billyt

"I usually perform 2-3 good hard stops from a good high speed run in 5th gear to warm them, then let them cool and resume normal operation. Do this 2-3 times to thermocycle them, then on a final trip do the same to get them and the disk good and hot and douse them with a water bottle to steam off." Warning to the wise on getting your disk hot and then dosing it in cold water! I have witnessed this resulting in the disk cracking and or warping due to the aneling effect that the radical drop in temperature causes. I was present when a friend of mine tried this and and then went over the bars after the brake disk shattered

How good? As ma maw would say, juist a brodie - a big roons slap o' dough wi' the tap hauf spread wi' steak cut sma' an' chappit ingins." "Syne the boddom hauf's luftit an' laid ower the tap an' scolpit ee aidge." "Nick oot twa holes ee tap fauld an' there y'are - a brode pie - a brodie - a bridie."

Hugh You may be correct! That would make sense.

Is the Evo frame painted or powder coated? My black frame is holding up okay, even after dropping it MANY times.

Hey Ralphy I am happy, very happy Just trying to help him get the answers he wants from the other riders by asking him to be more succinct in his questions. He wrote on his second post. "What do they go like and the clutch what is that like" What do they go like???? How does one answer an ambiques question like that with any degree of intelligence? If a person cant take the time to compose their question/s correctly and succinctly then they cant be taken seriously Maybe I am just getting too old and grumpy I am getting my zimmer and going back to the home for aging trials riders

"What they like" A silly ambiques question deserves a silly answer! Their kind of silver, and red with lots of aluminum parts and rubber! If you want someone to take your question seriously then ask some succinct questions, i.e. does the engine have much torque, any magneto issue etc!

Firstly it is a MIKuni, not a MAKuni. Try this test disconnect the throttle cable from the throttle tube/grip. Pull the end of the throttle cable barrel in and out. Does the slide still stick? If so your cable is kinked, damaged or at an extreme bend angle going down to the carb. Or it could be issues from the next test also. If it does not stick with the prior test, the two other options are. Is your throttle tube/grip sticking as you turn it with the throttle cable disconnected? If so remove it and check for burrs etc. Your slide may be sticking. Take the carb off and check slide for and slide track on carb for nicks, scratches etc.

Yeh, and makes the trials riding harder due to the blisters on ones hands!

Maybe cover it with Xispa stickers/graphics that way someone will think it is an illusion!

Hey Chewy, Did you actually look at the WHOLE video clip!

A ken that! I think others may think it a bicycle! Naebotheratawe!

Hey Cope, Would this help get rid of forearm pump? I know you have at least two of them in your garage http://www.youtube.com/watch?v=veHKdKElZ3w :banana2:

Nedrapler You need to clear some things up for us here. Are you talking about a TRIALS BIKE or a TRIALS MOTORBIKE?

I've always liked the idea of trials, particularly the long distance stuff. I am still dazed at the "long Distance" part! This guy is pulling our chains!

I'm planning to ride a trial this weekend. I will take note of the engines peformance. Hopefully the issue hs been resolved. Go kick some butt at the weekend ! Cheers BillyT

Mr Hill......... I will stick my little UV wand up yer a*** and set fire to your propane tank

I mentioned to Livlob to check for a missfire?

Why the hell am I giving you a headache? I do agree I am confused why Livlob is making it leaner in colder temps! Is there something we are missing in the translation here? The air is getting colder so turn the air screw in, the air is thinner up higher needing the air screw to be turned out more but only if it is warm and it is not in Colorado right now. I agree with Hank oops I mean Cope.................

Livlob Sorry! In my prior brief post (LOL) I was babbiling, not really focusing in with any real solution to your problem! If I am reading your post properly the bike is fouling plugs and they look normal when you pull them. Even though they look normal you feel the bike is running rough at idle or/and low rpm? Changing to a new plug does not fix the problem and it still runs rough? If so the plug is not the issue. if you re-install the same or a new plug it runs the same? The plug condition or symptom is witness to something else that is going on! The bike is not running bad because the plug/s are constantly going bad by themselves or need a slight tweek to the gap. The plugs are going bad due to the bike doing something wacky with the mechanics ie compression, rings, woodruf key, or electrical ie timing, wiring, grounding, magneto etc. You wrote: I changed the gap as per recomendation of a friend who said the engine would produce more torque because of the smaller plug gap. Funny thing here is that i did not notice any change in engine performance yet i set the new plug the same before installing it. I personaly thought that a bigger plug gap within recmended range would produce a stronger spark, that was simply an intuitive thought! That was my point in my looonnngg post. A slight change of the gap of the plug will not effect performance as long as it is in the range suggested by the bike manufacturer. You wrote: "Although i can push the kicker thru by hand without too much effort." what size of bike is this? Being able to push it through by hand may suggest low compression i.e. worn out piston, barrel, rings etc? I am also thinking it could be a ignition (mag, coil) problem, timing, woodruf key or a bad grounding issue of the coil, mag etc.! Even a bad high tension wire. If you just clean the plug you took out and re-install it does it run okay for while and then wet foul plug? I am really not sure how long it runs before it wet fouls a plug. Try this little experiment. Get your bike all warmed up, go to a really dark area such as your garage at night time turn off the lights while the bike is running. Get close to the spark plug area and observe, do you see any sparks around the spark plug area or sparks jumping from the high tension wire to ground? If so then the high tension wire is bad and leaking to ground (by ground I mean the frame etc). There should be no light show in and around the spark plug and spark plug wires. I have witnessed several bikes giving off a light show in a dark area with the spark jumping to the frame off the hi tension lead causing all sorts off intermittent problems! One caveat: because a plug looks wet does not guarantee it is wet fouled. Why? If a plug starts to fail due to the bike running lean and you pull it fairly quickly when you feel something is wrong it will look whitish and dryish. Leave that same plug in for a while and the bike will not run correctly due to the plug being weakened(lean fouled) and it will now wet foul due to not totally burning the fuel, now pull it and it will look wet fouled even though it is actually lean fouled! Confusing I know! It is important that you determine a wet or lean fouled plug ASAP. A lean fouled plug will fail quicker and you will have to change it. If the bike is lean fouling (note fouling as in going bad not totally bad yet) it tends to start easier but runs like crap. A totally lean fouled plug will neither start or run! A wet fouling (getting wetter) plug will run much longer and will make the bike harder to start due to it being wet. Of course when it is totally soaked it too will stop the bike from running or start! Hopefully you will get to the bottom of your problem soon. With lots of good folks supplying good answers/tips I am sure you will.

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