Author Topic: 400 F problem  (Read 744 times)

Offline boilermaker1

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400 F problem
« on: May 09, 2020, 05:56:01 PM »
Took my 400 out for a spin today.. For some reason it is bogging down when the revs hit 5000 , and will not rev above 5000..
Bike is been used regularly and ran fine a few days ago..Fuel is fresh.
Where should I start looking for the problem???

Offline Nurse Julie

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Re: 400 F problem
« Reply #1 on: May 09, 2020, 06:08:40 PM »
That's a pain 😢😢😢 I would check points / timing first and then drain the float bowls just to see if there is any debris you may have picked up in the fuel.
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Offline K2-K6

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Re: 400 F problem
« Reply #2 on: May 09, 2020, 08:08:02 PM »
You've not carried out the vintage 400 Four "restriction" method of preference  ;D have you?  That's putting something under the seat to store,  waterproof overtrousers being favourite item, that prevents the air intake being able to breath properly.

You'll not be the first,  or anywhere even in the thousands that have mastered this before  ;D

Offline boilermaker1

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Re: 400 F problem
« Reply #3 on: May 09, 2020, 09:05:28 PM »
Thanks for the suggestions,,,No. nothing under the seat

Offline Bryanj

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Re: 400 F problem
« Reply #4 on: May 09, 2020, 09:40:24 PM »
The other unheard of problem------honest----- is the trousers putting the choke on

Offline robvangulik

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Re: 400 F problem
« Reply #5 on: May 09, 2020, 09:51:37 PM »
Are all headers equally hot?I've had to fish a mainjet out of a float bowl once...the symptoms were like yours.

Offline Erwin83

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Re: 400 F problem
« Reply #6 on: May 09, 2020, 10:41:10 PM »
If you don't have electronic ignition, but still run old points, check if the ignition timing mechanism moves freely.
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Offline boilermaker1

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Re: 400 F problem
« Reply #7 on: May 10, 2020, 03:33:37 PM »
Update:::Bike now running fine again.. Turns out the cover of the air filter box had come off..
Again thanks to all who gave advise

Offline mike the bike

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Re: 400 F problem
« Reply #8 on: May 10, 2020, 08:52:27 PM »
I was going to suggest that😀
Where's that 10mm socket got to?

 

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