# Advice needed



## Bruteforce10 (Jun 25, 2010)

So yesterday i bought an 06 YFZ 450. It is running good but could use a carb cleaning. Here are a couple issues i have found. It will randomly idle very high at times and idle normal at others. I rode it for about 2 hours (turned it off and on without any issues) yesterday and i rolled over a hill and forgetting I had a cluth I stalled it out. After this it wouldnt start (thought i fouled a plug) so i put it on the trailer and brought it home but what threw me off is that when i got home it started after a crank or 2.

Another thing to add he said it had been sitting for a while. The mods it has consist of, Hmf, Jet kit, Air filter and no lid on the air box, and what they call the cam mod which i think advances the timing. 

I am open to all suggestions due to me know NOTHING about sport atvs lol. All help appreciated. But it does go about 80 MPH! :bigeyes:


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## whoolieshop (Mar 22, 2011)

Bruteforce10 said:


> So yesterday i bought an 06 YFZ 450. It is running good but could use a carb cleaning. Here are a couple issues i have found. It will randomly idle very high at times and idle normal at others. I rode it for about 2 hours (turned it off and on without any issues) yesterday and i rolled over a hill and forgetting I had a cluth I stalled it out. After this it wouldnt start (thought i fouled a plug) so i put it on the trailer and brought it home but what threw me off is that when i got home it started after a crank or 2.
> 
> Another thing to add he said it had been sitting for a while. The mods it has consist of, Hmf, Jet kit, Air filter and no lid on the air box, and what they call the cam mod which i think advances the timing.
> 
> I am open to all suggestions due to me know NOTHING about sport atvs lol. All help appreciated. But it does go about 80 MPH! :bigeyes:



Completely disassemble, clean with carb cleaner then blow out all the passages & jets with compressed air. This will probably fix most of your problems. 

If it doesn't have an inline fuel filter install one. Trash or varnish breaking up in the tank could clog your jets back up and possibly cause a nostart or lean condition.

The erratic idle could likely be a torn or leaking carb boot / intake manifold when you take the carb off check the boot real well for cracks. Try putting light pressure on the carb up, down, left, right. If the idle changes you've opened or closed a crack in the boot. A cracked boot is BAD, it allows unfiltered air to enter the engine carrying dust and dirt with it, the idle going up due to a cracked boot is due to the fuel mixture leaning out from extra air.

A partially restricted jet could also cause a high idle but it would likely stay constant, another likely culprit could be the slide in the throat of the carb. If it's dirty/gummed up it could be sticking. Again cleaning the carb will fix that issue!

Be sure that your throttle cable moves freely as well 

Also remember that an open air box flows better but the filter will need cleaning/replacement way more often, there's just so much more surface area exposed and the filter gets dirtier faster.


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## Bruteforce10 (Jun 25, 2010)

Thanks woolie!

Well after my TLC last night i have solved all of my problems which is good. Except now i have found a new one, BLOWN head gasket. At idle it will burn coolant out the exhaust like a mofo but quits when i rev it up. But when i rev it up it spews coolant out of the Radiator vent. Also when i pulled the plug it looked perfect so im assuming the coolant is keeping it clean. And i want to say my oil may have had a slight milk to it but i checked it at night so im gonna have to look again. 

So I have never blew a head gasket before and im just assuming that this is my problem lol. Anyone have any input? Look like it is time for me to learn the insides of a YFZ i guess :thinking:


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## redneckrancher420 (Jul 5, 2011)

Well better u found it now then it fail on u on a trail. Or if you kept riding it couldve caused serious damage


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## Bruteforce10 (Jun 25, 2010)

Yea only thing that ticks me off is that It failed the day after i bought it...


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