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Engine breathing V7

elkgrichard

elkgrichard

High Miler
Joined
Mar 31, 2014
Messages
551
Location
California
So what are the signs of an engine that is not breathing well enough.

Reason I ask, sometimes when I give the bike throttle, I get some slight knocking sounds, sounds like marbles in a can, very slight sound and not very pronounced, and then it goes away as the rpm's come up. Is this low octane, clutch noise, transmission noise. WTF is causing this, or maybe bad breathing? I'm using high octane top grade fuels so I know this is not pinging. It almost sounds like it's coming from the clutch maybe. So are these clutches known to rattle like this a little bit when you start off or give it some juice. It sort of comes and goes. It's mostly at the lower rpm's like below 3,000 rpm's. It sounds like the clutch to me, just want to find out if this is a characteristic of this motor or not.
 
Turns out it was the headlight bucket vibrating. Go figure.
SOB is falling apart with the inside plastic rim peeling away.
 
vagrant said:
3500 min. rpm
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Thanks for that , I have finely figured that out on this bike. Better to keep the rpm's up on this thing. Fifth gear is like some sort of overdrive gear to be used only on the freeway at like 75 mph.

It turn out to be the headlight falling apart. Very cheaply made bucket, POS
 
When I lived in Germany in the 70's, my German friend always told me Americans did not understand driving European vehicles. He said we lugged them too low and we should be staying in the upper RPM band. Du shift ven you vant to go faster. Never adopted his redline philosphy, but he may have had a point. He said the engines balanced better at higher rpms. He drove an Alpha on four wheels and had a classic DKW for a 2 wheeler. Glad you found the problem.
 
Hawghauler said:
When I lived in Germany in the 70's, my German friend always told me Americans did not understand driving European vehicles. He said we lugged them too low and we should be staying in the upper RPM band. Du shift ven you vant to go faster. Never adopted his redline philosphy, but he may have had a point. He said the engines balanced better at higher rpms. He drove an Alpha on four wheels and had a classic DKW for a 2 wheeler. Glad you found the problem.
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I work at an Indian dealership in socal. This is one of the top problems people have when they come in saying their bike isn't running right. They don't run them at high enough rpm's and end up getting a bunch of carbon build up in the heads. I have guys telling me that they are in 5th gear doing 35mph!!! and never go above 35/4000rpm's.
 
I've learned to run the crap out of my Harley's and they make great power and run awesome. At 3K they are making the power they want to make. Do not lug a bike. No bike is done a service by lugging it.

I was going to suggest you had a spark knock problem. Glad you found it in the headlight bucket.

Now go ride that darn thing and ride it like you stole it.

Remember RPM's!
 
With the breather system set up the old fashion way, to the atmosphere. I can now ride at higher RPM's without sucking the oil out of the motor, via the airbox vacuum causing me headaches.
 
YUP. Thanks to your post and I've done the research, nothing wrong with going out the back fender with a hose. No issue at all with pressure building up in the motor. I'm no longer losing oil, the slight mist out the back amounts to nothing. Maybe a small drop on the ground once in awhile. Easy to live with.

All these companies are having trouble with this because of venting into the air box or air cleaners and then the vacuum pulls the oil out of the motors.

All driven by EPA and government waste.

Somebody tried to say the motor would not breath good enough. Motors breathed for years into the open air without problems.
 
elkgrichard said:
With the breather system set up the old fashion way, to the atmosphere. I can now ride at higher RPM's without sucking the oil out of the motor, via the airbox vacuum causing me headaches.
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I've got a 2004 Breva 750 that seems to be getting a pool of oil in the airbox. Also weeping oil film at almost every joint in the crankcase & bell housing. May be over-pressure in engine to blame.

Anyone got a link and/or diagram showing re-routing of breather tubes to atmosphere? What do you do with (or how do you block off) the one-way valve in the hose from the airbox to the crankcase?

Thanks,

'Geezer
 
I found a bolt metric that I used to block off the crank case return hose fitting. I just had that size bolt in my junk can.

Just take the two breather hoses and put them on a Y and then hose it out to the back fender. I pulled all the other stupid hoses off the airbox and vacuum caped everything. 4 total......2 drain to sump and 2 that vented the heads.

I don't have pressure building up at all and no more oil in the airbox. That oil in the air box will plug up the oil separators and then you get pressure building up in the heads after awhile because it can't breath properly. Those oil separators are in a separate compartment sealed in front of the airbox, you can't access them to clean them. Other then maybe spraying it out with WD-40 from that hole that goes into the front lower inside of the airbox, or the inlets outside front of the airbox. Either way the system is frocked up, and it's easier and less hassle to go free air out the back fender with this thing. I think you ultimately end up with a less restricted breathing system. You will get the occasional drip out of the hose out the back fender, but it's very minimal and easier to live with then the current complicated system. The only reason you get the drip because of the poor design with the separator system inside the heads. It's a common issue with most bikes these days.

I've got my 2007 Bonneville breathing the same way and route the hose over the chain to lube it nicely. It's about the most perfect chain oiling system bar none. Just the perfect amount of oil mist to keep the chain happy. Replaced the chain after 35,000 miles and the sprockets looked perfectly new, just flipped those around and good to go.
 
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What about using a catch can on that line coming from the valve covers? I've seen some pretty small ones for motorcycles.

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That would also be probably even a better option yet, because you would not be dealing with that occasional drip. Just dump that thing out now and again. That's still another option, easy to add or subtract with this thing.

My 73 Bonneville had the fender hose, can't remember if it ever dripped or not. I never paid it any attention.
 
My bike is in the shop getting a bell housing leak addressed. If the oil is coming from the rear main crank seal, I think I'm going to follow your lead and go old school with the breather.
 
I've had issues with other bikes along these lines and have always found it better to just vent to the air. These vent to airbox/air filter systems just don't work as advertised.

I just can't deal with the mess inside the airbox, fouled plugs, crud building up inside of the combustion chambers. who knows what else could be going on with these insane venting systems.

I wonder if this stock vent system could be the cause of oil leaks?

The reason I say that, because a couple places that weep oil mist on my engine, are no longer weeping. They have remain dry of oil mist after washing the bike. Just something I've been noticing after I last wash the bike.
 
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pokeyjoe said:
My bike is in the shop getting a bell housing leak addressed. If the oil is coming from the rear main crank seal, I think I'm going to follow your lead and go old school with the breather.
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Joe,

Go over to the wildguzzi forum, they have a breather thread over there. One guy with a racer did a really nice set up with a catch can, he even incorporated the oil return line from the bottom of the can so the oil returns to the sump. All hidden behind the left side cover because he removed the airbox entirely on that bike. Look to me like he welded the bottom spigot onto the bottom of that catch can. Very clean job, I may go that route, wonder how lean removing the airbox would make the bike, I'm sure the fueling system would need some type of a new download. Wonder what download he used?
 
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