Bike Idles at 2500 RPM What have I done?

[jonsmyth]

I changed all my diaphragms yesterday. I also moved the circlip on the throttle jet up one notch away from the needle to lean it out. I did this on all carbs. At several points, I stopped and started the bike. It sounded OK. It idled OK.

Today, I decide to change the spark plugs so I can evaluate the new mixture- and discover #2 cylinder spark plug cap was dangleing on the other side so it was idleing on 3 cylinders.

I go ahead and finish changing and gapping all the plugs.

The dang thing races at 2200 rpm or higher, no matter where I put the screw.

The trottle cable is disconnected, as it broke and I got the new cable this afternoon so have not put it on yet.

No, the choke is not on. The linkages seem to all be functioning.

I do not see any loose vacuum hoses- but i know a leak may be part of it.

 

What to do? I can't sync carbs like this!

[MiCarl]

 

What to do? I can't sync carbs like this!

 

If you've got the throttle cables disconnected, the idle speed screw adjusted off the stop and the linkages are all fine then syncing is precisely what you need to do.

 

One or more of the butterflies is completely closed, holding the others open. Was hidden by your no firing #2.

[jonsmyth]

When I replaced the diaphragms, I did not seat them well and two came off. I built a little plastic tool to spread the seal, then worked each one around until they were all very tight. I get the concept now- no leakage!

Bike is running smooth at 1000 rpm and hitting smooth on all cylinders.

[GigaWhiskey]

When I replaced the diaphragms, I did not seat them well and two came off. I built a little plastic tool to spread the seal, then worked each one around until they were all very tight. I get the concept now- no leakage!

Bike is running smooth at 1000 rpm and hitting smooth on all cylinders.

 

Just forgetting to tighten a couple diaphramn screws will get poping in yer exhaust.