My ch 80 starts right up idles great but when I am crusing at top speed it feels like the engine is loosing power. if I let off the throttle and wait a sec and try again power comes right back. My question is do I need to make an adjustment to the needle and which way do I need to move it. I am running 20 to 1 fuel and have just got done with the break in period. tyhank you all.
Carb problem?
- Thread starter Neko
- Start date
I think the true test for the breakin/debugging is when you get back on your ride and it performs the sames as it did the day before-are you somewhat there yet?
what I've learned by experience with my new ride and mostly from all the knowledgeable folks here is that the beauty of the ch2s (china 2 strokeI) is it's simplicity. it all pretty much boils down to air, fuel, lubrication and exhaust.
I assume you have put a dremel to the exhaust flange to match the exhaust port (noticeable improvement in smoothness)
It may be time to go to 25-30:1 mix before you think of moving the needle (I've read about micro adjusting the needle with washer/shims to adjust between the notches)
plug diagnotics?: at top speed you might be 4 cycling until mix returns to optimal. is the insulator dark tan etc.
at top speed you may just not be getting enough air to meet the fuel stoicometric ratio 14.7/1 or so. check the air filter for oil.
what plug are you using? NGK here.
you know your engine best in your set up. but everything is somewhat interrelated. It's a great place to practice deductive reasoning no?
I'm learning along with you and I my trust in the engine is improving as it's performance becomes more consistent. I think the warm up is crucial and gradual "throttle up" in the beginning.
what I've learned by experience with my new ride and mostly from all the knowledgeable folks here is that the beauty of the ch2s (china 2 strokeI) is it's simplicity. it all pretty much boils down to air, fuel, lubrication and exhaust.
I assume you have put a dremel to the exhaust flange to match the exhaust port (noticeable improvement in smoothness)
It may be time to go to 25-30:1 mix before you think of moving the needle (I've read about micro adjusting the needle with washer/shims to adjust between the notches)
plug diagnotics?: at top speed you might be 4 cycling until mix returns to optimal. is the insulator dark tan etc.
at top speed you may just not be getting enough air to meet the fuel stoicometric ratio 14.7/1 or so. check the air filter for oil.
what plug are you using? NGK here.
you know your engine best in your set up. but everything is somewhat interrelated. It's a great place to practice deductive reasoning no?
I'm learning along with you and I my trust in the engine is improving as it's performance becomes more consistent. I think the warm up is crucial and gradual "throttle up" in the beginning.
the plud is a Ngk and the color is dark tan with black oil on the threads but that could be from the eariler running. the filter is clean now. ( just pulled and washed. could see threw it though)
as for the fuel I was fine the last tank with no noticed difference. It is for sure starved of something on the top end. I should be getting fuel due to the fact that the line is full. But could there be a clog in the bowl or needle?
that would just hurt the top end?
I was fine it ran the same for weeks then I had to redo the moter mounts and know I an noticeing this phenononom. I am at a loss.
thanks for all your help. I am sure it will work itself out. Just don't want to mess anything up.
as for the fuel I was fine the last tank with no noticed difference. It is for sure starved of something on the top end. I should be getting fuel due to the fact that the line is full. But could there be a clog in the bowl or needle?
that would just hurt the top end?
I was fine it ran the same for weeks then I had to redo the moter mounts and know I an noticeing this phenononom. I am at a loss.
thanks for all your help. I am sure it will work itself out. Just don't want to mess anything up.
I had a similar problem on mine. Turns out my motor mounts were loose, and the increased vibration shook up the carb so much that the carb bowl wasn't filling with enough fuel. Took me couple weeks to figure that one out.
Try tightening your mounts, and if that doesn't fix it, check that your carb is filling properly.
Try tightening your mounts, and if that doesn't fix it, check that your carb is filling properly.
thank you. I had just remounted the moter and was thinking I had done a better job. I am rethinking my attack and will give it another try sunday. I will repost what happens.
Hi Neko,
Long time motorcycle owner, first time china bike owner (just bought one, haven't built it yet) but for what it's worth, I can throw some food for thought your way.
Did the problem start right after switching to the new oil mixture ratio?
A mixture that yields a the dark tan color is what you want I would think. If it was starving for fuel, I think it would be more light tan to white. (After it's well broken in, light tan is ok.)
Plus, in my experience with motorcycles, when a 2 stroke starves, as when it runs out of gas, it will tend to lean out and run about 20% more powerful and rev high for a bit as opposed to losing power. (Same thing if you have an intake leak)
So, if it seems to be losing power until you back off and re-throttle, I might suspect that it's loading up instead of leaning out. (has anyone else found this to be the case, does it seem plausible?)
-Maybe the new oil ratio is the culprit. Revert to the mixture that didn't cause it for a while longer.
-Replace spark plug (simple and cheap...will rule that out before we get into it further)
-Maybe the carb mixture screw can be turned 1/8 th of a turn in, these tend to vibrate out sometimes. (However, looking at mine, this may only have an idle mixture screw so this tip may not apply to this carb, but you could try it easily enough)
-Or maybe the engine is running more efficiently and needs to be leaned out a touch (move clip up one notch to keep needle in jet longer).
Let me know if this makes sense to you (or anyone else- chime in please!)
If you still suspect fuel starvation, I have posted some more suggestions below:
I have heard that the intake gaskets are notorious for failing. Try spraying starting fluid at the suspected areas (mating flange and carb mount) and see if it changes the idle.
Next, Make sure your gas is clean and water free. (Dump out fuel bowl onto a paper towel, check for water, rust etc.) If the problem started after a tank was refilled, maybe some water was in the gas tank you filled it with. Also, sometimes these tanks are manufactured and sent out with major rust and junk in them. If some is found, pull the petcock out of the fuel tank, you should be able to clean the screen and tell if a lot of crap was in there.
If none is found, and everything is clean and flowing to the carb, I can give you some suggestions in the order of easiest to hardest and considering what it's like likeliest to be:
1) I suppose it could be possible (however unlikely but simple to check) that the vent/overflow port is clogged. I'm not familiar with this carb but I've seen some that were just a tiny weep hole that would get plugged eventually and need to be unclugged with a stiff wire. Looking at mine, it has a capped off vent, make sure its not plugged. (must allow air out for gas to go in)
2) Next, I would take it off and blow out the main jet with compressed air. Usually when they starve in the higher revs, it's due to the main jet clogging.
3) If that doesn't cure it, you could try moving the clip on the needle to see if it gets better. If worse, try it the other way. If not better, put it back. Not likely to be the problem since it ran correctly before but easy to do.
4) Less likely but possible, consider that the fuel float may be rubbing against the side of the bowl, causing it to hang up, or it could need to be adjusted to allow more fuel to flow in.
http://motorbicycling.com/f4/carburetor-pictures-how-install-rebuild-195.html
Good luck, let us know how it goes. It would be nice to know what eventually fixed it for you so the rest of us can shortcut to the cure.
-Scott
Long time motorcycle owner, first time china bike owner (just bought one, haven't built it yet) but for what it's worth, I can throw some food for thought your way.
Did the problem start right after switching to the new oil mixture ratio?
A mixture that yields a the dark tan color is what you want I would think. If it was starving for fuel, I think it would be more light tan to white. (After it's well broken in, light tan is ok.)
Plus, in my experience with motorcycles, when a 2 stroke starves, as when it runs out of gas, it will tend to lean out and run about 20% more powerful and rev high for a bit as opposed to losing power. (Same thing if you have an intake leak)
So, if it seems to be losing power until you back off and re-throttle, I might suspect that it's loading up instead of leaning out. (has anyone else found this to be the case, does it seem plausible?)
-Maybe the new oil ratio is the culprit. Revert to the mixture that didn't cause it for a while longer.
-Replace spark plug (simple and cheap...will rule that out before we get into it further)
-Maybe the carb mixture screw can be turned 1/8 th of a turn in, these tend to vibrate out sometimes. (However, looking at mine, this may only have an idle mixture screw so this tip may not apply to this carb, but you could try it easily enough)
-Or maybe the engine is running more efficiently and needs to be leaned out a touch (move clip up one notch to keep needle in jet longer).
Let me know if this makes sense to you (or anyone else- chime in please!)
If you still suspect fuel starvation, I have posted some more suggestions below:
I have heard that the intake gaskets are notorious for failing. Try spraying starting fluid at the suspected areas (mating flange and carb mount) and see if it changes the idle.
Next, Make sure your gas is clean and water free. (Dump out fuel bowl onto a paper towel, check for water, rust etc.) If the problem started after a tank was refilled, maybe some water was in the gas tank you filled it with. Also, sometimes these tanks are manufactured and sent out with major rust and junk in them. If some is found, pull the petcock out of the fuel tank, you should be able to clean the screen and tell if a lot of crap was in there.
If none is found, and everything is clean and flowing to the carb, I can give you some suggestions in the order of easiest to hardest and considering what it's like likeliest to be:
1) I suppose it could be possible (however unlikely but simple to check) that the vent/overflow port is clogged. I'm not familiar with this carb but I've seen some that were just a tiny weep hole that would get plugged eventually and need to be unclugged with a stiff wire. Looking at mine, it has a capped off vent, make sure its not plugged. (must allow air out for gas to go in)
2) Next, I would take it off and blow out the main jet with compressed air. Usually when they starve in the higher revs, it's due to the main jet clogging.
3) If that doesn't cure it, you could try moving the clip on the needle to see if it gets better. If worse, try it the other way. If not better, put it back. Not likely to be the problem since it ran correctly before but easy to do.
4) Less likely but possible, consider that the fuel float may be rubbing against the side of the bowl, causing it to hang up, or it could need to be adjusted to allow more fuel to flow in.
http://motorbicycling.com/f4/carburetor-pictures-how-install-rebuild-195.html
Good luck, let us know how it goes. It would be nice to know what eventually fixed it for you so the rest of us can shortcut to the cure.
-Scott
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A few of my bikes had this problem; it seems to be from vibration.
Some from the carb, others from the spark plug boot!
Some from the carb, others from the spark plug boot!
great help I had just remounted the moter and that could be the problem. although you can't move the motor at all. Still going to take it off and try again. although it seemed to have less vibration now than it did before. The spark plug boot did fall apart when I got to work after noticing it for the first time. Waiting on some of the good wire from norman to see if that helps. Could the cheap spark plug wire that comes with these chinia girl motors be the culprit?
I found that the the bowl on the carb was a little slow to fill up when at full speed so drilled the out the hole on fuel inlet very slightly bigger and no longer have the problem. This is an easier solution than adjusting float just be careful like everything to do it in small steps!!!. I am interested in the needle adjustment does moving the washer to the needle point make it leaner on take off or richer? ect
"C" clip on top is the leanest setting, bottom is the richest. Start at the second from the top and go from there.
I have gotten it remounted and a new chain on it. Rode to work and performed great. thanks for all the help.
I had a problem like this the choke was opening and close from the vibration. caused loss of power. had to wire down .
take off the aircleaner cover there is a small nut on the choke that you can snug up a little to stop the choke from moving from the vibs.
Yes sir, that is correct.
Also surging can be caused by the gas not getting to the carb fast enough to keep up with demand.
The stock petcock has notoriously slow fuel flow.
when running in the engine you will experience loss of power due to the increse in friction at high engine loads due to the increase in engine tempreature best to keep the speeds low during run in period after run in if the engine is still lacking power at speed try increasing the needle in the carb this will richen the mixture
