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  #1  
Old 10-18-2012, 05:19 AM
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Default Yamaha PW80 Not Running Right

     

Hi everyone
Back in January I pick up a 2007 Yamaha pw80 for $600 that need some TLC. I got it looking back to original condition but the engine has a problem.when I start it and run it cold it runs fantastic,exactly how it's suppose to run,but when I ride for a few minutes and it warms up it looses power when I pull the throttle and make a loud tingy noise and has very little power. I cleaned the carb twice,replaced the air filter, drainded the oil and put fresh gearbox and motoroil in it,cleaned the full tank and the filter on the fuel tap and I took the carb to a Yamaha dealership and had the float level set.i tryed putting the choke on but that just stalls the bike.

I done some research and I am now starting to think that it may be the piston,the rings or that It is getting way too much oil.

I'm really not sure and would really appreciate any help you guys have to offer!

Thanks,Tony
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Old 10-18-2012, 05:16 PM
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Default OK

OK, do a compression check to see if the top end is shot. Low compression will give off signals of being too rich and will loose power when warm. Also checl the exhaust silencer to be sure it is not clogged up or needs repacking.

Paw Paw
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Old 10-19-2012, 12:52 AM
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It is sure acting rich. Those can run a really long time in a set of rings if the don't get run out of oil too many times. That one should have a removable float seat. Make sure the gasket under it of the needle isn't leaking. Listen to paw on the plugged rchsust
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Old 10-20-2012, 03:07 AM
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I replaced the exhaust silencer on it about 2 months ago with a fmf powercore 2. I also gave it a compression test and it has good compression. I'm yet to check the gasket under the needle in the carby
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Old 11-06-2012, 10:02 PM
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I think the pw80 has a heater on the carb.
Usually when you start the 80 you need the choke and it will run like crap for a little bit COLD. When the heater coil warms up then I lip the choke off and off he goes.
Check the wires going to the carb.
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Old 11-07-2012, 01:00 AM
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I'll try that, whenever I put the choke on the bike sounds like its running out of fuel and unless I hold the throttle on it stalls.
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Old 11-07-2012, 05:50 AM
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Quote:
Originally Posted by liberator View Post
I think the pw80 has a heater on the carb.
Usually when you start the 80 you need the choke and it will run like crap for a little bit COLD. When the heater coil warms up then I lip the choke off and off he goes.
Check the wires going to the carb.
NO, NO, NO.... There is no heater in the carb. It is a very simple unit with very few parts. As Oss suggested you may have a leak at the float and the gasket.
I would also want to know exactly what the compression numbers were when you checked it and said it was good.
The power core silencer may also be an issue as it may have the intake and exhaust out of ballance now.

Paw Paw
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Old 11-09-2012, 07:07 AM
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I took the carb apart and checked the gasket and its fine. I also checked the float and its not leeking or anything. Ive got the carb, float and jets soaking in carb cleaner over night and ill assemble it tomorrow and give it a test ride. When i checked the compression i dident use a gauge i just put my thumb where the spark plug goes and pushed on the kick start lever and my thumb blew off the hole.
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Old 11-09-2012, 07:32 AM
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thump is clearly not enough to test compression. 120 psi is hard to feel
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Old 11-09-2012, 07:39 AM
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You need to do the compression test with a guage.

FYI: The jets will have to be cleaned better than just with a soaking. Todays fuels leave a hard deposit in them that looks clear, but is actually reducing the flow of the jets.

Paw Paw
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Old 11-09-2012, 09:02 PM
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Sorry
The heater is on the Yamaha 90 not the 80.
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Old 11-10-2012, 04:43 AM
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I put the carb back together and i cleaned the jets out with some wire and i also blew air in them with my compressor. I put it back on the bike, cranked it over and it ran beautiful until it warmed up then it just done the same thing which was make a tingy noise and have no power. I had a closer listen and the tingy noise isn't coming from the piston it somewhere else in the engine. I won't be able to get hold of a compression gauge until next week when i see my friend.
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Old 11-10-2012, 04:59 AM
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Ok, the noise sounds like it could be the piston as it's doing it after it's warmed up. It could also be some preignition if the piston and head have a bad carbon build up on them. It could also be a faulty crank bearing, but these little bikes seem to be very easy on crank bearings.
You will know more after you do a compression check.

Paw Paw
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Old 11-11-2012, 12:34 AM
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I took the front off the engine apart and had a look at the piston. The front of it has alot of thick black carbon build up on it, also the exhaust has thick black carbon build up around the manifold. The bore in the engine head looks very clean.the piston rings are very black.

Is it possible to clean the piston and rings?

Last edited by Yamy80; 11-11-2012 at 12:40 AM.
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Old 11-11-2012, 01:03 AM
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Default ?????

If you have that much black, you have blowby and the units need to be replaced. That is why the compression check was needed. When the engine gets warm with worn rings and piston your compression drops even further and thus the poor performance.

Parts link..http://www.bikebandit.com/houseofmot...5417#sch297095

Parts cost under $120 for everything needed.


Paw Paw
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  #16  
Old 09-20-2018, 09:29 PM
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Default Pw80

Have you found out the problem I have the same with mine please help
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