I was cleaning my bike after a ride this morning and noticed quite a lot of pre-mix appeared to have got around the back of the front fender presumably from going out of the breather tube and down the steering stem under hard braking with a full fuel load (bike is an '06 YZ250 I run at a kart track in supermotard trim).
This got me thinking for anyone that runs the OE breather tube set up - would this pre-mix possibly be washing away the grease in the bottom bearing race?
I've only ridden the bike three times since replacing the steering head bearings and am worried that the bottom one might need regreasing already!
Is this why so many riders seem to run aftermarket breathers like this one:
http://www.ebay.co.u...=item2313a1bffd
Breather tube possibly flushing steering bearings with pre-mix?
Started by
Owen J
, Jun 26 2012 07:03 AM
12 replies to this topic
Posted 26 June 2012 - 07:27 AM
im confused the breather tube is usally for your gas tank when you tip over so your gas don't squirt out, if you got premix on your rear fender its coming from your muffler , try changing the packing in the muffler, if this continues, use less premix or rejet your bike
Posted 26 June 2012 - 08:24 AM
cr250_gus
He is saying it's on the front fender, back section of it.
OwenJ
It makes a mess, but can't wash the grease off the bearing. If you think about it the stem is basically a hollow pipe that the bearing sits on the outside of. That fuel is running thru the middle of the pipe, in one end, out the other. It just empties out on top of the fender below the triple clamp.
He is saying it's on the front fender, back section of it.
OwenJ
It makes a mess, but can't wash the grease off the bearing. If you think about it the stem is basically a hollow pipe that the bearing sits on the outside of. That fuel is running thru the middle of the pipe, in one end, out the other. It just empties out on top of the fender below the triple clamp.
Posted 26 June 2012 - 08:51 AM
adam728, on 26 June 2012 - 08:24 AM, said:
cr250_gus
He is saying it's on the front fender, back section of it.
OwenJ
It makes a mess, but can't wash the grease off the bearing. If you think about it the stem is basically a hollow pipe that the bearing sits on the outside of. That fuel is running thru the middle of the pipe, in one end, out the other. It just empties out on top of the fender below the triple clamp.
He is saying it's on the front fender, back section of it.
OwenJ
It makes a mess, but can't wash the grease off the bearing. If you think about it the stem is basically a hollow pipe that the bearing sits on the outside of. That fuel is running thru the middle of the pipe, in one end, out the other. It just empties out on top of the fender below the triple clamp.
yea your right i mis-read his post,
Posted 26 June 2012 - 09:00 AM
Thanks both for your replies - the more I thought about it I'd come to the same conclusion as Adam but needed confirmation!
Isn't the breather supposed to have a non-return valve on it and mine is possibly broken or is this normal??
Isn't the breather supposed to have a non-return valve on it and mine is possibly broken or is this normal??
Posted 26 June 2012 - 01:28 PM
Budlite, on 26 June 2012 - 12:45 PM, said:
If you have the OEM check valve on your breather tube, remove it. They have a habit of sticking closed causing gas tanks to expand too much and split when the tank gets hot during the summer.
I live in the UK mate so not much chance of that
Looking at it more closely it's just a tube (no valve or anything!)
Posted 26 June 2012 - 01:33 PM
Budlite, on 26 June 2012 - 12:45 PM, said:
If you have the OEM check valve on your breather tube, remove it. They have a habit of sticking closed causing gas tanks to expand too much and split when the tank gets hot during the summer.
No fuel will get on the bearings but i've seen it mentioned here a few times as a concern.
Posted 27 June 2012 - 05:47 AM
The OP's concern is valid with certain bikes.
The TE610 has a steering lock that hooks into a slot in the steering tube. That slot can allow wash water or rain to pass from the inside of the steering tube out to where the bearings are. Yet another lame design element in that bike. If you vented the fuel tank with a hose down the middle of the stem, it could do the same. The vent system is a whole different set of problems, though, nothing to do with the stem.
The TE610 has a steering lock that hooks into a slot in the steering tube. That slot can allow wash water or rain to pass from the inside of the steering tube out to where the bearings are. Yet another lame design element in that bike. If you vented the fuel tank with a hose down the middle of the stem, it could do the same. The vent system is a whole different set of problems, though, nothing to do with the stem.
Posted 27 June 2012 - 08:47 AM
FRECNDY, on 27 June 2012 - 05:47 AM, said:
The OP's concern is valid with certain bikes.
The TE610 has a steering lock that hooks into a slot in the steering tube. That slot can allow wash water or rain to pass from the inside of the steering tube out to where the bearings are. Yet another lame design element in that bike. If you vented the fuel tank with a hose down the middle of the stem, it could do the same. The vent system is a whole different set of problems, though, nothing to do with the stem.
The TE610 has a steering lock that hooks into a slot in the steering tube. That slot can allow wash water or rain to pass from the inside of the steering tube out to where the bearings are. Yet another lame design element in that bike. If you vented the fuel tank with a hose down the middle of the stem, it could do the same. The vent system is a whole different set of problems, though, nothing to do with the stem.
Ironically I do also own an SM610 (the road going version of the TE) and have never really considered this as an issue for that bike! As you point out though it does seem to a problem on the Husky's but luckily I tend to ride it only in the dry and the vent for the tank on my bike is I think the standard small hole in the cap that most road bikes seem to have.
I'll be careful in future whenever I wash it though and might have to think about some sort of plastic or rubber cap for the stem, thanks for the heads up
Posted 27 June 2012 - 02:34 PM
I remember reading abotu this in Dirt Rider years ago. They said the gas coudl wash the grease out. I did nto believe it then, and done now. I suppose anythings possible , but....
On this bike, the top bearing gets water in it and lasts very little time unless you regularly repack it. The newer yz250f seals help, btu its still poorly sealed. I'd be grateful for some premix to wash the water out, truthfully.
On this bike, the top bearing gets water in it and lasts very little time unless you regularly repack it. The newer yz250f seals help, btu its still poorly sealed. I'd be grateful for some premix to wash the water out, truthfully.
Posted 27 June 2012 - 10:19 PM
Owen J, on 27 June 2012 - 08:47 AM, said:
Ironically I do also own an SM610 (the road going version of the TE) and have never really considered this as an issue for that bike! As you point out though it does seem to a problem on the Husky's but luckily I tend to ride it only in the dry and the vent for the tank on my bike is I think the standard small hole in the cap that most road bikes seem to have.
I'll be careful in future whenever I wash it though and might have to think about some sort of plastic or rubber cap for the stem, thanks for the heads up
I'll be careful in future whenever I wash it though and might have to think about some sort of plastic or rubber cap for the stem, thanks for the heads up
TE and SM have two hose barbs coming off the front of the tank. The lower one is just a drain in case you overfill it, to keep the overflow from running over the sides of the tank and getting in the seat, etc. The upper one is the actual tank vent and goes to the evaporative emissions system.
Posted 28 June 2012 - 07:57 AM
The fuel gets on the inside of the steering stem, the bearings are on the outside of the stem. No contact.
