Topic: CB750 K1 Carb Question

[cakey]

Just rebuilding my carbies on my Cb750 K1 and noticed something that I thought might be odd so thought I would check.

On carbies 1 and 4 there is only 1 brass plug with a hole in it either side of the main jet.

On carbies 2 and 3 there is 2 brass plugs with a hole in it either side of the main jet.

Just wanted to double check if this is standard or not.

Also out of the 4 carbies all the carb slides move freely up and down until I screw the lid down over the shaft and then they slide a bit stiffer. Is this normal or should there be a bit of lube on the shaft?

Thanks

[harisuluv]

That is normal.  Carbs 1 and 4 are on the ends, so they have no adjacent body to vent/duct air to.  Therefore it is a plug and not a passage.

Your second issue could be because of a few things.  Your slide rods might be bent, your forks or "fingers" on the linkage could be misaligned.  Lube is on the part you described but I find that you can smooth things out a lot if the "fork" part has a tiny bit of lube too, the top of the fork is curved to cam the adjusters, that's where it would help to have a smooth contact (hence lube).

[cakey]

Thanks Harisuluv, you have put my mind to rest with those plugs. I have been missing some pretty odd things along the way so I thought this was another.

The only thing I found out of wack with the carbies then was No#95 main jets instead of #120

I still don't have the carbies back on the racks yet or the forks. Just as is.

[harisuluv]

Ok, well in that case, you'll have to check if your rods are straight.  Sometimes if they are bent or something wasn't aligned correctly you can see where the chrome has been rubbed and is starting to show the base metal.  Looks like copper.  If someone has pulled on them hard, the "c" shaped clamp that the rod fits into will be bent up and widened a lot.  This will make the resting position of the rod inconsistent meaing that it might do what you describe cause it's not always in a centered position.

[cakey]

Ok, well in that case, you'll have to check if your rods are straight.  Sometimes if they are bent or something wasn't aligned correctly you can see where the chrome has been rubbed and is starting to show the base metal.  Looks like copper.  If someone has pulled on them hard, the "c" shaped clamp that the rod fits into will be bent up and widened a lot.  This will make the resting position of the rod inconsistent meaing that it might do what you describe cause it's not always in a centered position.

Great info. The slides did have to be pulled out because they were stuck so I will check. This them when I started. Hadn't been used in maybe 18 years

[harisuluv]

Come a long way so far, good job.  Next time try a heat gun or if you don't have one a hair dryer.  The slides are probably stuck from a layer of lacquer.  Heat up the slide area from the outside and it will liquify to syrup, then you can just pull the slide out.  If it's not working, you probably don't have it hot enough. 

If there is a lot of dirt or granular material everywhere sometimes i just soda blast the slide on each side for a few seconds just so I can clear out any debris or piece of sand that might wedge itself in there when pulling out the slide.  That way you won't scratch it the entire length of the slide.

It's always possible to get them out, but it's a matter of how much damage you do getting them out that's the hard part.

[cakey]

Definitely noted for thenextone thanks Harisuluv.

Sorry to ask all the questions but is there documentation anywhere of what fuel lines and sizes are need for these carbs. Mine were missing almost all of them.

I have figured out so far:

4 x small Darin fuel lines from the bowls to out past the swing arm
1 x main line (does this go to the two tee pieces between the carbies?)
3 x short fuel lines connecting the carbies (looks like hard plastic but possibly fuel line)

Does this all sound about right. I will try the Honda shop to see if I can get the lines

[harisuluv]

The tubing for between carbs 1&2, 3&4, the drain tubes, and the two vent tubes between 2&3 (usually about 10 inches long, they do NOT connect, they are just ducts to outside) are all the same tubing, which I believe is 3.5mm.

The fuel line is 5.5mm.

So you only need two different types of line.  They are still available for purchase OEM.  I would recommend OEM cause you aren't going to have an easy time finding 5.5mm fuel line anywhere else.  Otherwise, you will be stuck between 3/8 (little too tight) or 1/4 (little too big).  And then you will have to fiddle with clamps.  With the Honda stuff you won't need that, it will be tight and it won't leak.  If you want to do a super deluxe job you can just reuse those little clips that give it some more grip around the connections.  I'll PM you with a place where you can get them.

[cakey]

Great