My Tushy Is Very Sensitive!

[Guest majestyman340]

At the risk of feeling like Rappers here, taking his weekly flogging for his opinions, I am going to throw out a few things that may or may not draw opinions from others that may be interisted. As the title states, much of this is "seat of the pants" as I am not fortunate enough to have a DYNO sitting in the shed to prove or disprove anything! Some of this would need "Myth Busters" money to prove or disprove!

Firstly, Spark Plugs make a difference!

I believe they do! Many bikes run the standard plug such as a BP5ES closed down to as little as .020 or .5mm in an effort to accomodate the low power ignition systems on most bikes. You simply have to take advantage of what is there I think!

I have run the BP5EVX plug for several years now OPENED UP, taking advantage of its superior electrical properties and running at .027-.028(.7mm) providing better electrical flamefront (ignition) making for easier starting, better low end power and less fouling problems. I have even taken these plugs from bike to bike over the years without normal replacement. Yes they cost more! And I am not quite sure about the Irridium plug as it has a resistor which may defeat some of the electrical properties of the non resistor VX, but I do believe you could run it at .6mm at least with no problems.

Secondly, Addition of small quantities of Acetone to fuel to improve atomization.

You need to get on the net and do your own research on this. It is a topic upon itself, but I think it works in all vehicles. Maybe something to consider? I am somewhat conservative on these issues myself. There is much info out there! All I can say is that I have done it for the last couple years without problem. Seems to work!

Thirdly, Running ATF in a standard clutch and gearbox!

This is a topic which may vary by bike, but there are two things I can state with reasonable certainty!

1- the clutches in any automatic transmission are not designed to slip(much) or they will burn up! Or the oil will burn! Therefore you will get more bite! Good for some, not for others!

2- The premium ATF these days is that fully synthetic offered for Allison C-4 trannys! If it does not meet that spec, I would not use it! It is good stuff, but I am not sure it is great for all. A more common gearbox oil may provide better progression in the clutch feel! I am currently considering doing some experiments using friction modifiers in the ATF to "fine tune" to taste! Anyone done this?

Seems as though most of the testing on this stuff is "seat of the pants", I like to experiment a bit, but still remain conservative and go with what works and is proven. But at the same time it seems some of the folks around are soo hard headed they would not consider doing anything different and many still run bean oil at 40:1.

That should do for now, next I'll start up on Carbs!

Do the special plugs still benefit those bikes that have a proper programable digital ignition fitted? ( the ones with a handlebar switch to change settings)

Sorry not much idea about modern bikes, but heard that some have a motor where the main bearings are lubricated by the gearbox oil, and wonder if something like ATF is ok for these?

[ham2]

Do the special plugs still benefit those bikes that have a proper programable digital ignition fitted? ( the ones with a handlebar switch to change settings)

Sorry not much idea about modern bikes, but heard that some have a motor where the main bearings are lubricated by the gearbox oil, and wonder if something like ATF is ok for these?

Can't help with the plugs but the lubed main bearings you are describing are found in a GasGas Pro model.

My mates have used ATF in their Pro's with no problems.

[copemech]

Do the special plugs still benefit those bikes that have a proper programable digital ignition fitted? ( the ones with a handlebar switch to change settings)

Yes they should. To put it simply, a digital ignition really just changes "when" it sparks.

[jse]

Yes they should. To put it simply, a digital ignition really just changes "when" it sparks.

I've tried just about every plug I could get my hands on in my TY350 and Pro (my poor old test mules), some with numbers and letters on them that would take up half a sentence (o.k., maybe I hyperbolize a "little", but how bout a "NGKPZFR7G-G" or a "NDVK16PRZ11" for example)....... I've settled on an NGK BPR5EIX at .024" gap. Fairly easy to come by, although you usually have to have the bike shop order them as they don't usually stock that hot a plug. Compared to the standard plugs, they take a little less voltage to fire, resist fouling and have a slightly extended heat range.

The ignition curve ("map") in the CDI system on the modern two-stroke bikes kinda looks like a bell-shaped curve sloped to the right. The ignition-point-at-crank-degree will advance to a certain point and then retard at higher RPM's. Some two-stage systems will essentially "move" the curve left or right (starting earlier or later BTDC, but following the same path after), with the shape of the curve the same. Other two-stage/multi-stage systems will change the shape of the curve. I think the GasGas has had both on their Trials models at various times.

Jon

[copemech]

I've tried just about every plug I could get my hands on in my TY350 and Pro (my poor old test mules), some with numbers and letters on them that would take up half a sentence (o.k., maybe I hyperbolize a "little", but how bout a "NGKPZFR7G-G" or a "NDVK16PRZ11" for example)....... I've settled on an NGK BPR5EIX at .024" gap. Fairly easy to come by, although you usually have to have the bike shop order them as they don't usually stock that hot a plug. Compared to the standard plugs, they take a little less voltage to fire, resist fouling and have a slightly extended heat range.

The ignition curve ("map") in the CDI system on the modern two-stroke bikes kinda looks like a bell-shaped curve sloped to the right. The ignition-point-at-crank-degree will advance to a certain point and then retard at higher RPM's. Some two-stage systems will essentially "move" the curve left or right (starting earlier or later BTDC, but following the same path after), with the shape of the curve the same. Other two-stage/multi-stage systems will change the shape of the curve. I think the GasGas has had both on their Trials models at various times.

Jon

Jon's explanation on what I just said!

"Yes they should. To put it simply, a digital ignition really just changes "when" it sparks."

Hey Jon, did you notice that I am running, reliably with 10% more gap and the NON resistor plug BP5EVX platnum that you cannot get at O'Rieley's!

Oh ****, I am going to catch hell later!

[dan williams]

I've tried just about every plug I could get my hands on in my TY350 and Pro (my poor old test mules), some with numbers and letters on them that would take up half a sentence (o.k., maybe I hyperbolize a "little", but how bout a "NGKPZFR7G-G" or a "NDVK16PRZ11"

Jon

My current plug of choice is an AC Delco part number "4". I love it when I go into a parts store and tell the guy I need a Delco part and he scrolls through the computer parts screen to get to the Delco page and asks what the part number is.

The conversation usually goes like,

"What's the part number?"

"4"

"Er...4?"

"Yup, 4."

Laughter

It's a platinum plug that is the right heat range for my Beta, it's cheap and can be had at any automotive store. Never fouled one and the bike runs great. All I had to do was change the plug cap because it doesn't have the screw off nib at the top of the plug.

[jse]

My current plug of choice is an AC Delco part number "4". I love it when I go into a parts store and tell the guy I need a Delco part and he scrolls through the computer parts screen to get to the Delco page and asks what the part number is.

The conversation usually goes like,

"What's the part number?"

"4"

"Er...4?"

"Yup, 4."

Laughter

It's a platinum plug that is the right heat range for my Beta, it's cheap and can be had at any automotive store. Never fouled one and the bike runs great. All I had to do was change the plug cap because it doesn't have the screw off nib at the top of the plug.

Neat!

It's a heck of a lot easier to ask for a "4" rather than a "NDVK16PRZ11"! I'll pass that info off to my Beta buddies, thanks Dan.

Jon

[jse]

Hey Jon, did you notice that I am running, reliably with 10% more gap and the NON resistor plug BP5EVX platnum that you cannot get at O'Rieley's!

Oh ****, I am going to catch hell later!

Just remember that when I saw you yesterday at the Sooner Cup, I didn't mention this........

Jon

[copemech]

Just remember that when I saw you yesterday at the Sooner Cup, I didn't mention this........

Jon

He He, yea Jon, I noticed! Glad I did'nt get a lecture ! Ha!

But seriously, with reguard to the bikes that spec the standard NGK BP5ES as an example(not speced for a resistor) the addition of a resistor in an already weak(specially at startup) ignition cannot fare well in my mind. That resistor is just another obsticle in the chain. For those that have never broken a sparkie open, it is just a carbon pile put in series to reduce secondary ignition spikes production of RF signal generation throughout the leads. The modern auto ignitions can easily overcome this added resistance and even run gaps as high as 40-50 thou even with the smal COP(coil on plug) systems, because they have some good stable input voltages that the simple flywheels cannot provide.

When put into the science of a trials bike(if there is any), you need to get all you can get out of what little is available as far as electrical power and coils go! Plugs too!

I still see many recommend a .020 standard gap for conventional spark plugs to run reliably. The standard plug electrodes can actually shield spark exposure at that minute gap This is where even a resistor type platnum or irridium has an advantage, even at a closed gap, because of the more open exposure of the electrode design to actually doing the job of igniting fuel mix! The one benefit may just overcome the downfall in a given situation.

As they said on the space shuttle, it all works in theory?

Waiting for Biff results! Earth calling Biff! What is our KV limit here? My guess not much.

[jse]

copemech

"He He, yea Jon, I noticed! Glad I did'nt get a lecture ! Ha!

But seriously, with reguard to the bikes that spec the standard NGK BP5ES as an example(not speced for a resistor) the addition of a resistor in an already weak(specially at startup) ignition cannot fare well in my mind. That resistor is just another obsticle in the chain. For those that have never broken a sparkie open, it is just a carbon pile put in series to reduce secondary ignition spikes production of RF signal generation throughout the leads. The modern auto ignitions can easily overcome this added resistance and even run gaps as high as 40-50 thou even with the smal COP(coil on plug) systems, because they have some good stable input voltages that the simple flywheels cannot provide.

When put into the science of a trials bike(if there is any), you need to get all you can get out of what little is available as far as electrical power and coils go! Plugs too!

I still see many recommend a .020 standard gap for conventional spark plugs to run reliably. The standard plug electrodes can actually shield spark exposure at that minute gap This is where even a resistor type platnum or irridium has an advantage, even at a closed gap, because of the more open exposure of the electrode design to actually doing the job of igniting fuel mix! The one benefit may just overcome the downfall in a given situation."

This is an area where my expertise is a little short. I had the same question many years ago when living in Silicon Valley so I collared some of my MSEE buddies and posed the "resistor vs. non-resistor plug" question to them. They seemed to agree that the RF interference area aside, they couldn't really say that a resistor plug was necessary unless they had all the spec.'s on the CDI to draw a good conclusion. They could think of some instances where a resistor plug would compliment the ignition system and would be necessary.

Some later model automotive engines must use (non-inductive) resistor plugs for a proper "talkback" to the electronic ignition. Outboard marine Capacitive Discharge Ignition (CDI) such as those used on some Johnson and Evinrude marine engines require a special inductive type resistor (such as a Champion Q-type or NGK Z-type) and use of non-inductive resistor type plugs on these motors can cause misfire and poor performance, but I'm not positive if the same type of relevant question holds true (in the resistor vs. non area) for Trials bike CDI's.

As for gap, I usually recommend .020" for the earlier and less "robust" CDI systems like the MotoPlat and .024" for the newer systems (two-stroke), but if your bike seems to work fine at a larger gap, I don't see any problem. The auto plugs can be run at much larger gaps due to their ignition and engine management systems, and the number after the dash on the plug indicates the recommended gap, usually the numbers range from "-8" to "-20", which is a gap from .032" to .080". I would think that with an extended gap that is too wide in a Trials bike engine, there would be the distinct possibility of misfire under certain conditions. Trials bikes are a very weird animal and are tuned to perform under an unusually strict set of conditions and due to compression and CDI/jetting mapping, for instance, can self-distruct when those conditions/limits are exceeded. A long high-speed run on a highway (generally no problem with most other well tuned engines) can easily turn a Trials engine into a very expensive boat anchor quite quickly.

Hmmmmm. I guess what I'm saying is that I don't have an exact answer to the question posed, based on available data.

Jon

ps. Don't worry, Mark, I'm saving up several lectures to give you all at once.......

[copemech]

Purely out of ignoranomocity, today I tried to ohm out the actual resistor(carbon pile) out of a sparkie. I could not seem to get a good read on it, but it seemed to range between 500 and 1000 K ohm, quite high resistance for a limited output! (of which I have no idea).

[jse]

Purely out of ignoranomocity, today I tried to ohm out the actual resistor(carbon pile) out of a sparkie. I could not seem to get a good read on it, but it seemed to range between 500 and 1000 K ohm, quite high resistance for a limited output! (of which I have no idea).

I worked part time with some friends in a race shop tuning MX, drag and RR bikes and just about every time I'd run a meter on the various electrics (injection and CDI, for instance) and compare the measurements to the published spec.'s, I'd somehow be off a lot of the time. Drove me nuts! (o.k., now you know why I act the way I do.....). I used a good Fluke meter and was very careful, but it seemed like I often got a reading out of specified range, even though the bike ran great. Either the factories are using special calibrated meters or I am, indeed, electrically challenged....my guess is the later. Maybe it's the fact that I can't actually see (electrical properties) what I'm looking for, but Lord knows, I've felt it a time or two, especially the jolt I got one time from a Scintilla Vertex mag on a supercharged Keith Black engined dragster, the sucker instantly tightened every muscle in my body and knocked me about 12 feet back (well, there's another reason I act this way....).

Since this is "mechanical talk", I guess my question is on topic, but is there any "trick" to taking readings that provide consistancy? I know there are a lot of sharp people out there and I could sure use some pointers.

Jon

[copemech]

Since this is "mechanical talk", I guess my question is on topic, but is there any "trick" to taking readings that provide consistancy? I know there are a lot of sharp people out there and I could sure use some pointers.

Well Jon, since no sharp people have attempted a response, I will attempt to give you a pointer or two!

1- Keep your fingers off the probes, it screws up your readings and hurts your fingers, and clean your probes!

2-Ignore published specs as things do not always work the way thet the guy who wrote them thinks!

3- Just because something checks out according to spec does not neccessarily mean that it will function!

4-Working voltage readings or an O-scope will typically give you a better picture of what is actually happening, but only if you have something good to compare it to!

5- When in doubt, replace with known good component!

6- Forget about actually getting hold of anyone who actually knows about a problem because they will probably lie to protect their job!

7-With computerized systems, when things go bad(in the digital realm) you never quite know where to look because one thing can totally screw up many others and you have no way of monitoring which one is the culprit!

8-In the last decade or so, problems have been multiplied by a bunch of software geeks that do not have a friggin clue about the real world. Many of these are our offspring. You should have worn a condom!

[jse]

Well Jon, since no sharp people have attempted a response, I will attempt to give you a pointer or two!

1- Keep your fingers off the probes, it screws up your readings and hurts your fingers, and clean your probes!

2-Ignore published specs as things do not always work the way thet the guy who wrote them thinks!

3- Just because something checks out according to spec does not neccessarily mean that it will function!

4-Working voltage readings or an O-scope will typically give you a better picture of what is actually happening, but only if you have something good to compare it to!

5- When in doubt, replace with known good component!

6- Forget about actually getting hold of anyone who actually knows about a problem because they will probably lie to protect their job!

7-With computerized systems, when things go bad(in the digital realm) you never quite know where to look because one thing can totally screw up many others and you have no way of monitoring which one is the culprit!

8-In the last decade or so, problems have been multiplied by a bunch of software geeks that do not have a friggin clue about the real world. Many of these are our offspring. You should have worn a condom!

Mark, you have solved my problem!

Based on extrapolation from previous experience and gleaning small nuggets of deep wisdom from your Budda-like advice, I now take all my readings with a Cresent wrench (covered with a condom, of course, to keep my probe clean) and, voila!, all my readings are now consistant!

Kidding aside, it may be that I've been expecting "grading on a curve" information from a "pass-fail" testing instrument. I know that, in the race shop, we often had to resort to the "replace highest-suspect, single item at a time, with a known good component and re-test" technique when all else failed.

Jon