Topic: Help with PD46C setup

[TwoTired]

Center stand, tank mounted on stepladder next to the bike, about a foot higher than the installed position.

Is the tank full? 
Do you know about head pressure physics?

Tapping on the bowls - All four? Would all four floats hang up at once? They all seem nice and free.

Does seem a low percentage.  But, within possibility.  How do you know they are free?  Did you remove one of the outer bowls with it on the bike to check swing and operation?
There is a down stop for float swing to keep the floats from hanging up on float bowl bits.  Also, if the bowl gasket jumps the groove, it can interfere with float travel.

I should ask if you are feeding gas into the venting system instead of the fuel rail inlet (it's a bigger nipple for fuel inlet).

I didn't lap in the new float needles. But this is a flood, not a trickle. And my float needle seats look nice and clean and smooth.
Are these stock needles?
Spring pin free?
Spring pin fully extended when checking float height?

My floats were set at 14.5 when I opened the carbs up, but I have no idea how or even when this bike ran last. I'm changing back to 14.5 - seems to me like a sensible first step. I just hate taking these carbs off and on - and I worry that the insulators are going to give up on me from too much in and out. And I don't know how to set float height with the carbs on the bike.

Helps to be double jointed, particularly with the inner carbs, but it is certainly possible, as I've done it.  Quite a time saver.

Cheers,

[brewsky]

Finally got all my parts and started the bike today. As expected, big leaks out of the header pipes (new crush gaskets on order), but she started immediately and sounded smooth.

Until I hit the kill switch because there was fuel pouring out of all four carb overflows.

On advice from members here, I changed the float height from 14.5 to 12.5. Float needles are brand new from a reputable supplier, the seats are clean, and I do think I have the floats in right side up. So if I change back to 14.5, should that fix it?

Bowl drain screws tight?

Correct float valves? Mine were rubber-tipped.

Both sets of 46C's I got were set @ 14.5mm, and even with that setting, the levels by clear tube check, shows right at the bowl joint.

[Retroben]

Thanks for all the advice!

Bowl drain screws tight. Float needles are brand new stock rubber-tipped needles, the springs function fine .
Float height measured with the carbs tipped enough to let the float just contact the spring pin.
Bowl gaskets are perfectly in the grooves.
I've removed the two outer bowls and the floats do not appear to be binding.
The tank has half a gallon of fresh gas in it, petcock on reserve. Can't see how that would create any significant head pressure with a less than 12" drop through a 1/4" fuel line. But admittedly I'm not a physicist.
Fuel line is connected to the fuel inlet.

[Retroben]

I was able to get repros of the rubber velocity stacks from Paul Gabor for $30. They match the OEM stacks I have. They are longer than the ones for my 1973 CB500.

Paul's email is mybluebike2004@yahoo.com

I did order these from Paul and they are exact repros of the OEM part. This is a great service to the community! Thanks Paul!

[lucky]

Finally got all my parts and started the bike today. As expected, big leaks out of the header pipes (new crush gaskets on order), but she started immediately and sounded smooth.

Until I hit the kill switch because there was fuel pouring out of all four carb overflows.

On advice from members here, I changed the float height from 14.5 to 12.5. Float needles are brand new from a reputable supplier, the seats are clean, and I do think I have the floats in right side up. So if I change back to 14.5, should that fix it?

Bowl drain screws tight?

Correct float valves? Mine were rubber-tipped.

Both sets of 46C's I got were set @ 14.5mm, and even with that setting, the levels by clear tube check, shows right at the bowl joint.

If the fuel was all the way up to the float bowl /carb body joint it is way too full.
Something is wrong.

Remember the float MUST be measured with a float gauge,  calipers, or ruler BEFORE using a clear tube to see the level. See page  Page 60 paragraph #7 in the Clymer's manual. It then refers you to Chapter 6 to the illustration.
Then go to Page 125 (Clymer's) and look at illustration #13 at the bottom of the page to see how it is supposed to be measured.

[Retroben]

If the fuel was all the way up to the float bowl /carb body joint it is way too full.
Something is wrong.

Remember the float MUST be measured with a float gauge,  calipers, or ruler BEFORE using a clear tube to see the level. See page  Page 60 paragraph #7 in the Clymer's manual. It then refers you to Chapter 6 to the illustration.
Then go to Page 125 (Clymer's) and look at illustration #13 at the bottom of the page to see how it is supposed to be measured.

Don't have the Clymer's, but I did research on this site and others, and I'm convinced I'm measuring correctly.
The carbs are clean, new float needles, bowl gaskets, mains and slow jets.
I'll change the float height back to 14.5 before I go gremlin hunting any further.

[lucky]

If the fuel was all the way up to the float bowl /carb body joint it is way too full.
Something is wrong.

Remember the float MUST be measured with a float gauge,  calipers, or ruler BEFORE using a clear tube to see the level. See page  Page 60 paragraph #7 in the Clymer's manual. It then refers you to Chapter 6 to the illustration.
Then go to Page 125 (Clymer's) and look at illustration #13 at the bottom of the page to see how it is supposed to be measured.

Don't have the Clymer's, but I did research on this site and others, and I'm convinced I'm measuring correctly.
The carbs are clean, new float needles, bowl gaskets, mains and slow jets.
I'll change the float height back to 14.5 before I go gremlin hunting any further.

I think I understand you, but in any event the fuel cannot be all the way to the top of the bowl.

Also rubber tip needles cannot be used with seats made for metal tip needles.
The angles are different.

[Retroben]

I rode the bike 20 miles today. Took it as high as 7,000 rpm momentarily, but never exceeded 50mph (on purpose). The bike performs very spiritedly from what I could tell on such a limited run, but this was in town only. And having done only a bench synch (vac synch at first opportunity, have the device).

Changing the float bowl height to 14.5 stopped the overflow. No gas on the floor. So nix on the 12.5 height, at least for my bike.

Other than that, oil leaks all over the head and smoke from marvel mystery oil burning out of the pistons...different post.

Thanks to all who contributed to this little victory. And let me re-emphasize the importance of reading everything out there. It takes forever, but there is some good info posted, in the FAQs on this site especially. Until you have at least a tenuous grasp of the principles, you will never get it right, unless you're super fortunate.

And with Hondas, the closer to stock, the better! No more modded bikes for me ever.

[lucky]

Do your fuel supply hoses connect to the correct spigot or to the vent spigots???

[mickwinf]

hi just thought i would add my thoughts and my sympathy, as i have struggled with these carbs for many a long hour over here in England. I had a UK spec k3 and also a US import which i now think may be what you called a K4, as there were a few differences like the return springs.I used Sirrius in Canada as parts are hard to find here, i found them to be good quality.The float hight is definately 14.5 on these carbs. the leak sounds like float needles, did you replace the seats as well? They cant be lapped in as the tip is usually rubber. Just seen your last post sounds like you have it sorted! regards, Mick