Dirt Rider Magazine

Ctg93

My 2006 yz125 2 stroke died on me while i was riding today and it will not start bacc up?
What can cause this??

NZrider

cooking/seizing the top end, fouling a plug, ignition system failing.

this is a rediculously open ended question

Ctg93

Ok i change out the spark plug and it fired right up, could this be caused by too much oil in my bike? And exactly how oil should i put in the bike?

CRider2004

Mix 40:1 and don't putt around in low end throttle range.

Ctg93

Cool i appreciate the advice guys

JonC126

Can't baby a 2 stroke. Ride the hell out of it, but don't over rev it. My 03 yz goes through about 3 plugs a year. i usually get a plastic bag and keep a wrench and a spareplug zip tied to the top of my air box when I go trail riding. get a big medicine bottle, keep a plug in it and a small wrench incase you don't want to keep taking off the number plate to get the plug. Just zip tie it to the bottom of your rear fender, and you'll be good. but make sure it's secure, you don't want to just throw $5 away. 2 strokes are for experienced riders, is what my dad always told me.

BleedMarshall

I trail ride my YZ125, well, my son does now, and we keep a wrench and plug with us just in case. However, as I have the same year bike as you, I did go from a 32:1 ratio to just in between a 32:1 and 40:1 ratio and run an "8" plug as opposed to "9", which has helped in bogging and fouling. I also set the carb up a bit different, but I can't remember what I did now since it has been over a year since I did it.

That being said, you have to ride the bike hard in order to trail ride a 2t of this nature, and you need to have your jetting and needle right as well. Those 125s like to have their necks rung off, so make sure you are riding on the pipe more often than not nomatter if you are on a trail or on a track.

EEE299

i would try to avoid going to 40:1. i realize that many people do it, but less oil=more wear. just my 2 cents.

BleedMarshall

That is why I did not go to a 40:1 EEE299. A 32:1 ratio is 8oz of pre-mix to 2 gal. of gas. I use 7.5 oz. of pre-mix to 2 gal. of gas, which is just under 32:1, but not a 40:1. Funny enough, I ride the bike no different and the bike fouls far, far less. *shrugs* I changed the carb settings, using a 32:1 and trail riding, and used about two plugs a month. I keep the carb settings the same and just changed the mix ratio from 8oz. to 7.5 oz. and I foul plugs maybe once every three months now, and I ride the same. This is with an "8" plug as well. The YZ125 calls for a "9", but I went to an "8" for trail riding.

If you ask me, I think it is the carb itself and not the bike or settings. I was a huge Mikuni fan dealing with Harley-Davidson and was not a big Keihin fan. Now, I like the Keihin more so over the Mikuni. Just my $0.02 here as my KTM has the Keihin and it has fouled one plug, and I am almost ready to believe it was the plug that came with the bike in 2006, and it fouled this year.

davidcullen90

I would always run a 32:1, especially on a race bike like a yz. I run it on my bike and it's perfect. Any time your bike dies the first thing you should check is the spark plug. Also, make sure you have enough fuel in the bike. If you find you're constantly fouling plugs, check and clean your carb. If it still doesn't start, I'd check my oil, and then my top end. The top ends on these things blow from anywhere between 10-25 hours.

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