yfz crankcase breather hose???????HELP!!!

[mxpimp2000]

ok, i have a 06 yfz450 and i race motocross ONLY other than practice at other tracks, everytime after a race or practice i clean my air filter BUT i have a mess of oil from that freakin black box that the crank case hose and valve cover hose runs to spits a hell of alot of oil all over my air filter and ruins my foam filter not to mention the mess it leaves on my swingarm from the air box drain port i've seen that a some people have done away with this box and ran the tubes down in front of the rear shock below the lonkage and let it run out on the ground instead. ive also heard NOT to do this and some say YES do this i want a postive answer from someone that knows the pros and cons from this mod will this hurt my engine any way shape form?? do i need to get a crankcase filter and put on the hose or a PCV valve found on car/truck engines valve covers?? i need a 110% YES OR NO WHAT SHOULD I DO??

[Ride1Rob]

You can eliminate the box and run the hose freely. Run a filter there just to be safe. If it's doing this real bad you need to get it fixed (piston & rings). The rings aren't sealing correctly and are letting air from your intake get by. It's then pulled down into your cases where your oil is. This pressure has to be released and this is what the tube is for. This could also happen if you have a cracked piston. The bike still has enough compression to run but as the crack gets bigger, either it'll stop running, or you'll have the piston fall apart inside the motor (Not good). This normally happens from being too lean or too much time on the topend. I run my bike on the lean side for the performance so I rebuild my topend every year.

[mxpimp2000]

soo do i need 2 filter for both hoses or just one?? i race my quad about 2-3 times a month i give it everything its got wide open every lap, and the motor is all stock since 2006 never rebuilt but does get routine maintence valves set and oil changes it has a full exhaust, UNI filter, jetted,and the cam mod. it dosent spit oil out when u just ride it but when i race it the oil is a mess. the top end seems too good to be going bad it starts great and freakin screams everytime i ride it i dont know if my piston and rings are bad since i have no trouble out of it, where do i need to route the 2 hoses and stick the filter on at?

[Ride1Rob]

Just bc the bike screams doesn't mean that the topend doesn't need a rebuild. As you're applying more stress on the motor (hard riding) the more air it'll suck down into the cases. If you've been racing it the way you say since 06, then it's past time for for the topend to be catered to. 300hrs of putt riding are alot better than 100hrs of pure racing.

You only need one filter for the crankcase breather hose.

[mxpimp2000]

i just got the bike back in end of april first of may and got it from someone else it was bone stock never raced just rode trails and stuff he told me when i got it that it had been given hell everytime he rode it but the bike looked mint condition no wear on nothing looked brand new and for the deal i got i couldnt pass it up cuz i traded my built 426ex for it that was bad *** but i only had bout 2300 in that bike so i came out ahead the yfz is 100% mx setup now and i just started racing it this may till now, i stopped by my mechanix 2day to pick up some stuff and ask bout this mod removing the box and he said yes but dont put a filter on it bcuz then it would cause it to blow oil real bad cause of the blow by and stuff i trust him he is a well known guy in atv racing kenny cornwell owner and founder of rocky ridge racing he built the 1st aluminum 2009 yfz450 frames u can search on the forums and find the thread about the 09 yfz450's but back to what i was sayin he did tell me that i should go ahead and rebuild my topend and that u was right on the piston and rings could be goin bad and causing alot of the oil to blow out that hoses. thanks for the help man i appreciate it man

[Ride1Rob]

Putting a filter on the end of that breather hose is not going to cause oil to blow out of the hose. It's going to do that regardless b/c of the rings.

[mxpimp2000]

yes it will blow oil either way it goes but he said that itd blow alot more with a filter on it cuz it wouldnt have the proper flow he said he had put a filter on his bike he ran at reb bud and it spit over a half a court of oil he removed the filter and it quit..

[Ride1Rob]

Originally posted by mxpimp2000
yes it will blow oil either way it goes but he said that itd blow alot more with a filter on it cuz it wouldnt have the proper flow he said he had put a filter on his bike he ran at reb bud and it spit over a half a court of oil he removed the filter and it quit..

That doesn't make sense my man :ermm: . Think about it... if it doesn't have the proper flow, how would it flow more with the restriction from the filter. If anything, the filter would slow the flow. That'd be like putting a towel over your mouth and nose and saying that you can exhale better with it than without it. With that being said, the breather is not a place where you want flow. It's a place for excessive compression in the cases to escape. Along with the air, oil is pushed out. You don't want free flow of anything from that tube at all so a filter there is not going to make your bike run any better or any worse. I've been running one on mine for 3yrs now :ermm: .

The reason why his bike stopped leaking the oil wasn't b/c he moved the filter. It was b/c he had released so much pressure from his cases by loosing so much oil. Once it gets down to a certain level the pressure levels out. It may still spit, but not as bad...

[mxpimp2000]

i understand man lol but i may put a filter on it later when i get a chance but im sure it wont hurt not having one for the time being since the yzf450 dirt bikes have open hose coming from the valve cover and just drops down below the frame rails but thanks for the help man