Several months ago I disassembled the carbs on my F1, but life happened and I wasn’t able to tackle reassembly until this week. I took pictures during disassembly, but not enough it seems.

At this point I have five (5) questions (!!!):
1) I am not sure how the synchronization springs are supposed to go on. I took pictures of two ways I think it could work - which is correct?




or



2) The shop manuals I have show two “thrust” springs which appear to sit between the outer pairs of carbs, but are unclear as to where exactly they go. The only way I can see them going is like this :



is the above correct ?

3) what’s the purpose of the above mentioned thrust springs?

4) The shop manual mentions setting the float height after tilting the carbs between 15-45 degrees “from vertical”, but it isn’t exactly clear what vertical means, and when vertical, which way I should be tilting them. In my mind, in the picture below, the carbs are sitting vertically (ie on the diaphragm cover), and I think they want me to tilt the carbs towards the camera. Is that right?




5) the same section says to measure a distance with the float valve “lightly seated”. I can’t perceive a difference in seating, it seems like it can only be seated or not. Is this just a matter of experience or is it just semantics? How important is it that the valves for each carb seat at exactly the same angle?

6) The manuals also mention using a special tool to measure float height. Do I need this tool or are there other ways to do this. .

Thanks for reading !

 

This is correct. The spring keeps the throttle arm against the adjustment screw. This is how the relationship between one carburetor and the next is maintained.



Float adjustment. You'll notice that the Float Needle has a tiny spring loaded plunger on top. The float level of 8mm above the mating surface of the Float Bowl Gasket is not compressing that spring, but only touching it. In other words, any other movement of the float in an upward direction would cause the plunger to compress.

The bottom of the float should be 8mm above the gasket surface. You can use a caliper or anything else that can measure 8mm.

 

Thanks @IDoDirt . I had no idea the top of the float needle was spring loaded. Are there any rubber parts inside the needle ? Wondering whether I can stick it in carb cleaner.

also, did I guess right as to the location of the thrust spring in my pictures? I couldn’t figure out what it would do there, especially as it was fairly close to the bracket that goes across all the carbs.

 

There are no rubber parts inside that I know of, only the tip of the float needle. I'm not sure of the thrust springs since the F3's don't have them. Maybe some pictures from eBay or something might help with that determination.

 

Thanks again… I felt like a dummy when I took another look at the needles and noticed they were rubber. I just thought they were dirty , LOL

 

Hey @NuggyBuggyCBR did you get the floats measured ok?
I just did mine too. First time doing this on motorcycle carbs myself.
I found this video helpful on you tube. I bought the measuring tool on ebay before I saw this video for like $24 and it made it nice and easy. But seeing how the height is measured with the tool I think it would be fairly easy to make some sort of gauge yourself (like out of a small block of wood or something) as long as you understand where to measure from.

 

@Mr Lee : I haven’t had a chance to have a go at it as I am trying to get my fuel pump and relay sorted out first.

I ordered the MotionPro float height gauge from a local retailer but it still hasn’t come in.

I started thinking exactly what you were suggesting - that I could fabricate one relatively easily. I do have a small milling machine (I went through a period of buying metalworking tools without building much) that would be perfect, but you’re right - I could also make it with woodworking tools as well.

I also realized I could use something like this:
https://www.leevalley.com/en-ca/shop...e?item=88N9001
Or
https://www.leevalley.com/en-ca/shop...s?item=99W6306

I have the latter for woodworking, and am pretty sure I have the former as well (I ALSO went through a phase of buying a fortune of woodworking tools without building much, ), and I would bet they would be 100x more accurate than the MotionPro tool.

I will definitely check the video you link to. I seems that most articles and videos just say to measure at the highest point. I found some other places that claim that measuring height is not precise enough and that one ought to use a clear tube connected to the float drain and measure the height of liquid in that tube against some known part of the float. But this requires some specification of what the height should be relative to some fixed point on the float body, which the manual does not provide.

Thanks @Mr Lee ! I read your thread about rebuilding the petcock with interest and now that I have found mine, will be taking a look at it as well.

 

Awesome video, thanks! Near end is wet-test that I always do as final functional confirmation that floats are at proper levels.

 

@dannoxyz are there specs for the proper height for an F1 in a “wet test” ? I’ve seen people pick various reference points , sometimes qualified with a “plus or minus” 1mm, which seems to make the process quite inaccurate in itself. The service manual doesn’t list one, nor do the Haynes or Clymer manuals for the F1.


Or is it just important that all carbs are at the same level?

also just to confirm, is the carb in your picture from an F1? It looks different than what I remember mine to look like.

thanks!

 

This weekend I tried to adjust the float heights. I found it maddeningly difficult. It’s very hard to tell when the float valve is “lightly” seated. I got so frustrated I considered building a jig to incrementally raise one side of the carb so that I could free myself from trying to tilt it while going blind trying to see where the float valve is. Anybody have any hints? It seems so simple in the videos !!!