| Author | Message | ||
     Blks1l |
Just a quick question regarding the installation of the grommets, and PCV valves. Should they be installed with any sealant? | ||
| Djkaplan |
I didn't use any. No problems. | ||
| Bluzm2 |
Same here on 3 different bikes. No problems "dry". | ||
| Blks1l |
Well I guess that is what I was looking for. Thanks | ||
| Road_thing |
Has anybody sourced an alternative to the factory PCV's? Something that might be available at an auto parts store? rt | ||
| Bluzm2 |
Tom, Good question, I've not checked but I think I will soon. I have to put a set on my son's S2 before he comes home on leave. I'll take one of mine to the local NAPA and see what I can come up with. Brad | ||
| Road_thing |
Thanks! rt | ||
| Grahamnz |
This breather modification may be of interest.  Fed up with oil getting into the airbox but not wanting to fit a catch can and having to empty it regularly, I had this modification made and I'd rate it as a 95% success. After collecting the bike from the shop I took it for a 350km ride through the rural Wairarapa valley – my local day-riding area. It was pretty hot for this area(30C at times)and I gave the bike plenty of work to do over the Rimutaka mountain crossing – my local racer-road with a 555m summit - and on the country back roads, with many short bursts up to 150kph. On arriving home I did a hot-check of the oil and could detect no change from the mid point it was at after the last similar ride before the breather modification. When everything cooled enough to touch, I opened the airbox and was absolutely delighted at how dry it was. The missing 5%? There was just a trace of oil misting on the airbox top above the rear (now right) breather tube, but nothing of any concern. Nothing anywhere else and no trace of oil being sucked into the velocity stack. What the modification provides is a much longer breather hose from the hotter rear rocker cover PCV valve. The plastic – Harley Davidson – hose joiner must also provide some further restriction. Such an easy mod for the factory people to incorporate were they to hear of this successful experiment. Maybe my dealer will tell them. | ||
| Grahamnz |
To help understand why my mod was made rather than go straight to a catch-can, this is my take on it: All engines produce water vapour which will condense upon contact with cold surfaces. That's why condensation forms in mufflers after a cold start and in catch-cans with their air-cooled surfaces. Engines tend to go best in cool, misty conditions when they thrive on a mild form of "water injection" as used to be a ploy to boost the power of piston-engined aircraft. Having internal engine water vapour injested with the intake air is probably no bad thing. On the Buells the PCV valves on the rocker covers are meant to allow air to pass to the airbox but to baffle out most of the oil mist so that it drains back to the crankcase by way of passages provided for the purpose. Because the rear cylinder runs hotter than the front one, there is likely to be more oil misting form in the rear rocker box. Couple that with a very short hose from the rear PCV valve to the airbox and the way a 1200cc engine breathing through a rather small airbox must suck like a whale calf while trying to get air from anywhere it can, and it's easy to see why oil mist is blown and sucked from that breather but not noticeably from the front one. That's why the longer hose was fitted on the rear cylinder's breather. Much longer than the front one even. When engines are worked very hard, such as when racing, and especially in hot conditions, the standard breathing systems can be unable to cope, hence the need for catch-cans. What disappointed me with my bike was the way the rear breather couldn't cope even in normal use. The initial 350km after the mod were intentionally closer to racing in hot conditions than my normal road riding, so I was delighted at the improvement. I'm possibly wrong with all that. I'm often wrong. That's why I tend to suck things to see how wrong I am! Graham 2007 XB12Ss | ||
| Gotj |
Grahamnz, Thanks for posting your modification. I like the concept and may install it myself. The picture raised one question in my mind. Does the extra breather hose from the back cylinder have enough slope for any oil mist condensation to flow back to the rocker cover? The hose joiner would be one place for oil to collect and then possibly "spurt" into the air box. This may not be a realistic issue but if I do the mod, I will put the joiner farther back in the line if possible. Let us know what you find when you check again after many more miles. Again, thanks for sharing. | ||
| Grahamnz |
Gotj The joiner position was dictated by the retention of the very short original rear breather bent hose. The longer rear breather hose does generally fall from the joiner back to the PCV valve. When next I remove the airbox top I'll report my findings. I'm contemplating the addition of a Rob Crins right-side airscoop which should cool the rear cylinder better, which should also reduce oil fuming in the rear rocker cover, which should give the breather an easier task. | ||
| Grahamnz |
Now 1500km since the breather mod was made, so about time to look into the airbox again. Despite seeing 6,000 on the tacho quite frequently there was absolutely no sign of oil misting }coming from either breather hose. OK, the inside of the rear cylinder's breather tube was not bone dry like the front one, but no oil contamination evident on any other surfaces. That's now got to rise to at least a 99% success score. So glad I didn't go the catch can route without trying this mod. Things which may have helped are that I keep the hot-checked oil level no higher than two crosses from max on the dipstick, and always allow the motor to warm while just idling for a few minutes before riding off. That also ensures that oil which has drained down from the oil tank has time to be scavenged back to the working level. | ||
| Gotj |
Thanks for the update. Time for me to copy your mod. |
