Topic: New Visual Float Level Tool for the CB750

[cfairweather]

I have been developing a new tool to check the float levels.  I will probably sell this tool on eBay soon.  A plastic plug with rubber hose clamps will fit snuggly into the large hole on the side of the carb.  The clear tubes slide into the clamps and will stay in place unless you pull them out.  If you need to adjust the level, turn off the petcock, drain the carb using the tube and remove the carb bowl.  Make the adjustment and install the bowl so you can check it again.  Makes this task about as easy as it can get.  I like to set the levels using the lowest rim edge of the carbs.  On the CB750, the lowest edge is closest to the cylinder fins.  Simply compare the levels to the lower edge of the rim.  The level should not be higher than that edge and can be two or three millimeters below it.  You can use a straight edge from the lowest edge or just move a tube over to the lowest edge so you can get a close comparison.  I don't recommend starting the engine while using the tool for safety reasons.

[willbird]

That is a nice setup for sure, nice work.


Bill

[BenelliSEI]

I’ll be the first to order a set. Slickest I’ve seen so far. PM sent!

[MauiK3]

Really nice

[Finnigan]

Very good idea, thanks for sharing

[Tracksnblades1]

Great design..

I like that side by side comparison of the inner and outer..

[jwurbel]

Looks a lot better than my set up.

Any idea on anticipated cost?

[Rayzerman]

What is the thread size and pitch?  May fit more than 750's I'm guessing......

[cfairweather]

Thanks for your comments.  The drain screw thread size on the CB750, GL1000 and others is M6x0.75.  Some Kawasaki bowls also use the same thread size.  I am thinking to price it at $30.00 - $40.00 for a set, but I would like some advice. 

The brass tube fittings should only be tightened enough to make a seal.  The reason:   Is it is helpful to be able to screw the fitting into the bowl without the tube turning sometimes.   Also, you can adjust the tightness of the plastic mount by turning the nut.  If you tighten the nut, it will become tighter in the hole.  I like to have it where it is tight enough to stay in, but loose enough to where I can pull it out without loosing the nut.

[denward17]

Just as a FYI, these are not needed on the PD carbs (I don't think anyway).

I purchased a set (2) from Z1enterprises a while back to check the level on my 550:

https://www.z1enterprises.com/fuel-level-gauge-tool-kawasaki-suzuki.html

[cfairweather]

Thanks for the information.  I am surprised they are selling each tube for only 9 bucks.   I will consider selling my kit for less than I originally thought, maybe $25.00 and $5.00 for shipping ($30.00 including shipping).  I will list them specifically for the 1969 - 1976 CB750 SOHC as the mount will only fit these years.  The mount fits into the large hole on the carb.

[jwurbel]

My K2 used 5mm threads, not 6 for what it’s worth

[willbird]

My K2 used 5mm threads, not 6 for what it’s worth

Hmm my for sure unmolested CB750K2 for sure uses M6x.75...I chased a thread to fit on my G4003 Grizzly lathe.

[jwurbel]

 Now I am going to have to look. As I remember the 6 was too big.

[willbird]

Now I am going to have to look. As I remember the 6 was too big.

I bought a set of carbs from Ebay and some had a smaller drain plug so they did make bowls for the round tops that are smaller.

[cfairweather]

I made 5 kits and put them on EBay for $30.00 and that includes shipping in the USA.  If people like them, I will make some more, but for now, just 5 sets. 

https://www.ebay.com/itm/276813586992

[BenelliSEI]

Looking forward to my set. Thanks!

[jwurbel]

Verified that I have 5mm not 6mm screws.  Also matches my Carbtune fitting as well.  If you make more, and 5mm is an option,  I am in.

Great idea, by the way.

[cfairweather]

What is the thread pitch of the 5mm drain screw you are using?  The vacuum sync hole is a M5 X .8.  Sounds like the 5mm drain screw is used on other carb sets, so I will probably look at making some.     Thanks for your input.  I am pretty sure that someone modified your bowls at some point, because to my knowledge, all 1969-1976 CB750 SOHC bikes, that use these carbs, had 6mm X .75 screws.  I am guessing that one of your bowls had stripped threads and someone fixed the threads with an insert.  He probably did all four just to make them all the same.  This is total speculation and I might be wrong. 

[seanbarney41]

I have seen the 5mm drain screws on 69-76 type carbs...thinking the 5mm were 69, 70, some of 71?, not sure at all

[cfairweather]

I have a 1970 and two 1971 CB750s and they have 6mm X 0.75 screws. Interesting...

[seanbarney41]

The float bowls are also completely inter-changeable.  Also, quite sure I have seen a couple racks with 3 6mm and 1 5mm or vice versa.

[cfairweather]

I will make some M5X.8 tubes in about a month.

[BenelliSEI]

I think my Sandcast has the small Derain screws, but easy enough to swap on some later bowls…..

[cfairweather]

My 70 has smaller screw heads, but it still uses 6X.75 threads.

[seanbarney41]

My 70 has smaller screw heads, but it still uses 6X.75 threads.  I don't know what "Derain screws" are, but my 70 model might them since they are a bit different than later years.  What size threads are on the sandcast?

uh oh...maybe that smaller head was all I was thinking of!

[willbird]

My 70 has smaller screw heads, but it still uses 6X.75 threads.  I don't know what "Derain screws" are, but my 70 model might them since they are a bit different than later years.  What size threads are on the sandcast?

The more I think about it I realize that was the difference not the thread size. Sorry if I added any confusion.

[BenelliSEI]

Got my kit today. Looks great! Thank you Cedric.

[Medyo Bastos]

Nice!


Sent from my iPhone using Tapatalk

[beemerbum]

I made 5 kits and put them on EBay for $30.00 and that includes shipping in the USA.  If people like them, I will make some more, but for now, just 5 sets. 

https://www.ebay.com/itm/276813586992

Will these work on my 1972 K2 750?

[PeWe]

Just as a FYI, these are not needed on the PD carbs (I don't think anyway).

I purchased a set (2) from Z1enterprises a while back to check the level on my 550:

https://www.z1enterprises.com/fuel-level-gauge-tool-kawasaki-suzuki.html

That is very cheap.
I bought their fuel level gauge for my Mikuni VM29. I think it cost $25US each 2014.
I later ordered 3 more to measure all at the same time.
They fit my TMR too.

https://www.z1enterprises.com/fuel-level-gauge-tool-for-vm29-rs34-rs36-smoothbore-carbs.html

[BenelliSEI]

We each chose our options. Personally, I find the “clear tube” simple and quick.

[PeWe]

See the actual level will prove that fuel  level is OK in bowls.
It has helped me.

I had thoughts about too low levels in my CB750 stock carbs. Fuel starvation from ca:120kmh and up

After fiddling with fuel levels....
It was a little kinked fuel hoses. If hose pipe on carb is angled wrong which can happen when making space when adjusting the fuel screw.

I have used braided hoses on my K6 for many years so softer stock style hose was  a NOS experience

[cfairweather]

BeemerBum-Will these work on my 1972 K2 750?

Yes, unless someone installed different float bowls on your bike or resized the float bowl threads.  If they don't fit, I will either refund you or send you an additional set with the thread size you specify.  It would be best if you verify they are M6 X .75 before you order, but I will try to make you happy either way.

[Rayzerman]

I made 5 kits and put them on EBay for $30.00 and that includes shipping in the USA.  If people like them, I will make some more, but for now, just 5 sets. 

https://www.ebay.com/itm/276813586992

You might want to revise your listing to mention the M6 x.75..... your list of compatible bikes would increase.... cb350F has those threads.....  also, why only a set of 2 not 4?

[scottly]

Cedric, if you want to offer these to members directly, you should post them in the classified "For Sale" section.

[rotortiller]

Float level is like a toilet tank level, viewing the actual level is easiest and best for the ideal flush lol. Our crude, old-school technology requires crude and simple maintenance methods. After float system maintenance clear tube viewing is a great way to verify expected results, it removes any questions as to workmanship. No need to drain and measure contents since we are concerned with the fluid level in the bowl because that can affect the jets performance. Anal people may level adjust the bike to make the carbs sit in a perfect position while doing the clear test. That being said, I have found published dry bench float settings to be accurate enough with the correct parts installed. It'd be a cold day in hell when I drained the bowls to measure the contents, any fluid above the float valve would add to the fluid volume.

[Deltarider]

The clear tube tool I made in the 90s has been used twice. Too much a hassle. Besides the tube is now hard as rock. My method which I've described before, has proved to be less time consuming. I welcome criticism from those who have actually applied it.

[cfairweather]

Thanks for your comments on this new tool.  I think there has been enough interest in this for me to make some more and I will implement most of your suggestions.  I prefer selling on eBay because they simplify international shipping and save me money on USA shipping.  I am able to just print a label and ship it instead of standing in a long Post Office line.