Help Please! Bike shutting down!

[KROGOTH]

Ok...At high revs bike stays on. As soon as I throttle back it starts to misfire
and then shuts down. Hard to start too! A mechanic told me it is a lose wire
somewhere that is causing this. What are your thoughts all?? Is this an EHC issue? The bike stays on no problem when I have throttle revved up. Only when I let go does it misfire and then shut down!:bang::bang:

 

[LARS]

Maybe a jet of injector slightly clogged,try seafoam?,,I'm not an expert but it's a simple try.

 

[bryant1609]

Have you check to see if the enricher is in the on position? Have you changed anything on the Carb before this starting happening?

 

[KROGOTH]

Thanks all for the feedback. No nothing was changed prior to this. And the enricher I never use. And yes I checked to make sure it was not pulled.

 

[bigdogtech01]

Ok...At high revs bike stays on. As soon as I throttle back it starts to misfire
and then shuts down. Hard to start too! A mechanic told me it is a lose wire
somewhere that is causing this. What are your thoughts all?? Is this an EHC issue? The bike stays on no problem when I have throttle revved up. Only when I let go does it misfire and then shut down!:bang::bang:

Did you check for an intake leak? Might not be electrical, could be fuel/air related. Easy to check.

 

[KROGOTH]

How do I check for an air intake leak?

 

[bigdogtech01]

How do I check for an air intake leak?

With the motor warmed up and running at idle, spray the intake seal area near head with brake/parts cleaner. Make sure you spray from intake side pointing it towards primary side. Spray just a small amount directly onto intake seal area. If the motor dies down, changes at all in RPM then you have bad intake seals. Make sure you spray both front and rear cyls.

 

[bigdogtech01]

Also check your little black rubber boots over the extra nipples on the top of the carb. They do tend to go bad often. If they have any dry rot to them, replace them with new. You can buy them at most any auto parts store. Sold as 1/8" plugs.

 

[Killerdog]

i agree..mine dry rotted and it would misfire like crazy..easy fix

 

[KROGOTH]

Thanks guys for the inputs. I had my mechanic look at it and he still is insisting its an electrical shutdown due to the misfiring when it happened last night. I started the bike and let it run for a minute revving up and down, and nothing bad happened, no pops no backfires and it stayed on. I will take it out tomorrow and see what happens.

 

[Raywood]

Thanks guys for the inputs. I had my mechanic look at it and he still is insisting its an electrical shutdown due to the misfiring when it happened last night. I started the bike and let it run for a minute revving up and down, and nothing bad happened, no pops no backfires and it stayed on. I will take it out tomorrow and see what happens.

I think an electrical issue would effect the bike at all times at all rpms. I would pull the carb and give it a good cleaning checking the jets to make sure they are clear and blow out all the passages. And like others said make sure all the holes are plugged and the vent lines are connected with good connections.

 

[bigdogtech01]

I agree Ray. I would be willing to bet it's not electrical. Did the Tech even look at the carb? Who are you taking the bike to? Hole in the wall shop or well known service center?

 

[silver09]

Sounds like a carb issue that would be the easiest thing to look into instead of electrical thats time consuming:down:

 

[Ohmster]

Sounds like an intake leak to me. I doubt its an electical issue but if it was it could possibly be a crank position sensor. The EHC only supplies power to the ignition module and does not control the firing of the bike. To eliminate any power issues to the ignition module you can verify if the red led light is still illuminated on the ignition module after the bike shuts off. If you can get it to repeat the issue easily make sure your in a safe area. After the bike sputters and shuts off coast to a stop and remove the seat and look at the ignition module. If the light is still illuminated then your not having a power supply issue. However if the light is out then don't be quick to condem the EHC since it could be a wire short issue on the right hand pcb board. All it takes is a 30mS ground input on that off wire circuit to cause the EHC to shut off power to the ignition module. However with the hard starting issue after it dies I doubt its a power supply issue.

If its a crank sensor issue that one is a bit tougher to narrow down. A faulty crank sensor can pretty much end up being a R&R and cross your fingers since it creates its own voltage to the ignition module via AC voltage. So about the only way to verify that without just doing a R&R on it would be to put it on a dyno and verify its wave is good with an oscope.

To wrap it up without writing a novel would be to take what was suggested before about checking for an intake leak to begin with and go from there.

Gluck!

 

[Raywood]

Sounds like an intake leak to me. I doubt its an electical issue but if it was it could possibly be a crank position sensor. The EHC only supplies power to the ignition module and does not control the firing of the bike. To eliminate any power issues to the ignition module you can verify if the red led light is still illuminated on the ignition module after the bike shuts off. If you can get it to repeat the issue easily make sure your in a safe area. After the bike sputters and shuts off coast to a stop and remove the seat and look at the ignition module. If the light is still illuminated then your not having a power supply issue. However if the light is out then don't be quick to condem the EHC since it could be a wire short issue on the right hand pcb board. All it takes is a 30mS ground input on that off wire circuit to cause the EHC to shut off power to the ignition module. However with the hard starting issue after it dies I doubt its a power supply issue.

If its a crank sensor issue that one is a bit tougher to narrow down. A faulty crank sensor can pretty much end up being a R&R and cross your fingers since it creates its own voltage to the ignition module via AC voltage. So about the only way to verify that without just doing a R&R on it would be to put it on a dyno and verify its wave is good with an oscope.

To wrap it up without writing a novel would be to take what was suggested before about checking for an intake leak to begin with and go from there.

Gluck!

Ohmster, where you been buddy. The man has spoken. Heed his words. :2thumbs:

 

[Ohmster]

Ohmster, where you been buddy. The man has spoken. Heed his words.

Been living the simple life Ray although its getting boring. Just now getting my own shop set up though. Wont be much to begin with since I wont quit my day job and I'll make this an evening and weekend thing but I do have my first customer to build a custom bike for. I might post pics of the ongoing project here on the web site just for grins.

You have my personal email Ray so keep in touch. You come back through Kansas anytime in the future let me know so we can go drink a cold one together.

 

[Slider]

Also check your little black rubber boots over the extra nipples on the top of the carb. They do tend to go bad often. If they have any dry rot to them, replace them with new. You can buy them at most any auto parts store. Sold as 1/8" plugs.

I just pulled on mine and they broke off. Time to replace thanks

 

[Raywood]

Been living the simple life Ray although its getting boring. Just now getting my own shop set up though. Wont be much to begin with since I wont quit my day job and I'll make this an evening and weekend thing but I do have my first customer to build a custom bike for. I might post pics of the ongoing project here on the web site just for grins.

You have my personal email Ray so keep in touch. You come back through Kansas anytime in the future let me know so we can go drink a cold one together.

I'll only come back if I get to see that cute wife of yours!!!!

 

[KROGOTH]

Thanks again guys for your input on this. Unfortunatly I am halfway around the world in a little island of Malta. There are no big dog servic ecenters here and I am relying on a
friend who is a mechanic and also built his own custom bike.
I told him what you guys said and he mentioned if it was a carb issue it would be happening all the time. This was initermittent. And when I said why does it stay on at high revs then, he pointed out since I was producing more electricity the internal relay
did not trip and only when on low revs would whatever is shorting trip it out. Yesterday bike started fine at low revs no issues. Tonight I will take it out for a ride and see what happens and let you guys know.
The one thing I did do right before I left was add a little octane booster, since the gas here is low on it. Do you think that would do anything to cause this? Thanks again all.

 

[bigdogtech01]

Thanks again guys for your input on this. Unfortunatly I am halfway around the world in a little island of Malta. There are no big dog servic ecenters here and I am relying on a
friend who is a mechanic and also built his own custom bike.
I told him what you guys said and he mentioned if it was a carb issue it would be happening all the time. This was initermittent. And when I said why does it stay on at high revs then, he pointed out since I was producing more electricity the internal relay
did not trip and only when on low revs would whatever is shorting trip it out. Yesterday bike started fine at low revs no issues. Tonight I will take it out for a ride and see what happens and let you guys know.
The one thing I did do right before I left was add a little octane booster, since the gas here is low on it. Do you think that would do anything to cause this? Thanks again all.

Your friend is wrong. If it has an intake leak it can still run down the road at high RPM's and go unnoticed untill you let off the throttle. Not saying it's not electrical but to test for an intake leak will only take you a few minutes. You can do it yourself. Just do what I have already posted a page back.
WHat year is your bike? It is possible you have an ignition switch going bad. If it's the old 5 degree switch, it could be shutting the bike off and one due to vibration. Do the lights go off when the bike cuts out? Get more info for us please.