I have a 81 yamaha xs 400 . it runs great but one thing i noticed is when I first start it to let it warm up the exhaust will make a popping noise on the right side which comes and go's. But after it warms up I don't notice it as much. The left side exhaust dont pop. what should I check for?

I have a 81 yamaha xs 400 . it runs great but one thing i noticed is when I first start it to let it warm up the exhaust will make a popping noise on the right side which comes and go's. But after it warms up I don't notice it as much. The left side exhaust dont pop. what should I check for?

Hi Dave,

I guess your bike is misfiring when cold. Perhaps you should adjust the mix screws & balance the carbs .... TBH while your at it I would check the tappits, Timing & Dwell and along with that put some new plugs in & this should fix the problem.

Regards Jim

Hi Dave,

I guess your bike is misfiring when cold. Perhaps you should adjust the mix screws & balance the carbs .... TBH while your at it I would check the tappits, Timing & Dwell and along with that put some new plugs in & this should fix the problem.

Regards Jim

This is my first bike I know it has new plugs in it . How do I balance the carb.? I don't know a much about bikes. What are tappits? Is the mix screws on the carb.? Thanks again

This is my first bike I know it has new plugs in it . How do I balance the carb.? I don't know a much about bikes. What are tappets? Is the mix screws on the carb.? Thanks again

Hi Dave,

Tappets (translate from English) = Check the Valve Clearances .MM intake .MM exhaust

To Balance the Carbs you will need vacuum gauges

The Mixture screws would be adjusted in conjunction with the balance operation.

As you are new to mechanics it would be good to track down a workshop manual to familiarize your self with the bike and some mechanical terms etc etc, but if you want a talk thro let me now

Regards Jim

Hi Dave,

Tappets (translate from English) = Check the Valve Clearances .MM intake .MM exhaust

To Balance the Carbs you will need vacuum gauges

The Mixture screws would be adjusted in conjunction with the balance operation.

As you are new to mechanics it would be good to track down a workshop manual to familiarize your self with the bike and some mechanical terms etc etc, but if you want a talk thro let me now

Regards Jim

I just weighed each carb and balanced them by filing some alloy off one side!!

I just weighed each carb and balanced them by filing some alloy off one side!!

I went to start the bike now it don't make the popping sound anymore. But one thing I noticed was after it sat for a bit i noticed gas coming out of the one side of the carb. I was told that the float was stuck open . What would be the best way to clean it . I was told to get some carb. cleaner and spray into it. What would you suggest?

I went to start the bike now it don't make the popping sound anymore. But one thing I noticed was after it sat for a bit i noticed gas coming out of the one side of the carb. I was told that the float was stuck open . What would be the best way to clean it . I was told to get some carb. cleaner and spray into it. What would you suggest?

its usually the little needle valve that goes you canget them from ebay or sirrus consolidated. easy enough to do, but you need to take the carbs off the bike first.

I just weighed each carb and balanced them by filing some alloy off one side!!

Hi Drewps

how droll

Regards Jim

Hi Drewps

how droll

Regards Jim

its usually the little needle valve that goes you canget them from ebay or sirrus consolidated. easy enough to do, but you need to take the carbs off the bike first.

Thank you for everyones help!!!!!!!!!

Thank you for everyones help!!!!!!!!!

Hi Dave,

just looked back thro the pervious posts and for some reasaon the site lift MM rather than 0.1 mm and 0.15 mm

Regards Jim