Genesis 120 carb - difficult start when cold

[62crusr]

I have a 2007 Nytro (Vector) owned since new that I have difficultly during a cold start.

It turns over and starts fine initally and for the first 15 seconds or so. After this I need to hold the throttle open slightly as I bring down the choke for it to stay running. Even after the temp light goes out (choke is off) it will not stay running. It is also difficult to build RPM. Once the motor is hot it starts fine. It will occassionally have a slight backfire when shutting it off during riding.


I've done the following;
- dissassembled and cleaned carbs (bowls, jets, etc...). Reset pilot screws to 2 turns out.
- syncronized carbs
- tested TPS resistance and measured voltage with key on - ok
- installed new plugs
- cleaned plug/coil contacts and applied dielectric grease
- checked carb boots for cracks - ok
- used gas line anti-freeze on one tank of fuel


If anyone has any ideas I would appreiciate it.

thanks

 

[Groomerdriver]

Has it been doing this since new? My .02 is to take it to a reputable dealer and have them disassemble and clean the carbs, reinstall and synch them.

A local dealer claims that these carbs have so many passages to clean that the DIY kinda guy like me (you?) can't get at them all. I also do not have the tool to synch the carbs.

 

[twomorestrokes]

You state that it has difficulty building rpm. is that warm also or just cold? Have you put in a fresh set of plugs?

Carbs aren't that complicated. Watch for the springs and check balls though. Make sure the idle circuit passages are clear.

 

[hossZ28]

it almost sounds like 1 of the cylinders is flooding (over fueling) does the condition change or improve by adding or reducing the choke ?is the choke cable and Individual linkages on each carburetor moving freely? These are somethings you may also want to check.Oh I also forgot If you didnt replace the spark plugs already do it now a fouled plug will give you the same symptoms mine did it after pulling out of storage and not letting it warm up before shutting it off I would start here first for the price of 3 spark plugs may save you fromsecond guessing your next move.

 

[62crusr]

Thanks guys.

Groomer - its only been doing it this season

2morestrokes
- difficulting building rpm just when cold/luke warm, not hot
- I put a fresh set of plugs in at the beginning of the year
- I blew out all the passages with compressed air. There was no gum in the carbs at all. They were clean.

Hoss
- I checked the plugs and they all look very similar - very light grey
- it does seem to need to go off the choke earlier than it use to
- all linkages appear to move freely

 

[cameron]

check the compresson,good luck.

 

[Groomerdriver]

I'll throw a few darts:

1. plug wire going bad?

2. these sleds have coils don't they? coil going bad?

sounds like something electrical to me....

 

[Maineman]

Mine starts instantly at full choke, but as soon as the light goes off it stalls. Then ya gotta play with the throttle a bit to keep it going. After that it's fine. I'm still trying to figure out the best way to handle it.

 

[twomorestrokes]

Mine starts instantly at full choke, but as soon as the light goes off it stalls. Then ya gotta play with the throttle a bit to keep it going. After that it's fine. I'm still trying to figure out the best way to handle it.

How long do you leave the choke on?

 

[Gone Blue]

Last year my RS was a bear to start when it was cold. It would crank a bunch of times then catch but only run a couple seconds then die. It would do this a couple of times before it would idle and warm up. I have since cleaned the pilot jets and this season it starts almost instantly when cold and idles perfect as it warms up. I had to do soak my pilot jets as they were really plugged up. Did you make sure that they were clean when you assembled the carbs? G.B.

 

[Maineman]

Mine starts instantly at full choke, but as soon as the light goes off it stalls. Then ya gotta play with the throttle a bit to keep it going. After that it's fine. I'm still trying to figure out the best way to handle it.

How long do you leave the choke on?

I'm usually out there with it and kinda move the choke as needed. But as soon as the light goes out the engine shuts off. It's like there is a sensor there or something.. It starts right up again and if you tweek the throttle a bit it idles on its own.

 

[62crusr]

Cameron - seems to have the power it always had so I kind of doubt its compression.

Groomer - yes the coil sits on top of the plug. Doesn't seem to be an issue when warm though. Not sure what I can test without just replacing parts.

Gone Blue - I blew the jets out with compressed air and then looked through all the holes with a light on the other side. Everything was nice and clear. I may need to take apart again just to make sure.

Maineman - I beleive when the temp light goes out the engine timing is changed. Advanced or retarded, not sure which.

 

[cameron]

sometimes hard cold start is an early sign of a seal gone in the motor.Lets hope this is not your problem.

 

[twomorestrokes]

sometimes hard cold start is an early sign of a seal gone in the motor.Lets hope this is not your problem.

Is that with 2 strokes though?

 

[Bradford]

Any updates on this? I have an 06 nytro with the same problem. didn't clean the carbs or sync them this year so I assume that's all it is

Brad