hi guys, i have a grubee 48cc with a cns v3 carb i think its a 2011 model... i have built three of these bikes and am also a master automotive mechanic so i pretty much know what im doing but, this is getting annoying this engine running with the clutch pulled in idles fine but when i give it gas it bogs for three seconds then revs up slowly. it also has no top end i can floor it with the clutch pulled in and it will not over rev. i have taken the carb apart and blew through every hole and also removed the main jet and blew through it. i have checked the rubber seal between the carb and intake manifold tube. any ideas would be much appreciated. thanks in advance its just that i don't have too much time to mess with it just looking for ideas?
48cc grubee bogs off idle
- Thread starter beserkr
- Start date
My 48 w/cns does very well at low rpm and off idle but it takes a super lot of messing around with to get it even close to being right.
It's NOT worth the time spent.
It is wise to spend the $20 to have an NT carb shipped to you.
Then you can make the suitable main jet adjustment, set the needle for mid-range, and your troubles are over.
Best
rc
It's NOT worth the time spent.
It is wise to spend the $20 to have an NT carb shipped to you.
Then you can make the suitable main jet adjustment, set the needle for mid-range, and your troubles are over.
Best
rc
hey took the advise of an other person and drilled out the EPA cap on the cns carb made life much easier! got it tuned in fast and it blubbers a lot less now am going to 32 to 1 mix with synthetic oil today and think that will help also. there is some great posts under CNS carb adjust that will help you get rid of the lag on throttle response to
Well i lowered the fuel level in the bowl, drilled out and messed with the mixture screw, i got it to rev up a little better from idle but its still messed up. Top speed is up but still not perfect. Im going to lower the fuel level some more and see what happens. I pulled the spark plug and it looked perfect for wot but it just still feels like its holding back. Im getting to the point where i just want to get a nt carb and be done with it. This cns carb sucks! i have another bike with a nt carb that runs perfectly.
no intact the numbers on the carbs are the same. started running premium fuel with a synthetic oil yesterday and wow what a difference. on one of the card pages it talks about rejeting but you need to be able to solder and have the right size drill bits will see if i can find it again and post the link for you. got mine running pretty well but with the new fuel etc. have to readjust i do know when you take off the muffler cap they run way but you better be away from houses since a noice complaint would not be cool
high octane "premium" fuel in a happy time engine is a waste of money. they are low compression engines and high octane fuel has no effect on the way these things run.
you have to do more than just take the muffler cap off to make them run better.
you have to take the baffle out of the muffler and modify it to flow better because the baffle plate restricts exhaust flow. taking the end cap and baffle assembly out is just like running a straight pipe, and that really doesn't have any effect other than more noise.
you need a little back pressure on a 2 stroke, and a modified baffle, will make the engine run better than with no baffle at all.
of corse your bet bet is an expansion chamber with a modified, free flowing baffle (or stinger) on the end.
Well i got it all back together and its running some what rich now and its still running like crap. So I have gone lean then rich still runs like crap both ways Im thinking ignition timingbut there is no adjustment there so what should i do next? This engine came with a three electrode plug wonder a-if its the right plug and b- if the gaps are right?
Put an NGK plug in there (I would upgrade the plug wire and boot too).
On the CNS, I have found blowing through the jets not to be sufficient to clean, specially the smaller idle jet and the enrichment jet.
Speaking of the enrichment jet. Being that it adds extra fuel (instead of being an air choke) you can use the enrichment lever (choke lever) to help diagnose the condition that is causing bog. Ride into the bog range, then open the enrichment jet, if the bog goes away your too lean, if it gets worse your too rich already.
Also, a simple test you can do to check your float level, warm up the bike then turn off the fuel valve while riding. If the motor runs better after a few seconds with the fuel off (then a short while before it dies) you would probably benefit from adjusting the float to lower the fuel level in the bowl.
Again, you probably need to ream the idle jet rather than just blowing air or carb cleaner through it....
PS Lowering the fuel level in the bowl (via float adjustment) well have a general leaning effect overall...
On the CNS, I have found blowing through the jets not to be sufficient to clean, specially the smaller idle jet and the enrichment jet.
Speaking of the enrichment jet. Being that it adds extra fuel (instead of being an air choke) you can use the enrichment lever (choke lever) to help diagnose the condition that is causing bog. Ride into the bog range, then open the enrichment jet, if the bog goes away your too lean, if it gets worse your too rich already.
Also, a simple test you can do to check your float level, warm up the bike then turn off the fuel valve while riding. If the motor runs better after a few seconds with the fuel off (then a short while before it dies) you would probably benefit from adjusting the float to lower the fuel level in the bowl.
Again, you probably need to ream the idle jet rather than just blowing air or carb cleaner through it....
PS Lowering the fuel level in the bowl (via float adjustment) well have a general leaning effect overall...
http://motorbicycling.com/showthread.php?p=296926 check out this thread its got a great break down of how to tune them. also there is a thread about plugging 1 of the 2 vent tubes on the scew side of the carb.
Ok i messed around for long enough and the thing still ran like crap! I put a nt carb on it from another bike and it runs perfect! Not a problem at all! I am ordering a nt and short manifold for it right now and in the future will have a ton of these cns v3 carb for sale! I will never mess with one again! What a waste of time, drilling jets messing with float levels and idle speed and mixture screws. Also the short manifold helps with the low end bog. I tried it with the long manifold and the short manifold and hands down the short one has a instant throttle response and the long manifold has a two second lag!
I think the longer z-tube is probably gonna be an issue, I have the nice short intake and my cns works fine...
it was too rich buddy, nice attitude. besides there are many reasons for a bog off idle....
i have built over ten bikes with these 48 cc grubees and have found every one to require a different jet size. 90% have to be soldered and drilled to a smaller size then the stock #71-#68 size jet. i have even had a 66 cc engine repuire a jet size of #76 so like i said they are all different.
Nice attitude?
I've built far more things than motorized bicycles .
I know carbs and jetting , and I know that no 2 are the same no matter what your working on.
try building a 287 cubic inch Pontiac v-8. with dual rochester. 2 barrel carbs, and get it to run right.
I did, and that's what's in my current car. try building a 66 triumph bonneville with risk 389 also mono-block carbs and make it run right. well, I did, and that'd my current motorcycle.
try building a 396 cubic inch big block chevy, put it in a 72 nova. and have it run the 1/4 mile in 11 seconds with the stock 2:73:1 gear ratio in the rear end. well, i did and that was the car I built when I was in high school. I've been around this stuff my whole life, and I've built several other cars, motorcycles, engines, transmissions, fuel systems, nitrous systems and all kinds of other crazy stuff. these China 2 strokes are the simplest engines out there.
I've built far more things than motorized bicycles .
I know carbs and jetting , and I know that no 2 are the same no matter what your working on.
try building a 287 cubic inch Pontiac v-8. with dual rochester. 2 barrel carbs, and get it to run right.
I did, and that's what's in my current car. try building a 66 triumph bonneville with risk 389 also mono-block carbs and make it run right. well, I did, and that'd my current motorcycle.
try building a 396 cubic inch big block chevy, put it in a 72 nova. and have it run the 1/4 mile in 11 seconds with the stock 2:73:1 gear ratio in the rear end. well, i did and that was the car I built when I was in high school. I've been around this stuff my whole life, and I've built several other cars, motorcycles, engines, transmissions, fuel systems, nitrous systems and all kinds of other crazy stuff. these China 2 strokes are the simplest engines out there.
hahaha, you're cool.....
maybe you should try and be a little more helpful. i dont have to boast, my actions and kindness towards others here speak for them selves. no one on this forum isnt looking to getting into a pissing contest, so if you dont have anything helpful to say please dont say anything.
