HALP! please help a noob figure out why his bike is running like crap!

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cserpico

New Member
Jan 2, 2015
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illinois
So I built my first bike a few weeks ago. It is one of those cheap 80cc chinese two stroke kits that I put on my mountain bike.
The build was smooth with no real problems and this thing is so fun to ride but it is really hard to start. Part of that might be the cold weather but I can not start it at all without spraying some ether into the air filter and on really cold days that doesn't always help. When it does start its not easy. I built this bike to be my only form of transportation and it sucks that I can only get it started sometimes and its so much effort. I have to start it with the choke closed and once it runs a few blocks I open up the choke and it runs great and is pretty fast but I can not get it to idle at all. It dies every time I stop but after it has been running, even if just for a minute it starts right back up so this isn't a huge problem, I don't mind peddling after stopping to get it going again. I messing with the idle screw a little but haven't been able to fix that problem. I am not very mechanically inclined and I know jack about 2 stroke engines.
Any tips on how I can get this to start up easier? how to get it to idle would be a plus but that's not a huge deal. It just sucks that I can never take it anywhere because if I have to carry a can of starter fluid with me and if the engine gets cold I might be stranded.
 
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Animatronicus

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Dec 13, 2014
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Fresno
I feel your pain! These engines can be pretty puzzling. You need fuel, air and spark to make it go. It could be something simple. You said it always dies when you stop, so when you stop keep the engine running with the throttle and adjust the idle screw. If its not idling then it might not be getting enough fuel? Or too much? I would find what the stock setting on your idle screw is supposed to be. Also make sure your fuel line is clear. Your magneto could be shoddy? or a bad connection so go through your wiring. What else can there be? Anyone else?
 
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cserpico

New Member
Jan 2, 2015
29
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illinois
Animatronicus said:
I feel your pain! These engines can be pretty puzzling. You need fuel, air and spark to make it go. It could be something simple. You said it always dies when you stop, so when you stop keep the engine running with the throttle and adjust the idle screw. If its not idling then it might not be getting enough fuel? Or too much? I would find what the stock setting on your idle screw is supposed to be. Also make sure your fuel line is clear. Your magneto could be shoddy? or a bad connection so go through your wiring. What else can there be? Anyone else?
Click to expand...
Thank you for the response. It is a cheap china kit so I doubt I could find any instructions in English which sucks because I would like to know the stock setting for the idle screw. Also, off topic but I am totally new to motorized bikes and I am hearing a lot of disturbing things about these china kits. I had planned on gradually customizing this thing into something really respectable. Do you think there is any point? Like, is there a good chance this thing will last?
 
Ronzworld

Ronzworld

Member
Feb 21, 2014
118
1
18
Regina,Saskatchewan
well ... I'm just trying ta figure where I should even start with this ... first thing I will say is that the idle screw has no 'stock' setting ... start it and keep it running with your throttle and turn the idle screw in until you don't have to use the throttle to keep it running .. then continue to adjust until you like the speed at which it is idling ... don't be afraid to turn the screw in .. crank it til it idles ...if you turn it all the way in and it still won't idle then you have other problems .. like possibly an air leak which could also be your starting trouble .. but lets not get all off on a list of could be's until we know if it will idle ... I would guess that the fact that it won't idle could be making it harder ta start for the simple fact that when you are pedaling away trying to get it started it will only do so once you have the throttle held in just the right spot (as there is no 'throttle off' spot where it will keep running so it won't start in that position for sure either) ... So get a screw driver ready and get it started and then crank in the idle screw ... once you get this far come back and post your results and we will go from there ....
 
Ronzworld

Ronzworld

Member
Feb 21, 2014
118
1
18
Regina,Saskatchewan
oh yeah ... I don't think starting fluid is a very good idea ... how cold is it there and how long does it sit out in that weather ? I ride all year up in Canada ... some days past -40 ..although you can't expect them to start past -20ish w/out being indoors or at least warmed up first .. I use a propane tourch sometimes ta warm mine if it's been outside past -20 for anything more then about an hour ... but don't use anymore ether ... esspecially if you have any hope of making it last ... and don't be so quike ta knock these little motors ... for what they're worth , once properly set up , they actually do what they were intended ta do quite well ... if they didn't work at least 'kind of good' I doubt that half the country would be riding them ...
 
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cserpico

New Member
Jan 2, 2015
29
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illinois
That makes sense, I live in Illinois so it gets pretty damn code. I think I am going to buy a cheap heat gun to warm up the block before trying to start it when its really cold. I will report back and let you guys know what happens.
 
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fatdaddy

fatdaddy

New Member
May 4, 2011
1,516
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San Jose, Ca.
Animatronicus said:
I feel your pain! These engines can be pretty puzzling. You need fuel, air and spark to make it go. It could be something simple. You said it always dies when you stop, so when you stop keep the engine running with the throttle and adjust the idle screw. If its not idling then it might not be getting enough fuel? Or too much? I would find what the stock setting on your idle screw is supposed to be. Also make sure your fuel line is clear. Your magneto could be shoddy? or a bad connection so go through your wiring. What else can there be? Anyone else?
Click to expand...
there is no "Stock setting" on the idle screw. All these engines run a little different from the last one ya bought. Just turn in the screw (or turn out) Till it idles where ya want it.
I've got brand new engines with bad coils.A weak coil will make it REAL hard to start.But First I would go simple, Start with a good NGK plug (I use NGK B6HS) and a better auto grade plug wire. Copper core is best and expensive, Any good plug wire is better than that Chinese crap. Coils are $10 or $12 and may solve yer problem. A bad CDI is rare, but it happens, Usually a bad CDI and it wont start AT ALL.
WIRING: blue to blue, black to black. DON'T hook up kill switch yet. Make sure no bare wires touch ANYTHING. PROLLY NOT yer wiring though. Sounds like a bad Coil. BUT I've also got bad kill switches, They can short JUST ENOUGH to make it hard or impossible to start.
everyone calls the COIL a magneto. The magneto is just a spinning magnet, The COIL is what goes bad.
 
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2door

2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
All good advice so far but I need to ask because this isn't uncommon with a new builder;
You are disengaging the clutch when you come to a stop, aren't you? Some folks unfamilar with standard transmissions and clutches expect the engine to idle like a car with an automatic trans. You'll have to squeeze the clutch lever below about 10 MPH.

You didn't say what carburetor you have but the idle speed screw on most of them is not a mixture control but simply a mechanical block that keeps the throttle from closing completely when you screw it inward (clockwise). The more you screw in the faster the idle speed because the throttle is being lifted or opened slightly.

Let us know what you find. Also air leaks were mentioned. Again not uncommon but typically an air (vacuum) leak will cause a fast idle, not a slow or no idle.

Tom
 
fatdaddy

fatdaddy

New Member
May 4, 2011
1,516
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San Jose, Ca.
AGAIN, listen to 2door. Air leaks will NOT make it hard to start. It will affect idle and top end performance. WHEN you get it running close to right, there is a very simple way to check for carb seal air leaks. It involves water and a mustard squeeze bottle. Or catsup bottle. My ole lady cought me squeezing out the last of the almost empty catsup bottle down the sink and thought I was nutz. WHAT THE HEck ARE YOU DOIN? She sayz. I tried to explain,She still thought I was nutz. Hey baby, I need it to check my carb. She didn't care about my carb, which I thought was totally unreasonable. I guess we have different ideas about WHAT'S important.
fatdaddy.usflg
 
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cserpico

New Member
Jan 2, 2015
29
0
0
illinois
2door said:
All good advice so far but I need to ask because this isn't uncommon with a new builder;
You are disengaging the clutch when you come to a stop, aren't you? Some folks unfamilar with standard transmissions and clutches expect the engine to idle like a car with an automatic trans. You'll have to squeeze the clutch lever below about 10 MPH.

You didn't say what carburetor you have but the idle speed screw on most of them is not a mixture control but simply a mechanical block that keeps the throttle from closing completely when you screw it inward (clockwise). The more you screw in the faster the idle speed because the throttle is being lifted or opened slightly.

Let us know what you find. Also air leaks were mentioned. Again not uncommon but typically an air (vacuum) leak will cause a fast idle, not a slow or no idle.

Tom
Click to expand...
Wow, I had no idea about squeezing the clutch at low speeds. Now I feel like a jackass. I will see if that makes a difference. Thank you! The carb is just the standard carb that came with my cheap kit. That's all I know about it.
I am totally ignorant about small engines but I intend to learn them like the back of my hand which is why I joined this group. I see lots of friendly knowledgeable people so I am sure I can be a pro eventually.
 
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cserpico

New Member
Jan 2, 2015
29
0
0
illinois
fatdaddy said:
AGAIN, listen to 2door. Air leaks will NOT make it hard to start. It will affect idle and top end performance. WHEN you get it running close to right, there is a very simple way to check for carb seal air leaks. It involves water and a mustard squeeze bottle. Or catsup bottle. My ole lady cought me squeezing out the last of the almost empty catsup bottle down the sink and thought I was nutz. WHAT THE HEck ARE YOU DOIN? She sayz. I tried to explain,She still thought I was nutz. Hey baby, I need it to check my carb. She didn't care about my carb, which I thought was totally unreasonable. I guess we have different ideas about WHAT'S important.
fatdaddy.usflg
Click to expand...
That made me legitimately laugh out loud haha!
 
S

Slogger

Member
Sep 8, 2014
544
4
18
nohio
I vote for the better spark wire and NGK plug. The new wire should be installed carefully, making sure its center is centered on the spike when you begin to twist it in.
Also make sure you are getting the cylindrical clip inside the boot snapped down on the spark plug right. I had trouble starting sometimes, I was doing plug checks and not putting the clip back on right sometimes. Those times it was really hard to start and idled rough.
These engines are simple to keep running. You only need real tools and skills if you go to take it all apart, which isn't really necessary. Watch for air leaks, keep it out of the rain and tighten your bolts and you should go far on the china doll.

Feel free to run that idle screw in, keep the slide lifted with the throttle as you do it so it doesn't get jammed into the slide. Good luck!
 
fatdaddy

fatdaddy

New Member
May 4, 2011
1,516
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San Jose, Ca.
cserpico said:
That made me legitimately laugh out loud haha!
Click to expand...
you shoulda seen her spin out when she walked in and I had a motor tore apart on her coffee table, HEY,my show was on and I don't have a T.V. in the shop. again, no understanding whatsoever. Whatcha gonna do? so now every once in a while when walking past she just mumbles, (F'n A-hole) to me and keeps walking. (I mean c'mon,only ONE little scratch on the table babe.) like I said, NO understanding.
fatdaddy.
 
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cserpico

New Member
Jan 2, 2015
29
0
0
illinois
Slogger said:
I vote for the better spark wire and NGK plug. The new wire should be installed carefully, making sure its center is centered on the spike when you begin to twist it in.
Also make sure you are getting the cylindrical clip inside the boot snapped down on the spark plug right. I had trouble starting sometimes, I was doing plug checks and not putting the clip back on right sometimes. Those times it was really hard to start and idled rough.
These engines are simple to keep running. You only need real tools and skills if you go to take it all apart, which isn't really necessary. Watch for air leaks, keep it out of the rain and tighten your bolts and you should go far on the china doll.

Feel free to run that idle screw in, keep the slide lifted with the throttle as you do it so it doesn't get jammed into the slide. Good luck!
Click to expand...
Yeah, I do plan to put on a better spark wire. Heard that the ones that come with the kits suck. Already added a good plug. Hopefully the new wire will help some.
 
C

cserpico

New Member
Jan 2, 2015
29
0
0
illinois
fatdaddy said:
you shoulda seen her spin out when she walked in and I had a motor tore apart on her coffee table, HEY,my show was on and I don't have a T.V. in the shop. again, no understanding whatsoever. Whatcha gonna do? so now every once in a while when walking past she just mumbles, (F'n A-hole) to me and keeps walking. (I mean c'mon,only ONE little scratch on the table babe.) like I said, NO understanding.
fatdaddy.
Click to expand...
lol I do some gunsmithing on the side and anything that doesn't require a bench or a vice gets done on my kitchen table where its nice and toasty and my old lady hates that too. I always clean up after myself but she seems to think we will all get poisoned by gun solvents or something haha
 
A

Aussie Mad Dog

New Member
Jan 1, 2015
13
0
0
Tynong North, Victoria, Australia...
fatdaddy said:
there is no "Stock setting" on the idle screw. All these engines run a little different from the last one ya bought. Just turn in the screw (or turn out) Till it idles where ya want it.
I've got brand new engines with bad coils.A weak coil will make it REAL hard to start.But First I would go simple, Start with a good NGK plug (I use NGK B6HS) and a better auto grade plug wire. Copper core is best and expensive, Any good plug wire is better than that Chinese crap. Coils are $10 or $12 and may solve yer problem. A bad CDI is rare, but it happens, Usually a bad CDI and it wont start AT ALL.
WIRING: blue to blue, black to black. DON'T hook up kill switch yet. Make sure no bare wires touch ANYTHING. PROLLY NOT yer wiring though. Sounds like a bad Coil. BUT I've also got bad kill switches, They can short JUST ENOUGH to make it hard or impossible to start.
everyone calls the COIL a magneto. The magneto is just a spinning magnet, The COIL is what goes bad.
Click to expand...


One of my bikes was screaming along well (A80 off eBay) with no issue... But one thing led to another and it started dying... Would sort of run while moving but got dead at low revs and finally gave up the ghost...

The inlet manifold flange had broken and was leaking air big time...

Wound up switching it to another bike - and it wouldn't start at all...

I used the same CDI unit - I swapped out the magneto with a 9000v one from Screaming Roo here in Oz - still no go...

Swapped out the CDI unit with again another SR one - runs like a demon...

The key words here are "Cheap" & "Not Working"... Use better electrics in these bikes and I reckon everything else will keep working as it should...

drn2
 
C

cserpico

New Member
Jan 2, 2015
29
0
0
illinois
Aussie Mad Dog said:
One of my bikes was screaming along well (A80 off eBay) with no issue... But one thing led to another and it started dying... Would sort of run while moving but got dead at low revs and finally gave up the ghost...

The inlet manifold flange had broken and was leaking air big time...

Wound up switching it to another bike - and it wouldn't start at all...

I used the same CDI unit - I swapped out the magneto with a 9000v one from Screaming Roo here in Oz - still no go...

Swapped out the CDI unit with again another SR one - runs like a demon...

The key words here are "Cheap" & "Not Working"... Use better electrics in these bikes and I reckon everything else will keep working as it should...

drn2
Click to expand...
Based on everything I have read and heard I think a new spark cable might do wonders so that will be my next step. I am actually about to go for a late night ride now though while there is no traffic and try adjusting the carb along the way.
Thinking about going through a state park that is not far from me.
 
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Aussie Mad Dog

New Member
Jan 1, 2015
13
0
0
Tynong North, Victoria, Australia...
cserpico said:
Based on everything I have read and heard I think a new spark cable might do wonders so that will be my next step. I am actually about to go for a late night ride now though while there is no traffic and try adjusting the carb along the way.
Thinking about going through a state park that is not far from me.
Click to expand...
Just a thought for ya... If you are running a power wire from the actual magneto (the white wire on most eBay A80 conversion kits) then stop doing that cause you are draining way too much power from it...

Just use other types of lights...

drn2
 
C

cserpico

New Member
Jan 2, 2015
29
0
0
illinois
Aussie Mad Dog said:
Just a thought for ya... If you are running a power wire from the actual magneto (the white wire on most eBay A80 conversion kits) then stop doing that cause you are draining way too much power from it...

Just use other types of lights...

drn2
Click to expand...
I don't have any lights on it at the moment but that is good to know for future reference!
 
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