honda_freak

Hi jrsunt Here is an explanation of this picoscope recording, which is just a simple compression test - where I measure pressure/vacuum over a period of 720 degrees, and at the same time I also measure the ignition voltage on the spark plug. The compression test is done with the kick starter on - so the engine is not running. The fact that the engine is not running causes the RPM to fluctuate a lot during the valve timing measurement, and therefore the measurement is not as accurate as if it were a multi-cylinder engine - where the RPM is much more stable - this is actually the same as aussiechris has explained in previous answers. But as aussiechris writes - it can be used as a guideline regarding valve timing.

Hi Chris These are really good oscilloscope captures you have recorded here and will certainly benefit people when they have an ignition-related problem. I myself am also a little surprised at how it goes from wasted spark to non-wasted spark in such a short time horizon - I would not have believed this if it were not for your fine evidence here. I also find your note regarding an injection timing in the combustion stroke just after TDC a bit strange. But I can also confirm that this matches my captures of injection timing in the compression stroke TDC and which occurs 25 degrees after TDC. This is very important evidence of when and how the ignition system works on a Honda Montesa 4RT and other motorcycles / scooters with similar battery-less systems. It seems that there are quite a few secrets that need to be discovered. Just keep up the good work. Regards Honda Freak

Hi Chris After reading your comment and thinking about what could trigger this extra ignition event, I largely agree with your second explanation for a misfire. Since this is a compression test, I held the throttle wide open for maximum air intake, and perhaps this could create an extra ignition event? That's my best guess. For my compression test, I used the WPS500X pressure transducer from Picoscope with 3 measurement ranges, which is a great diagnostic tool for many different things. If you are interested in learning more about batteryless systems, I can recommend this document from SAE.ORG entitled "Implementing Software and Hardware Solutions for Batteryless Systems" JSAE 20139094, which describes many of the issues associated with starting a single cylinder 4-stroke engine. It is a very detailed document that provides many new perspectives on the internal processing of the ECU. I have a feeling that the document is based on data on batteryless systems from Honda - as there are references to a document entitled "SAE TECHNICAL PAPER: JSAE 20066507", which deals with the development of electrical systems for four-stroke motorcycles for trials motorcycles. There are also many other references in the document, so all in all a very interesting piece of technical literature - which can certainly be used for a broader insight into troubleshooting a motorcycle equipped with a batteryless system. Regards Honda Freak

Hi aussiechris Interesting topic regarding wasted spark ignition on Honda Montesa 4RT. A few years ago I recorded some oscilloscope captures of the secondary ignition system versus compression pressure on a Honda Montesa 4RT model year 2007. It should be said that these captures were taken during kick start of the engine, which is in contrast to your measurements. But looking at this oscilloscope capture where I measure the secondary voltage on the spark plug wire versus compression pressure over two revolutions of the engine - it is clear to see the extra ignition event characterizing a wasted spark system. This was my small contribution to the discussion about wasted spark systems.

Hi. The regulated voltage should be between 13.5 to 14.5 volt at 1800 RPM - so 12.5 volt is definitely to low. If voltage is low when engine is running - must it be very low during cranking of the engine and if the lower threshold at 6 volt to activate the ECU isn´t reached it wouldn´t start. As "thall1" mentioned the condenser wiring could be bad - so it would be a good place to start your diagnostic search. One thing to remember about the batteryless system is how important the condenser is during start of the engine. Hope you make it work. Regards Honda Freak

When you can not activate the fuel pump manually with a 12 volt battery externally connected, so the problem must be inside the fuel pump. Try to measure the resistance at the fuel pump connector, when you can not activate the pump by 12 volts from an external source like a battery. Another thing regarding the fuel pump connector is to verify that the power and ground wire is not wrongly connected inside the 2 pin connector !!! As the fuel pump is operated as dc motor, it could turn the motor the other way around if the wires are misplaced inside the connector.

Hi thall1 Your rectifier/regulator result seems fine if you remembered to push a little on the terminals pins as I've told before is this part very vital for a correct result. One thing about the fuel pump motor. Since this is a DC motor it may have points on the commutator, which has higher resistance than the other, thereby having difficulty to start the fuel pump motor. Can you meassure the electrical current to the fuel pump wit a DMM or a current clamp !!! Have you tried with a new capacitor !!! Regards Honda Freak

I dont know whats wrong with this attachment file, maybe the web administrator at this forum could have a look at it.

Hello Thall1 The resistance control you are referring to in the workshop manual is the resistance of the charging coil from the flywheel - there is no test of the rectifier / regulator in the workshop manual. The file I uploaded here describes how to test the diodes inside the rectifier, so if you know how to use a digital multimeter should be an easy task to accomplish. You must remember to push a little on the terminal pin, when making this test, or you can get a false reading. I hope you will solve this problem or at least get some answers on what to do next ! DIODE TEST.pdf Regards Honda_freak

Hi From this webshop http://www.cmsnl.com/products/unit-assy-condenser_31700nn4003/ you can buy the requested 10 uF condenser for your Honda Montesa 4RT. Regards Honda Freak

As Jonnyc21 already had shown here about to test a capacitor - wouldn't I repeat what he has written other than to say - that the capacitor is very vital part of the battery-less system and without the help of the capacitor during startup is it nearly impossible to start. What I think you should check on your trial-bike has something to do with ECU voltage on terminal pin 5 on the ECU. Without five volt on this terminal 5 wouldn´t the ECU be able to activate the ignition and the fuelpump system properly. Before you make this measurement be very carefull not to bend or break any terminals pins. You could make some extension leads to put in the ECU connector. Remember when you make this mesaurement to put your DMM to record peak value as this voltage are not a steady reading or else you would get a false voltage reading. Based on the result of that test - another test of the flywheel generator coil and recitifier / regulator may be necessary to conduct. BTW is there a consistant blue spark between the sparkplug electrodes !!! Regards Honda_freak

It seems like the fuel injector are getting it fuel backwards through the fuel pressure regulator - that's odd. Maybe the fuel pressure membrane are faulty !!!

What fuel line are you talking about - is the fuel feed hose or perhaps the the fuel return hose !!!

You could have a potential short circuit in your fuel pump or in the wiring harness. Remember that the red power cable that feeds the fuel pump also deliver power to the the other components on the bike. But, if the bike runs without fuel pump electrical connected - would I suspect the fuel pump to be faulty. Can you hear or feel if the fuel pump are running !!! Regards Hond Freak

Hi This thread http://www.trialscentral.com/forums/topic/56730-4rt-no-spark-help/page-2#entry404207 that I comment may give you another direction to follow in terms of diagnostic possibilities. I'm not saying it would solve your problem, but it is good with another objective view on how to troubleshoot such a problem as missing spark. Regards Honda Freak