atomik nitrous 160 wheelieing problem

[MrPister]

ok soo I'm new hear and have only recently bought my first pit bike and so far the only thing wrong is when i do a wheelie and then come back down if i try to accelerate it seems to bog and then splutter and then stall … I'm not sure if its a valve clearance issue or tuning issue or what but it is very annoying

 

[my67xr]

welcome to Miniriders,

don't forget to drop by into our Introduce Yourself thread and say g'day too.

when you blip your throttle, is there a slight hesitation ?
if so, you could have a blockage in your Primary circuit of the caby.
it may just need a pull down and decent cleanout ?

cheers, craig

 

[MrPister]

a blockage already ? it hasn't even done 3 tanks yet

 

[timeeh]

my guess would be water/crap in the carb too. Try draining the float bowl on the carb, i'm thinking that when the front wheel drops the water (or whatever is in the bowl) is mixing with the fuel, which will cause it to sputter. As for a blockage, could be that too, they do seem to have a fair bit of platic threads come out of them especially from brand new.

 

[MrPister]

ok i will go drain it and take it for another ride and will let you know the result

 

[my67xr]

ok, you didn't mention if it was new or used in your original post.

what carby is on it ?

have you done the valve clearances yet ?
.003" on the inlet and .004" on the exhaust
this video link might help you

[video=youtube;QJciyJRJh8Q]http://www.youtube.com/watch?v=QJciyJRJh8Q[/video]


have you tuned the carby to suit, adjusted the mixtures, moved the needle clip, and done a Spark Plug chop ?
you might want to check the float level too

 

[MrPister]

ok well i am about to set the valve clearances this arvo and the motor is the 160 yx motor with the stock carb***8230;whats a spam plug chop ? and how do i check the float level ? I'm pretty mechanical but all my other bikes have efi ha

 

[my67xr]

a Spark Plug chop is when you check the colour at the Electrode/Insulator

run the bike at WOT in 3rd or 4th gear for around 15 seconds or more,
then shut the bike off, pull the clutch in and stop.
then pull the spark plug out and look at the colour
it should be a light tan colour if the Jetting/Needle clip settings are right.

with the Float height,
if you have the fuel bowl off and turn the carby upside down, the float should sit level, with the needle and seat closed.

the Molkt carbys really need a bigger Pilot jet too, TBolt US recommend a #25 Pilot Jet for the 140 GPX engines
so i guess maybe a #30 Pilot Jet ? and i'm pretty sure they use Keihin round jets for the Main Jet, same as some OKO's
DHZ would have them, but might pay to ask
does your pilot jet look the same as the 3 on the left ?
http://www.dhz.com.au/buy/oko-carburetor-slow-main-jets/CARB-012-OKO

 

[MrPister]

i cat see any adjustment screws like this at all on my carboy dunno what the hell I'm doing with it atm ha

 

[my67xr]

does the carby look like this ?

the mixture screw, is to the right of the idle speed screw(centre)


the jets in the link above,
are screwed into the base of the carby, you will need to remove the fuel bowl to see them

 

[MrPister]

yeah thats exactly it I'm gonna try to do a spark plug chop tomorrow s the neighbour wasn't to happy about me ridng around trying to figure out what was going on ha

 

[my67xr]

thought i better mention something too,

keep an eye on the chain tension, cause you'll need to replace it soon.
it will stretch and jump off the front sprocket, possibly breaking the cover, and or damaging the stator pickup

get a good quality DID/RK chain for it, they start around $25 and up

 

[MrPister]

yeah i have already had to tension it twice

 

[GooseMan]

I had a simialar problem with those carbies mate, when I try and hold a wheelie or just drop the front and blip the throttle it would die. I fixed it with a new oko carby. I wasn't 100% sure if it was the float level being too high ( although it didn't overflow or anything) or if it was just a bad design of carby. As in when dropping the front wheel it would get a surge of fuel splash past the jets or something and flood the engine?

Just thinking about it more now and remembered it was fine whilst riding up hill so couldn't imagine it being a float level issue. Molkt carbs are crap though, oko26 is the way to go for these engines.

If it was a mixture issue it would most likely have problems while riding normally and blipping the throttle etc. It wouldn't rev out properly, if yours is anything like how mine was it should peek out fine.

 

[zwebx]

moklt are crappy, hit a jump and it bogs... not the nicest thing to learn while in the air...

 

[GooseMan]

Hang ON! just remembered something else lol (my memory is shocking at the moment), if it got bumpy riding up hill or if it were extremely steep it would also die.

 

[my67xr]

the Molkt are a bit hit and miss.

this is the go if you like flatslides- http://www.dhz.com.au/buy/oko-26mm-...nifilter-140cc-150cc-160cc/CARB-05-26-UNI-KIT

 

[MrPister]

so what does everyone think just go for a new carb ? I'm not fussed in getting a new one as i read around and a lot of people say the stock one is crappy.. what carb should i look at?

 

[Snaptrax]

Defiantly the oko 26mm mate. The flat slide will also make the bike a bit more snappier.

 

[motorman]

+1 the OKO 26mm.

You will never look back or have any of these issues.