post carb cleaning, trouble

There is definitely a different profile to the stock needle versus the MikesXS adjustable needle. In this pic for reference from L-R, Heiden Needle, Stock Needle, MikesXS Adjustable Needle:



FYI, I moved to the Adjustable Needle and corresponding Needle Jet with no improvement.

Kent

In your very 1st post, you said you replaced the needle and the part it fits into, which would be the needle jet. Exactly what needle and needle jet did you install? I ask because stock ones are designed or chosen so that the needle will not come all the way out of the needle jet at full slide lift. It's a safety thing.

I would pull and check the needle and needle jet numbers. The stock needle is a #5HX12 and has just the one slot for the e-clip (as pictured above). It measures about 50mm from the clip slot to the tip. The Canadian needle is a #5IX11 and has 5 clip slots. From it's top slot to the tip is about 50mm. That means that running it in the normal middle slot will have it sitting about 2mm higher which will make it much richer.

The stock needle jet is a Y-0. The Canadian version is a #336-Y-0. About the only difference I can see between the 2 is that the Canadian version has more bleed holes down the sides. Now technically speaking, I would think that more air bleed holes should result in a leaner running jet. However, combined with the richer (shorter) Canadian needle, the results seem to be an overall richer running midrange circuit. I will also mention that the stock and Canadian parts are made to be run as matched sets. Things won't work right if you stick the Canadian needle in the stock needle jet or the stock needle in the Canadian needle jet.

If your components check out OK, the only other thing that comes to mind is that maybe you assembled the slide and needle incorrectly. There are several washers on the needle and a small spring. They go in a certain order .....



If, for instance, you put the spring under the washers instead of on top, that would raise the needle too much and make it richer. It might also explain why it was able to pop out of the needle jet at full slide lift. As I said, that shouldn't be able to happen.

5twins, in the very 1st post (of this thread) I said "Replaced the float needles and the part they sit in"...so talking about the float needles (and seats) there, and not the slide needles. I haven't replaced the slide needles at all, although I did pop the emulsion tubes (needle jets) out to make sure they were clean. But I didn't inspect them for roundness or wear at the top aperture. Then I saw a pic somewhere where it shows that aperture (where tube sits into throat of carb) kind of worn out and not perfectly round....so it could allow more gas into the throat of the carb. So that possibility is what I want to eliminate now out of the whole scenario.
Took carbs off today.
Also bought a float height tool. The floats are about where they need to be, but will re-check everything in detail when I take them apart.
thanks for everything....

Kent, thanks for the info..... do you think your carbs had been gone through or worked on before you got them, like by a previous owner? Today while I was re-reading the carb guide I read the part about where if the tiny holes get poked through by too large a wire it could enlarge them, and I forget exactly what it says - but I remember the word "grief" was involved - and having to replace the carb body!

Well, someone had definitely been in them as there were a few small tool marks on the jets and such. The factory brass cap over the mixture screw was missing as well. As for the pilot holes, I can understand them getting messed up with some real aggression, but I would think you'd be able to see or feel some abuse around those holes.

Kent

OK, so you think you still have the stock needles and needle jets? Check the numbers to make sure someone before you didn't make some changes. If you find your needle jets worn, Mike's does still sell that original Y-0 jet, but not the nonadjustable stock needles anymore.

5twins said:

OK, so you think you still have the stock needles and needle jets? Check the numbers to make sure someone before you didn't make some changes. If you find your needle jets worn, Mike's does still sell that original Y-0 jet, but not the nonadjustable stock needles anymore.

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Yes I believe they are stock. I removed the diaphragm assy's to inspect the rubber, it all looked completely un-messed with. Will try to find numbers on them! The only thing that was out of the ordinary is that one of the needle jets sat a bit loose before I screwed the main jet in. That little slot/guide that lines them up is loose. Might be that the little stub in carb body (guide) is damaged and smaller though, rather than the slot in needle jet being enlarged. Will try and swap it side to side.
thanks

kvanderploeg said:

Well, someone had definitely been in them as there were a few small tool marks on the jets and such. The factory brass cap over the mixture screw was missing as well. As for the pilot holes, I can understand them getting messed up with some real aggression, but I would think you'd be able to see or feel some abuse around those holes.

Kent

Click to expand...

hope you can find a solution. It can definitely mess with your mind. I gave up on a pair of XS carbs once. Sure hope not to do that this time.

I found my solution. I ordered a set of VM34's from 650Central.

Kent

kvanderploeg said:

I found my solution. I ordered a set of VM34's from 650Central.

Kent

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!!!!!!!!!!
well that's cool - hope they work great. Are they on yet?

You won't be able to I.D. your needles unless you remove them from the slides. The part number is stamped up near the top, just below the clip slot(s). That area ends up inside the slide when assembled. You can also look for the Mikuni trademark emblem on them. That will tell you if they're an original Mikuni item .....

Haven't gotten them yet. Maybe late this week. Fingers crossed...

Kent

Old School carbs' work looks and has been reported as excellent.

^On the subject of needles, I'm interested in your Radio Shack washer mod. Is there a number for the washer? How to do it is obvious once you get the washer?

gggGary said:

Old School carbs is having a rough time tonight He got storm damage to his house is kind of down and apologizes for the posts. I hope things get back on track for him, he has always been welcome here and his work looks and has been reported as excellent.

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hi gggGary, what's to apologize for?
I also hope he and his property are OK.

Em

This thread makes me dizzy-- are we troubleshooting more than one set of carbs?

You would think so, huh, lol. Nope, I think it's just one old beat up set of BS34s.

Nope, just mine. However, I was comparing notes with Kent, who was having pretty much identical symptoms.

Same prob. Right side runs rich enough to gas foul plug enough so that side runs intermittently or not at all. (pipe stays cool) Left side is rich too, but not as bad.

Have had carbs off the bike to adjust or swap out floats several times.

Checked other factors, compression is good.

So I'm looking into reasons besides the floats that would cause way too much gas to go into the right side.
(this is all mostly just at idle by the way, just testing it in the driveway)

So I'm thinking maybe the needle jets or the needles are worn, allowing more fuel in.

Need to take home a loop from work so I can examine them. Carbs are back off the bike as of yesterday.

Anyway if this thread is becoming too confusing maybe it should be deleted?

I was thinking if I ever get it solved though, it might be helpful for someone else.

xjwmx, take one of your needles to R/S and look at the washers and get ones that fit.
Leo

^I was thinking it was more the thickness. Little switches usually come with a special thin washer under the nut. Have you tried this? Any results to report?