billyt

Okay since you insist! LOL Warning it will be long and confusing due to my long winded writing skills! The thoughts below are mine, may be controversial but mostly based upon scientific fact, and some basic fundamentals and common sense, really! Feel free to tell me I am full of crap, if you do then help me see your point of view! Firstly the fuel air mixture is ignited by the UV portion of the spark wavelength, approx 360 nano meters! In my opinion the setting of the gap in the plug is somewhat of a misnomer, and the hot plug, cold plug is mostly misunderstood. Let me try to elaborate! Plug Gap: Every ignition system out there on a motor bike has the ability to produce electrons that will jump across the gap to complete the circuit. This gap has a very small range that it will be effectively functional to producing a strong spark or circuit completion. Common theory states that "Too big a gap and the signal will be weak, too small a gap and the signal will be weak", "make the gap large for better low speed running"! I beg to say that the gap has absolutely nothing to do with low speed running etc. All these statements are in my mind, education and experience nothing more than urban myth (sorry Cope). Here is why I make this statement. The gap in a plug is a mechanical and electric function of the mag that it is connected too. The gap range/adjustment is there to match the ability and strength of the mags ability to pump out enough current to jump a gap. Thus the range adjustment in every plug is there to find this efficiency, once set, unless one changes to a different type of mag there should be no need to do little tweeks to the gap! It is basically matching the gap to get the best out of the mags ability. Simple so far? BUT here is where the crazy part comes in to play. The bigger the gap (within the effective range of the mags output) in other words widening the gap at the widest part of its effective range will afford a spark that is longer in duration, NOT necessarily HOTTER. The pre determined gap by the bike manufacturer is there to match the plug to the current output of the mag that they are using in the bike. They have experimented and found the best gap to give the best spark (best spark means good current flow and also letting the flow of current stop). I will come back to that momentarily! On a modern gas stove or fireplace there is a piezo for starting the gas to burn. Turn on the gas and press the ignition switch (activating the piezo causing a spark) this in turn ignites the gas and the gas keeps burning even though the piezo igniter is turned off. The fireplace or stove does not burn any better if you keep the piezo activated does it? If you had a pressurized can of ethanol (like a paint spray can) held it up and pressed the nozzle and then held up a BIC lighter, struck it, the spray would ignite as long as the ethanol fuel was flowing even though the lighter was turned off after the initial ignition of the fuel, As long as there was fuel that was ignited by the initial spark any subsequent fuel would burn whilst one held the nozzle down. The fuel spraying out the can would not burn any better, hotter if one kept the flame of the lighter lit! So, we only need to ignite the in coming fuel and then the flame will propagate and burn any subsequent fuel that is still coming in regardless if the initial spark is gone! So back to why I said contradict myself? If the wider gap does not make the burning gas any hotter then why make gap as big as the mag can a handle? In my opinion it is a timing thing! There is only one pulse per revolution and the in coming fuel air mixture only needs to be ignited flame propagation will do the rest. Having a wider or smaller spark plug gap from the optimum gap will not make the spark hotter or colder. The synchronization of spark to the fuel and air being at the correct part of the cylinder head (at full compression hence why we fire the plug before top dead centre to afford full spark and in length and current) at the right time is the key to why the gap setting. Having a spark that is at its most efficient due to the gap for the longest period to match the incoming vacuum cycle imperative. The correct gap not only affords the best current transfer equating in a good spark but also taking full efficiency of the electrical pulse thru its pulse cycle reaching full potential quicker and longer. The length of the spark is critical to burn propagation from a timing aspect. The on and off cycle of the spark plug critical to efficient RPM's. The proof of this is that you can have the best spark, but if it comes at the end of the vacuum cycle (and after full compression at the head) when most of the gas is pouring out the exhaust transfer port then it does you no good. If the spark starts at just the right time it will start the burn and then propagate until all the fuel is burned even though the spark has subsided. Having the spark reach its strongest signal a the correct time is not just a function of the ignition timing alone, gap and ignition timing both play a part in this equation. The gap in a plug is set to find the perfect balance between of the energy from the high tension coil. The low voltage, relatively higher current energy coming from the mag to the input to the coil is then stepped up to a higher voltage and somewhat lower current at the coils output (high tension lead to the top of the spark plug). That resident energy has to consume or share some to jump the gap, once the gap is bridged it then has to flow across the gap and go to ground, the current or UV portion of the current ignites the fuel. Too small a gap and not enough current is drawn but is easily bridged, a larger gap takes more energy to bridge the gap and then draws more current to keep the energy flowing, but runs out quicker due to the mag pulse being past its firing point! This effect can be seen in the contacts of a regular switching relay. The other function of the gap is as follows: If you look at most relays that are passing high current repeatedly thru the point they are burnt black by the current or EMF phoneme. The current wants to keep flowing when the contacts open and tries to arc across the opening contacts and does so by supplying or drawing more current hence why the contacts go black as the metal melts and carbons eventually. This high current erosion will eventually eat away at the contacts making them all jagged and uneven causing them not to make good contact when they do close. They will get to the point when they need to be burnished and then eventually replaced. The point is that it takes current to jump the gap in the plug, too big a gap and it takes a lot of energy leaving very little to flow once the current bridge is made. This bridging takes time as well as energy! This relay example is mentioned as the flowing current across the gap has to stop as some point. This is not purely left to the firing time alone (mag past ignition time) as the signal gets weak or cut off from the mag it the plug will still try to draw current. Having the gap wrong can keep this spark going at the wrong time. If a trials bike is turning over at 3000 RPM that equates to 50 pulses per second. That is very quick, basically it has to fire and stop firing in a VERY short time period yet still have long enough and strong enough spark to ignite the fuel. If this stopping and starting of spark at the gap was not desired then high current could be supplied continuously from the mag thru the coil to the plug resulting in the fuel being ignited even before or at top dead centre and that would be a bad thing! As the bike increase in RPM its firing pulses get quicker, but the rate the fuel burns at is constant. I am going to guess that the firing pulse from the mag is much shorter than the burn rate at higher RPM's? If one could see a graph of the spark plug current across the gap it would be an arc as it climbs and descends all this within a VERY short time frame yet only ignites the fuel at near the top of the curve. The gap plays two roles helping the current flow creating spark and helping the spark stop drawing current due to back EMF. The gap distance acts like a mechanical brake helping to break down back EMF as the current flows down the back side of the curve it does not have the energy to keep firing or rather draw more current. That concludes my theory about the plug gap being more about a timing thing than just a hotter or colder spark at low revs compared to high revs being set by the gap. In conclusion set the plug at the recommended gap and leave it alone. If the plug is fouling it has nothing to do with the gap. If you think you are making the bike run better at low RPM by changing the gap please tell me how that works? : As for hot plugs and cold plugs that is nothing more than the ceramic shroud that affords the plug to retain heat or dissipate heat. A hot or cold plug does not make a hotter or colder spark.. period! A protruding plug tip extends more into the incoming mixture of fuel and air combustion area, some say it gives you a cleaner burn and also increase compression by consuming space? The spark generation or circuit completion of a plug is also subject to being blown of course or out by the incoming fuel air mixture. If the gap is too wide the spark can be blown off course and not make contact with the other side of the plug tip. That is why drag racers etc used to index their spark plugs, they tried to turn the spark away from the in rushing fuel and air mixture. I agree with Jon that a modern trials bike should not need to be cleaned out all the time. The excess smoke out the exhaust is mostly the function of the oil and gas separating in the crank cases and stinger. Why? The oil and gas mixture is swirling by many rough surfaces (kept rough deliberately to keep the oil and gas mixed and swirling) when the mixture is down in the crank area before it is transferred up the ports in the cylinder at low RPM/s there is not enough head on the vacuum subsequently the heaver oil tends to separate from the gas sticking to the rough surfaces. A bye product of this effect is also engineered in to help lube the lower end. When you rev out the bike there is more vacuum pulses per minute thus a more constant vacuum (not stronger) pulling up the excess oil from the prior separation at lower rpm/s. This effect is not as obvious with todays oils, but in the past it was an issue. Keeping mind that the oil in your gas mixture does not burn on each stroke but rather is used for lubrication and most of it gets blown out the exhaust pipe with some of it staying in the end stinger. The higher pulse rate or exhaust scavenging at higher RPM's help blow it out. Livlob. You said you changed nothing yet your plugs are fouling! Are they cold fouling or hot fouling? Two different scenarios of what to check! As for Dan's comment I agree that the problem may not be the plug but rather your fuel type or weather related. Knowing if you are popping a plug (hot lean foul) or cold (rich) fouling a plug is important in figuring out what is going on! It is VERY hard and unreliable to pull a plug out and look at its colour and change jetting based upon the colour. I know, I know people tell you to do this all the time. Urban myth! When you read a plug what are you reading. Pilot jet, Needle, Slide, main jet? They all contribute to how the plug gets carbon and or fuel deposits on it. Or in fact how hot the plug gets due to the fuel/air mixture being to hot i.e. lean. If we agree with this statement then think of the following: A normally run trials bike has the throttle opened all thru the carb ranges i.e. pilot jet, needle, slide, main jet. All of these jets, slides and needles contribute to various amounts of fuel to air ratios to the cylinder/plug. The main jet supplying the largest amount or contributor. I am totally confused when a guy pulls a plug looks at it and states "the pilot jet is too lean" how the hell can he say that when he has just exposed the plug to fuel from the pilot jet, needle, slide and main jet. The pilot jet could be just fine or even rich, but due to him opening up the throttle and the maim jet taking over maybe it is very lean causing a lean condition on the plug????? The best way I have witnessed is to get all the jets in the bike, (after of course you have warmed up the bike with what ever jest you had in it) new plug and only open the throttle up to the pilot jet. Pull the plug, if all is okay, put the plug back in, ride and open the throttle to the needle, pull the plug if all is okay move on, keep doing this all the way until you get to the main jet. If you are now at the main jet you ride and pull the plug and it is lean or popped then you know it is primarily the main jet you are reading! All the jets play a part in a wide open throttle but this way helps you break down what part of the carb is causing plugs to go out on you. Plugs can go bad from way too lean a condition and/or way to rich a condition. WHEW... sorry for being so long winded............

JSE, Livlob, Cope Can I inject on this topic if I play nicely? LOL I do not want to turn it in to another suspension article were I got off on the wrong foot by getting all pished off at you know who! I want to try and clear the air on common misconceptions around spark plugs! I am sure you three know this stuff but rather I want to share it with those who do not! Pretty please!

Good to hear that! You performed as simple change in oil and felt the results. Good for you! Cheers!

I used configure as a heading rather than "design". If you could configure a trials bike that afforded you the ability to raid the parts bins of any current trials bike manufacturer what would this "Parts Bin Raided" configured trials bike look like? An example would be, The engine out of a 2100 Beta Evo, The 2011 GAS GAS PRO frame, The 4RT shocks, etc, get the picture"? And what would we call it? Basically: What engine configuration: i.e. 2T or 4T What size cc: What engine: What frame: What dia of forks: What forks: What forks: Upside down or conventional: What Rear Shock: What plastic: What wheels: What (factory) colour: What factory graphics: What clutch: What brakes: Should be an interesting configuration!

John I will get family back in Forres to order it for me. They can send it over to me. Looking forward to seeing it! Thanks BillyT

John Are these disks in PAL or NTSC format? Will they play on a North American DVD player? Thanks.

"The older I get - the faster I was" " Dave in my case I think back The older I get the I realize how stupid I was when I was younger. What was I doing letting two Spanish guys tie a rope around my waist swinging me over the mid part of a waterfall and telling me to catch Jordi if he falls, **** come to think of it maybe it was the bike I was supposed to catch as it was the only water-cooled Beta out there??? LOL If only Dale M would release the VHS old tapes on DVD I could see that madness again LOL............. Dave , Is there big smile because I am a long way away from BC? If so cheeky monkey! LOL

Dan gets the prize! Pigeon Forge TN There is a video out there of me hanging from a waterfall as minder/mechanic with Jordi'e brother. His brother had me tied around the rope to catch Jordi on the waterfall section if he should need help as there was no where to stop on the slippery wet rocks. Waste of time as Jordi went right up the waterfall as if it was not there. Ah memories!

Bang on Dave. we still have something in common as we are both bald now! LOL

NOPE! Try again! HINT: First US exposure of water cooled Beta

I look like a Roy Orbinson wannabe in this picture LOL Any guesses were this was taken? And what round?

Just trying to learn how to post pictures. This is me on a 125cc Beta

Good one Steve........ And I vouch that he sounds like Hank Hill, **** they all do down here! LOL That was my original point Steve. What has the forks on the beta stopped him from doing? Too much time in the theory books and not enough time on the bike honing his technique. Any more earthquakes up there? Cheers

"If we all agree to the above then we can proceed. If not, lets get the basic design of the forks hashed out so we can make set-up changes and know what we are changing otherwise its meaningless. Again, maybe I am the only one who isn't in the know, but I doubt it." WHY................ Some of the good folks on this site have figured out how these forks work long before you! Some people do not care in how they work they just want them to work. The bike has to work in harmony not just a all out intensive focus on a set of forks! Some folks need to know all the technical details in how every part works on the bike. I am by nature the latter as it seems you are also! Nothing wrong with that at all. I have been curious about how all this works from a technical view point for about thirty two years now in the trails arena. God I messed up a LOT of bikes and bikes parts due to my curiosity. Hopefully I have learned something from my apprenticeship of life in trials? I applaud your curiosity and encourage it, but do not forget those whom came before you! Please tell us how long you have been riding trials? I can bet that you rode motocross or enduros before venturing into trials? There is no doubt that you have some technical abilities, but you come across as newbie to trials and one who will not take the advice of those who have been there done that! I am by training a degreed Mechanical & Electrical Engineer and can talk technicalities and theory all day long with you. BUT there comes a time to put the calculator and books aside and trust experience, in both experiments, years of riding TRIALS, making many mistakes in trying things, by those who came before you with technical abilities, and there are many! Do you honestly think that you are the first one to try get specs from Paoli, Beta on the forks? Are you trying to say that changing the oil viscosity in the compression fork does nothing? You need less theory and some practicality. If you are saying this then you are also saying that all who have tried this have their head up the a*** at the results! "If my understanding above is correct, then oil viscosity does not have any affect on the magnitude of the compression resistance which means changing the oil wt in this fork leg does nothing." Bull**** to the above statement: Do this experiment: Drain your left fork leg oil, measure it, put in the same amount you took out. BUT put in 2.5 weight fork oil. Go ride! Drain your left fork leg oil: Measure the amount you took out: Replace it with 15 > 20 weight oil. Go ride! If you tell me there is no difference in how the bike feels acts rides then you have no business being on a dirt bike let alone a trails bike then you need to stick your head back into your theory books to figure out why! I give up!

Dan you bring up a VERY important point. Traditional trials tells us that one should be able to stand on the pegs and move one's body weight up and down, subsequently the bike should move up and down as one unit, front and end back end in harmony, with todays riding style who the hell knows? LOL. Lots of usage of stored energy as Dan mentions.

I will address each of your comments: First off it is not my idea! Lots of people I know use this simple, quick, cheap method of stopping the bottoming out. "While your idea will slow the forks compression speed down the probability of the fork being harsh has been increased and the front to rear balance of the bike will be off." Obviously you have not tried this as there is nothing harsh about it. It is a slow controlled compression of the front forks.It is a proven method! The bottoming out scenario we are talking about here is a downhill or a drop off, so the bike is already out of balance. "Also after being heated thicker oil is going to change viscosity more than thinner oil will." That comment is lost on me ????? "Having the correct front and rear springs made for your ride weight costs about $230" How the hell do you figure out $230? for front and back end Most of the springs for trials come from Europe and a rear spring alone cost anywhere from $200 > $300 alone with shipping , duties etc. Think of this, to get a heavy front spring to compress one needs to place more energy transfer into it. That can be done by the rider being heavier or proper loading of the riders weight into the front forks. This bottoming out issue is not a simple as just installing a heavier spring. A heavier spring will take more energy to compress it obviously, but once compressed it will return a lot more energy back in the return stroke making the rebound quicker and less controllable. To overcome this more energy and stop it rebounding far to quickly you have no choice but to adjust the re-bound adjustment screw and possible there will not be enough adjustment left to slow the fork down due to rider weight and/or how heavy a spring you put in, or you can always change the re-bound fork oil for a heavier oil and between the re-bound adjuster and heavier oil get the desired effect you seek OR you will be caught in a vicious circle of springs/oil/adjustments etc. Do you want a controlled fork or a pogo stick? Basically trying to stop bottoming out by just a spring alone will transfer the problem into the return stroke. It is much easier to dissipate the energy in the return stroke of a lighter compression spring than a heavy return spring. By using a heavier fork oil in the compression side less energy is transferred into the return stroke. Basically if it takes 200lbs of force to compress a spring it will spring back with maybe 80% of that energy. Here is something for you to think about based upon physics and several riders experiences. I will exaggerated this in order to make my point. If one were to remove the front forks ability to compress and you road forward pulling in the brakes and try to do a nose wheelie to kick the back end to one side it would be EXTREMELY difficult to do! Why? In making the front end so ridged one has changed the pivot point at the triple clamp making it much higher with reference to the back end of the bike. When the forks travel down as they do in a normal bike front end they lower the pivot point with reference to the back end. If the forks could travel down further than normal it would much easier to get the back end in the air. The point here is this. I have witnessed and tried guys bikes who had stiffened their front end to the point that they could no longer get the back end of the bike up in the as they could prior to making the front end so stiff. You want all the travel in the front, you just want to do it in a controlled manner. A REALY stiff front set of forks will cause the front to push rather than turn. Once again the lower triple clamp effect from the forks compressing is critical to a turning correctly. In the prior example of removing any movement of the front forks one would have a very hard time in making the bike tract around a wet loose turn. Your milage may vary depending upon your weight riding style etc. To me the bottom line is that everybody should be able to customize their bike the way they want to. In doing so they should know what technical options are out there to do so. Changing springs and re-valving or shimming is one way, changing oils is another way or a combination of both. To each their own. In either case starting off simple is always the way to go, one step at time, change one thing and see what happens I also agree with Dave Rhodes comment about not making any changes until the bike has a good few hours on it! One other distinction is this: I have seen people get confused with the forks mechanically bottoming out Vs Hydraulic lock. Mechanically Bottoming out is the fork reaching the end of its travel, hydraulic lock is when they have put too much oil in the fork! To check this out or verify which one it is do the following: wrap a cable tie around one of the fork sliders. Slide it all the way down to the fork seal. Go ride, the cable tie will be pushed up by the travel of the fork and will stay put on the slider as to were it was slide up by the fork leg as it travels. The cable tie will become a witness as to the amount of travel the fork is making. Common sense when looking at were it stays will tell you if your are using a lot of suspension travel or barely any. In other words if you have six inches of travel in your forks and the cable tie has moved two inches from the travel of the fork leg and you felt the fork being restricted and at the end of its travel you properly have too much oil in the fork i.e. hydraulic lock. On the other hand if the cable tie has moved all the way up the leg and you felt the forks bottoming out then you are mechanically bottoming out the suspension. PS: Ron it is TRAYNOR not Trainer later mon ami.

Not with standing all the technical research behind Livlob & Nif40 I and I do respect their technical knowledge! For the real world & 99% of club riders out there. Dump out the stock Italian fork oil that Beta got from Olive garden salads. Use 12 > 15 weight fork oil in the compression side, set sag! (should take care of bottoming out) Use 2.5 > 5 weight fork oil in the rebound side, set rebound adjustment per preference. (will rebound quickly) Go ride and enjoy! The Beta front forks are not perfect, no trials bike are, but they are dam good stock! This is a pragmatic, cheap, quick answer/test from one who has experienced MANY Beta's and has also experienced the bottoming out on drop offs and I only weigh 150lbs. Think about it! There is no need for the same viscosity of oil in each fork if they are performing different tasks? The other thing to keep in mind is temperature and altitude. The higher the temperature the thinner the oil is going to get this will dramatically change the way your fork works regardless off what shim stack or spring changes you make per Livlob & Nif40. The oil's job in any fork is to change the flow of oil into heat there bye displacing energy into the fork leg surface area, basically the fork leg acts like a heat sink drawing energy away from the slider. Basically if you ride in a hot part of the country your fork oil is going to get thinner and thinner as you ride that day. A 10 weight oil in the fork at the start of your ride in your compression fork may very quickly act like a 5 weight oil causing you to bottom out very easily as it heats up. By starting out with heavy oil (12 > 15) in the compression side it may act like a 10 weight oil still affording good compression resistance making the chances of bottoming out less after it heats up. The same is true for the rebound fork oil. It too will get thinner in a hot area as you ride. The thinner it gets the quicker the rebound will be, BUT you can adjust the dial at the top of the rebound fork to slow it down if need be! That is is why remote shock reservoirs in the back in order to allow a bigger container to draw heat away keeping the rear shock at a more cooler temperature by placement of the reservoir i.e. Ossa. Sorry guys, you are technically correct but unfair to the Beta forks and not very pragmatic solution for the average Joe out there who has forks that are bottoming out. Start simple! Oil is cheap and it is easy to try what I am suggesting. Respectfully BillyT

Mmmm interesting how your mind drifted to MENS underwear? There was no mention of mens underwear in my post. I am still trying to get Andy to post pictures of the Paddock Girls in their underwear.? LOL I will tel you later on how to dial in your forks, granted they will not be as good as the others out there but will be a hell of a lot better than they are in stock form. Cheers!

When your bike gets to the point of empty it goes lean and atomizes the fuel greater than the 14:1 ratio that is normal, causing a VERY lean mixture thus making the engine run away!

"I suspect that the 200 has less vacuum and struggles to lift the fuel the extra distance." Mmm.......... Yet a 125cc Beta does? It is pressure that pushes the fuel up the jets not vacuum! The vacuum is important and must be present in order to move fuel up the jets but it is the atmospheric equalization at the top of the piston that is pulling the fuel.