Monobloc 389 Float Bowl Help

AgentX · Aug 15, 2018

Is this range of motion for the float normal? Lacking a frame of reference (first bike with Amals) it seems rather limited to me. The tickler can barely reach the float.

If it's not normal, what could be the issue? Incorrect float? Incorrect needle?

Thanks!

Beach · Aug 15, 2018

Correct float. Might want to replace float needle with a brass one with vinton tip, check float level and see if you need the washer under float jet. The tickler is supposed to push down on float at highest level to flood float bowl for easy starting.

texasSlick · Aug 15, 2018

Proper fuel level is at the "pip" near the center of the bowl cap. Place a 12 to 16 inch length of 1/8 " ID clear tubing over the idle jet, curve tubing into a manometer to see fuel level when the cap is in place. Add (increase fuel level) or remove (decrease fuel level) washers under the needle seat to adjust level.

I agree with Beach .... The float is correct, but the needle and/or seat may be incorrect.

Slick

AgentX · Aug 15, 2018

Thanks both for the info...will check the fuel level.

The tickler seemed to stop functioning correctly; it won't seep gas out the top when depressed. When I saw how the tickler barely touched the float, I figured maybe it has a problem.

Bodger · Aug 15, 2018

AgentX said:
Thanks both for the info...will check the fuel level.

The tickler seemed to stop functioning correctly; it won't seep gas out the top when depressed. When I saw how the tickler barely touched the float, I figured maybe it has a problem.

Sometimes when the gas in the float chamber evaporates, the residue on the needle jet can glue it on to the seat. I think this is a modern gas phenomena. When this happens pushing the float down with the tickler doesn't have any effect. The next time pushing the tickler down doesn't have any effect take the float cover off and see if the needle is stuck in the closed position.

AgentX · Aug 18, 2018

Thanks again, guys. I had a hard time getting a good seal on the tubing around the pilot jet, but once I got it somewhat right, the level seemed a bit low. Waiting on a brass needle now.

AgentX · Aug 23, 2018

Just to follow up, the brass needle seems to allow more movement, and the tickler gets a nice push on the float. Odd, because it seems just about the same length.

texasSlick · Aug 23, 2018

AgentX said:
Just to follow up, the brass needle seems to allow more movement, and the tickler gets a nice push on the float. Odd, because it seems just about the same length.

The seat orifice may have something to do with it. I think (think means I am not certain) the same needle was used with a 0.100 orifice seat and also with a 0.125 orifice seat. Naturally, the needle will penetrate deeper into the larger orifice.

Slick

AgentX · Aug 25, 2018

Ah, so that's what the .125 stamped on the seat hex flats refers to. Very good to know.

(Luckily, I am way too mature to giggle at all at your last sentence.)

Thx!

Monobloc 389 Float Bowl Help

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