Ventilation Valve

[blackbeard]

What is the Ventilation Valve, on the newer Ruckus's. I don't have one on my 03, but it is on the 09. What does it do? Why isn't it on the earlier models? Thanks.

[Dandy Dan]

Good question. Basically, when the Ruckus was initially designed, the only ventilation the engine had was a single hose coming out the front of the engine. This hose ran from the top of the valve cover back to the airbox and it vented fumes from inside the engine to the airbox so they would then enter the combustion chamber and be burned (thus lowering emissions). This is preferable than simply venting the engine to the environment.

However, as you can imagine a single vent hose does not provide very good ventilation because the air exiting the engine is sharing the same hose as the air that is entering the engine to replace it. Accordingly, fuel fumes (that leaked past the rings or valve seals) would linger in the engine instead of venting quickly. These fumes would then contaminate the oil and reduce it's lubricating properties. Ultimately, this lead to a high rate of crankshaft bearing failure as these bearings weren't lubricated properly once the oil degraded. It's unfortunately common for 2003-2005 Ruckus's to experience crankshaft bearing failures after 7000 miles or so, depending of course on how often the oil is changed and what quality of oil is used.

My first Ruckus (a 2003) had the crankshaft replaced at 12,000kms (7500 miles) under warrantee for a different issue (I bungled the end of it where the variator slides on) and then it experienced this common crankshaft bearing failure at 27,000kms (16,000 miles) and then again at 34,000kms (21,000 miles) and the current owner told me it needs another crankshaft now at 42,000kms (26,000 miles). I sold this Ruckus after the 27,000kms failure. I was quite religious with my oil changes (every 600-1000 miles) which got me 15,000kms (9500 miles) on a crankshaft whereas the new owner is less diligent and he only got 7000kms and then 8000kms on his crankshafts.

So that's basically the deal with the early Ruckus's crankcase ventilation. Thankfully Honda addressed this problem for the 2006 model year. Basically, they added another ventilation hose (to the top of the engine at the timing chain tensioner) which is strictly an entrance for fresh air to enter the engine case, so now the original hose is just exit only. This new system should provide much better ventilation in the engine and indeed, reports of crankshaft bearing failures are way way down.

In addition to the new entrance hose, Honda added all that stuff hanging off the frame as part of the new ventilation system. I'm not totally sure what it all does but I believe it's mainly a one way reed style valve so that air can only enter the engine through this hose and not exit.

If you think about the volume of the crankcase, you'll realize it's constantly changing as the piston moves up and down. As the piston moves down, it decreases the volume of the crankcase and then as it moves back up the volume increases. If you unplug your engine ventilation hose and feel the flow, you'll see the air is pulsing as a little gets pushed out and then sucked back in. Because it's the same hose that is breathing out and sucking in, it does a poor job of exchanging the air....just like how a snorkel doesn't work for a diver if it's too long.

So this new system essentially sucks the fresh air in the new ventilation hose as the piston rises up and the volume of the case expands. Then when the piston comes back down, it's reducing the volume of the case so the engine exhales but it has to exhale through the original hose because of the one way reed valve in the new hose.

So basically that's it, what I'm not sure of is whether they added a one way valve to the original hose as well, so that air could only be exhaled (and not inhaled) through this hose. If they didn't, it seems that the engine would inhale air through both hoses and then just exhale through the original hose, which would be less effective but it would still be exhaling about twice as much air as it's inhaling through this hose so the system would work. I don't think they did add a one way valve in the original hose but regardless, the new ventilation system works much better than the old one.

As the owner of a 2003-2005 Ruckus, you need to be aware of this problem so you can do your best to minimize this impacts. I strongly encourage you to change your oil every 600 miles to help your crank bearings last as long as possible. If they do fail, you'll need a new crank from Honda (which comes with new bearings on it) for about $125 and then you can rebuild your engine yourself in about 8 hours (if you know what you're doing) or twice that long if it's your first time. Either way, get the service manual. If you aren't up for doing this job yourself, you may as well sell the Ruckus to someone who is because getting Honda to repair it will cost you around $1000 with all the labour involved.

[blackbeard]

Thanks for the reply. Which brings up another question. Can you use synthetic oil in the Ruckus, after breakin, and wouldn't synthetic oil solve the problem of oil degradation?

[yaris]

the service manual say to use synthetic, this is what I use and I never had problem, and my ruckus have 14380km and I ran it with not enough oil for 200km and ran it out(or almost) of oil because of a bad crankshalt seal on the variator side

[Dandy Dan]

Sure you can use synth oil after break-in but it won't solve the oil degradation problem....it'll just slow it somewhat. Obviously a better oil can stand up to more contamination but any oil is going to suffer in these harsh conditions which is why frequent oil changes are a must. FYI, I always used synthetic oil in mine after break in....either Mobil 1 or Amsoil.

[sr50r]

Dandy, I was eyeballin' the parts diagrams on ronayers.com and there's a part no. for the crank bearings alone, what's up with changing the entire crankshaft?

Also, your words sparked more ideas in my head as for how to better the vent system. I had the idea of implementing an automotive-style PCV system, but was too focused on automotive engine where the crankcase volume doesn't really change, to consider that the ruck's crankcase acts like a big air pump and doesn't need engine vacuum to suck the fumes out of it.

[tmcRuck]

I suppose when the bearings wear out they cause catastrophic damage to the crankshaft itself, requiring both to be replaced..

[budwyzer]

Hello, I want to ask some questions about crankcase ventilation and know this is an old thread but after searching for days hopefully someone can help. I have a 2005 honda Metro. I would like to increase crankcase ventilation on this older scooter. I have seen some info about changing the Cam Chain Tensioner with a later model, run a hose to a car PVC valve then run to another (gas)filter. It seems Ruckus owners are more knowledgeable than Metro owners or I'm the dummy that can't find any info on Metropolitans and venting 2005 and older scooters. My question is will a 2006 Cam Chain Tensioner work on a 2005? Can I use a 2006 Ruckus Tensioner or should I use a 2006 Metro Tensioner. Thanks for any help or recommendations on increasing the bearing life on this older scooter, bought it used with 2.5k miles. I have only put 50 miles on it but doing my first oil change now. Thanks in advance.