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pw50 dirt bike rider - no power!

Joined
Sep 30, 2007
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#1
I recently bought a pw50 yamaha for my son and the darned thing just doesn't have enough power! I've taken off the power reducer that was screwed into the muffler and taken the screw by the throttle completely out. Still no power for him to ride on rough terrain. The darned thing won't ride through dirt/heavy grass field terrain.

Can anyone please provide help? There has to be a sensor or something else to do. I know I can get more power of the bike because I've read of others racing theirs. Believe me, a small kid on a bicycle can keep up with this pw50 right now.

Any help is much appreciated. Thanks! :bang:
 

CaptainObvious

Formally known as RV6Junkie
Damn Yankees
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Jan 8, 2000
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#2
Did you buy it new or used? I ask because maybe the bike is in need of a top end. If it is new, take it back to the dealer for an inspection.

PW50's aren't known for their speed or abundance of power. How big is your child? Maybe he/she needs a larger or more powerful bike.
 
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#3
7 years old. First time rider. So he's not real "active" with the bike. I believe it's a problem because others race these bikes and this one won't even run in the grass.
 

ctdyno

Damn Yankees
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Feb 10, 2007
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#4
what year is it, like captain obvious said, might need a new top end, or maybe the clutch is slipping??
 

Patman

Pantless Wonder
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#5
If you pulled the restrictor out of the exhaust (the flat washer thing where it connects to the cylinder) and have the throttle limiter either backed out all the way or removed and you are still having power issues the engine needs freshened because my son started on one and it pulled my 210 pound butt around. Honestly 7 is a bit old/big for a PW50, something like a XR/CRF50 would be a much better choice.
 

Jasle

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#6
Reading your post though it sounds like you did not take the restrictor out at the head/pipe. it is part of the crush washer. There is no restrictor to speak of in the muffler other than the spark arrestor which you should leave in if your riding in grass and trails.

you can get a ring/pinion from the yamaha qt50. it is 5.7:1 instead of 4.9:1 quite an improvment in bottom end takeoff ability.
yes people race the pw but they suck. racers will rejet instantly to a 67.5 main jet. this helps minimally. when on the race track with beginner riders the bikes still need help up the hills. you need a kid that can tap them out. make no mistake, just because people race them does not mean this is a race bike. maxed out this bike has half the power of a lawnmower.

main problem is the clutch engages so early. this is to tame it down. buy some aftermarket clutch springs. they increase stall speed and make the bike take off harder. a little scarier for newbies though. YT60 piston and overbore help a lot if your not going to race it.
 
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Apr 3, 2002
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#7
There is something wrong. The worn out top end is posssible.
also a clogged exhaust/silencer is possible. Also these bikes are very sensitive to dirt in the carb. My daughters pw hauls
my 180 but around so surely a 7 year old on the lawn should have plenty of power.