| Author | Message | ||
     Josh |
>For those who have oil puking problems through the head breathers, Buell is encouraging us to make two modifications to the middle rocker box The instructions for The Cure back in '96 advised these changes. I tried all kinds of stuff on my '96 Sporty to reduce spewage incl: barely enough oil, The Cure (incl above mods), different brand of umbrella valves, 98 oil pump and WestTek oil passage plug, KrankVent, oil separators from a big twin, voodoo. Then I bought the Buell (S3) and decided to run Mobil1 in it. To make it easy on myself I switched the Sporty to Mobil1 as well. It never spewed again (unless I over filled the oil). | ||
| X1glider |
Maybe the oil mist is contained better if it has to travel further to get out? More time for gravity to pull the oil back down away from the heads? Seems to me with the small area the air crankcase air had to travel up the pushrod tubes to the head, there was a lot of competition for the oil to drain back down. Maybe there is now more room for each to go their own way. | ||
| Aaron |
I'm not following you ... why does it need to travel farther in the XB? Seems like it's the same path as the XL, out the crankcase, through the gearcase, up the pushrod tubes, and out the breathers, no? The only difference I can see is that putting the check valve between the crankcase and gearcase instead of at the rocker box exit isolates the gearcase and rocker boxes from the vacuum created when the pistons go up. How does that reduce spewage? There must be more to it. Blake's thoughts on pressure wave travel might be the answer, I'm not sure. Blake, I need to check on that vent connection. I'm under the impression it's the same as the Blast, i.e. off the back of the gearcase cover, but I'm not certain. Someone with an XB could go look. | ||
| Hootowl |
It could be that the only reason for the switch was longevity. The reed valve in the case probably hangs out longer than the rubber umbrella valves. It also probably provides a more positive closure than the umbrella valves, reducing the back and forth flow. | ||
| Sarodude |
Something else to think about - though this may be talking out of my ass... The Blast / XB have a pushrod manifold - not 2 skinny tubes. Is there greater volume in the pushrod manifold vs the pushrod tubes? I imagine there would be but I've never really looked inside mine. If so, might the change in velocity affect anything? If that's the case, I wonder if anyone who's installed the pushrod tube kit on a Blast or XB has noticed a change in spewage... -Saro | ||
| Aaron |
I wonder if it has anything to do with trying to pull oil down the drain holes as the pistons move up. Maybe the stretegy is to get less oil out the breathers by scavenging the rocker boxes better? | ||
| X1glider |
I'm just trying to help brainstorm, I've never seen inside an XB, so I'm guessing. Plus I also was visualizing the reed in the S&S case instead of what I read about the location of the reed in the XB. My mistake again. Saro understood my line of thinking since it's one common tube for each bank of pushrods. More area and less pressure and velocity would allow the oil to drain back down easier instead of collecting in the milled path in the rocker box. | ||
| Sarodude |
Duh... Bob - I didn't realize that's what you were trying to say! -Saro | ||
| Aaron |
Okay, Bob, now I understand what you're saying, the larger volume of the pushrod tubes will lower the velocity of the blow-by, thus possibly making the draining easier. Makes sense. But it still doesn't explain the position of the reed valve. The more I think about it, the more I think it has to do with the oil drains for the heads. If I'm visualizing it correctly, it basically makes a circle out of it, pulling oil down the drains as the pistons rise. As the pistons fall it won't generate much pressure on the drains in the opposite direction because the reed valve opens. That's a pretty significant design difference from the umbrella valve setup, where both sides of the drains are connected to much the same place pressure-wise. Seems like it's got to be the reason. I still think the S&S setup is better, it does the same thing plus it isolates the oil pump scavenge inlet from the vacuum of the rising pistons. | ||
| X1glider |
If the reed lets air flow from the crank case to the cambox and not the other way, how would the pistons moving up pull the oil back down the drain. The reed would be closed on the upstroke, no? So how could it create suction to pull the oil down? As for the oil pump, maybe one day we'll have electric pumps so we can reduce mechanical drag and free up a pony. | ||
| Aaron |
The head drains come out in the crankcase, not the gearcase. | ||
| X1glider |
Are the reeds a "normally closed" or normally open" valve? If it's normally closed, until crankcase pressure pushes it open wouldn't the path of least resistance be the drain? Potential spewage? | ||
| Aaron |
Yeah, but I can't imagine it takes much pressure to open that reed valve. | ||
| Blake |
Notsip apparently ain't playin' here no more?  | ||
| Aaron |
Bummer. I think he probably could've made a good contribution. He just went about it wrong. | ||
| Buckinfubba |
Well, I know I am a few days late on this but what can I say. And I didn't read everything everybody said so I'll do my best. As far as "chrome bore Cylinders", no we use nikasil. Now I ain't been here forever, so I will try to find out for certain tommorrow, but no I've never heard or seen our front cylinder breaking or fracturing. Like I said I'll find out tommorrow. As far as the XB/Blast breather thingy. We've been using those rocker tops on the race bikes since they came out on the Blast. Most of the difference that I can make out why they don't spew as much is this... The tube of the breather element that is in the rocker has a different travel path that makes it harder for the oil to get all the way thru. If you had a cutaway view, what you would see is angled ledges and a filter at the top. What these ledges do is let the air thru and discourage the oil from making it to the top. The oil that does then has to make it thru a filter to actually leave the engine. Plus the valve down in the crank case works in two ways with the pressure from the pistons, the up and down motion and all that. I hope this helped a little; I will investigate the cylinder breakage. Seesya, bubba | ||
| Blake |
The answer from Tilley's on the broken front cylinders... Tilley's has never broken a front cylinder on a Buell race bike, nor have they ever run chrome bore cylinders; they use nicasil plated cylinders. | ||
| Timbo |
Today I was able to reroute my breather lines out of my airbox and into a catchcan. This is something I have been wanting to do since I installed the factory race kit. The amount of oil I was getting in the airbox wasn't excessive, but I prefer to keep that out of my intake. I wanted to keep the routing clean and the catchcan as hidden as possible, while still being accessible for draining. The following photos are of what I made and where I located it. This is the bracket that I made out of some flat aluminum stock I had. The holes for the zipties are drilled at an angle to make it easier to replace them after draining the can with the bracket still in place. The catchcan is made from a travel size bottle of shampoo.  | ||
| Timbo |
Sorry got hung up there, here is the image.  | ||
| Timbo |
The next thing I need to do was plug the holes in the breather box where the vent lines were. I used short bolts and flat washers with a thick rubber washer in between to seal it. On the other side is another flat washer and a nylon lock nut.  | ||
| Timbo |
Here is how the hose routing looks now, under the breather box. Very easy and clean with a "T" fitting.  | ||
| Timbo |
Here the bracket is in place and the catchcan is mounted to it (off the bike).  | ||
| Timbo |
And here is a shot of it mounted on the bike. This shot was take in macro mode with the camera on top of the swing arm looking in at very close range.  | ||
| Timbo |
Lastly, here is a shot from the side/rear of the bike. It is fairly well hidden, and as you can see, is well away from the movement of the swingarm.  All in all I'm happy with it, and it only cost me five bucks and change to do (hose and "T" fitting). Timbo | ||
| Noface |
Timbo, What about a filter? I don't see one. I just completed the same task on my 9R. Look in the KV under Engine Breather thread. I used duct tape to cover the holes in the air box as I forgot to get the hardware for that, so I'll have to get that taken care of soon. Your mounting location looks like a great way to go. Mine cost me $13, but I had to buy a pack of zip ties... I was out. L8Tr, Jody S. | ||
| Road_Thing |
Timbo: Looks great! Very clean, nicely done. I can't tell from the pics if this is potentially an issue, but if any of those nuts/bolts/washers you used to block the old holes in the breather box are located downstream of the air filter, you want to be VERY sure that they can't come loose and get sucked through your motor. That event would run your costs up way past $5! r-t | ||
| Torqd |
think that is funny RoadThing...we had a carb bolt back out of the ring and get swallowed into the motor...went from one cyl to the other through the y manifold....jacked up both intake valves and the heads...not fun:-) Good word of caution Road Thing! | ||
| Blake |
I agree. I would recommend replacing the nylon nut with a loctited stainless steel nut firmly torqued. | ||
| Xb9 |
I used automotive silicone adhesive built up as a plug for the holes, that won't go anywhere, and if it does, won't do any damage. | ||
| Rick_A |
I thought any silicone based products were a no-no on EFI vehicles. |
