though as I know your not really supposed to do that on break in but it was too hard to resist on a long straight strip lol but at least it broke in to normal cycle at the top end.
So as I said my 1st tank or 1/2 gallon was at 16:1 and my second tank is almost done with maybe about 1/4 tank left at this 20:1 mix and now I have a proper red gas can so am going to do my next FULL gallon mix at 25:1. Picked up this super cool mixing syringe called the miximizer with ratios to gas right on it http://i235.photobucket.com/albums/ee175/martynbiker_photos/Fixing my CT90/DSC08324.jpg I so wish I had that with my 1st to motors. Almost makes mixing oil fun lol.
So as I said my 1st tank or 1/2 gallon was at 16:1 and my second tank is almost done with maybe about 1/4 tank left at this 20:1 mix and now I have a proper red gas can so am going to do my next FULL gallon mix at 25:1. Picked up this super cool mixing syringe called the miximizer with ratios to gas right on it http://i235.photobucket.com/albums/ee175/martynbiker_photos/Fixing my CT90/DSC08324.jpg I so wish I had that with my 1st to motors. Almost makes mixing oil fun lol.
I found myself at Canadian Tire today so I picked up a pack of B6HS plugs and a gapper and set the gap to 027 and right off the bat there is a mega power increase. Its 4 stroking a little less at the bottom end with the new plug but it is still on its break in so things wont be perfect yet. After the 1st tank of 16:1 (oops) and still about a quarter left of this tank at 20:1 this is what my original stock plug looks like
