66 cc carb problem need help.

skyhawkcannondale

skyhawkcannondale

New Member
:-||I have a 66 cc motor and the carbs poors gas out of the air breather part when it runs and it's not running right at all but when i had my buddys speed carb on her she would fly man,, so what the heck is my problem with my carb??????????? Also when it warms up and when you pull the clutch in it will high rev like a mother until you kill the motor also.weird right? need help with that also.it almost looks like the gas is being blown out of the carb when running.
 
if it's pouring out, check the float, make sure it's not full of gas. if it is, you need a new one. it should be air-tight (or fuel-tight) otherwise it won't "float."

one reason for a really high idle is the throttle cable is too tight or binding.
 
i dont think the carb slide is binding, i think its sucking air from some were.case seal or something,it starts easy and revs pretty good but soon as it starts warming up .it starts to high rev like a an air leak.but i might be wrong we put my speed carb on it it ran better but it still over revved with the clutch in,anyone chime in to help a buddy out
 
if you tried both carbs and had the same problem, i'd look for an airleak at the manifold to motor seal. spray some carb cleaner around it and if it sputters, you've got a leak and need a new gasket, and maybe try sanding the manifold surface with a piece of sandpaper taped to a glass surface to get it smooth.
 
Hi Been Tryin... Bairdco is absolutely right that the leaking problem is indicative of either a hole in the float or a metering valve not properly seating allowing excess fuel to be dumped through the throat of the carb. He is also correct that the high idle is indicative of an air leak causing a lean condition. It sounds that you are utilizing the NT card rather than the CNS1 or CNS2 version of the racing carbs.

My personal view is that it is unsafe to use spray carb cleaner or WD 40 to find leaks in 2 cycle engines because both are flammable and if not properly used especially by those who are not well versed in where and how to test it can result in serious injury.

First things first you said your bike ran well with a "racing Carb" right? The thing to consider here is the the CNS1 and 2 carbs both have an internal seal in the throat of the carb that decrease the chance of air leaks where the NT carb doesn't have any seal at all.

I would suggest to try some RTV silicone around the throat of the carb and along the clamp slot to minimize any air leaks first. If you do feel the need to resurface the intake flange I dont recommend to use glass because a friend did that and the glass broke and cut him bad. I use a piece of polished cultured marble about an inch thick and a foot square as a micro flat surface.

The biggest thing here is the High RPM situation you are describing and if in fact it is due to an air leak ten running the engine for extended periods will lead to severe damage. Get that corrected and the leakage problem will probably take care of itself.

Let us know your results.

Mark
 
WD40 is no longer flammable, (shouldn't it be called "WD41" then?) which kinda blows, 'cause now all i that happens is my lighter becomes useless, and those pesky black widows just get greasy, instead of bursting into flames.

while carb cleaner is indeed flammable, i highly doubt that it would ignite if it came into contact with the exhaust, unless it was glowing red hot, and then anything near it would become flammable.

i suppose it's possible, though.
 
Well here's a breaker ,, breaker for you boy's i fixed the carb problem the intake gasket was blown out but it high revs bad now when you pull the clutch in but it took of alot better and faster,, dang i wish i can find out why it's high reving so bad like it want's to pop the motor or something,, it starts so easy with no problem what so ever.NEED MORE HELP PLEASE!
 
Just for a try, did you check your Idle adjustment? Sometimes its just turned in to tight For my bike I had to turn it out about two turns before I got it right. I tried two different carbs on my bike and I used my old manifold instead of the new one that came with the kit, mainly because the older one was alloy and was much better made.

I did get the gasket that goes between the carb and the manifold and that really helped.

Mike
 
skyhawkcannondale still sounds like an air leak if you cant get it I am in Miamisburhg Oh let me know and you can bring it down. I have a couple extras csrbs and stuff. Maybe you, I and Been trying can all get together for a ride sometime since we are all so close.
 
Help!...Grubee 66cc engine still has, or seems to have fuel delivery problems with that "dribbling" petcock. Where/What is everyone using to replace this junk?. I have raised the metering rod as high as it will go to make this slug driveable, but that makes it 2/4 stroke on the top end. I am using a pocket bike tuned pipe, at a reasonably long length to give good bottom/mid power. I AM an old dirt bike/Kart racer/RC boat racer, so know a bit about 2-strokes. I am tempted to toss this Chinese Junk tank, and use something with a decent petcock. Expensive, but tried my local small engine shop, and found nothing...Help...Cudaman88.
 
Cudaman if the petcock is removable check to see if there is a plastic screened filter above the petcock... If so they tend to clog. Personally I broke mine off and replaced with an inline clear filter... Other than that if the petcock is removable it is also available through many of the suppliers that advertise here.

Look at WW Grainger as they have several small 1/4" brass valves available if you want to get away from the stuff in the kits.
 
Last edited:
Since you have a dribbly petcock.
Sounds a little too personal but I'm sure it's all bike related.
Here's a sure fire winner to replace it with:

Sick Bike Parts

Did you raise the "metering rod" that is attached to the throttle slide
barrell? Is the c- clip on the bottom slot?

When you raise the needle jet you enrich the mixture for up to about 3/4 throttle.
If it 4 strokes at the top end you may need to re-jet the main jet down a little.

These engines will need to be tinkered with and adjusted until you iron out all the wrinkles.
Be patient and don't give up.
Use the search feature to read up as much as you can before you start to get frustrated.
This a is a good hobby, but it is one that will tests your skills and patience occasionally.
There"s nothing "plug and play" about building a motorized bike.

Hope you can get your bike's leak fixed.
It'll always be something...
TiM
 
Last edited:
Thanks "Mark..."
I neglected to indicate that this slug of mine needs major choke to get going, so that's why I lowered the c-clip to richen up. If I don't use this over-rich position the low speed driveability is so lean, it won't go. I even moved the "choke" (if you want to call it that...really a richen-up plunger)to the right side so, I can feed choke into it to accellerate...then pull it back to normal, once it's screaming. This thing does Go!...But...Compared to my Yamaha KT100 Kart engine...sucks big-time. I am tempted to put/adapt a diaphram/pump carg off a chainsaw,(like the Kart engine), so I can adjust the high speed needle while driving, to suit conditions, i.e. cold, or warm weather.
Oh...thanks for the link...the 9.95 petcock looks good from Sick Bike> Will try that 10 dollar solution first...After all, I just found this thing is illegal in B.C.
anyway. Guess I'll find some off-road mountain bike trails here in the Vancouver area.

Thanks again...Cudaman88
 
Cudaman What carb are you currently using on the 66cc skyhawk? If it is the CNS2 you might think of ordering a CNS1 as some of the 2s have had some problems albeit I have found that they tend to run too rich rather than lean for the most part. IF you happen to be using the NT carb make sure to seal around the clamping slot and the throat of the carb with RTV Silicone as it doesn't have an internal seal and clamp ring like the CNS1&2 have, the air leak at this juncture will cause a massive leaning condition. If you have rulled out air leaks at the carb and they are properly mounted and sealed then read over this post on finding air leaks:

http://motorbicycling.com/f52/basics-port-polish-port-matching-16646-6.html#post237700

I have been working with the Tillotson and their HU butterfly venturi and HA Barrel carbs for the last few months and drilled a port below the cylinder for the pulse with some good results. I've also had some good luck with the Wabro WA series for the 66cc engines.

Let me know and I can send you pics of the mounting we have at this time.
 
Last edited:
hey skyhawkcannondale i am having the same problem. i just got a boygofast 66cc 2 stroke motor off ebay and the stock carb i think is crap or im just doing something wrong. i can get it going and it idles ok with the choke on but then after its running for a bit it starts to die. and when i take it off it revs really fricken high and either dies or i have to kill the motor. i tried adjust that screw with the spring on the side of the carb but that didnt even do anything. and when i tried riding it i could go a little far and it would just bog down and stop. also it seems like the gas doesnt seem to want to get form the tank to the carb. i have the gas valve on it just doesnt go down the line, until i unscrew the gas cap and it flows to the carb. i need help!! and i cant seem to figure out how to put a post on this site yet. just decided to sign up since i have so many questions that i cant seem to find the answers to.
 
Last edited:
bairdco said:
WD40 is no longer flammable, (shouldn't it be called "WD41" then?) which kinda blows, 'cause now all i that happens is my lighter becomes useless, and those pesky black widows just get greasy, instead of bursting into flames.

while carb cleaner is indeed flammable, i highly doubt that it would ignite if it came into contact with the exhaust, unless it was glowing red hot, and then anything near it would become flammable.

i suppose it's possible, though.
Click to expand...

WD-40 now uses CO2 as a propellant, which is not flammable, but it still contains Stoddard solvent, which is flammable.
 
You must log in or register to reply here.
Back
Top