A bit of a head scratcher

[Vee4DFW]

The bike has been running rough after a rejet and a bowl level adjustment so we tried to do a sync. Upon putting that morgan carbtune on it we notices no vacuum reading out of carb # 2. You had to goose it to 3K to get it to read anything. We cracked the airbox and noticed that the diaphram was moving at idle. We opened up the carb and made sure the diaphram was sealed to the carb properly. Put everything back together and still no-go.

We then switched diaphrams with the rear carb to eliminate the obvious. After the swap the diaphram was still moving at idle with no vacuum reading. It actually popped the carbtune hose off the port when we gave her some throttle. Again the other carbs are fine.

Carb boots are new and checked for proper seal.


Any suggestions would be appreciated.

 

[texmax]

34 views.... anyone, Bueler. :biglaugh:

 

[mr.maxx]

could it possibly be an issue with the carbtune???

 

[maleko89]

Switch hoses and see if the reading switches sides.

Otherwise, push slide back and check position of throttle valve. Make sure carb is fully seated in that boot too.

 

[texmax]

Switched hoses on Carbtune. Carbtune is good. Throttle valve looks equal to others. Checked clamps on #2 carb boots...tight. What puzzles me is why the hose pops off on the #2 manifold. Also told him to check springs on sync screws to make sure they weren't binding or cockeyed. I think RagingMain had that problem.:ummm:

 

[Vee4DFW]

Randall,

When I took the carbs off I found that the number 2 butterfly was slightly open. I had to hold it up to the light to see it. I believe it was a weak spring because I checked the linkage and sync springs and they all seem to be lined up . At any rate, I did a carb exchange with Sean and got a sweet set with only 1500 miles on them. I popped those babies in last night but I have to sync them.

I got my carbtune in only four days. I'll have to run over to your house and give you back yours after I get my carbs zeroed in.

 

[Firewrench]

Have you done a leak down test yet? You may be getting a slight backfire through the intake valve(s) on that cylinder. May be time for a valve adjustment.