Question about 2003 Yamaha YZ 125

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Kicking oil out exhaust

Just done top end rebuild, and ran bike in, now bike spitting black oil out exhaust

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  • bookerm Apr 16, 2009

    mix is 33-1



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Repack the silencer and what are you mixing ratios for fuel??

Posted on Apr 15, 2009


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Pulsar 220 Bike emits little smoke even after Rebuild, how do I fix?

Did you clean the bore REALLY REALLY good with hot soapy water and a brush before assembly? Need to remove all the grit from the honing process. Test by rubbing hard with a white cloth.It MUST still be white after rubbing. If not then clean it again. It will wear out the rings quickly if it's not right. Solvent will not clean it properly.

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My son was riding his 2004 blaster was having a blast but ran it for about 4 hours. When he went to ride it home ess than 5 blocks away it stalled and the kick start seized and won't puch down. In addition...

Sounds like you need a rebuild. Dont use cheap china parts, go online to And get this. This should be everything you need to rebuild it. Now you need to MIX your oil. Not use the tank. Google blaster oil tank bypass and just remove the tank as it can tear up the engine badly. The oil pump can send shards of plastic into the crank and cause it to fail. Once you have done this, You can have the engine built, mix the oil 32:1 and insert into the gas tank. After this is all complete it should all be running even smoother then before. For any other help go to

Aug 08, 2013 | Yamaha 2004 Blaster Base

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I have a 1991 KX250, my issue is that when the bike starts to hit top end it starts to spit and sputter. At the time the bike started up just fine didnt have as much compression while kicking it as before...

Not 100% on the KPS but my guess would be a 20 year old bike I doubt if a after market cylinder would be available so more than likely still the original? The stamp KPS may even be Kawasaki Production System logo but again not 100 % Low compression would be a likely contributor to spits and splutters at high revs - some other likely possibilities would be spark plug breaking down at high load, fuel mix bit high in oil, partial blockage in carbi jets may be limiting fuel when wide open throttle.Any of these could give coughs and splutters at high RPM's These days you generally only resleeve the cylinders rather than rebore but if your cylinder is in not to bad a shape then a simple honing tool can clean them up quite nicely If you about to rebuild with new piston kit and gasket kit I would recommend full compressed air clean of the carbi as is all off anyway would only add hour or so to do then with your new piston kit you would be back to full power again
I not certain with Kawasaki ratings but all the Yamaha YZ's I build and race the pistons are only rated for 20 hours use your's would not be to much different I would guess
Good luck with your rebuild from the sound of things you should be back to normal as soon as you button her back up
regards Jamie

Jun 04, 2011 | kawasaki GT650S Sport Comet 650 S...

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Hi, i recently bought a yamaha blaster 200cc quad bike and when i went out on it i forgotten to put some 2 stroke oil in with the fuel tank, and when out on it. now it wont start, please could you tell me...

you probably seized the engine. The piston rings have most likely scored the cylinder wall. At the very least you will have to rebuild the top end. Oversize rebuild kits are available. You will have to have the cylinder bored to a larger diameter to accept the oversize piston kit.

The crankshaft is also lubricated by the oil in the fuel. There is a possibility that the crankshaft is also toast due to lack of lubrication. You will have to tear the engine down (top end) to verify the damage. you could remove the exhaust and look into the exhaust port to view the condition of the piston.

You may be able to find a used engine at a reasonable cost from the internet. Google search.

Jun 03, 2011 | Yamaha yZF15 Motorcycles

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Why does my cr 125cc 2001 smoke when i start it but then clear up and spit oil on to my swing arm and out the exhaust

Excessive oil in the exhaust could be worn out piston rings. Has the bike ever had a top end rebuild? If it's been ridden even moderately in the last 10 years, it's probably due for a new top end.

Mar 01, 2011 | 2005 Honda CR 125 R

1 Answer


Well, I don't know a lot about the electronics on your harley but it sounds to me like either a fuel problem or an exhaust restriction problem.

I had a bike that would not run over 60 miles per hour once. I did everything including a complete top end overhaul. Still would not run over 60 mph, would start spitting back out of the carb. Turned out to a pair of baffles stuffed way up inside the pipe.

I would not think that at 38K, you'd need a top end overhaul. Unless the bike has been severly abused, you shouldn't be thinking of a top end job until 50K at least. Have they done a compression test on the bike. That will tell the story as to whether or not you need a top end job. Still I would not expect a poor top end to cause a problem in a specific speed range. If the top end is in poor shape, it effects the entire RPM range.

I'd suspect a mid range lean condition caused by the electronic fuel control. Take the bike to a shop that has a dynometer and an exhaust gas analyzer. Have them run the bike up and watch the fuel mixture throughout the RPM range. It shoud be between 13.8 or 14.0 all the way though the range as best as I can remember. Now, I'm not an expert on all this but I have seen it done a time or two. The 13.8 mixture is slightly rich, but it will help the engine run cooler and be more driveable. The EPA doesn't like it but so what. I do know that the bikes come set to run very lean from the factory.

Like I said before, I'm an "old school biker" and I work mostly on Evo's and earlier bikes as I don't know much about the computerized controls of todays bikes. So, take what I've said here with a grain of salt. But, I hope it helps.

Good Luck

Jun 04, 2010 | 2005 Harley Davidson FLHTCUI Electra Glide...

1 Answer

Spitting oil

you put too much oil on your engine, 2.8L without filter change. 2.9L with filter change is the recomemded if you exceed you bike will spit the excess oil sometimes the oil goes to air cleaner have your air cleaner check and cleaned

Oct 27, 2009 | 2002 Aprilia RS 250

1 Answer

125 twin recent rebore 1000 miles ago one exhaust

Its a little hard to tell without seeing the exhaust color.Black is oil.brown is fuel.If the bad cyl. still has a good plug it may not be oil.Check the smoky exhaust carby.It may be you do not have complete firing on the bad cyl.MAYBE.Does the bike run well once you get the revs up under load?Check for inlet leaks that may change the fuel mixture on the suss. cyl.There is a few more things but start at these things 1st.After a complete rebuild,these problems do start.I hope this helps

Aug 23, 2009 | 1972 Honda CB 250

1 Answer

Spitting black

I have an 06 cr 250. I used to mix my fuel at 32:1 and it ran fine for a year or so as of late it's been fouling plugs every single ride. I've ridden 2-strokes all my life and know how to ride the powerband but lately its been spitting oil out of every seam in the exhaust. It used to maybe have a couple drops after a ride out the end of the pipe but now its leaking from the connection from the case, the pipe to muffler connection and a lot out the back of the muffler. i switched to 40:1 about a month ago and that's what is happening, i couldnt imagine what it'd be like if i left it at 32:1. I took the carb out and looked at my jet sizes, they are both a size smaller than stock. Any help? Also, the bike is so tempermental that I have to have all my gear on when i start the bike because I cant take my hand off the throttle for even a second or else the bike will foul the plug and die literally within 2 seconds. I know they arent meant to idle but its kinda extreme. my friend has a 2005 cr 250 and mixes 32:1 has no problem, can start his bike on the stand and walk away from it for 5 mins and put his gear'd idle for at least 10 min before it'd die, but he'll kick it and it'd start right back up. I've heard running bean oil would help, but I've also heard it has a tendancy to seize up the rings? any truth in that? ,I would try more gas in your mixture, before you start changing everything. Its all in the way your ride, some people can do 32:1, some 40:1(me), some 50:1. ,,,

Nov 10, 2008 | 2003 HM CRE 250

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