|
Post by wamgaming on Sept 12, 2018 11:32:24 GMT -5
I bought a TaoTao 80cc BBK from a guy off of craigslist. He told me that he had done many upgrades to the moped.
I have been trying to track down and issue ever since I have gotten it. The issue is that after riding the moped, my back smells like horrible exhaust fume (at least I believe its coming from the exhaust because its my back). The smell is noticeably worse during cold days and not so apparent in the heat of summer.
Here are some additional things that might contribute to this problem. 1. There is a very strong smell of gas when warming up on cold days, and typically some white smoke for about 1-3 mins if its really cold out. When it is warm outside/ when the engine is warm; this is not an issue.
2. The moped revs up really high for takeoff, it catches for takeoff bringing the idle down, then revs up again to get going 10mph+.
3. Moped idles well at startup, after a few mins when the electric choke comes off, the idle is not as stable. After riding the moped for 5 mins (and it is warmed up); lower rpms bog the moped.
4. Going up hills when warm, makes a rather loud clattering noise, not sure where it is coming from. However it goes away immediatly after backing off throttle. Typically only occurs when going over 3/4 throttle, or trying to get up steep hills.
I can not tell if the smell on my back is that of burning oil, or that of unburned fuel, but it is very noticeable and not coming from the fuel tank.
Any help would be greatly appreciated.Thanks
|
|
|
Post by scootnewb on Sept 12, 2018 12:36:40 GMT -5
Hmm. I think some of the things you've mentioned are from burning oil? Erratic idle can be caused by an air leak. Clattering noise going up hills? Yikes.
Check all your fuel and vacuum lines and replace any that are suspect. Get it idling and spray carb cleaner around the carb and lines and see if there is a change when that happens. Checking the valves may be a good idea too.
80cc BBK's (83cc) the 50mm ones can cause problems with the crank bearing. It can be too much for them. The kits marketed as 80cc are really 72cc. I would find out which one was installed and if it still had the stock head.
|
|
|
Post by wamgaming on Sept 12, 2018 12:53:17 GMT -5
Hmm. I think some of the things you've mentioned are from burning oil? Erratic idle can be caused by an air leak. Clattering noise going up hills? Yikes. Check all your fuel and vacuum lines and replace any that are suspect. Get it idling and spray carb cleaner around the carb and lines and see if there is a change when that happens. Checking the valves may be a good idea too. 80cc BBK's (83cc) the 50mm ones can cause problems with the crank bearing. It can be too much for them. The kits marketed as 80cc are really 72cc. I would find out which one was installed and if it still had the stock head. I have already went through and checked the lines, in fact I took off the vacuum petcock and changed it to be gravity fed (to completly eliminate that potential problem). I have checked the valves multiple times, and they are all within speck. Why do you think that its burning oil rather than too rich of a mixture? Id like to start by answering that question, so what would be the best way to figure out?
|
|
|
Post by scootnewb on Sept 12, 2018 16:40:49 GMT -5
Perhaps from running rich and maybe from improper valve adjustment? I think though it's usually attributed to worn piston rings. For that you have to remove the head and jug to check. I also removed my petcock during a trouble-shootingg session and replaced it with this type. www.amazon.com/gp/product/B06XWC44T8
|
|
|
Post by gsx600racer on Sept 12, 2018 16:56:47 GMT -5
That's the moisture in the exhaust being burned/evaporated off as the engine warms up.
CVT needs to be checked and tuned. Possibly the wrong belt is being used(too long).
Pilot jet in carb might be too lean and/or air screw on carb (not idle screw) may need a be adjusted.
Does it make the same noise while its on the center stand and revving up the engine to simulate the same speed ?
My guesses are would be check the cvt or there is something loose and your hitting the right rpm vibration/residence frequency for it to make the noise.
Also the main jet might be too lean and or compression is too high and under a load @ high rpms your getting detonation/knocking.
As for the smell, does it look like the exhaust was recently painted ?
|
|
ratdog
Scoot Enthusiast
Posts: 342
|
Post by ratdog on Sept 12, 2018 23:10:50 GMT -5
OK, I have much worse thoughts. A BBK makes a very large increase in compression.. are you running premium fuel? I would recommend you go to 93 octane fuel.
The noise you hear, is it more of a raddle? I’m thinking you could very well be getting pre ignition ( knocking)
Pleas pull the plug and take some pics for us. I want to see the inside of the plug, the white part. I’m willing to bet that you are running way too lean and the motor is starting to eat it’s self from the inside
What plug and what oil are you running.? Have you changed the oil since doing the BBK? Oil is not expensive, I’d love to see you do an oil change and look carefully at the drain oil. What I would be looking for is if the oil seems to have very small silver flakes in it. Looking at it in the sun would make it look like “ glitter” was in the oil. I normally drain the oil thru a paper filter to see if we catch any engine in the oil. To me, oil is cheap and plugs are cheap. All the BBK bikes I have done are running 20w50 mobile one oil and a NGK C8HSA plugs. The C8HSA plug is one step colder then standard to hold up in the much higher heat the BBK produces. I think the smell may just be that your bike is running way too hot.
Other then the BBK, did you change anything else? Has anything ever been changed in the CVT? Just wondering if someone changed the springs inside the clutch. Have you, or anyone before you changed the weights? How many miles would you say are on your belt, and has it ever been changed? Might be worth popping the cover off the belt and checking the size belt it has and if the belt showes any wear. Also smell the inside of the cover.
Now you have your home work assignment...
|
|
|
Post by GrumpyUnk on Sept 14, 2018 11:22:15 GMT -5
I will add to the above the following:
Was all of the engine cooling shroud assembly re-installed after the BBK? If some 'back yard engineer' decided it was not needed, and left it on the workbench or garage floor, or binned it, you need to replace it ASAP. If the shroud is left off, or not assembled as original, the cooling air from the blower will not be directed over the heated spots and carry away excessive heat. The result is that the piston will get melted and make the rings stick, or there'll be significant damage to the cylinder wall. Consequence is it will no longer start.
I assume(yeah, I know) that you are detecting an odor in your clothing, and figure that the exhaust gas it getting pulled from the muffler area and against your back when you are riding. Is the exhaust tight to the cylinder head? Does the exhaust pipe leak? Is the exhaust pipe tight to the muffler inlet? Some have a three-bolt fitting to connect the pipe to the muffler. IF you have one of those, is the gasket between the two pieces installed and intact? Is the muffler the normal or a 'performance' version. If the latter, it is possible the exhaust gas is being misdirected such that it is being pulled against your backside rather than dissipated. Got any peekshures? tom
|
|
|
Post by wamgaming on Sept 15, 2018 20:29:44 GMT -5
I will add to the above the following: Was all of the engine cooling shroud assembly re-installed after the BBK? If some 'back yard engineer' decided it was not needed, and left it on the workbench or garage floor, or binned it, you need to replace it ASAP. If the shroud is left off, or not assembled as original, the cooling air from the blower will not be directed over the heated spots and carry away excessive heat. The result is that the piston will get melted and make the rings stick, or there'll be significant damage to the cylinder wall. Consequence is it will no longer start. I assume(yeah, I know) that you are detecting an odor in your clothing, and figure that the exhaust gas it getting pulled from the muffler area and against your back when you are riding. Is the exhaust tight to the cylinder head? Does the exhaust pipe leak? Is the exhaust pipe tight to the muffler inlet? Some have a three-bolt fitting to connect the pipe to the muffler. IF you have one of those, is the gasket between the two pieces installed and intact? Is the muffler the normal or a 'performance' version. If the latter, it is possible the exhaust gas is being misdirected such that it is being pulled against your backside rather than dissipated. Got any peekshures? tom Sorry for the delayed response everyone. Thanks for all the help. To answer a few of the questions. I have been having this issue for almost 2 years now, but as winter closes in, I wanted to get it solved. When riding the moped in the winter, the smell increases exponentially. Today was around 96F outside and the fumes were still not nearly as strong. I have also noticed that the smell is not present when idling(possibly a little at startup on the choke, but its gone after 20-30seconds.) The moped seems to rev very high in mid range(no lack of power, maybe just upgraded clutch springs?). I have a hunch that the issue stems from the clutch not dis-engaging when going down hills or coming to a stop. The motor has tiny pops as it comes to a stop, with the motor dropping rpm's very low after the clutch finally disengages(2-3mph). I have indeed checked and the exhaust is fastened tightly to the head, and there is no leaks around the pipe connection. I am also wondering if it could be a bad valve (cupping or something). The problem seems to go away after riding at WOT for a few miles, and the moped typically idles/runs much better when warm.
|
|
|
Post by scooterpimp on Sept 16, 2018 0:26:44 GMT -5
Runs better after wot run , kinda sounds like its loading up.& clearing out .?
|
|
ratdog
Scoot Enthusiast
Posts: 342
|
Post by ratdog on Sept 16, 2018 9:29:03 GMT -5
The engine running at high RPM once going, has nothing to do do with the clutch. ( at least shouldn’t have). The clutch locks up at much lower RPM, maybe 1500 to 3000 depending on the springs. Of course it is possible the clutch is completely shot and no longer has any friction minterial at all, but that has nothing to do with the springs.
The CVT has two main parts. The rear section that drives the the wheel through the clutch and the front portion called the variator. Inside the variator are roller weights ( or sliders in some modified engines). Has the variator spins, these weights push out from the center against levers that act to push the drive disk toward the fixed drive disk. That action fources the belt “up” the front drive disk. Th it back there is a spring and the tourque driver that try’s to resist the rear drive disks splitting apart. The belt dosent stretch so there is a constant tug of war between the front trying to get “bigger” and the rear trying to stay “ bigger”
The faster the variator spins, the more the weights “ push” against the lever to make the front drive “ bigger”. Now the weights give more push if they spin faster, or they can give more push if they are heavier. In a stock engine, the weights are balanced against the spring/ torque driver so that it keeps the engine at about 7500 RPM as the bike goes faster.
When we modify the engines, this RPM while accelerating often increases. To change this “accelerang RPM” we often change the weights inside the variator. Basicly, slightly heavier weights bring the accelerating RPM back down to the rage it was in in the unmodified engine. Do you have a tach? It would help a lot if we knew what RPM the bike is running up to while in the acceleration phase. Just a wild guess, this might help your “high RPMs” issue. Of course we can’t suggest a weight, if we don’t know what the bike has now. Pure guess, and I could be very wrong, going to 6 g roller or ( my choice) slider MIGHT help.
You still have not showen us a pic of your plug tip. It’s hard for us to help if all we are doing is making guesses. My personal thoughts at this point is if you have two years of issue, you might want to get some slightly heavier weights and a new belt of the correct size. Also, when you pull the belt cover, you can get a better idea if your having belt issues.
One of the things that is so hard for those of us trying to help is that we have the tools to test this stuff in our shops and we could most likely run through all this stuff in less time then it takes to write about it
BTW, tinny “pops” sounds a lot like it might be back fires, which is often a indicator of the bike running lean. What grade gas are you using?
|
|
|
Post by GrumpyUnk on Sept 16, 2018 10:11:44 GMT -5
FWIW, I would expect the clutch to disengage a little bit before the 2-3mph speed. What's that mean? Dunno. tom
|
|
ratdog
Scoot Enthusiast
Posts: 342
|
Post by ratdog on Sept 16, 2018 16:44:25 GMT -5
The clutch I Gabe’s based on how fast it is turning. Many of us are used to the clutch being on the engine so the engine shat RPMs set when the clutch disengages. With the CVT, it is after the trans., so it dosent disengage when you let go of the throttle.
|
|
|
Post by GrumpyUnk on Sept 18, 2018 10:36:24 GMT -5
I did not understand all the comment, but knew the clutch will stay engaged as long as the rpms are maintained above a set point. On coasting to a stop, I would expect the rpms of the clutch, bound to the input shaft of the final drive reduction gearbox, to fall below clutch engagement rpm at some number above 2-3 mph. It all depends on the clutch springs installed. I have not done math to determine the actual 'theoretical' disengage speed based on the clutch color installed and the attendant engage rpms. The high rpm sets should let the engine drop to idle sooner than those with lower engage rpm settings. tom
|
|
|
Post by fugaziiv on Sept 18, 2018 10:45:16 GMT -5
Is it doing this?
Matt
|
|
ratdog
Scoot Enthusiast
Posts: 342
|
Post by ratdog on Sept 18, 2018 21:46:20 GMT -5
Looks to me as if you have bad muffler bearings. Of course it could be the vifacating vertabor is out of adjustment. I would suggest you pull the engine down and check to see if the the circle clips are in the right position...(BMFG)
|
|