Bonneville America Forums Forums Technical Forums General Tech Crankcase Breather

Ok, so I've been having this problem ever since a few months after I took out the air box. It seems that no matter what I do I just cannot get oil to stop coming out of the crankcase breather. When I first took out the air box there wasn't much of a problem. A few months later, for whatever reason, I've been blowing oil out of the breather. At first I thought it was too low so I lengthened the hose and moved the filter right up under the seat. It helped a little but didn't solve the problem. So this winter when I had my bike apart I decided to route a new hose all the way so that the filter sits up near the ignition coils. seemed like a good idea, I figured that the oil wouldn't travel that far... I was wrong. I took it out yesterday for my first long-ish ride (120 miles) since my winter upgrades and when I got to where I was going there was oil all over the front of my engine, coming from the breather filter. Now I'm fairly sure that it's not normal. If I'm wrong feel free to correct me. Any suggestions on possible causes, fixes, solutions to this problem would be great.

Mine blows out prety good also

Tim,
Setting the filter above the engine will cause the hose and filter to fill and/or plug regularly. I routed my hose so that it exits below the frame where all the other vent hoses are. This way, as it blows out it vents down onto the road as I ride. I also have a KrankVent installed so it never breathes in, just out as the pressure builds during cylinder falling.
The KrankVent touts itself as a HP increaser, but I did 3 test dynos with and without the KV, and there is absolutely no difference.

So why does oil leak out of there? And what would be considered a "normal" amount to leak out? Maybe I'm beating you to the questions Tim.

Is it possible that your oil level is high or do you actually have an excessive blowby problem. I have driven mine for miles on end WFO since 2003 and have never seen any oil come out of the crank vent except one time when I overfilled it during an oil change.

Kit's right, If you haven't checked your oil level, do so. Too much is no good.

What viscosity of oil are you running? How many miles on the bike? Filtration type and do you drive on any gravel roads???

Blowby is usually due to worn or improperly seated rings.

You might want to perform a compression test to see if things are normal. First test dry and then test wet (squirt oil in cylinders to coat rings). If there is a large difference and you aren't up to spec, the rings could be worn or the cylinders scored.

Answers:
Right now my oil level is right in the middle of the two level marks which means that yesterday when this was happening it was a little on the high side of normal but still with in spec
The oil I'm using right now is Shell 30W dino oil for breakin purposes (I just installed my big bore) I don't think that it's a compression problem but I guess it wouldn't hurt to check. The reason I don't think it's compression is because it happened before my big bore and it happens now, the chance of the same problem being caused by the same issue both before and after boring the cylinders, and replacing the pistons and rings is kinda slim. It's possible that because I'm still breaking in my motor and my rings aren't fully seated it's adding to the issue, but being the root cause, probably not, but like I said, it won't hurt to check.
Filter: Puralator pure one
Gravel Roads: No, the roads here suck because it is the north east and that's just how roads are in the north east but no gravel

How long have you been running the 30W dino oil? A little thin for the bike. With the new rings installed blowby should actually decrease as the engine breaks in unless the ring end gap was set too wide.

If you have enough miles on it for breakin, switch oils to the 20-50 and run it hard.

I too have seen oil blown both into the air box and once, after a long, fast run, quite bit came out on the ground from the vent tube. I know the bike wasn't overfilled and I have always used 20-50. Triumph tech was no help and it hasn't happened in the last 10,000 miles that I know of.

I have this problem also. I had oil in the air box before i removed it and installed the freak. Now the filter gets wet but does not seem to leak excessively. I have checked the level of the oil and it is within the specs. I guess after reading here it is a problem others have also.

I see a small dribble of oil after nearly any hard ride at speed (30 miles, freeway). It comes from the vent tube, and is just a few drops (a little looks like a lot).

My crankcase is not overfilled, and I have never had to add a drop of oil in over 50k miles. She just "marks her spot".

Least of my worries, unless somebody thinks it is or should be correctable.

No sweat Bw, it is normal. Mine gives off a drip or two on occasion of a long hard day of playing.

It is just a little blow off from the pressure that builds up under the pistons as they come down after firing. The blow off is designed to eleviate the excessive pressure builup in the lower case of the motor. It helps to keep the case sealed up and prevents blowing out gaskets as well.

Not a worry unless you get a lot, all the time. Then most likely it is over filled with earle.

My bike had started using oil on trips. It turned out it was in fact coming from the breather hose to the airbox. I was using as much as a pint on a 500 mile trip. I always kept the oil in the middle between the lines.

My dealer thought it was the rotary breather or seal which have been known to fail. BUT, when I took it in they realized when my casing was replaced (starter) I now had the new style breather (no rotary breather).

They called Triumph who suggested running at the bottom line and see if it uses as much. My dealer said let him know after the next trip if it is better. Triumph claims it may be "seeking it's own level". My dealer said that if it still is using significant oil, he would pull the cover and see if the holes that allow the oil to fall down are clogged or maybe enlarge them. The new versions have a labyrinth like channel with holes that should allow the oil to fall and not blow out the breather hose. I'll know more after my trip to New Orleans this month.