DAS Forum für Yamaha XT600 und XT600Z

[font size="1" color="#FF0000"]LETZTE BEARBEITUNG AM 22-Mai-2007 UM 16:45 Uhr (GMT)[/font][p]Now is the cylinderhead I quest you about perfect. When I took away the head I saw an old helicoil wich has loosen from the cylinder. The hole was now already 10 mm big. Then I took a 12 mm bolt and bore a 8 mm thread in the middle and put loctite on it and down in the cylinder where I have made a 12 mm thread. I strongly recomend this to other who got the same problem.
Now to my new problem...

When I have drived to the job in the rain for a couple of theys the enging died at high rpm´s(>4000rpm = ded) I thougt it was the secondary carburettor but there was everyting perfect. Then I change a contact to the ignition unit and then the engine was as new again I thought. Now the engine starts when it is cold but when it is warm and I drive at low rpm´s and gives the engine full throttle it stopps emmidiatly and refuses to stars again before it is cold. Please help me again I am so tired on this bike now... Can it be the ignitioncoil that is broken or bad? It is poossible to check the voltage to the coil whith a multimeter or must I have an oscilloscope?

The bike is an XT 600 1988 with 27000 km:)

hy,

not that i would think that i know the problem, but if you tell the model, maybe someone will know

Hi,

I'm not too sure about the '88 model, but if it has a sidestand switch, I would check it (ok, it's irrespective of the rpm but you never know). Problems in the rain may be related to bad connectors (corrosion) everywhere. I would check CDI, ignition switch, all connectors related to the ignition system (sounds like a lot of work to do...). Or the CDI itself... This is the electrical side. Reading you comment I can also imagine a failure in the fuel system. Do you ride with a tank-bag? Check your breather pipe and make sure it's free (does your fuel tank fizzle when opening the filler cap?). I once had problems when opening the throttle fully and when lowering/adjusting to the manuals value the fuel level in the carburettor it was gone - ok it's unlikely but if your fuel level is completely wrong it can cause lots of trouble. Another thing I have heard about are very small cracks in the cover material of the ignition coil which lets it run properly as long as the oil is cold but when it heats up and the coil expand it causes a short-cut and it doesn't work anymore. This answers your last question a bit. It should be possible to check the coil by a resistance-meter but when it's cold it'll be alright. You'd have to heat it up or drive the bike until it doesn't work anymore. Difficult. I haven't done it but checking the ignition impulse coil the repair manual for a '90 and up model says: resistance between blue/yellow and green/white wire: between 184 and 276 Ohms. I assume, when its heated up it showes a short-cut (hopefully).

Anyway good luck... and if you have solved the problem please post the solution.

Greetings

Mr_Moto

You wrote that you have checked the carb.

Have you checked the Choke too?

I had the same problem with an old KTM some years ago because the carb never switched from 'cold start' to 'warm run'.