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Old 04-22-2011, 10:39 PM   #37
Brtp4 OP
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Joined: Sep 2006
Location: Bend, OR
Oddometer: 1,987
AP Timing

The biggest hassle of the carb install was figuring out how to time the accelerator pump. You have to time the squirt to start a little late, and 2. limit the duration of he squirt to 1.5 secs, to not bog the motor.

The newer FCR-MX pumpers have a leak jet, which can be changed out to control the squirt. A larger jet bleeds fuel out of the circuit instead of pumping it into the motor. It is quantitative and works well. But, the older FCR slant body carbs like the 35 do not have leak jets. There is an accessory from Boyesen that duplicates the bleed-off, so I got one to try:

and mounted it up:

I started testing the squirt off the bike, with odd results. The pump would hesitate, then squirt for what seemed like forever, definitely not 1.5 seconds. No amount of adjusting was helping, and I was getting confused.

By now I had burned a load of time and money ordering various diaphragms and add ons, and was getting kinda frustrated. I finally decided to just send the carb to Eddie Sisneros ("Burned" on Thumpertalk) and have him set it up. After a few days , Eddie discovered that the squirt passageway WAS NOT FULLY OR PROPERLY DRILLED FROM KEIHIN. "Yeah, the thing would hesitate and spit, and then squirt forever. I drilled the hole, wired the AC pump linkage, and now it is fine." Good news, I would have never spotted this, and would have chased the squirt timing forever.



Bend, OR

Brtp4 screwed with this post 10-04-2014 at 05:50 AM
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