1999 Pw80 Help

[jsmith811]

My friend just bought a 99 PW80, it seems to run rich & is very weak for a 80cc. I know its a PW, but I have seen them run in the pits at races alot better. I was thinking of going one size smaller on the main to clean it up. Is there any other free mods to help these bikes ? any airbox mods or exhaust restrictors ??

 

[smatta4u]

we have a pw50 that also seems very rich. you will probably need to go leaner throughout the whole carb - not just the main. i checked at the yamaha dealer and they listed one size above and below main jets for that carb and did not list a leaner needle. (my clip is already in the top groove)
i don't if parts are as easy to get for these carbs because it's a oil injected
type system. i haven't seen them listed on many websites anyway. the pw50's have a exhaust restrictor at the front of the pipe you can remove.

 

[drk98]

the pw 80 also has a restrictor where the pipe joins the head.easy to remove -major improvement. we also went one leaner on the main

 

[ewbish]

My daughter just came off a 2001 PW80. She raced that bike for about a year in our local playbike class and consistently beat all other PW's, TTR90's, XR80's, and some XR100's. Simplest and quickest way to make a PW80 go better: Pull the washer out of the head/pipe joint and throw it away. Remove the snorkel from the airbox. Replace the stock filter foam with a good quality aftermarket foam, you will have to cut it yourself. Open up the airbox, I don't suggest drilling the front as mud will quickly plug it, but drill several 1/4 inch holes in the back along the sides, make sure you don't bypass the airfilter. The PW's run very rich from the factory, after all this you will be much closer, I live at 4500ft and from this point all I had to do was drop the needle one clip. If you really want more power, replace the ignition with a pre-1994 PW80 ignition, this will allow you to advance the timing. Also, if they race, remove the silencer. The bike won't be much louder, but you will gain about 2 hp. Don't trail ride without it though. If your kid rides it hard and tends to like a bit of airtime, frequently check the engine mount bolts and the swingarm bolts, they will tend to loosen up rather quickly.
Eric B.

 

[smatta4u]

i think i remember someone talking about drilling holes in the silencer to help it flow better. i am not sure where they put the holes though. ewbish - good tip about opening up the air box, im going to do that asap.

 

[ewbish]

I strongly reccomend that you don't drill the silencer. If your kid only rides on a track, that would probably be fine. But if you take 'em trail riding you have just opened yourself up to a fine for modifying the spark arrestor. I simply took mine off when at the track and left it on every where else.
Eric