CB carb question

[stevenontheinterweb]

Alright. I figured out I have a dead cylinder and checked everything and Im guessing it seams to be the carb. So I took the float bowl off and I wanted to clean out the jets. I stuck the straw of the carb spray in the middle bigger one and the carb cleaner shot right through.

Now the smaller one on the side. I stuck the straw in there and the spray wasnt going through. So I unscrewed it and took it out. I tried to stick a pin throw it (as shown in picture) but it doesnt go through. Is this correct? Or is it suppost to flow right throw it?

 

[Bobdot]

It should flow right through like the others. I wouldnt recomend sticking a pin in there as the brass material is soft and the pin can cause damage to this very tightly toleranced piece. Try using thin fishing line instead. I usually like to soak the jets in a small bowl of carb or brake cleaner for a while, shake it around a bit and then try blowing cleaner through again. If you have an air compressor, blow that through but hold on tight to theat jet so you dont loose it. Let us know if that works, if not what kind of CB is it? I or someone else on here might have a suitable replacement.

bob.

 

[IndieSol]

Go to a music shop and get some piano wire or some guitar string, which ever is cheaper. They should be also be sold as jet cleaners.

 

[teazer]

Looks like a CB750 slow jet.

The orifice in that jet is much smaller that the pin. It's a very small hole. In addition, the shape of the orifice makes a huge difference to teh rate at which fuel flows through it - it's all about Coefficient of discharge, - so poking it is likely to change the effective size.

I'd just order one or if it's a CB750 let me know, I have a few of them here not going anywhere.

 

[crazypj]

The number on jet is hole size
38 pilot is 0.38mm or about 0.015" (fifteen thou)
Pin is about 0.030"~0.040"

 

[CCRider]

I thought that on that jet the flow doesn't go straight through, but comes out the orifices on the sides of the tube.

CC

 

[stevenontheinterweb]

Thanks all for the info.

Yeah, I think I jacked it up by trying to jam that clothes pin through it. crap. But yeah, I just looked real good and I can see a little light through it. I guess I know now. Live and learn.

Its a 75 CB550

yeah, if anybody has a spare size 38 jet they can part with that would be great! Please let me know.

Thanks again

 

[Swapmeet Louie]

Thanks all for the info.

Yeah, I think I jacked it up by trying to jam that clothes pin through it. crap. But yeah, I just looked real good and I can see a little light through it. I guess I know now. Live and learn.

Its a 75 CB550

yeah, if anybody has a spare size 38 jet they can part with that would be great! Please let me know.

Thanks again

If you have a HONDA dealer in town they will have those in stock. Like $4.00 each

 

[johnnylaw]

I have a 76 550 and trying to get those was really tough. It could be that my dealer is the shits, but all the online stuff was sold out too. Now i have two different sets of 38 slow jets for kehien carbs that dont fit my carbs. Make sure they know exactly what they are ordering. filthy bastards wouldnt let me return them after either.

sorry, i'm still a little upset about it.

 

[stevenontheinterweb]

Ill tomorrow and see fi the dealer has them.

Jet question. If the stock jet is a 38, using the stock air box. If Im now running Uni spong filters with more air flow, should I run a bigger jet for more fuel? Maybe like a 40??

Im thinking I might as well make that adjustment now.

 

[teazer]

I thought that on that jet the flow doesn't go straight through, but comes out the orifices on the sides of the tube.

CC

Not quite. The holes are to pick up air from the air jet via the air screw. Air mixes in the nozzle to help atomize fuel.

 

[johnnylaw]

Ill tomorrow and see fi the dealer has them.

Jet question. If the stock jet is a 38, using the stock air box. If Im now running Uni spong filters with more air flow, should I run a bigger jet for more fuel? Maybe like a 40??

Im thinking I might as well make that adjustment now.

I'm running Uni's and a 4 into 1, and ended up keeping the 38's due to lack of supply. it does feel a little lean thru that range, but its really not bad. I read somewhere else that if you up your main 3 steps (from 100 to 115, like i did) then you should up your slow jet one step (to 40).
theres lotsa carb faq around the web, just google it.

 

[garagedoreen]

I just picked up some 40 slow jets and 110 main jets. Im running Uni spong pods and a 4-1 Kerker header. I guess Im going to try that set up. I think I jacked up one of my 38 slow jets so I might as well try the 40s if I got to get a new set anyways. And why not try the 110. I do remember not getting too much power on the high end of the band too.

 

[jimmiejoe]

I just finished the carbs on my CB500 The jets where so plugged up in took hours...L have a set of the tinyest drill bits even for modeling purposes trains of course I carefully found the right ones to use filling up the flutes of the drill bits cleanning them again and again pain staking work...The old gas had shelac so hard finally punch a hole thru it..The other thing u could try would be some spring steel purphase at hobby shops..U'll have a selection of sizes to choose from get a few different sizes u'll need in the future if you work on carbs

 

[teazer]

I'm a cheapskate too, but with jets, it's cheaper and simpler to get new ones. That way if you need larger or smaller to get the jetting right, at least you know where you are starting. Drilled and poked jets are unlikely to flow at the same rate as they did when new.