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2008 pw50 help

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hey guys i recieved this pm, thought that you might be able to help me, help him out,

2008 YAMAHA PW50

Hello,

I have made some modifications as listed below, but the bike still reacts like is has a rev-limiter. The bike starts cutting out at about 35 MPH. Is there something that still needs to be done to prevent this?

I removed the rev-limiter box by unplugging the black box with the rubber strap located under the seat. I can start the engine with the switch in the run position. I have installed a Yamaha PW50 Super Power Up Kit that I purchased from Ebay. It consist of Boysen Reed Valves, larger main jet, 2 spark plugs, high flow air filter designed to fit the stock air box. I drilled holes in the stock air box. I have modified the silencer, but decided to run the bike with the silencer removed.

Please help?

_____________________________________________________-

35 mph is very fast for a pw50, i think he is reaching its limits if nothing else, but i have never actually clocked a mod pw50 to see what it top speed was but i was always guessed it was close to the 40mph mark anyway, if anything at all is wrong im guessing its weak spark or timing issue, but i still think it just might be the extent of the machines limits and nothing at all is wrong,

what do you guys think??

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I agree. Unless he is riding it on a smooth surface I wouldn't want it to go any faster.

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Sounds as though it is peaking out to me. Why on earth would you want a PW to go that fast anyway?? I am with you theyroyz71, I have already said in the past they go better than they handle.

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yep i agree 35-40 is about the fastest i think these bikes can go, the mods are really to help low end and torq not overall top end speed, but i have seen these bikes races oval track and im thinking the person you sent me a PM might be racing oval dirt track with it and want more top end,

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May try a taller tire if there is one. It will be slower off the line but you might get a bit more top end. I know a lot of mx guys run the QT Gear to help it pull hills and start better but I don't know if there is a taller ring and pinion set available.

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these bikes have too big of main jet stock and they get rich at high rpm causing it to misfire , if this guy put in a bigger main thats probably why it wont wind out and acts like it has a rev limter 🙂

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these bikes have too big of main jet stock and they get rich at high rpm causing it to misfire , if this guy put in a bigger main thats probably why it wont wind out and acts like it has a rev limter :D

BINGO 🙂

I think you just hit the nail on the head!

very good advice, i bet 10-1 thats it.

thanks for the help

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Stock main on a pdub should be a 70. That is what we ran at Lorettas in 2006. I know a lot of guys ran a 67.5 or even a 65 but I didn't want to take any chances with our motor seizing up in the scorching heat.

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I ran a 65 main in both my P-dubs and never had a problem, the bikes are day and night with jetting.

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I assume he still has the oil injection hooked up. I know at high rpm the OI pump is really dumping in the oil which may cause it to load up. Of course also depending on the jetting and load on the motor.

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I ran a 65 main in both my P-dubs and never had a problem, the bikes are day and night with jetting.

Our pdub won the Shaft Class at Loretta Lynns in 2005 and finished 5th Overall in 2006 with the stock 70 main jet.

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Our pdub won the Shaft Class at Loretta Lynns in 2005 and finished 5th Overall in 2006 with the stock 70 main jet.

utah at 4400 to 8400 ft and the 70 will foul plugs all the time, a 65 or even a 60 is what we run up here, most of the time they have 60 main bored to 62 or 63 for racing

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We are at a much lower elevation. You probably do need to jet down with the thin air up there.

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Our pdub won the Shaft Class at Loretta Lynns in 2005 and finished 5th Overall in 2006 with the stock 70 main jet.

I belive it , but with the air around here they wont rev with a 70 , I have a 65 in my son's and it has a few mods , we are only 800 ft elev. but the temp and humitity probably put's the dencity alt. at 4000 ft 🙂

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