Excess sludge in YFZ450 intake box???

[mrobinson]

After about everyother ride I'm noticing a lot of oil/water collecting in the bottom of my intake box. I've got an 04 YFZ450 that has White Bros Exhaust, K&N Filter (box open), and is jetted.

Any ideas what could be causing this sludge build up? Is it normal to have to clean that box out after every ride?

Any help would be appreciated...

[predator dad]

I had the same problem and everyone said it was normal. I am still a little worried about it though. I just keep a close eye on it and wipe it out if I see any oil in there.

[atva_63]

This is normal. Go to the hardware store and buy a few feet of hose and run a new crank case vent hose up around your motor and run it down in front of your radiater and back to the ground.
this is the only way to keep it from spitting oil all over your bike.

[mrobinson]

Thanks for the responses. I just wanted to make sure there wasn't something internally wrong with my YFZ that my lack of attention would make worse.

The hose suggestion is great. I'll get it done b4 the next dunes trip.

[Ride1Rob]

That's not NORMAL! That bikes don't do that when you purchase them and when it starts doing it that's a problem. When was the last time that you had a topend rebuild? Mine did it and when I tore it down to check it my piston had a crack in it. This was allowing air to be pulled down into the crankcase. The air and oil would go up through your crankcase hose, through the blackbox under your left rear fender, and into the hose that connects to your intake box. It's trying to push that access air out. It could also be because your rings are going bad.

[atva_63]

A cracked piston will do more than give you blow-by. You should of been able to notice a difference besides the oil in your airbox.
Ask any top racer or any top engine builder they will tell you the same about the hose. I have had 4 different yfz's they all had blow-by.They were not wore out, I tear my motors down every 10-12 hrs and re-ring or replace anything that needs replaced

[Ride1Rob]

Originally posted by atva_63
A cracked piston will do more than give you blow-by. You should of been able to notice a difference besides the oil in your airbox.
Ask any top racer or any top engine builder they will tell you the same about the hose. I have had 4 different yfz's they all had blow-by.They were not wore out, I tear my motors down every 10-12 hrs and re-ring or replace anything that needs replaced

Of course it will do more as time goes on. The crack gets bigger thus leading to a break which can either shut the bike off due to lack of compression or break and all hell break loose inside the motor. That's obvious! But like I stated, that's one thing that can lead to oil being in your intake. I've had (1) YFZ that I bought in February of 04 and my bike has only done that when it was a compression issue from either rings not sealing correctly or a cracked piston. I've done 1 complete motor rebuild (Currently rebuilding it the 2nd time) and 3 topend rebuilds in those 4 yrs. And if you're rebuilding that topend EVERY 10-12 hours and still having blowby you must not be breaking it in correctly :ermm: .

[250r4life]

are you talking about in the airbox, under the filter?

i never have oil/water chillin in there...

[atva_63]

Yes deffenetly a cracked piston will couse alot of blowby.
My First incounter with blow-by was a 04 I had baldwin build for me. I thought something was wrong in a bad way. I called him up and he said (laughing)" Damn yamaha. Most of them do that when run hard or raced". I usually break in my motors on back compression. Never keep a steady throttle and don't over rev. I have never let the problem bother me becouse it is so common. I know people who replace pistons every 10 hrs. I am not talking leasure rideing. I am talking full blown race motors. I always thought a gasket kit and rings are cheeper than blown motor IMO

[mrobinson]

Okay, so the oil in my air box might be normal (as further investigation and other posts have also indicated), or I might have a cracked piston (or other serious issue) and getting abnormal blow-by.

Since the quad has never really been raced hard and also had an easy break in, I'm going to take the more optimistic stance (and initially cheaper) and approach it as just normal overflow.

If anyone is interested I did find some additional help suggesting a vent hose catch can solution. Here is the link:
http://www.kawieriders.com/forums/index.php?showtopic=13286&hl=oil+catch+can