Carb with pinched tube

Does anyone know what the part is called and what it does? This part was not listed in the diagrams I have found.
It looks like someone has tried to pull the part out with the pair of pliers, failed and then left it. It is pinched at the end and cracked along the sides. Only one of the 4 carbs has this issue.

These are 28mm mikuni with the accelerator pump but this is not the carb with the pump.
The bike is a KZ1000 B2 ('78)

Thanks

That i believe is where the choke (enrichener circuit) pulls fuel from

floivanus wrote: That i believe is where the choke (enrichener circuit) pulls fuel from

I respectfully disagree. The enrichener pulls through a cast hole in the bowl through the brass jet at the very top of the pic with the O-Ring around it.

If I had to guess it's the pickup for the mixture screw but I don't know for sure. You might try to use some pliers gently to bend it back open then use an awl or pick even a large sewing needle to try to get it round again.

Hope someone with direct experience with those carbs chimes in.

jdvorchak wrote: I respectfully disagree. The enrichener pulls through a cast hole in the bowl through the brass jet at the very top of the pic with the O-Ring around it. ....

Nope. The brass fitting with the o-ring is a pump nozzle --- the other end of it projects into the carburetor bore.

floivanus is correct.

Is it only the one that's like that? I've seen them like that in carbs, some have a small hole in the end and others are crimped like that to restrict the size of the end.

I have the same carbs, but the tube in mine has the end closed apart from a very small opening in the middle. I believe it's done to restrict the amount of fuel that can be sucked up when using the enrichment circuit. Depending on how your cold starts are, it may not matter even if someone did crush it as long as fuel can get through. The opening is definitely not meant to be the full diameter of the tube.

@readhawk4
Yes, there is only one like that. Cold starts seem to be fine.

I don't recall seeing that pinched tube in that type of Mikuni carb, but it's possible at some time, one of the carbs could have been swapped out. If the engine runs fine on a cold start and nothing is untoward on that cylinder either too rich, or no enrichment, I don't think I'd worry about it, as it's not a straight forward fix like screwing in a new jet. Is the tube the same length as the others?

I'm guessing those tubes are probably pressed in with the casting hot, if you wanted to remove it you'd need to apply heat to get it out, unless someone knows differently. I have a set of parts carbs, if you really want/need to change that out I could see if I can get one out for you. On my 73 Triumph Tiger, the float height on the Amal carb is actually adjusted by moving the brass seat in the carb float bowl casting by warming it up and then moving it up or down to the required position. The float bowl material expands much more than the brass with only a little heat and it moves quite freely, but locks up when cold, so I'm envisaging something similar here.

I think the tubes are all the same length - they look about the same in the picture here but the angle of the picture could be deceiving.

I have yet to start synchronizing the carbs so I don't know whether one is less efficient than the others. When I get to that point, I may need to replace the tube - thanks for the offer to help find one in your parts!!

I have never dealt with multiple carbs before. The only thing I have seen that may indicate an issue is that the left most (rider's left) exhaust header pipe is blue while the other 3 are gold in color from the heat.

Blue is lean, gold is perfect.
Steve

The tubes appear the same length as you say, I was wondering if the tip had got broken of at some point and the crimp was a "repair". Seeing as the enrichment is used for cold starts only and the pipes would also be cold at that point I don't think any difference in mixture from the enrichment circuit would effect the color of the pipes, however bluing does indicate a lean situation during normal running, so something may be off on that carb. If it was an odd one someone swapped in at some point, check the jet sizes are the same. Check your float levels too, if the fuel is lower in the bowl than it should be and the others it will make it run leaner because the fuel has to be sucked up further through the jets, than at the proper level. That's why when you turn the fuel off and run the engine to run the fuel out of the carbs you will quite quickly notice it running differently and sometimes not wanting to idle. If you have adjustable needles you might want to check the circlip position, that it's in the same notch as the other cylinders. If your carbs have not been synchronized, as you say, it could also be the position of the slide on that cylinder relative to the others causing the mixture to be off. If I were you I'd go through the carbs, clean and check jet sizes and settings, float heights, synchronize etc. and that will likely resolve your problems, Then at least you'll have more chance of being able to tell if the odd enrichment tube is causing any problem on cold start.

Perhaps someone will chime in who has changed that tube, or knows exactly how to do it, if it's really simple then it might be worth doing, I'll be happy to send a replacement to you.

Thanks redhawk4. i will definitely take you up on that offer.

I will plan on going through carbs this weekend and check these things. I know the jets are all the same (132.5 main and 20 idle) The main jets are, big according to the previous owner, because the engine has an 1197 kit with 10 1/2 : 1 compression. It also has pod air filters and a 4 into 1 vance and hines.

Thanks to you too, Steve

I had 5 minutes to spare so went out to the garage, I put the electric heat gun on the corner of the carb body, by the tube while holding the tube with needle nose pliers pulling gently just using the friction of the carbs on the bench for resistance after maybe 20 seconds the tube came away so easily I thought I'd broken something, but no, as I guessed from my Triumph experience the casting expanded enough for it to slide right out with no force required. It's on my desk PM me your address and I'll put it in the mail for you. You should be able to drop your crimped one out the same way and put the new one right in. Obviously allow for the fact my carbs have been sitting around for years lying useless, where as yours have had gas in recently, so don't burn your bike and garage down in the process and blame me

To confirm the dimensions, length appears about 25 mm of the tube that is is exposed with about 3.5- 4 mm in the larger round recess in the carb body and about 3,5 mm holding it in the carb body - 32.5 mm overall length when removed. Outside diameter is 3 mm.