Flat out or nothing?
- Thread starter brett7777
- Start date
When you are pulling the clutch in a little bit you are letting it slip slightly.... Doing this you can get the bike to roll on its own from a stop (no pedaling) but it is not something you really want to do. The gearing on the motor is not setup to have the low speed pull to get you going from a stop, so you have to burn up the clutch while rev'ing the engine to do so, which is not good to do. You should pedal to get rolling and then ease out the clutch all the way to ride. I think you have this part figured out by now....
Similarly, when your motor is running rough and your ride is jerky, pulling in the clutch a bit will let it slip ever so slightly and will smooth out the ride, but this is not proper either. Keep in mind, the motors sprocket is chained directly to your wheel, if the motor is not turning smoothly the ride is gonna be rough! These motors tend to smooth out at around 15-20MPH even when not tuned up that great, but tend to run rough at slower RPMs if the tuning is a bit off...
Now, when you are talking about tuning a 2-stroke there are LOTS of variables.... Fuel mix, dampering factors of the intake (air filter) and expansion chamber (exhaust), carburetor adjustment, even environmental variables such as sea level, barometric pressure, temperature, you name it! LOL I don't mean to make it sound overwhelming, but I don't want to gloss over important variables either...
So back to your bike... I am sure you listen to it run when you ride, you can get a lot from listening... I assume it sounds pretty smooth when riding about 20MPH, does it sound the same when running slow, or does it sound like it is running rougher? I am asking this because you could have other mechanical issues not related to the how the motor is running that make your ride rough at slow speeds, like chain alignment or chain tensioner issues etc. If the motor sounds like it is running rough when the ride is rough, getting pops instead of the purr, then you probably need to tune it up a bit before it will run smoothly....
Most builds require the carb to be a bit off level, if yours is right on that is great, you probably don't need to do any float adjustment...
On a single jet carb the only internal adjustment you have (besides the float) is the needle setting and jet size. It is entirely possible that your jet is not ideally sized on a brand new kit depending on the size of the motor, what carb etc. I have read some people with 48cc motors say they need to lean their jets a bit, I had to richen mine on my 66cc (CNS carb).....
Before you start thinking about jetting your carb you should break in your motor completely and get off the breakin fuel on to a regular mix, then you need to identify the condition your engine is running with in your problem range (lean or rich) and make proper adjustments from there.....
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If you haven't already, take out your spark plug and take a look at it. Compare it to the chart in this link....
Spark Plugs
This should help you identify what condition your bike is running with. Now, if your bike runs well at WOT (Wide Open Throttle) and so you ride at WOT mostly, when you pull the plug it might look proper. However, when running roughly at mid throttle it may be lean or rich, but your plug doesn't reflect this cause you ride WOT all the time to avoid the roughness.
To check out what is going on in the rough throttle range do a plug chop. Warm up the bike and ride it in the rough range a while, then simultaneously pull the clutch, let loose of the throttle and hold the kill switch. Pull the plug and match it to the chart to see whether you need to richen or lean up your mixture in that throttle range then change the e-clip on the needle to make the adjustment (for mid throttle range). (ALWAYS let the motor cool before you remove the spark plug!) Moving the e-clip toward the pointed end of the needle will pull the needle out of the jet a bit, allowing more fuel to flow, thus richening the mix (more gas per air). Moving the e-clip away from the pointed end lets it go further into the jet, lets less fuel flow, and therefore leans up the mixture.
Spark Plugs
This should help you identify what condition your bike is running with. Now, if your bike runs well at WOT (Wide Open Throttle) and so you ride at WOT mostly, when you pull the plug it might look proper. However, when running roughly at mid throttle it may be lean or rich, but your plug doesn't reflect this cause you ride WOT all the time to avoid the roughness.
To check out what is going on in the rough throttle range do a plug chop. Warm up the bike and ride it in the rough range a while, then simultaneously pull the clutch, let loose of the throttle and hold the kill switch. Pull the plug and match it to the chart to see whether you need to richen or lean up your mixture in that throttle range then change the e-clip on the needle to make the adjustment (for mid throttle range). (ALWAYS let the motor cool before you remove the spark plug!) Moving the e-clip toward the pointed end of the needle will pull the needle out of the jet a bit, allowing more fuel to flow, thus richening the mix (more gas per air). Moving the e-clip away from the pointed end lets it go further into the jet, lets less fuel flow, and therefore leans up the mixture.
Is this e clip inside the carb where the jet is? take carb off & remove float bowl to get to it? thanks for all the advice, very helpful, knew nothing about these when I bought it
& yeah i thought about chain tension / alignment; as far as I can I see all that is ok. the motor also doesnt seem to be popping or anything. that's why i find it a bit of a mystery. I just dont want to have ride flat out everywhere - half throttle would be good sometimes !!!
The e-clip is on the needle, the needle is in the slide (the barrel thing that is on the end of the throttle cable). To get at it you have to pull the top part off the carb where the cable goes in, then the whole deal pulls out. My carb is different than yours, I have two screws, I think you have a cap that screws on the carb with the throttle cable coming out of it? That is what you need to unscrew to get at the needle... I seem to recall a youtube video that showed the whole deal for your carb, so try searching youtube... Or you can also refer to the destructions.......
Thanks NC, the vendor got back to me & gave the same advice, they say the carb is often set up too rich from the factory & thus can affect mid range running, has said for me to adjust the needle to a leaner setting.
Thanks again for the help.
Thanks again for the help.
The needle clip was already at the 2nd to lowest notch, but I took it to the lowest notch (closest to the wide end of the needle) & it just revs out immediately to the highest revs possible, turning the idle screw doesnt help, just had to hit the kill switch before I blew the motor from the screaming revs. plus the throttle cable, which was already too long, is now so long that the cable sheathing wont even sit unside it's sleeve at the throttle end anymore. The only alternative would be to adjust the clip so that the motor runs richer, which I think is what was causing the shuddering problem. So Im a bit stuck here.
Maybe the groove Ive used is the '4th groove' which is not even meant to be used? So that means the motor was already set lean. What other choices do I have to get it running right?
Maybe the groove Ive used is the '4th groove' which is not even meant to be used? So that means the motor was already set lean. What other choices do I have to get it running right?
I was being a dummy, I realized I didnt have the slide in properly & reinstalled. I didnt have the cable in the slotted washer.
Hey I think there's an improvement (this is in the '4th notch', the diagram says there are 3, but it was already in the 3rd to I took it to the 4th) (closest to the fat end of the needle)
There is still some shuddering tho, but not as much as before. I guess this is about as good as it gets for this motor? is there a leaner jet available or anything? do these NT carbs just have one jet in them?
Hey I think there's an improvement (this is in the '4th notch', the diagram says there are 3, but it was already in the 3rd to I took it to the 4th) (closest to the fat end of the needle)
There is still some shuddering tho, but not as much as before. I guess this is about as good as it gets for this motor? is there a leaner jet available or anything? do these NT carbs just have one jet in them?
oh ok will a #68 be a bit leaner? where would I get one of those? (need somewhere with Int'l shipping)
btw is the jet accessible after taking off the float bowl, is that correct? does it just unscrew out?
I found that it doesnt shudder as much with the leanest needle setting, especially after a few minutes when it's warmed up more. There is still quite a noticeable shudder though in the earlier part of the acceleration process. I guess the part when you're moving from pedalling speed to using the motor. Maybe about 5 to 10 miles per hour?
The problem with this is that it does things like shaking the metal shims outta my motor mounts! Ive now RTV siliconed these shims in so they stay put.
This is what the vendor said about jets:
"I’ve just had a look up and we can get jets in increments of 0.25mm. A 68 means 0.68mm. so we can get 0.65mm, 0.675mm 0.70mm"
Would the 68 be the 0.675? Is this likely to make much difference?
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These are peddle assist motors! I Mean you have to peddle 10 miles an hour just to turn the motor on.. In better words you are first gear..After 10 the motor can represent second gear.
#64 jet just fixed my shuddering problem..screams now
Oh..hadto grind part of the threaded part away to get it to "seat" properly
Thanks. maybe I should just order the 3 jets. or just the 65? what cc is yours, & which carb?
#64 jet just fixed my shuddering problem..screams now
Oh..hadto grind part of the threaded part away to get it to "seat" properly
the jets were like 3 bucks each..it's a 66cc (thats top secret) "49cc officer"...
I'm at sea level (ok 10 ft above) and the #64 changed the whole feel of the bike...less vibration..snappy...etc..
nt carb...second slot from top....idles like....forever....
Has anyone found theirs runs better by adjusting the needle to a richer setting? Like the 1st or 2nd nearest groove to the needle pointed end?
I did a test ride today, it doesnt shudder so much at lower speeds but it is much slower at full throttle...
I did a test ride today, it doesnt shudder so much at lower speeds but it is much slower at full throttle...