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Yahama V Star 1100 with oil in the air box.

I bought a 2003 V Star 1100 with about 40k miles.  The bike ran very well but back fired, mainly on deceleration.  This was anoying me so I took it to a local shop.  The bike had after market pipes (unknown make) and I was told that the carbs needed to be jetted. I asked him to do that and requested that he check it over and fix anything else that he thought should be done.  He worked on the carbs for me, replaced the exhaust gaskets, and one of the valve covers. (Cost of a little over 600.00)  There was no more backfireing and the motercycle seemed to be runing very well for about 400 miles.  One day I went to the store and it was running fine when I got back home and parked it, but a couple of days later I started it up and it was running on just one cylinder.  I rode it back to the motorcycle shop (about 5 miles) to have them look at it.  They listened to it and said they were sure that it was either a bad wire or a coil, and asked me to leave it with them.  I checked back about a week later, he showed me where it had oil in the air box and said that the only thing it could be is a bad ring, and told me that I was looking at about 1500.00 to fix it.  The motorcycle was running fine, did not smoke, wasn't burning any oil, and did not seem to have a miss.  When it was worked on there was obviously no signs of a ring problem.  As far as I know they havn't done a compression test or anything, just saw the oil in the air box and made their diagnosis.  Could this be something else, or even possible something caused by something they did that may have caused the problem. 

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23 Comments

have a look at the oil level sometimes if oil is on the high side it can vent into the air box

I check it often, but have not had to add any oil since I bought the bike. Tell me if I am wrong, but I was thinking that if something caused a cylinder to not fire at all, that the cylinder would not warm up enough for the rings to be effective. Although I did only ride the bike about 6 miles with the cylinder not working.

Buy a compression gauge and test the cylinder yourself. According the service manual pages 3-14 and 4-15 is should be between 128 psi and 156 psi.
You might have a stuck or improperly seated valve which would not allow proper combustion.

I have the last of the 1100 with 13000 km on the clock and it also gets oil in the air box. Mine is under warranty still but all tests so far have found no issue. Not that I actually believe that. It is possible that the PCV is not working correctly, and this will be my next line of testing on mine. Il keep you informed what happens as well

Beachy, how about fitting a small filter from SCA onto the end of crankcase breather hose and stop it from feeding back into the airbox. The only reason I can see for the designers to do that was to meet emissions rules.

Yeah that is pretty much the case Steve, but hey this bike is new and under a 5 year warranty considering I have only had it 12 months now it shouldn't be doing this. It is a sign of ring blowby at the worst case but it could. Just be vapour collecting. I'll be calling in today to talk to them about it and hopefully take it in tomorrow

that just what happens with the 1100's

There is nothing wrong with your bike engine all get oil in the air box it is a build up from crankcase ventilation thats all. Every 10000ks just give it a wipe out. Have been doing this on 2 from new vstars over the last 8 years. You are good to go. There is no need to rejet on aftermarket pipes just run 98 octane instead of 91. Now if you were to feed it more air then you could rejet. Do you want fries with that

Sorry Dennis, I can't agree with that. My training as a mechanic tells me that any oil in the air box is a sign of the rings letting an amount of compression build up in the crankcase. Mitsubishis were notorious for it and I'm disappointed that the 1100 is doing it after 13000 Kms. I've had several VStars and this is the first to do it. The engine breather plugs into the back of the air box so it is possible that there is oil vapour build up because the PCV valve isn't working correctly and that is what I am hoping for. This was also confirmed by Yamaha today.

there is always some crankcase build up and it has to be vented somewhere. I wouldnt be tearing down an engine from a bit of vapour oil. I would be a ripp off mechanic if I was telling ppl go ahead spend the money

That is my whole point Dennis. Modern engines have a positive crankcase ventilation system PCV and that should eliminate the build up in the air intake. My engine is under a 5 year warrantee by yamaha so I don't give a rats if they rebuild it. As long as it doesn't leak oil al over the engine and fill the air filter with oil. And for the record, I never once ripped off anyone when I was operating my mechanical business. In fact I was often referred to new customers because I didn't.

Noticed a little oil in left side air box on my 06 RSTD 1300. Guess I have an idea where to start looking now.

I have oil getting into my carb I believe it's the rite side of the carb

What can I do cause it's caused smoke to come out of the bottom pipe

When I ride I have a thin coat of oil on th right side of my bike Fi checked all the bolts and I tightened everything to speck and I still get oil only on the right side . Can someone help me out please

Just about all the cruisers I have had have got a little oil ventillation build-up in the air Box it is a very common issue you could replace the PCV If that is really what you want to do but about 90% of after market ones are crap. There isn't anything wrong with your bike man . I'm at 50000 miles on my 2000 the star 1100 With after market Cobra pipes and that motha runs like a champ. Wipe it down every so often keep a fresh Air cleaner and ride

Oh and I forgot to add, a lot of times this is common On the 1100 v stars When you check your oil make sure your bike is standing upright straight and that your oil level is closer to the lower level indicator not be higher indicator just below half and between the 2 indicators of this will correct that ish you and miss cases. Convectional oils cause this problem as well make sure using a good brand I use Royal purple

Ridgerunner What did you find out mine is doing the same left side box

Add oil getting to my airbox

Run both the compression test and a leak down test. The combination will let you know what shape the engine is in and pay attention to the advice on checking the oil.

Only 6000 miles air filter completely soaked not just mist in box .Bought used last year 4500 miles 2007 year.

My 2003 vstar 1100 , has oil leak . it appears to be coming from the valve adjustment covers . Is this a common problem with these bikes ?

I just pulled my air cover filter off of my 2004 1100 V-Star and I've got oil in the bottom of my box it dripped out about o like a quarter or maybe little less than a quarter of a cup. Is this normal for this to happen the bike only has 12 thousand miles on it

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