Old Dirt bike
Rookie
Joined: Feb 2009
Posts: 63
Likes: 1
From: Chicago
your float is stuck.period....
It most likely was parked with fuel in the bowl and gummed in the up position for the float. then the fuel evaporated over time and the float PIN is stuck into the orfice. the float will swing up and down but the pin is stuck and not opening when the float lowers into the bowl. Happens all the time on old bikes sitting around, 2 strokes mostly because of the premix.
It most likely was parked with fuel in the bowl and gummed in the up position for the float. then the fuel evaporated over time and the float PIN is stuck into the orfice. the float will swing up and down but the pin is stuck and not opening when the float lowers into the bowl. Happens all the time on old bikes sitting around, 2 strokes mostly because of the premix.
Rookie
Joined: Feb 2009
Posts: 63
Likes: 1
From: Chicago
Take the carb off and tank it if you can.
If not, use lots of carb cleaner and clear out every jet orfice it the thing.
You will need a very thin piece of wire, the best i have found id to take a wire brush, and pull on estrand of wire from it with needle nose or vise grips. use this strand of wire to work into the jets and the float needle and seat.
On another note, you said a little 125 but didn't say 2 stroke or 4 stroke.
The 4 stroke has a choke circuit that is an enrichment jet, and it clogged up on my son's TTR 125 4 stroke. you need to do the same thing on the choke side, i'm not sure how the choke is on the older YZ125's ( 2 stroke)
If not, use lots of carb cleaner and clear out every jet orfice it the thing.
You will need a very thin piece of wire, the best i have found id to take a wire brush, and pull on estrand of wire from it with needle nose or vise grips. use this strand of wire to work into the jets and the float needle and seat.
On another note, you said a little 125 but didn't say 2 stroke or 4 stroke.
The 4 stroke has a choke circuit that is an enrichment jet, and it clogged up on my son's TTR 125 4 stroke. you need to do the same thing on the choke side, i'm not sure how the choke is on the older YZ125's ( 2 stroke)
Record Breaker
Joined: Aug 2007
Posts: 1,041
Likes: 0
From: Central NY
Check out Bikebandit.com. You can enter your make and model, and get fairly good exploded views of all the major bike systems. You can also order parts for a pretty good price.
Jet orifices are tiny; as in wire or hair diameter. It takes almost nothing to clog them. I've got a Kawi EX500 project bike, and its carbs were badly gunked up. Barely ran when I bought it. I pulled them completely apart, unscrewed the jets, everything, and bathed them in carb cleaner. After reassembly and fresh gas, it's night and day. Rips to 10,000 RPM without hesitation, and starts on the first crank.
+1 on the wire brush trick! I used a wire cone brush and ripped strands out of it; the wires are thin but wavy, and do a good job.
One word of warning, carb parts are *soft*, as you probably realize. The bodies are "Pig metal", which is basically junk, and the internals are brass-like and easily gouged.
Make sure you are getting good fuel flow from the tank. The petcock should stream fuel without sputtering or stopping. I doubt a 125 dirtbike is like this, but my Kawi requires engine vacuum to flow fuel. The little valve inside goes bad often and can cause headaches.
Buy a fresh spark plug for $3 at NAPA, clean the spark plug cap. You can check the gap, but they're pretty good from the factory nowadays. That pretty much eliminates spark as the problem, unless your electronics are bad. Also get a fresh fuel filter for $5 or less (not a fuel-injection filter, a plain see-thru one), to keep junk out of the carbs.
You'll get it running! There really is nothing to these older bikes.
Jet orifices are tiny; as in wire or hair diameter. It takes almost nothing to clog them. I've got a Kawi EX500 project bike, and its carbs were badly gunked up. Barely ran when I bought it. I pulled them completely apart, unscrewed the jets, everything, and bathed them in carb cleaner. After reassembly and fresh gas, it's night and day. Rips to 10,000 RPM without hesitation, and starts on the first crank.
+1 on the wire brush trick! I used a wire cone brush and ripped strands out of it; the wires are thin but wavy, and do a good job.
One word of warning, carb parts are *soft*, as you probably realize. The bodies are "Pig metal", which is basically junk, and the internals are brass-like and easily gouged.
Make sure you are getting good fuel flow from the tank. The petcock should stream fuel without sputtering or stopping. I doubt a 125 dirtbike is like this, but my Kawi requires engine vacuum to flow fuel. The little valve inside goes bad often and can cause headaches.
Buy a fresh spark plug for $3 at NAPA, clean the spark plug cap. You can check the gap, but they're pretty good from the factory nowadays. That pretty much eliminates spark as the problem, unless your electronics are bad. Also get a fresh fuel filter for $5 or less (not a fuel-injection filter, a plain see-thru one), to keep junk out of the carbs.
You'll get it running! There really is nothing to these older bikes.
Last edited by cramerica; Mar 25, 2009 at 09:14 PM.
Champion
Joined: Jun 2008
Posts: 3,300
Likes: 2
From: Plattsburgh, NY
I used to use bike bandit to get OEM parts when I raced...
And cramerica is right those ol' 2 strokes were cake to work on. Once all mx bikes switched to 4 strokes the already too expensive sport got twice as expensive and I could no longer afford racing and school. I hate it, everyday I still wish I could race...
But good luck on getting her running. She'll go.
EDIT: cramerica, those bikes don't have fuel filters.
And cramerica is right those ol' 2 strokes were cake to work on. Once all mx bikes switched to 4 strokes the already too expensive sport got twice as expensive and I could no longer afford racing and school. I hate it, everyday I still wish I could race...
But good luck on getting her running. She'll go.
EDIT: cramerica, those bikes don't have fuel filters.
Last edited by bpark8824; Mar 25, 2009 at 11:14 PM.
Record Breaker
Joined: Aug 2007
Posts: 1,041
Likes: 0
From: Central NY
A 2008 Ninja 500 still doesn't come with a fuel filter from the factory. Most people (unless the love dismantling carbs) add one in-line afterwards to keep rust and dirt out of the carb. Especially with older tanks. It certianly won't hurt anything.
I think small 4 strokes are cool, espically the way the manufacturers cram modern tech (4 valve heads, DOHC) into a tiny motor. But you can't beat the sound, smell and power of a 2 stroke. Check out some Youtube videos of old Kawasaki Mach Triple 750 2-strokes. Brutal.
I think small 4 strokes are cool, espically the way the manufacturers cram modern tech (4 valve heads, DOHC) into a tiny motor. But you can't beat the sound, smell and power of a 2 stroke. Check out some Youtube videos of old Kawasaki Mach Triple 750 2-strokes. Brutal.
Last edited by cramerica; Mar 26, 2009 at 09:31 AM.
Champion
Joined: Jun 2008
Posts: 3,300
Likes: 2
From: Plattsburgh, NY
I used to love my 125 when I raced. When I first started on a 125 i was all of 115lbs and couldn't touch the ground barely. That was a blast. Hitting powerband up hill on that thing was so much fun. I wish the sport stayed 2 strokes. 4 strokes are for lazy riders. You actually have to work to make a 2 stroke stay in its powerband and use all of its power.