Bike bogging at low RPM

Springbok

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Good day.


I am new to this forum and I have a question. I have bought a 1982 XS 400 heritage special. The bike has +-13 000 km on it.

I have cleaned the carbs and I have manage to get the bike running.


The issue I am dealing with is the bike is bogging down if I crack on the throttle. It bogs down at low RPM.

If I increase the throttle slowly it gains RPM and revs fine.


I would also like to add that the right side carb / cylinder back fires some times when revving / letting off the petrol.


Any suggestion on what the issue might be ?


Thanks
 
Have you checked for vacuum leaks at the rubber carb mounts? Also maybe valve adjustment and carb synchtonization/balace
 
I have visually checked the Carb mounts for cracks and I did not see any.

I think I will just replace them to be 100 % sure. Once I have done that I will try balance / synch the carbs.


Thanks for the help
 
You can spray carb cleaner around them to check for cracks or leaks. You will notice a difference in the idle. I have had to replace them on all 4 I owned.
 
You can find loads of carb synch info online and in posts on here. You can even find methods to bench synch them to get close before you use a manometer. Remember,if you synch them before you make valve adjustments you will probably have to do it again.
 
I will try that this weekend.

So I will ask this question and its probably a stupid one but I am going to ask it anyway.

If you watch the clip I attached what are your thoughts on the engine sound.

I should off added that I have to place my hand over the back of one of the carbs to cold start the bike.

Thanks
 
Last edited:
I think the valves sound noisy but they tend to be that way
As far as the hand over the carb, that answer is above my pay grade and knowledge!
 
Make sure the carbs have the stock intake setup and air filter/boxes. If you don't that's the issue.
 
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