# YT660 dies



## octane (Dec 3, 2018)

Hey guys , my 2012 YT660 dies when I go from idle to full throttle. 
I try to move the throttle very slow ,but it still dies.
At full throttle it runs strong , its just the transition from idle to anything other than idle thats the problem.
Any tips?


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## RedOctobyr (Mar 2, 2014)

Very nice machine! It sounds like your carburetor is dirty. As a short-term solution, you could try adding partial choke, and see if that helps it keep running as you increase the throttle. 



But cleaning the carburetor will most likely be required. You could try a cleaning product that you add to the fuel, but you will probably need to disassemble the carburetor to clean it properly.


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## octane (Dec 3, 2018)

Ok thanks .. i will have a look at the carb.. its the main nozzle that could be clogged?


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## octane (Dec 3, 2018)

Hmm only thing its almost brand new , not much hours on it ... shouldn't be clogged up this quickly... i mean , it could be , but I dont think its very likely.
Wonder if there is an idle mixture screw?


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## RedOctobyr (Mar 2, 2014)

If it's like many small-engine carbs, that would at least be the easiest one to clean. I don't know about Yamaha engines, but for some machines, that main jet can be removed by just removing the carburetor's bowl, and then unscewing the "retainer" that holds the main jet in-place. You might be able to take it out without needing to actually remove the carburetor from the engine. 

In which case you could certainly try removing just the main jet, cleaning it thoroughly, including any holes going sideways through it, and reinstalling it. 

There may be other items that require cleaning as well, but they're more likely to require fully disassembly of the carb.


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## RedOctobyr (Mar 2, 2014)

In the US, at least, mixture-adjustment screws are pretty much gone, due to the EPA's emissions regulations. If you have a mixture screw, definitely try unscrewing that a bit, to richen the mixture. 

The machine isn't old, but gas can go bad and gum up the carburetor. The US uses ethanol in the gas now, which degrades quickly if it's not treated with stabilizer. If Norway doesn't use ethanol or some other alcohol in the gas, then it should last longer before gumming up the carb, but it can still happen. 

If the machine has a fuel-shutoff valve, it's good to run the carb dry at the end of the season. With the engine running, close the fuel shutoff, and run it until the engine dies (you can also add choke as the engine begins to die). This gets the gas out of the carb's bowl, so there is less opportunity for it to degrade and gum up the carb.


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## octane (Dec 3, 2018)

I will have will have a look  i know the older ys624 have an pilot jet which handles idle mixture ... could be that which is clogged...
man I wish I had a service manual


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## Coby7 (Nov 6, 2014)

Make sure the fuel shut off is fully open. Push throttle lever all the way up to choke, start then just pull back a notch to full throttle. Don't even go to idle and let it run for a few minutes.


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## octane (Dec 3, 2018)

hey coby , yea thats how I start it ... and it runs fine at full throttle , or 50% throttle.... its just when I go all the way down on the throttle , and try to slowly move the throttle up again, thats when it dies


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## Coby7 (Nov 6, 2014)

I wouldn't know, mine is always full throttle or idle never in between. I never tried what mine did if I throttle up slow, I just go from idle to full throttle in one quick sweep.


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## RedOctobyr (Mar 2, 2014)

octane said:


> hey coby , yea thats how I start it ... and it runs fine at full throttle , or 50% throttle.... its just when I go all the way down on the throttle , and try to slowly move the throttle up again, thats when it dies


Oh, sorry, I misunderstood. I thought it was simply unable to run at full-throttle. If it can start at full-throttle, and can also idle, but dies when you go from idle to full-throttle, that seems odd. 

If you add some choke, does it get better, or worse? If there is a medium-throttle circuit in the carb, that might be dirty/clogged. Adding some choke might help you get through that transition, if you're running lean during that time.


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## octane (Dec 3, 2018)

Here is the issue


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## octane (Dec 3, 2018)

Ok seem to have fixed it .. i had a hunch the idle was too low , so i just adjustet the idle up a bit , and now its running sweet


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## RedOctobyr (Mar 2, 2014)

Awesome! Yeah, your first idle speed was REALLY low, it sounded like it was close to stalling. Glad you got it fixed.


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