running rich.

[Frankie39]

i have a new bike so at first i though it was maybe because its new and it hasnt run itself yet, but changed the plug yesterday and still rich. if you slightly hold the revs up in N you can hear it popping. its a molkt carby, a 160cc atomik nitrous bike. i know ive been told to change it to an oko 26mm carby but for now id just like it to run good. anybody have this carby or bike who has fixed the issue?

i will end up getting a new carby, along with a big bore exhaust from DHZ, i might end up taking it to a motorbike place to get fitted and properly tuned at the same time, but for now any ideas will be great.

 

[Cactus Jack]

You need to check that the float level is right ... and then that the mixture screw is adjusted right ...

Then do a throttle chop run in 4th gear ... get the bike peak revving then kill the ignition without backing the throttle off first ... Stop ... Pull the plug and check it ... IF it's still black you need to go down in main jet sizes ...

It's best to do the check with the needle clip in the middle groove ... moving the clip upwards drops the needle and leans the mixture ... lowering it enrichens the mixture ...

 

[Frankie39]

sorta following... ill suss it out when i get some time.... next few days.
is there any gains to be had with the 28mm or flatside 26mm carby?

 

[Cactus Jack]

Here's some more jetting info ... Powroll says plug reads aren't 100% reliable ... but your bike is stock with the manufacturers jetting so it should be close enough for you to not harm anything ...

JETTING SPECS

The flatslide 26 mm OKO's should work best with a stock 160 since your intake manifold bore is 26 mm and their venturi is 26 mm too ... so you'll get your maximum possible (stock) top end power without losing bottom end power ... A genuine 26 mm carb is bigger than a MOLKT or VM-24 Mikuni ... which are both only 24 mm where it counts ...

Over in the states they're using the TB Keihin PE 28 copy carbs on bigger motors because they're easy to tune and the power delivery is smoother ... As Sean01 has stated ... some people don't like the strong bottom end snap of a flatslide carb ...

 

[Frankie39]

yes i would prefer it not to snap but more of a build up, at the same time no one wants it very sluggish either..... all i plan on doing it the big bore exhaust, and IF need be for better A/F control is the carby, which ever will be best suited... not planning on spending $1000 on the complete 184cc bore kit, so carby and exhaust will do me fine for performance, some new bars i think is essential n tyres though!