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one spark plug lean...one rich

4672 Views 8 Replies 4 Participants Last post by  4everrunning
I just installed an Area P full exhaust on my 08 250R as well as a Dynojet kit. I was hoping the recommended settings would work but...of course not. It is running poorly below 4500 RPMs. I have now moved the needle lower and it seems to be running fine now.

However, that is not what this post is about. After removing the spark plugs, that were used with factory settings, one side appears to be running lean while the other running rich. I have not tried to sync the carbs as none of that has been touched. I do know that the factory settings for the fuel/air screw is different for each side. Could that be the reason one side shows rich and the other lean? Should I have the carbs re-synced?

Any advice would be appreciated.

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Hopefully you've properly synced your carbs but I'm not exactly clear you have based on what I've read here...

Syncing the carbs is the final adjustment you will make to the carbs(really only one carb is adjustable) after you have made any changes to your bike i.e. exhaust or jetting changes...

Syncing involves the adjusting the vacuum pressure that the carbs draw while the engine is at idle... Synchronizing the carbs balances the pressure so that they are functioning within the same vacuum pressure range thus equalizing the amount of air/fuel mixture that is drawn into the combustion chamber.

Hopefully this is what you adjusted as the final step in the process of the changes you made as this will make for a happy bike and a happier rider... :eek:hyaaa
Did you use one of these... or something equivalent...?


If not I'm not sure how you would use a pencil to sync the carbs especially if you have taken them off the bike...

A carb sync tool such as the one linked above is used to measure the vacuum pressure drawn by each carb and allow you to tune them to each other thus synchronizing the carbs...

This is done with the carbs on the bike warmed up and idling...

Did you preform this type of procedure...?

If not then the carbs are not synced...
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