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Need help with carb tuning!!!

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Need help with carb tuning!!!

PostAuthor: Shane058 » Thu Jun 20, 2019 9:17 am

What r the steps to properly tune my carbs??? Idel speed, pilot screw adjustment, float height, n carb sync. What order do I need to do them in???

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Re: Need help with carb tuning!!!

PostAuthor: bstig60 » Sat Jun 22, 2019 1:25 pm

Adjust idle speed to 1000-1100 R's, There is a built-in gauge on the Mikuni's that shows the correct float height adjustment. Pilot screws should be set at 2.5 turns out from a soft seat, and adjusted for the best idle on each cylinder from there. Once the above is done, sync the carbs using a manometer.
Idle speed will need to be re-adjusted as needed during the process.
Bill
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Re: Need help with carb tuning!!!

PostAuthor: baxterj787 » Thu Jul 25, 2019 2:08 pm

Bstig60 has some sound advice.

Take the air filter off to access the slides. Make sure the slides / diaphragms have a smooth return and return at the same rate. If one has a smooth return and the other snaps back, you may have to replace the CV diaphragm. I replaced both of mine from a site in the UK. It was a pain but I made it work.

CV carbs are very sensitive to air leaks upstream of the fuel outfall. Make sure the airbox lid is sealed (no cracks / gasket is present and intact). I had to make a gasket for my lid as the gasket was gone. The bike ran worlds better with a proper seal.

Regarding the fuel screws mentioned in the post above, it is worthwhile to remove them and blast some gum-out into the ports. Before blasting, MAKE SURE you have retrieved the screw / spring / small flat washer / small o-ring. If that o-ring disappears or is damaged, the bike will not run right no matter how the carbs are adjusted. Also makes carb syncing kinda hard...

The ports that is being cleaned out is the pilot or low-speed circuit and terminates in the carb throat. If that port is blocked, the result is no fuel or inadequate fuel at idle up to about 3k RPM. This also will make carb sync kind hard...

Finally, the jets need to come out of the jet blocks to be cleaned. Inspect the jet block gaskets and the o-rings that go around the main jet nozzles. If those are damaged or missing, the bike will not run properly. The little black rubber plugs that squeeze into the end of the jet blocks also need to have a pretty snug fit.

Next time I am in my carbs I will be building a powerpoint to post up here. Maybe in the spring?
Good Judgment comes from Experience. Experience comes from Bad Judgment.

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