Nate82
Active Member
Okay so this is my first post in this form so I'm going to give as much details as possible in order to try to get help with my issue that I'm having with my 80cc 2-stroke china doll.
Let me first start off by saying I am a certified small engine mechanic and very much know what it takes to make an engine tick. With that being said I am far from a professional and definitely not a professional with these China dolls. So on to my issue. I threw this bike together put everything together the way it should be wired everything up. Fired it up and she ran great still needed to be broken in obviously. Stupid me didn't think about the break-in the first time I took it out that was the first run then I realized s*** I got to break this motor in properly.
That's when I decided that I would do a few runs and let it cool off then another run, let it cool off then another run at varying throttle positions letting it cool in between. It seemed to have been breaking in perfectly fine, and I was even starting to get a little bit better in the RPM range at the top end then suddenly one day it wouldn't start. I pulled the plug, checked for fire, there was fire but the plug was wet from trying to get it started. I ended up ditching that cheap Chinese plug and putting in the NGK replacement (the br6hs, gapped to just below 0.030 of an inch so it's probably Gapped to 0.028- 0.029 of an inch), gave her another try and it fired up right away.
Ran pretty good for two days on that new plug then suddenly I started losing power on the top end and a little bit of sputtering in the mid-range, I got it home, pulled the plug, the burn rate looked pretty good so I checked the gap and set it perfectly to the above gapping that I mentioned earlier then put it back in, I adjusted the NT carburetor needle and put the clip on the second Notch down from the top, ( I'm right about at sea level here maybe slightly above it but only by a hundred or 200 ft), and I also took the air box off cuz there seem like there was a lot of fuel in the foam so I wanted to see if maybe the motor was getting flooded from the airbox or restricted from the airbox.
Well I took her onto the road it fired right up easily and then took off like a bat out of hell, faster and so much more responsive than I've ever seen this bike run. Before it was giving me a hard time just trying to get the 48 km an hour after I did that she would go to 50 km an hour easily and top out at 55 km an hour on flat ground. Smiling and grinning from ear to ear I drove her back home, shut her down and put the airbox back on. After a cool down I decided to take it out for another run, suddenly hard starting issues again, got it started but lots of power loss and back to it struggling to even get to 45 km an hour.
I've adjusted the fuel Every Which Way on that needle valve and never got any better results this time. Their is most definitely a spark with it out of the motor however I'm wondering if under compression if it's just not enough Spark because this is what I'm kind of boiling it down to is the CDI is just not putting out what it should in order to let it rev out at those RPM ranges and burn the fuel. The other thing I could be looking at is a vacuum leak but I've made sure the carburetor is well seated and I do have the O-ring. The gasket is not blown in the head, I've checked it just by looking at it with the flashlight there's not even a drop of oil around it not to mention I've had those stupid Factory Dome nuts torque down not too long ago to 12 ft lb equally so it's not a head gasket.
I'm thinking about ordering a new CDI and might as well get a better Magneto while I'm at it and I'm hoping that the issue is it's just not running a strong enough Spark. There's got to be a reason why throwing a brand new plug in there made a difference also there's got to be a reason why taking the brand new plug out after I noticed some performance issues starting to happen again, cleaning it up, regapping it and putting it back seem to make all the difference in the world. But only for a short period of time, (one run).
I do notice a little teeny bit of oil making it past the gasket on the clutch/crank side. I suppose this could be an indicator of a poor crank seal causing a vacuum leak? I do have a lot of trouble getting the idle set to idle low without it stalling (regardless if it's nice and warmed up ir not) I pretty much have to turn the screw in at least 10 turns and it's a little high idle for my liking almost as if I'm getting into the throttle at that point and bypassing the idle Jet, however I'm not sure of that. S
o I guess my question is am I on the right track and what things should I be doing from here aside from paying attention to possibly weak spark and trying to correct an issue in that area that may or may not be an issue. I am very quickly finding out, certified small engine mechanic or not, that these Chinese Motors are most definitely the finickiest Motors I've ever dealt with. Like it is very hard to get these to tune and run exactly the way they should without running into more issues. It doesn't take much of a change, or an issue to cause a major difference (loss) in performance.
Oh also just so everyone knows I'm running 32 to 1 ratio of gas oil. I got about a little over 500 km on this motor and it was running fine until the initial spark plug issue around 500 km in. I'm kind of at a loss here, this is starting to baffle me.
I really don't want to have to buy another motor if the issue lies within the cheap things that come with it to make it tick such as the cheap CDI Etc. Something I haven't checked is the plug wire connection to the CDI and to the boot. I noticed after watching a video (it wasn't the exact same CDI as mine) however it was a factory CDI (likely the 100cc CDI) but it was the style that does not require the adapter plate on the plug, but on that particular CDI he was able to unscrew the wire from both the boot and the CDI box, trimmed it a bit on both ends then screwed it back in thus ensuring there's a good connection there. I'm not sure if I can do that to my CDI or not but it is the factory CDI that comes with the 80cc motor kit. I believe this is the newer mold as well.
One thing I can notice right off the bat is that it looks like they use the old mold for the crankcase cover and a new mold for the block it lines up but it's obvious I got a spot where it doesn't line up perfectly although the bolt lines up perfectly. Looks like they were aware of this at the factory and they just threaded the bolt hole so it all matched up weather it lined up with the circular part or not if that makes any sense. I suppose I could take a picture to show you all but that is not the issue.
I guess what I'm asking is am I on the right track with looking at the CDI and Spark and stuff or should I be more concerned about a possible vacuum leak at the crank seal where I'm seeing a little bit of oil around the crankcase cover gasket at the base however that was when I was running that ridiculous 16 the one ratio since I cut that out I don't notice nearly as much oil ending up there. Any help and pointing me in the proper direction would be very much appreciated.
For my first post on this form I really wanted to be able to post about how much I love my bike and how fast it's running and how perfectly it's running but surprise here I am making my first post about what the heck is wrong with my motor or whatever is wrong with what makes that motor tick. Could it be that is still breaking in it just hasn't got to the point where she can top out like it should? sometimes it will and sometimes it won't most times it won't. If its started and idling with the clutch disengaged she will rev right up but under load she struggles at the higher RPM range and that's assuming the starting issues are eliminated.
And generally I do have the starting issues eliminated I'm more having problems with wide open throttle. I want this bike to do what it's supposed and run the way it's supposed to. Another thing I noticed is that when it's not topping out like it should overall it is not nearly as responsive neither. I can feel it sometimes too trying to kick in at that higher RPM range and hit that power band and then it'll back off and then sometimes it'll kick in and hit at the higher RPM range and take rate off like a bat out of hell topping out at 55 km an hour, very rarely does it do that for me though usually it'll get to about 40 km an hour and then start struggling to get to the 45 it's advertised to do.
suppose I could take solace in the fact that I've read threads were people have brand new Motors and they can't even get them started and they got so fed up with it that they just gave up. At least mine will start now and run I'm just not happy with how it's running and how sometimes it'll start hard then I have to mess around with the plugs and stuff.
There's got to be something that's causing this issue. If I'm going to spend money on aftermarket parts or replacement parts I want to make sure I'm buying the proper ones. So any help would be greatly appreciated. thank you all in advance guys.
Moderators Note:
I broke up that "Great Wall of China" solid wall of text to something that someone will want to read...lol.
Let me first start off by saying I am a certified small engine mechanic and very much know what it takes to make an engine tick. With that being said I am far from a professional and definitely not a professional with these China dolls. So on to my issue. I threw this bike together put everything together the way it should be wired everything up. Fired it up and she ran great still needed to be broken in obviously. Stupid me didn't think about the break-in the first time I took it out that was the first run then I realized s*** I got to break this motor in properly.
That's when I decided that I would do a few runs and let it cool off then another run, let it cool off then another run at varying throttle positions letting it cool in between. It seemed to have been breaking in perfectly fine, and I was even starting to get a little bit better in the RPM range at the top end then suddenly one day it wouldn't start. I pulled the plug, checked for fire, there was fire but the plug was wet from trying to get it started. I ended up ditching that cheap Chinese plug and putting in the NGK replacement (the br6hs, gapped to just below 0.030 of an inch so it's probably Gapped to 0.028- 0.029 of an inch), gave her another try and it fired up right away.
Ran pretty good for two days on that new plug then suddenly I started losing power on the top end and a little bit of sputtering in the mid-range, I got it home, pulled the plug, the burn rate looked pretty good so I checked the gap and set it perfectly to the above gapping that I mentioned earlier then put it back in, I adjusted the NT carburetor needle and put the clip on the second Notch down from the top, ( I'm right about at sea level here maybe slightly above it but only by a hundred or 200 ft), and I also took the air box off cuz there seem like there was a lot of fuel in the foam so I wanted to see if maybe the motor was getting flooded from the airbox or restricted from the airbox.
Well I took her onto the road it fired right up easily and then took off like a bat out of hell, faster and so much more responsive than I've ever seen this bike run. Before it was giving me a hard time just trying to get the 48 km an hour after I did that she would go to 50 km an hour easily and top out at 55 km an hour on flat ground. Smiling and grinning from ear to ear I drove her back home, shut her down and put the airbox back on. After a cool down I decided to take it out for another run, suddenly hard starting issues again, got it started but lots of power loss and back to it struggling to even get to 45 km an hour.
I've adjusted the fuel Every Which Way on that needle valve and never got any better results this time. Their is most definitely a spark with it out of the motor however I'm wondering if under compression if it's just not enough Spark because this is what I'm kind of boiling it down to is the CDI is just not putting out what it should in order to let it rev out at those RPM ranges and burn the fuel. The other thing I could be looking at is a vacuum leak but I've made sure the carburetor is well seated and I do have the O-ring. The gasket is not blown in the head, I've checked it just by looking at it with the flashlight there's not even a drop of oil around it not to mention I've had those stupid Factory Dome nuts torque down not too long ago to 12 ft lb equally so it's not a head gasket.
I'm thinking about ordering a new CDI and might as well get a better Magneto while I'm at it and I'm hoping that the issue is it's just not running a strong enough Spark. There's got to be a reason why throwing a brand new plug in there made a difference also there's got to be a reason why taking the brand new plug out after I noticed some performance issues starting to happen again, cleaning it up, regapping it and putting it back seem to make all the difference in the world. But only for a short period of time, (one run).
I do notice a little teeny bit of oil making it past the gasket on the clutch/crank side. I suppose this could be an indicator of a poor crank seal causing a vacuum leak? I do have a lot of trouble getting the idle set to idle low without it stalling (regardless if it's nice and warmed up ir not) I pretty much have to turn the screw in at least 10 turns and it's a little high idle for my liking almost as if I'm getting into the throttle at that point and bypassing the idle Jet, however I'm not sure of that. S
o I guess my question is am I on the right track and what things should I be doing from here aside from paying attention to possibly weak spark and trying to correct an issue in that area that may or may not be an issue. I am very quickly finding out, certified small engine mechanic or not, that these Chinese Motors are most definitely the finickiest Motors I've ever dealt with. Like it is very hard to get these to tune and run exactly the way they should without running into more issues. It doesn't take much of a change, or an issue to cause a major difference (loss) in performance.
Oh also just so everyone knows I'm running 32 to 1 ratio of gas oil. I got about a little over 500 km on this motor and it was running fine until the initial spark plug issue around 500 km in. I'm kind of at a loss here, this is starting to baffle me.
I really don't want to have to buy another motor if the issue lies within the cheap things that come with it to make it tick such as the cheap CDI Etc. Something I haven't checked is the plug wire connection to the CDI and to the boot. I noticed after watching a video (it wasn't the exact same CDI as mine) however it was a factory CDI (likely the 100cc CDI) but it was the style that does not require the adapter plate on the plug, but on that particular CDI he was able to unscrew the wire from both the boot and the CDI box, trimmed it a bit on both ends then screwed it back in thus ensuring there's a good connection there. I'm not sure if I can do that to my CDI or not but it is the factory CDI that comes with the 80cc motor kit. I believe this is the newer mold as well.
One thing I can notice right off the bat is that it looks like they use the old mold for the crankcase cover and a new mold for the block it lines up but it's obvious I got a spot where it doesn't line up perfectly although the bolt lines up perfectly. Looks like they were aware of this at the factory and they just threaded the bolt hole so it all matched up weather it lined up with the circular part or not if that makes any sense. I suppose I could take a picture to show you all but that is not the issue.
I guess what I'm asking is am I on the right track with looking at the CDI and Spark and stuff or should I be more concerned about a possible vacuum leak at the crank seal where I'm seeing a little bit of oil around the crankcase cover gasket at the base however that was when I was running that ridiculous 16 the one ratio since I cut that out I don't notice nearly as much oil ending up there. Any help and pointing me in the proper direction would be very much appreciated.
For my first post on this form I really wanted to be able to post about how much I love my bike and how fast it's running and how perfectly it's running but surprise here I am making my first post about what the heck is wrong with my motor or whatever is wrong with what makes that motor tick. Could it be that is still breaking in it just hasn't got to the point where she can top out like it should? sometimes it will and sometimes it won't most times it won't. If its started and idling with the clutch disengaged she will rev right up but under load she struggles at the higher RPM range and that's assuming the starting issues are eliminated.
And generally I do have the starting issues eliminated I'm more having problems with wide open throttle. I want this bike to do what it's supposed and run the way it's supposed to. Another thing I noticed is that when it's not topping out like it should overall it is not nearly as responsive neither. I can feel it sometimes too trying to kick in at that higher RPM range and hit that power band and then it'll back off and then sometimes it'll kick in and hit at the higher RPM range and take rate off like a bat out of hell topping out at 55 km an hour, very rarely does it do that for me though usually it'll get to about 40 km an hour and then start struggling to get to the 45 it's advertised to do.
suppose I could take solace in the fact that I've read threads were people have brand new Motors and they can't even get them started and they got so fed up with it that they just gave up. At least mine will start now and run I'm just not happy with how it's running and how sometimes it'll start hard then I have to mess around with the plugs and stuff.
There's got to be something that's causing this issue. If I'm going to spend money on aftermarket parts or replacement parts I want to make sure I'm buying the proper ones. So any help would be greatly appreciated. thank you all in advance guys.
Moderators Note:
I broke up that "Great Wall of China" solid wall of text to something that someone will want to read...lol.
so forgive me if I ask questions that have already been answered, just ask 
