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Started my XJ650 Turbo today, after standing still for 20 years. Everything overhauled of course, carburettors, fuel valve, fuel regulator and a new fuel pump. The engine runs, but pops out of the exhaust. Anyone have any idea what that could be.
Thanks for contributing ideas.

Habe heute meinen XJ650 Turbo gestartet, nach 20 Jahren Stillstand. Alles natürlich überholt, Vergaser, Benzinhahn, Benzinregler und eine neue Benzinpumpe. Der Motor läuft, springt aber aus dem Auspuff. Hat jemand eine Ahnung was das sein könnte.
Danke, dass Sie Ideen eingebracht haben.

Hallo Dirk, does the engine run on all 4 Cylinders? Did you ride the bike or did you just start the engine and let it idle?

I made the experience that an engine that stood around for years runs much smother if you ride it a few dozen kilometers.

Hallo Dirk,

Ich kenn das so nicht.
Meine Motoren hatten immer nur Aussetzer oder sind auf einem Zylinder gar nicht gelaufen.

Wenn es knallt ist nach meiner Ansicht unverbranntes Gemisch die Ursache das sich unkontrolliert entzündet.
In Deinem Fall würde ich erst mal die Zündanlage überprüfen.

Die Widerstände hab ich durch ein Stück Kupferdraht ersetzt da die Zündkerzen mit "R" einen Widerstand zur Entstörung haben:

http://www.xj-forum.de/cpg133/displayim ... 835&pos=82

http://www.xj-forum.de/cpg133/displayim ... 835&pos=83

Die Zündspulen dürfen keine Verbindung zur Masse haben:





Gruss Axel

turboadmin hat geschrieben: ↑Fr Okt 28, 2022 1:34 pm Hallo Dirk, does the engine run on all 4 Cylinders? Did you ride the bike or did you just start the engine and let it idle?

I made the experience that an engine that stood around for years runs much smother if you ride it a few dozen kilometers.

Yes the engine runs on 4 cylinders. I think that because the engine has been standing still for 20 years, the valves do not close completely. Despite me, before I started overhauling, all 4 cylinders have 10 bar gauge pressure. You're right, I just need to drive the engine for a while with a good fuel cleaner.

yamahammer hat geschrieben: ↑Sa Okt 29, 2022 9:41 am Hallo Dirk,

Ich kenn das so nicht.
Meine Motoren hatten immer nur Aussetzer oder sind auf einem Zylinder gar nicht gelaufen.

Wenn es knallt ist nach meiner Ansicht unverbranntes Gemisch die Ursache das sich unkontrolliert entzündet.
In Deinem Fall würde ich erst mal die Zündanlage überprüfen.

Die Widerstände hab ich durch ein Stück Kupferdraht ersetzt da die Zündkerzen mit "R" einen Widerstand zur Entstörung haben:

I hadn't thought of that, great. I will do that first, very simple to do. 2.5 m^2 copper wire?
Cheers,
Dirk

Ignition Wire is not Standart Copper Wire. And You can not replace it.
It is in the Ignition Coils casted.

Just cut the Wire at the Plug End for some Millimeter until You see the Metal inside.

As I refered I replaced the Resistors in the Plugs with Copper Wire.
The outer Plugs are these:

https://www.racing-planet.de/zuendkerze ... 5123165f6f

Regards Axel

yamahammer hat geschrieben: ↑Mo Okt 31, 2022 11:19 am Ignition Wire is not Standart Copper Wire. And You can not replace it.
It is in the Ignition Coils casted.

Just cut the Wire at the Plug End for some Millimeter until You see the Metal inside.

As I refered I replaced the Resistors in the Plugs with Copper Wire.
The outer Plugs are these:

https://www.racing-planet.de/zuendkerze ... 5123165f6f

Regards Axel

yamahammer hat geschrieben: ↑Sa Okt 29, 2022 9:41 am Hallo Dirk,

Ich kenn das so nicht.
Meine Motoren hatten immer nur Aussetzer oder sind auf einem Zylinder gar nicht gelaufen.

Wenn es knallt ist nach meiner Ansicht unverbranntes Gemisch die Ursache das sich unkontrolliert entzündet.
In Deinem Fall würde ich erst mal die Zündanlage überprüfen.

Die Widerstände hab ich durch ein Stück Kupferdraht ersetzt da die Zündkerzen mit "R" einen Widerstand zur Entstörung haben:

http://www.xj-forum.de/cpg133/displayim ... 835&pos=82

http://www.xj-forum.de/cpg133/displayim ... 835&pos=83

Die Zündspulen dürfen keine Verbindung zur Masse haben:





Gruss Axel

Hi Axel,
I checked the ignition coils and the spark plug caps. Everthing allright. Of course I removed a piece of the ignition coil cable, for better contact. Next week, if it doesn't rain, test drive.
Cheers,
Dirk

Made a test drive with the 650 Turbo today. The cold start was bad. I still had brake cleaner this to start the engine. I then went to the gas station for fuel Shell V power. So far everything went well, engine ran well. Then drove to the highway and with about 100km/h (unfortunately we are not allowed to drive faster here) everything went well for about 25 km. After this the engine started to stall, and reacted very slowly to the gas. When switching back to 5, the engine did pick up. Drove about 7 km and off the highway. The engine immediately stalled and would not start again. Not even after 1.5 hours of waiting. The motorcycle but charged on a trailer. I'm going to see what I can find on Monday.

Habe heute eine Probefahrt mit dem 650 Turbo gemacht. Der Kaltstart war schlecht. Ich hatte noch Bremsenreiniger dabei, um den Motor zu starten. Ich ging dann zur Tankstelle, um Shell V Power zu tanken. Bisher lief alles gut, Motor lief gut. Dann zur Autobahn gefahren und mit ca. 100km/h (hier dürfen wir leider nicht schneller fahren) ging für ca. 25 km alles gut. Danach begann der Motor abzusterben und reagierte sehr langsam auf das Gas. Beim Zurückschalten auf 5 sprang der Motor an. 7 km gefahren und abseits der Autobahn. Der Motor ging sofort aus und sprang nicht mehr an. Auch nicht nach 1,5 Stunden Wartezeit. Das Motorrad wurde aber auf einen Anhänger geladen. Ich schaue am Montag mal was ich finden kann.

Hi Dirk, did you try to open the tank cap? Perhaps the ventilation is clogged.

Another possibility could be a bad fuel pressure regulator.

I once had a bad fuel line from the tank to the fuel pump, when it got warm it collapsed and restrained fuel flow. The bike went slower and slower until it stalled totally.

Or you may have dirt in the fuel filter in the pump.

Hi Georg,
That last one is a good one. I have mounted a new return charge, that could be the problem. I think there is gasoline in the oil. Have a closer look on Monday. With the 750 I put a steel spring around the return, I will do that again now. Thank you.
Cheers, Dirk

Hi Dirk,

In the opening Post You say that Carbs are done.
Did you replace the Foat Valves?
Do You have a new Seal in the Fuel Petcock?
You say there is probably Fuel in the Engine Oil.
I allways replace these Parts when I do the Carbs:



A the End I check the Fuel Level:





For Fuel Petcock do not use another one (do not Work):

https://www.cmsnl.com/yamaha-xj650l-max ... 6g2452300/

Remember: These Parts do not last for ever. After Years the Rubber is worn out and the Softener is gone.

Good Luck Axel

Kneggie hat geschrieben: ↑Sa Nov 12, 2022 8:25 pmThat last one is a good one. I have mounted a new return charge, that could be the problem. I think there is gasoline in the oil. Have a closer look on Monday. With the 750 I put a steel spring around the return, I will do that again now.

Im sorry but I do not understand your post. What is the "return charge" and what kind of spring did you put around it?

I believe the bike stalls because it gets not enough fuel. Why should there be gasoline in the oil? ( I know there can be gasoline in the oil and this is not good, but it does not cause the bike to stall, at least not immediately...)

Hi Georg,

an Engine also stalls if there is too much Fuel.

All my Engines had Liters of Gasoline in the Oil Sump.
That means the Petcock, the Check Valve and the Float Valves don't work properly and Fuel is dripping.
I also do the Check Valve during overhauling my Bikes:



Good Luck Axel

hornschorsch hat geschrieben: ↑So Nov 13, 2022 9:56 am

Kneggie hat geschrieben: ↑Sa Nov 12, 2022 8:25 pmThat last one is a good one. I have mounted a new return charge, that could be the problem. I think there is gasoline in the oil. Have a closer look on Monday. With the 750 I put a steel spring around the return, I will do that again now.

Im sorry but I do not understand your post. What is the "return charge" and what kind of spring did you put around it?

I believe the bike stalls because it gets not enough fuel. Why should there be gasoline in the oil? ( I know there can be gasoline in the oil and this is not good, but it does not cause the bike to stall, at least not immediately...)

Hi Georg,
I think the return line is kinked. This will prevent the fuel pressure regulator from venting the fuel into the tank. As a result, the carburettors have overflowed, and therefore the gasoline in the crankcase. But on Monday I will look and hope to find the cause. I'll keep you informed.
Cheers

Ah, you mean the fuel return line from the pressure regulator to the tank. If that kinked suddenly, perhaps also if it got warm, that would have cause a fuel overflow in the carbs. Originally all the fuel lines have these spiral springs on them and perhaps its a good idea to use them.

If the float valves or the check valve do not close accurately, this usually only causes problems when the bike stands still for a longer time. Fuel then drips bit by bit into the turbocharger and the engine. If you ride, the bit of fuel that flows through is used up by the engine. It may run a bit richer or stall when idling, but if you open the throttle the float valves are open anyway...

Fullquote edited by moderator

yamahammer hat geschrieben: ↑So Nov 13, 2022 9:00 am Did you replace the Foat Valves?
Do You have a new Seal in the Fuel Petcock?
You say there is probably Fuel in the Engine Oil.
I allways replace these Parts when I do the Carbs:

A the End I check the Fuel Level:

For Fuel Petcock do not use another one (do not Work):

https://www.cmsnl.com/yamaha-xj650l-max ... 6g2452300/

Remember: These Parts do not last for ever. After Years the Rubber is worn out and the Softener is gone.

Hi Axel,
All the above things have been done, including the float level checked.
I transferred the tank from the 750, with a reconditioned fuel tap. I checked the check valve today, also works properly
Cheers,
Dirk

Hallo fellow readers,

An upgrade of my Yamaha turbo vicissitudes
Checked everything today: the fuel lines, see if it can kink somewhere when the engine is warm. All tube springs were fitted except at the tube to the fuel pump. This has now been installed. Fuel filter leaked, so installed a new one. Started before the garage, started immediately. Let it idle for a while, then hit the road again. This time the engine stops after 1.6 km, and after 10 waits started with the gas fully open. The engine started again and struggled to stay on. Back to the garage drove about 1.2 km. For the garage it continued to run, let it run for another 15 minutes. The engine did that without any problems. It's getting a bit dull, the popping is over now. But a ride with it is daring. I think the engine is getting too much fuel. The spark plugs checked, spark plug 1 to 3 light brown and spark plug 4 pitch black. The spark plugs are dry. I checked the oil from Saturday's ride. There was fuel in the oil, it is now out and I have now put cheap oil in it to flush. After today's 2 km no fuel entered the crankcase. The oil level has remained the same. The only thing I can think of is to adjust the carburettors and hope this is the issue. But I doubt that's it.

Hallo Mitleser,

Ein Upgrade meiner Yamaha Turbo Wechselfälle
Heute alles gecheckt: die Benzinleitungen, mal schauen ob es bei warmem Motor irgendwo knicken kann. Bis auf das Rohr zur Kraftstoffpumpe waren alle Rohrfedern verbaut. Diese wurde nun installiert. Kraftstofffilter undicht, also einen neuen eingebaut. Vor der Garage gestartet, sofort gestartet. Lassen Sie es eine Weile im Leerlauf laufen und fahren Sie dann wieder auf die Straße. Diesmal geht der Motor nach 1,6 km aus und nach 10 Wartezeiten mit voll geöffnetem Gas an. Der Motor sprang wieder an und kämpfte darum, anzuhalten. Zurück zur Werkstatt fuhren wir ca. 1,2 km. Für die Werkstatt lief er weiter, noch 15 Minuten laufen lassen. Das hat der Motor ohne Probleme gemacht. Es wird ein bisschen langweilig, das Popping ist jetzt vorbei. Aber eine Fahrt damit ist gewagt. Ich denke der Motor bekommt zu wenig Sprit. Die Zündkerzen geprüft, Zündkerze 1 bis 3 hellbraun und Zündkerze 4 pechschwarz. Die Zündkerzen sind trocken. Ich habe das Öl von der Fahrt am Samstag überprüft. Es war Sprit im Öl, jetzt ist es raus und ich habe jetzt billiges Öl zum Spülen rein getan. Nach den heutigen 2 km ist kein Sprit ins Kurbelgehäuse gekommen. Der Ölstand ist gleich geblieben. Das einzige, was mir einfällt, ist, die Vergaser einzustellen und zu hoffen, dass dies das Problem ist. Aber ich bezweifle, dass es das ist.

The specifications of the fuel pump that I have installed.
Die Spezifikationen der Kraftstoffpumpe, die ich installiert habe.

Dirk hat geschrieben:I think the engine is getting too much fuel. The spark plugs checked, spark plug 1 to 3 light brown and spark plug 4 pitch black.

This is too much Fuel on #4.
But it should not kill the Engine.
3 working Cylinders are enaugh to keep it alive,
At the Moment I run out of Ideas with my Experience ...

Edit: Try another Set of Spark Plugs. I had a Brand New Set and one of the NGK failed as it came out of the Box.
Fortunately I knew the Engine was running properly bevore I put new Spark Plugs im it ...

Good Luck Axel

Hello XJ650 Turbo Fans!
Dirk, did you check the small filter which is in the rubber fuel line in front of the fuel pump? In my case this was almost fully blocked by debris from all the years.
You mentioned that cilinder 4 sparkplug is black, could this being caused by a faulty coil, or is cilinder 2 sparkplug normal colour?

Kind regards,
Ger

yamahammer hat geschrieben: ↑Mo Nov 14, 2022 6:25 pm

Dirk hat geschrieben:I think the engine is getting too much fuel. The spark plugs checked, spark plug 1 to 3 light brown and spark plug 4 pitch black.

This is too much Fuel on #4.
But it should not kill the Engine.
3 working Cylinders are enaugh to keep it alive,
At the Moment I run out of Ideas with my Experience ...

Edit: Try another Set of Spark Plugs. I had a Brand New Set and one of the NGK failed as it came out of the Box.
Fortunately I knew the Engine was running properly bevore I put new Spark Plugs im it ...

Hallo Axel,
Yes that is also possible. Bad spark plugs are rare, but worth a try. New spark plugs this week.
Thank you Dirk

Turboger hat geschrieben: ↑Mo Nov 14, 2022 6:37 pm Dirk, did you check the small filter which is in the rubber fuel line in front of the fuel pump? In my case this was almost fully blocked by debris from all the years.
You mentioned that cilinder 4 sparkplug is black, could this being caused by a faulty coil, or is cilinder 2 sparkplug normal colour?

Hallo Ger,
There is a new fuel pump with supply line. New filter, the original point filter is no longer in it. So it can't be that.
Cheers,
Dirk

Hi Dirk,

I use a Gauge like this one to make shure the Bike has korrekt Fuel Pressure:

https://www.ebay.de/itm/295092003121?mk ... Lqahsd1w75

Good Luck Axel

If the engine idles 15 minutes without problems, i dont believe that the float valves are the problem.

Does the engine stall when riding with boost pressure or when riding constantly with lower speed and without boost?

Perhaps such a fuel pressure gauge that axel posted could help. Fuel pressure should be boost pressure + 0.1 Bar.

Georg hat geschrieben:Fuel pressure should be boost pressure + 0.1 Bar.

Fuel pressure should be boost pressure + 0.2 Bar.

Good Luck Axel

Hi Axel and other co-readers,
Found out today that there is fuel in the oil again. Miraculous oil multiplication appears to have this engine. The must have sunk in my shoes a bit today. Ordered new spark plugs. I had to think about my XJ900F that I had from 1995 to 2010, it also happened regularly that the spark plugs stopped sparking. So now Iridium, the 750 has platinum spark plugs and it works well. Perhaps just change the fuel regulator, or at least test whether it is at 0.2 bar. Despite that, all of that was already done before I put everything together. Okay then, nothing goes by itself.
Cheers and until the next story.
P.S. I'm off air for a week, my youngest is getting married next week, I'm busy with that now. See you after the 28th.

turboadmin hat geschrieben: ↑Mi Nov 16, 2022 1:15 pm If the engine idles 15 minutes without problems, i dont believe that the float valves are the problem.

Does the engine stall when riding with boost pressure or when riding constantly with lower speed and without boost?

Perhaps such a fuel pressure gauge that axel posted could help. Fuel pressure should be boost pressure + 0.1 Bar.

Hi Georg,
I had read over your piece, sorry.
The first time I had driven 34 km, the engine started to struggle after driving with turbo pressure for a while.
The second time, the engine wasn't even warm. And I had to hold back for a few cyclists.
The day before yesterday I replaced the 4th spark plug for a platinum spark plug, at the first start a mega bang in the exhaust. After this the engine started well and continued to idle well. So different spark plugs was a good tip from Axel.
After this I didn't go on the road again because of very bad weather here. And I only have a good week left, after this I can't go on the road for 3 months. Measuring the fuel pressure while driving seems to me to be useful, at least you know what's happening.
Cheers,
Dirk