| Author | Message | ||
     Notsip |
This is not going to be solved in just one posting, so be paitent and we will eventually get through it. First of all I would like to take the time to say that I have been building Hi-Performance packages for the H-D engine for many years and the one thing that I have learned is that Harley-Davidson has done a very fine job building and designing their engines for the past 19 years and I tip my hat to them. It has been proven that if a H-D engine is maintained and ridden properly it will last most customers 50,000 to 100,000 miles. Job well done guys. Now we take an engine that has a very repitable history and now we insert it in a sport bike frame that is used mostly for extreme riding conditions. We have a 50 hp engine as a power plant in this sport bike that is to be ridden by mostly converted Jap bike riders. Most of these guys riding style are extreme to say the least. The Jap engines are designed for this type of abuse. If it was to be known, most of the Jap bike riders never have found the maximum potential of their motorcycle because they come down with the "White Knuckle Syndrome" before they reach that point. For the one's that have reached that point, all I can say is you must have a 1/2" wire cable for a pucker string. Now let move on to the first phase of solving these problems. It is a well know fact that the H-D engine is designed for a power plant to produce Torque and Horsepower. It is definately not designed to be used as a engine brake as most performance riders use it for. If you get into a corner a little bit hot and the brakes are not slowing you down as much as you want, what is the first thing that you do? The normal rider that is on the verge of have the pucker string tightened up is to start grabbing the cluch and down shifting into the next gear down, and then if that doesn't do the job we grab the next gear down. Now at this point you are using the engine to it's maximum potential as a engine brake. Just the opposite of it's intended use. This is where the problem begins, you now have the front forks collapsed to their maximum capabilities under front braking, now the rear end is starting to chatter as the rear wheel is in the process of lift off and the rear brakes gave up 50 ft. back. Now with the shock mounted on the bottom of the engine (most earlier models)we endure the problem of the shock trying to shove the bottom of the engine case forwards and then backwards as the rear wheel chatters. With the engine being used as a structural part of the frame what is this going to do to the distortion of the engine. Sometime I wonder if a Cat Deisel engine would withstand this abuse. With this aluminum engine combination being used I would say that this engine is being very overstressed for it original purpose. Now withall of this happening just going in a straight line, lets add in some 20 mph switch back "S" Curves so we can stress the top part of the engine to its max. What a nitemare for this engine to go thru. The best thing you can do is invest in a supreme set of brake calipers and rotors and quit using the engine as a brake. Took me three deterioated engines to finally convince Jimmy Felice to stop using the engine on our Yamaha Super Bike as a engine brake. He stopped and the engine problems disappeared. The first thing I would like to discuss is using the engine as a brake (we are all guilty at one time or another, me included). This is the most damaging thing that can be done to any engine. The first thing that you do when you run your bike off into the corner is snap the throttle shut, then apply the brakes to their maximum potential and if that doesn't slow you down you start grabbing gears to down shift to. As you do this you are increasing the RPM's of the engine, the more gears that you down shift the higher the RPM's become. And I'm almost positive that no one is looking at the tach at this time, they are probable saying "O-Shit" this is going to hurt so where can I find the softest spot to land. In reducing your speed in this manner you are causing a lot of confusion and problems in your engine. Such being throttle goes from WOT position to Slammed Shut Position. When the throttle slide or thrttle plate is completely shut the Carburetor or Fuel Injection is not allowing any intake charge to be passed through the port and into the combustion chamber. The only thing that is allowing fuel to enter the combustion chamber is the slow speed or piolet jet which is approxiamately 2%-4%. Now you have an engine that is running at approxiamately 6,000 RPM's with a 2%-4% fuel supply ( which should actually be running on a 165 M.J. at this RPM. The problem this causes is two fold. 1) The engine is going to run very lean and the spark advance is going to be at full andvance with very little fuel being drawn into the combustion chamber. So what is this going to cause? "Excessive Heating Problems". 2) With the engine running at extreme RPM's with the throttle completely closed, this is not going to allow any air or fuel mixture into the combustion chamber and this disallows any type of combustion in the chamber. When there is no combustion happening in the combustion chamber to help propell the piston on the down stroke it is going to create a vaccuum on top of the piston. With this vaccuum being created on top of the piston it is going to drawn air from some where to try to satisfy the negative pressure on top of the piston. Where is this air going to come from. The only place it can come from on a supposed compression stroke is to draw it from the course of least resistance, and this is going to be up past the piston rings and this inturn contaminates the next charge of mixed air and fuel comming into the combustion chamber as the throttle is being opened for acceleration. With all of this happening your oil consumption will increase, your performance will decrease and your engine is going to run hotter. Review this information and if you have any questions or input, feel free to post it and we will discuss it. This only the first post in a series of approximately ten. Hopes this helps you in some way of understanding what is happening in your engine. Notsip | ||
| Notsip |
This is not going to be solved in just one posting, so be paitent and we will eventually get through it. First of all I would like to take the time to say that I have been building Hi-Performance packages for the H-D engine for many years and the one thing that I have learned is that Harley-Davidson has done a very fine job building and designing their engines for the past 19 years and I tip my hat to them. It has been proven that if a H-D engine is maintained and ridden properly it will last most customers 50,000 to 100,000 miles. Job well done guys. Now we take an engine that has a very repitable history and now we insert it in a sport bike frame that is used mostly for extreme riding conditions. We have a 50 hp engine as a power plant in this sport bike that is to be ridden by mostly converted Jap bike riders. Most of these guys riding style are extreme to say the least. The Jap engines are designed for this type of abuse. If it was to be known, most of the Jap bike riders never have found the maximum potential of their motorcycle because they come down with the "White Knuckle Syndrome" before they reach that point. For the one's that have reached that point, all I can say is you must have a 1/2" wire cable for a pucker string. Now let move on to the first phase of solving these problems. It is a well know fact that the H-D engine is designed for a power plant to produce Torque and Horsepower. It is definately not designed to be used as a engine brake as most performance riders use it for. If you get into a corner a little bit hot and the brakes are not slowing you down as much as you want, what is the first thing that you do? The normal rider that is on the verge of have the pucker string tightened up is to start grabbing the cluch and down shifting into the next gear down, and then if that doesn't do the job we grab the next gear down. Now at this point you are using the engine to it's maximum potential as a engine brake. Just the opposite of it's intended use. This is where the problem begins, you now have the front forks collapsed to their maximum capabilities under front braking, now the rear end is starting to chatter as the rear wheel is in the process of lift off and the rear brakes gave up 50 ft. back. Now with the shock mounted on the bottom of the engine (most earlier models)we endure the problem of the shock trying to shove the bottom of the engine case forwards and then backwards as the rear wheel chatters. With the engine being used as a structural part of the frame what is this going to do to the distortion of the engine. Sometime I wonder if a Cat Deisel engine would withstand this abuse. With this aluminum engine combination being used I would say that this engine is being very overstressed for it original purpose. Now withall of this happening just going in a straight line, lets add in some 20 mph switch back "S" Curves so we can stress the top part of the engine to its max. What a nitemare for this engine to go thru. The best thing you can do is invest in a supreme set of brake calipers and rotors and quit using the engine as a brake. Took me three deterioated engines to finally convince Jimmy Felice to stop using the engine on our Yamaha Super Bike as a engine brake. He stopped and the engine problems disappeared. The first thing I would like to discuss is using the engine as a brake (we are all guilty at one time or another, me included). This is the most damaging thing that can be done to any engine. The first thing that you do when you run your bike off into the corner is snap the throttle shut, then apply the brakes to their maximum potential and if that doesn't slow you down you start grabbing gears to down shift to. As you do this you are increasing the RPM's of the engine, the more gears that you down shift the higher the RPM's become. And I'm almost positive that no one is looking at the tach at this time, they are probable saying "O-Shit" this is going to hurt so where can I find the softest spot to land. In reducing your speed in this manner you are causing a lot of confusion and problems in your engine. Such being throttle goes from WOT position to Slammed Shut Position. When the throttle slide or thrttle plate is completely shut the Carburetor or Fuel Injection is not allowing any intake charge to be passed through the port and into the combustion chamber. The only thing that is allowing fuel to enter the combustion chamber is the slow speed or piolet jet which is approxiamately 2%-4%. Now you have an engine that is running at approxiamately 6,000 RPM's with a 2%-4% fuel supply ( which should actually be running on a 165 M.J. at this RPM. The problem this causes is two fold. 1) The engine is going to run very lean and the spark advance is going to be at full andvance with very little fuel being drawn into the combustion chamber. So what is this going to cause? "Excessive Heating Problems". 2) With the engine running at extreme RPM's with the throttle completely closed, this is not going to allow any air or fuel mixture into the combustion chamber and this disallows any type of combustion in the chamber. When there is no combustion happening in the combustion chamber to help propell the piston on the down stroke it is going to create a vaccuum on top of the piston. With this vaccuum being created on top of the piston it is going to drawn air from some where to try to satisfy the negative pressure on top of the piston. Where is this air going to come from. The only place it can come from on a supposed compression stroke is to draw it from the course of least resistance, and this is going to be up past the piston rings and this inturn contaminates the next charge of mixed air and fuel comming into the combustion chamber as the throttle is being opened for acceleration. With all of this happening your oil consumption will increase, your performance will decrease and your engine is going to run hotter. Review this information and if you have any questions or input, feel free to post it and we will discuss it. This only the first post in a series of approximately ten. Hopes this helps you in some way of understanding what is happening in your engine. Notsip | ||
| Crusty |
Interesting. Please continue. | ||
| M2me |
Yes, please continue. I must admit that I had been using engine braking more and my breather pukeage had been getting worse. Up until now I hadn't connected the two things. I always thought using engine braking was harmless. | ||
| Blake |
Some constructive criticism... "It is definately not designed to be used as a engine brake as most performance riders use it for. Though not the primary design criteria for ANY engine, the scenario of engine braking is certainly considered as part of the overall operational spectrum when engineers design an engine. "The normal rider that is on the verge of have the pucker string tightened up is to start grabbing the cluch and down shifting into the next gear down, and then if that doesn't do the job we grab the next gear down." I disagree. I think most riders simply grab the clutch and nail the brakes in a panic stop. Who has time to down shift? I see engine braking more prevalently used in more controlled situations such as when downshifting prior to entering a turn. I do agree that the engine is often used as a brake. I do agree that this scenario is usually more severe when riding a sport bike compared to a cruiser. I do agree that the Buells get revved harder than their Sportster cousins. So while I disagree with your attempt to explain the circumstances leading to severe engine braking, I agree that your basic premise remains intact... that Buells are exposed to more severe more frequent engine braking than their Sportster cousins. I disagree that it is common for Buell riders to get the rear wheel chattering under hard braking. It is just not common for anyone to ride like that on public roads. Even under aggressive braking while on the track, my experience is that the rear wheel will slide nicely, I've never had it chatter as you describe. In any case, your point about the front shock mount imparting significant distortion into the engine is interesting. Let's look at the loadpath for that...  Shock Reaction Load Path Red indicates tension and blue indicates compression internal loads being carried by shock and engine case, respectively. Black indicates applied loads at support points (isolators) and center of mass of engine/tranny/swingarm. As you can see the shock load reaction is carried by the cases between the swingarm pivot and the front shock mount. A load will always follow the most rigid path between two points. I cannot imagine any significant load from the shock load reaction making its way into the cylinders or even the lower end. It would have to go WAY too far out of it's way to do so. I can see that the front isolator will impart loads into the engine via the front cylinder head, especially under hard braking. I've witnessed the phenomenon you describe wrt combustion chamber vacuum sucking oil past the rings. With the bike on a dyno and heated up when the throttle is allowed to close with the engine then in braking mode, inevitably you will see a small puff of white smoke as oil is sucked up past the rings. I don't understand how that would cause the engine to run hotter. Since there is no combustion, or very little combustion, and the cylinders are drawing in extra oil, how do you see the engine becoming hotter? That makes no sense at all to me. As to your Yamaha superbike experience. Though you may have a valid point, there is absolutely no way to be sure. It is what we call anecdotal evidence. There are way to many other variables that would need to be eliminated before you could be certain that engine braking was the cause of the premature wear. Engine braking imparts far less stress and heat into an engine than operating at WOT. To demonstrate this to yourself, make a dyno run from 2500 RPM in 5th gear all the way to 6,800 rpm then let the throttle snap closed and see how long it takes for the engine to drop back down to 2,500 rpm. The ratio of the time required to accelerate from 2,500 to 6,800 rpm to the time required to decelerate from 6,800 rpm to 2,500 rpm will give you a rough estimate of the ratio of the engine stresses imparted by engine braking compared to those at WOT. The actual ratio will be even smaller due to frictional effects (without the frictional effects it would take even longer for the dyno/engine to decelerate). I look forward eagerly to the rest of your presentation. | ||
| Spiderman |
DUN DUN DUUUUN | ||
| Blake |
One more thing, though you have not yet connected the two, I see M2me has somehow already inferred that engine braking exacerbates breather spewage. I can see how it sucks oil up past the rings to be then expelled out the exhaust. I cannot see how it would put more oil mist into the breather circuit. I should probably wait until you are finished making that connection. Never mind... One other suggestion. Before questioning the structural integrity of the aluminum alloy engine cases, you might want to take a look at the loads and resulting stress/strain levels that you are contending cause a problem. I predict that if you do, you will be surprised at how low they actually are. After all, you are talking about a material that can withstand tens of thousands of pounds per square inch of stress versus loads measured in mere hundreds of pounds. I'm not saying it isn't possible that chassis loads significantly distort the cylinders. I'm just skeptical and wondering if you have actually measured such distortion, or if you are presenting a theory. Okay, I'll clam up. Gotta go pick up some parts. | ||
| Hans |
To pull your right feet now and then, while driving steady, would have been very good for the lubrication of pistons and the upper part of the cylinders because oil mist will be sucked up till there by closing the throttle now and then. I think that is the underlying reason why riding with changing RPMS is emphasized specially during the breakin period. I would not have thought that the mixture would be too lean at suddenly closed throttle: Less air but not less than at idle: Only the airspeed will be much higher than at idle and the created suction on that pilotjet will be greater, giving a richer mixture. Don`t look upon my remarks as negative: I like this topic very much and all the explanations: The reason to be fond of low revving engines is the fact that I still can get some mental picture of what happens in the engine. Screaming engines .... are just screaming. Question I have never found an answer for: What keeps the engine cooler at an prolonged idle as can happen at an railroadcrossing: Letting the bike just idle with as less combustions as possible or those very short blips to take advantage of the cooling effect of the stream gas from the acceleration pump ?? Hans | ||
| Djkaplan |
Interesting; trying to connect the engines use as a stressed member to oil spewage. I'll have to relate this to a friend of mine who rides a Sportster and has the same spewage issue. His bike shouldn't be doing it with the conventional cradle frame. Maybe it will stop now. | ||
| M2me |
I have to clarify my earlier post. I should have said I hadn't considered engine braking as a possible cause of my increased spewage. I did overfill the oil last August and I have always assumed that was the cause. But even after the oil was back to a normal level I seem to have more oil coming out of the breathers. I have suspected that the rubber ring that seals the air cleaner cover has gotten so saturated with oil that it just seems like more oil is still coming out the breathers. By the way, has anyone ever replaced that rubber seal ring? Can it be bought at a dealer or could a substitute be used? I've tried to clean it but there is no way to completly get the oil out. | ||
| Notsip |
Let's have some more input from you riders. The more information that is brought up, the better we can discuss them. Don't be afraid to get involved. Most everyone is, has or will be experiencing this problem. So with more symtoms exposed the easier it will be to understand what is happening. M2me, Blake, Hans and Djkaplan: Thank you for your responses. Please don't jump to conclusions that the structural integrity of the engine case is the cause of the spewage. It is only a small part of the cause. Like I said before this is probably going to be about ten part series to what causes spewage. Some of the cures are going to take some time, effort, money and a change in riding style for some people. Let's kick around some thoughts and experiences. | ||
| Jim_Witt |
I've never had any smegma spewage on my 98 S3T in 45,000 miles. Still running the stock bread-box, never had any problems with muffler bracket, still running the original V&H that was installed the day I took delivery, I'm not using synthetic oil, changed the ignition module, added a thermostatic oil-cooler, have never over filled the puppy and I do a lot of engine braking. To me, my S3 runs as strong today as the day I bought it. I've also been told by a few Sportster dudes they have the smegma spewage syndrome too. -JW:>  | ||
| Blake |
Non of my three M2's have exhibited oil spewage. Even on the track with the mandatory catch can, nothing, nadda, zero, zip. And I think Hans is correct... There would be no reason for the mixture to be lean under engine breaking, at least not with a carburetor. Hans is simply WAY too smart.  | ||
| Aesquire |
Engine braking (EB) does a couple of nasty things, the shock loading as forces are reversed throughout the drivetrain, and the possibility that engine rpm may exceed redline, a lot. While EB, the rev limiter does little, as combustion forces are not the driving force. | ||
| Aesquire |
Myself, conditioned reflexes usually have me tap dancing downshifts in panic acceleration moves, not engine braking. (you know, the squirt out of the way of the lane changing drunk) I never developed the EB habit, I prefer the controllability of a foot brake. | ||
| Hootowl |
Aaron, Blake, or whoever knows, please explain to me why over-filling, (or simply filling to the high mark) causes spewage. The crank is not spinning in the oil tank. The oil pump pumps oil out of the engine faster than it pumps it in, so why would there be more oil in the engine case if the tank is full? I've never really understood that, though, like a good little boy, I keep the level half way between the marks like I've been told. Please enlighten me. Also, has anyone had any success using the PCV valves from a Blast! in a twin? I'm thinking about drilling holes in the rockerbox lids and giving it a go. There's room enough under the tank for them. Don't scream yet, I'll be using spare lids. | ||
| Xb9 |
Somethin's wrong if your EB'n instead of using the real brakes on a modern motorcycle ........ isn't the engine for goin and the brakes for stoppin? Only thing ya should be doing with the gearbox under braking is getting it in the right friggin gear for when your ready to give it somemore. | ||
| Rick_A |
I'd think engine braking would be more harmful to two strokes...decelerating from a long straight at high rpms gives a little less fuel/lube in that application...caused many a tuner and rider a nightmare from what I've been told. Whether that's entirely accurate or not I'm not sure...but watch the GP's...if a two stroke seizes, it's almost always at the end of a straight. I think if anything...hard, abrupt deceleration is harder on the tranny than anything else. I've locked my rear tire at speed a few times for shits and giggles...never had a hop or skip. On bumpy pavement it may be a different story. I've watched my A/F ratio on a dyno during decel, too. It had an extremely short duration lean spike then went to a normal range. Deceleration does support normal combustion. If it wasn't...you'd be spittin' and sputterin' all the way down. FI systems are mapped to deal with it as well...look at the XB...it's even mapped to reduce engine braking. I've never had a problem with oil in my catch tube either...nor have I even seen smoke out the exhaust on decel on dyno runs. I'm not exactly easy on the bike, either. | ||
| Bluzm2 |
Hoot, I have Blast rocker box covers on my M2. They work great. Far less pukage. Still a bit though. Probably mostly moisture with a trace of oil. The spooge is much clearer now, far less tan than before. They really clean up the right side of the motor too. Just a couple of SS bolts in place of the breather bolts. Brad | ||
| Steveford |
An old adage springs to mind: brakes are cheaper than engines. | ||
| Dave |
Let's not take this to the nth degree. All engine braking on the street cannot be avoided. C'mon now...hand off throttle does not mean fingers/foot on the brake. Qualify it as high RPM engine braking perhaps... I'll have to take exception to "...using the engine as a brake (we are all guilty at one time or another, me included). This is the most damaging thing that can be done to any engine." I can think of a multitude of other things more damaging. But lets go on. DAve | ||
| Blake |
Hoot, I'd like to know the same thing. Never made a lot of sense to me either. The only thing I can imagine is that the increased height of oil in the tank adds that little bit more pressure to the system, allowing more oil to collect in the rockerbox. The added height may submerge and thus hinder the venting and return oil flow to the oil tank as well as aiding the supply flow. Use the mental experiment method of imagining the extreme case of a filled oil tank that is 100' tall. You'd have over 30 psi at the base of the tank before it made it to the pump. If the return line and vent were located halfway up that tank, it would require 15 psi just to return the oil to the tank, not including viscous dynamic effects of a submerged outlet port. Imagine how well your exhaust would flow if it's outlet were submerged even by just a few inches. I recall someone here who purchased a Metmachex (sp?) aluminum oil tank and was disappointed that due to the location of its vent was unable to make use of the advertised added capacity, since doing so caused submersion of the vent and subsequent pukage of oil from the breather.  XB9, So when coming into turn 2 at the local track, having to slow from 100 mph to 40 mph, how would you propose I keep the engine from exerting braking forces on the rear tire?  Whether you intend it or not, the engine will act as a rear brake, albeit a poor one. The only time I consciously use the engine as a brake is when negotiating a long downhill run. What I think is more common is that in aggressively attacking a set of twisties like Deal's Gap or any other world class sport biking road, we leave the bike in a lower gear. Rather than upshift then immediately downshift to get good drive upon apexing the corner, we just leave the bike in 2nd or third gear. How do you keep the engine from acting as a brake in that scenario? Answer... you don't. Aesquire, I think you are talking about dropping the clutch after a premature downshift. I would not class that as what we are referring to as "engine braking" nor would I call it a normal or acceptable operation. Rather, what you describe is both a dangerous and very damaging operation that indeed may exceed the intended operational envelope of the engine. Whenever downshifting, one should ALWAYS either blip the throttle to synchronize engine with tranny OR gently/slowly allow the clutch to engage. Even when synchronizing the engine with transmission, the clutch lever should not be carelessly dropped but rather given a soft landing so to speak. The effect of engine braking is as controllable as the foot brake; simply use the throttle. It is a very effective control when leaned hard over negotiating a turn aggressively. Rick raises an excellent point that may tend to support Notsip's contention. The XB9 ECM includes an annoying (to me anyway) momentary delay in it's fuel mapping for on to off/closed throttle transitions. This has also been documented by the mainstream press. When the throttle is closed, there is a momentary lag, maybe a half second before the fuel supply is shut down to the normal level you would expect at closed throttle. Even the race ECM includes this lag. It is very annoying to me, at least at slower engine speeds. I'm wondering now if it wasn't done for more reasons then those offered publicly by Buell. I think the reason initially given was to ameliorate the harsh initiation of engine braking, to give a softer transition in going from on to off throttle. Pesonally, if I want a slow/soft transition, I'd prefer to be able to simply roll of the throttle softly myself. | ||
| Hootowl |
Brad, Do they bolt on with no mods? Blake, I understand what you're saying. However, the oil pump will increase its pressure to maintain flow, so it would still evacuate the crankcase, even if it had to push a little harder due to an overfilled tank. It would simply shoot oil out of the tank vent. Right? Wrong? | ||
| Blake |
Yes, but we are not talking about scavenging the crankcase, we are talking about the amount of oil pooling in the rockerbox and the amount of oil mist in the rockerbox. The rockerbox appears to drain solely by virtue of gravity. In looking at my bike, the vent line from the oil tank seems to communicate with the inside of the cam case. Not sure what conclusions can be drawn from that. Will think on it a while. | ||
| Hootowl |
Blake, Why would an overfilled tank cause pooling of oil in the rockerboxes? The engine isn't feeding itself more oil just because there's too much oil in the tank. The amount of oil in the tank doesn't make the oil drain from the rockers at a different rate does it? I'm not doubting the validity of the practice of keeping the oil a little on the low side, I just want to know why, and what causes the excess blowby. | ||
| Blake |
Hoot, I'm working from both sides of the problem trying to mentally converge on the answer. One side is that we know overfilling the tank causes excess oil to blow out the breathers. The other side is that we know to be blown out the breather there must be excess oil either pooling around the umbrella valves or concentrating as mist and making its way to the rockerbox and out the breathers. Why that happens I have no idea. I have a hunch it has something to do with the vent line's port becoming submerged inside the tank, but I'm just guessing. Maybe Notsip will enlighten us. |
