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Author Topic: Bike poops out on hard throttle (or full throttle)  (Read 1902 times)

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Offline zhamid

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Bike poops out on hard throttle (or full throttle)
« on: August 20, 2020, 03:50:58 pm »
I can make the rpm go up if I am gentle with the throttle. But hard throttle (or full throttle, even if I increase it to full gently) makes the engine hesitate. Somethings it bobs (as if I am in a very high gear) and other times it feels like someone did a kill switch. 

Assuming the fuel manager is fine, what else could be wrong? 

- I ordered new spark plugs to eliminate that possibility, waiting for them to arrive.
- I cleaned the air filter with the K&N cleaner and K&N oil (I have the K&N filter).

What else should I check?

The bike has a Cobra slip-on exhaust, a Cobra intake (that uses the K&N filter) and a Cobra fi2000r fuel manager.  I'll take out the fuel manager this weekend to eliminate that as a possibility, but until thn I want to see what else to test because I don't thinnk it's the fuel manager. 



Offline DelawarePete

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #1 on: August 20, 2020, 04:00:16 pm »
It's probably the cobra fuel processor.  may need to adjust the pots, or just remove it.
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Offline legion95928

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #2 on: August 22, 2020, 05:51:06 pm »
It's probably the cobra fuel processor.  may need to adjust the pots, or just remove it.

--- Agreed!!!
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Offline zhamid

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #3 on: August 23, 2020, 02:40:22 pm »
It's probably the cobra fuel processor.  may need to adjust the pots, or just remove it.

--- Agreed!!!

Tried, didn't help!


What I've tried:
1. The fuel controller has manual pot settings (3 different pots). I've tried every permutation.
2. I took out the filter and completely cleaned it. 
3. I've taken out the fuel controller completely, it just made it run leaner (and therefore pop more), but otherwise the same symptoms. 
I haven't tried changing the spark plugs yet, but ordered them and am waiting for them to arrive.   I don't think it's the O2 sensor because it idles perfectly and is perfect if I mainain <= 3,000 rpm.   
It might be the throttle position sensor, but I doubt it.  There's no symptom below 3,000 rpm and beyond that point it feels more like it's too rich or too lean.   
Any other ideas? What else can I try?

Offline Pir8

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #4 on: August 25, 2020, 03:01:13 pm »
With the Cobra Fuel Controller, are you supposed to run an O2 sensor?  Most FCs say to remove it. 

Pull the sparks and see what condition they are in.

It also almost sounds like it could be a badly slipping clutch. How many miles?

Offline DelawarePete

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #5 on: August 26, 2020, 12:38:14 pm »
Fuel pump might be taking a sh!t on you.
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Offline zhamid

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #6 on: August 27, 2020, 06:34:15 pm »

It also almost sounds like it could be a badly slipping clutch. How many miles?

I am not mechanically inclined. How would a slipping clutch cause this, considering it happens on neutral too.

Offline DrM

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #7 on: August 27, 2020, 08:34:18 pm »
I would very curious to learn what happens when you put your new sparkplugs in. 

Offline Pir8

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #8 on: August 28, 2020, 12:24:26 pm »

It also almost sounds like it could be a badly slipping clutch. How many miles?

I am not mechanically inclined. How would a slipping clutch cause this, considering it happens on neutral too.

Ha! Sorry, didn't see that it happened in neutral too.  Otherwise, if RPMs go up and bike speed doesn't, that's a pretty good indicator of a bad clutch. 

Did you pull spark plugs yet?  See this article: https://motorizedbicyclebuilder.com/how-to-read-your-spark-plug/ (Not an endorsement, didn't even read it; but the chart at the bottom is what you need).  So even before you get the new sparks, you may be able to tell a lot by pulling BOTH plugs and comparing them to the chart in the linked article.  This bike's plugs are EASY to pull out.

I didn't see the mileage in the posts.  That could help us help you. (for example, if it's over 15k miles, I think it should have had the valves adjusted? did it?) 

Offline zhamid

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #9 on: August 28, 2020, 11:07:55 pm »

It also almost sounds like it could be a badly slipping clutch. How many miles?

I am not mechanically inclined. How would a slipping clutch cause this, considering it happens on neutral too.

Ha! Sorry, didn't see that it happened in neutral too.  Otherwise, if RPMs go up and bike speed doesn't, that's a pretty good indicator of a bad clutch. 

Did you pull spark plugs yet?  See this article: https://motorizedbicyclebuilder.com/how-to-read-your-spark-plug/ (Not an endorsement, didn't even read it; but the chart at the bottom is what you need).  So even before you get the new sparks, you may be able to tell a lot by pulling BOTH plugs and comparing them to the chart in the linked article.  This bike's plugs are EASY to pull out.

I didn't see the mileage in the posts.  That could help us help you. (for example, if it's over 15k miles, I think it should have had the valves adjusted? did it?)

Thanks, that's the project for this weekend :).

It only has 6,000 kms. But it's 5 years old and I am the 3rd owner, so who knows.

Offline zhamid

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #10 on: September 02, 2020, 03:52:45 pm »
I would very curious to learn what happens when you put your new sparkplugs in.
Didn't help :(. Same problem.

Could it simply be a blown fuse?
« Last Edit: September 02, 2020, 03:57:05 pm by zhamid »

Offline Pir8

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #11 on: September 02, 2020, 05:25:06 pm »
What did the old plugs look like? 

Online lunkhead

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #12 on: September 03, 2020, 02:24:33 am »
Test your clutch switch. Another forum member recently said his Bolt didn't run right when he removed it. It's wired to the ECU so it'll rev differently whenever the lever is pulled in. If the nub broke off or the switch is faulty, it'll act as if the clutch is always pulled in and run poorly under load.
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Offline zhamid

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #13 on: September 03, 2020, 10:13:20 am »
Test your clutch switch. Another forum member recently said his Bolt didn't run right when he removed it. It's wired to the ECU so it'll rev differently whenever the lever is pulled in. If the nub broke off or the switch is faulty, it'll act as if the clutch is always pulled in and run poorly under load.

Thanks, I'll check it out. Question: would that cause a problem in neutral?

It happens in neutral too.

Offline DelawarePete

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Re: Bike poops out on hard throttle (or full throttle)
« Reply #14 on: September 03, 2020, 10:33:45 am »
fuel pump
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