Must be my month for carb slides...

[dbeardslee]

So last week I was fighting with a bad mid-range stumble on my brother's bike. It had three different problems, the last of which was carb slides with the circlip one notch too low. So today I jump on Betsy for a run to the post office, and she's stumbling between 3 and 4.5k. Felt suspiciously like what my bros bike was doing, so I pulled the carbs and went straight for the slides.

Before I put her up for a Rip Van Winkleish nap, I had been working through an issue that wound up being caused mostly by green Mikes XS coils, but during the process I had changed the slide needles. I couldn't remember if I had put the stockers back in or not, but the slide needles looked awfully gummy when I cleaned them last week.

I dug around and found a brand new set of Mikuni 5GZ6's, and when I compared them to the slide needles that were installed they looked a little longer. About one notch's worth of longer. So I swapped out the needles with the circlips in the center position, and as if by magic, the stumble is gone.

I'm getting a little tired of pulling carb slides, but I must say, the recent experiences are helping me improve at diagnosing mid-range stumbles. And I'm getting a much better idea of what those needles do.

[3Phase]

Doug,

What were the numbers on the needles you replaced with the 5GZ6 needles, were they Mikunis or something else?

.

[dbeardslee]

Doug,

What were the numbers on the needles you replaced with the 5GZ6 needles, were they Mikunis or something else?

.

They had no markings on them whatsoever. I think they were the ones that were in the carbs when I bought the bike, though.

[3Phase]

They had no markings on them whatsoever. I think they were the ones that were in the carbs when I bought the bike, though.

Bleh. But congratulations on finding the right Mikuni needles!

No-name needles would mess up the carburetors unless you had the right no-name jets and non-name emulsion tubes to go with them or an accurate crossover chart and a boatload of time and tools and tuning experience.

.

[dbeardslee]

Bleh. But congratulations on finding the right Mikuni needles!

No-name needles would mess up the carburetors unless you had the right no-name jets and non-name emulsion tubes to go with them or an accurate crossover chart and a boatload of time and tools and tuning experience.

.

They've been sitting in a box in my basement for the past four years waiting for their day in the sun. Can't remember where I got them, it's been so long ago.

I found another set while I was digging around too. They're marked Y80, and I have absolutely no idea what they go to. They've got little caps in the bags with them like the plugs that go over the mixture screws on the later model carbs. Maybe I'll use those needles for hors d'oeuvres skewers or something.

[BowlingSS]

I am glad you got that problem solved.

Bill

[dbeardslee]

I am glad you got that problem solved.

Bill

Meeeeeee too!

I got checking around this morning and found out the XS750's used 5HX6 needles, and according to what I read they're basically the same as the 5GZ6's only a little shorter. Which sounds exactly like what I pulled out of the carbs. They'd probably work okay if the clips were one notch higher. I'm going to give 'em a good soak in the carb cleaner basket, move the clips up a notch, oil 'em and put 'em away. Hopefully I'll remember what the heck they are if they ever see the light of day again.