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NX650 stalls suddenly

By Renas,
in XR600R & XR650R/L

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Apprentice

Renas

Posted
Posted

Hi guys,

sorry if I missed the right forum for this, but still my bike is quite close to XR... Or was some time ago? ?

Anyway I have Honda NX650 Dominator, and it has a problem I'm not able to find for some time already. It's quite hard to explain, but I'll try :applause:

After some time of roding it starts to stall suddenly. The process is:

- Turn cold engine on. Fine.

- Steady idling speed, good reaction to throttle.

- First 15-20 minutes of riding everything is OK.

- A few harder accelerations or quick throttle openings up to red line and back several times. Then bikes starts to stall on gear (tacho goes down and up, engine stalls and fires up again, then after a few seconds stalls again)

- If I stop for a few seconds. Starter. It fires up. (Sometimes backfires before that). This repeats a few times.

- Going on road again and stalling after a few seconds. (Touching throttle leads to sudden stalling.) This stalling is instant, revs are just drooping to 0 right a way I touch the throttle.

- Raising revs up to 3000 rpm leads to stalling.

- I wait for 5 minutes. Starts again. And if I'm not raising revs up to 3500 rpm it goes as nothing happened. As son as I touch throttle harder same story repeats.

- After riding in very gentle way for 20 min. again story repeats progressing to the point when it's stalls and as soon as I touch the throttle it stalls again and again.

Checked ignition wire, spark plug, spark plug cap... Where els I should look for the problem? Thought that it could be problem with electrical part, but apparently not. Carburetor? Then why engine works as usual for some time before and after (5-10 minutes) hard acceleration?

Sorry for the complicated story and possibly my language... :ride:

Thanks for any tips and help!

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Grand Master

Beyond The Pale

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There are a couple of things that I can think of. First is restriction in the fuel tank vent. As fuel is used, air needs to get in. If it doesn't get in a vacuum develops. After a while no fuel gets to the carb. To test, ride until it quits. Remove fuel line from carb or tank. If fuel flows freely, this is not the issue.

The other thing is to check for spark. Get another plug and use it to check spark. First try it cold. Then try it after the problem occurs. If the spark is weaker when the problem is happening then there is something wrong with the ignition. I don't know if the NX650 uses a stator coil for the ignition power source, or if the ignition runs off the battery only. If it uses a stator coil, they are known to fail, but not too frequently.

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Apprentice

Renas

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Thanks for the tip! I'll check for spark and tank for vacuum.

I do not have enough theoretical knowledge, so my only concern is if there could be an issue with the carburetor. It lacks of fuel due to internal barrier or external? If internal, what happens? Is there any reservoir for the gasoline to stay and supply the engine? And when it used too quickly engine stalls?

Any chance that the problem is carburetor itself? Or if it has it, this is permanent and doesn't relate to period of riding?

Thank you!

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Experienced

captb

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Sounds like fuel starvation, as mentioned in above post tank vent, if the tanks not full leave the cap loose and see if the problem is gone, my NX had a vent line on the top of the cap but that was 1989 yours may be vented differently, I would drain the float bowl on the carb, brass screew at the carb bottom, maybe water or crap in it. I drain mine whenever I wash my bike.

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  • 4 weeks later...
Apprentice

Renas

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Hi there,

at last I found the problem. When fuel valve is on "Normal" and in tank there are 8 liters of gasoline left, it starts to choke and stalls after a some time. Though switching valve to "Reserve" solves the problem.

It seams that fuel pressure is not enough after some fuel is burnt. Is it possible fix the valve? What could be cause of fuel starvation in this case? Faulty valve? Filter?

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Grand Master

XR650L_Dave

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Posted
Hi there,

at last I found the problem. When fuel valve is on "Normal" and in tank there are 8 liters of gasoline left, it starts to choke and stalls after a some time. Though switching valve to "Reserve" solves the problem.

It seams that fuel pressure is not enough after some fuel is burnt. Is it possible fix the valve? What could be cause of fuel starvation in this case? Faulty valve? Filter?

Could be a partially plugged in-tank fuel filter, or the tank may not be venting, or a partially blocked fuel hose/filter.

On reserve, will it run all the way down to empty?

Dave

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Veteran

rmhrc630

Posted
Posted
Hi guys,

sorry if I missed the right forum for this, but still my bike is quite close to XR... Or was some time ago? ?

Anyway I have Honda NX650 Dominator, and it has a problem I'm not able to find for some time already. It's quite hard to explain, but I'll try :applause:

After some time of roding it starts to stall suddenly. The process is:

- Turn cold engine on. Fine.

- Steady idling speed, good reaction to throttle.

- First 15-20 minutes of riding everything is OK.

- A few harder accelerations or quick throttle openings up to red line and back several times. Then bikes starts to stall on gear (tacho goes down and up, engine stalls and fires up again, then after a few seconds stalls again)

- If I stop for a few seconds. Starter. It fires up. (Sometimes backfires before that). This repeats a few times.

- Going on road again and stalling after a few seconds. (Touching throttle leads to sudden stalling.) This stalling is instant, revs are just drooping to 0 right a way I touch the throttle.

- Raising revs up to 3000 rpm leads to stalling.

- I wait for 5 minutes. Starts again. And if I'm not raising revs up to 3500 rpm it goes as nothing happened. As son as I touch throttle harder same story repeats.

- After riding in very gentle way for 20 min. again story repeats progressing to the point when it's stalls and as soon as I touch the throttle it stalls again and again.

Checked ignition wire, spark plug, spark plug cap... Where els I should look for the problem? Thought that it could be problem with electrical part, but apparently not. Carburetor? Then why engine works as usual for some time before and after (5-10 minutes) hard acceleration?

Sorry for the complicated story and possibly my language... :applause:

Thanks for any tips and help!

Try your CDI - swap one out and see how you go.

The NX is ostensibly a XR650L motor, not XR600R motor.

The NX CDI fires up under 12 volts not 80-100 like the XR6.

Fuel delivery seems fine

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  • 2 weeks later...
Apprentice

Renas

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Hi there again,

the problem is still there and I need some more thoughts on how could it be solved. So, any thoughts are more than welcome... ?

Finally I have clear understanding when the problem occurs.

It stalls when I open throttle wide and do it quite aggressively, after some moments it chokes and stalls. If I try to start the engine again, it usually backfires at first try. Second - and its running. If I turn throttle again wide open, it stalls again. But if I wait a few minutes and open throttle very slowly, it accelerates and goes like nothing happened. As soon as I start hard acceleration, it stalls again.

Seems like problems with fuel? Should I wash tank, and carburetor? Air filter is almost new... What should I check as well?

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Apprentice

Renas

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No, I have cleaned only float reservoir and it's needle.

Just before leaving my garage I found that spark cap was loose and barely holding on the spark. Am I right that if that could be the cause, then this would happen not only when I open throttle, but all the time?

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Apprentice

Renas

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I'm really really pissed off... Not able to solve the problem for a month or so! I have checked fuel valve, cleaned the carb, changed spark...

After cleaning a carb, idling got little bit weird. After worm up, idling got to 2000 rpm, than reduced it to 1400 rpm, and after 10 minutes it was stalling on idle due to too low revs.

Stalling still there and I don't know where to look forward... Damned! ?

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  • 2 weeks later...
Newbie

bzack

Posted
Posted

I think it is an Electrical problem. The Fault might be with the Coil, Condenser, Spark Plug, Spark Plug Cable or any other part present to deliver the Spark. Whats happening is that Somewhere along the circuit there is a short and the strength of spark is not being carried to the Spark Plug. It could be a Faulty part or simply a loose or rusty connection.

I had a similar problem with my Yamaha RD 350 (2 Stroke, 2 Cylinder).

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Apprentice

Renas

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I think it is an Electrical problem. The Fault might be with the Coil, Condenser, Spark Plug, Spark Plug Cable or any other part present to deliver the Spark. Whats happening is that Somewhere along the circuit there is a short and the strength of spark is not being carried to the Spark Plug. It could be a Faulty part or simply a loose or rusty connection.

I had a similar problem with my Yamaha RD 350 (2 Stroke, 2 Cylinder).

Thanks! I'll check everything. Where have you been all this time with these suggestions?!

?

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  • 2 weeks later...

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