Help Find A Cure for Crazcnuk's bike?

[Crazcnuk]

It looks to me like it is lean at the top too, but when I went to the 120s the midrange got VERY rich.

If I drove at 4000 or less for any more than a few minutes, the bike would load up big time. I would have to drop a gear and roll around at 5000+ to clear it out.

For whatever reason, the PO had 45 Pilot jets, with stock mains. This would have added to the low-mid richness.

What was happening, I believe, is that the engine was very rich at the bottom, but too lean at the top.

Incidentally, I got my best mileage with the needles down one notch, and Derwat is having the same results with his.

My next test will likely be, floats at stock height, needles down one notch with 115 mains.

I don't think the needles can block the passage at full throttle, no matter what, unless you happen to have needles from a completely different carb. If they could, changing mains would have no affect, since if the needles were restricting top end fuel flow, then changing main size wouldn't do anything, and in effect the needles would be controlling top end too.

There has to be a point where the needles are, for all intents and purposes, out of the way.

What is interesting is that I hit the max top end at about 1/2 -2/3 throttle movement. After that there is a big dead spot.

I have another entire engine, new main and rod bearings, seals, gaskets, 1200cc barrels w/pistons, that I am trying to get around to in my shed. My cylinder head has been gone for 2 years waiting to be redone.

[Ken Talbot]

Just thought here, but are the mains you're playing with all the same brand/type? i.e. do the size numbers on them all actually mean the same thing?

[egsols]

Hey Craz,

I got thinking about the taper thing so while I was out in the garage a couple of minutes ago, I pulled down one of my 81 carbs, have a box of them in pieces. Anywho, I pulled out the needle from the 81 and compared against one of my 79 5 step needles I got in the carb kits.

By eye the 79 looked much thicker at the tip. I set my calipers at 1.5mm and put the 79 needle in till it stopped. I got it in about 5 mm. I did the same with the 81 needle and it went in about 10mm. I can't tell the difference in length cause I don't have a 79 diaphragm and I didn't take the 81 needle out of its diaphragm. The 81s are running the 300 tubes. Judging by the spacing for the clips a 5mm difference seems pretty big.

I agree that the needles shouldn't block the passage at wot but like you said, as long as they are the right needles.

You and Derwat are at a higher altitude so probably leaning the carbs with the needles would help.

As far as you maxing out at 1/2 to 3/4 throttle, maybe your cable is too long, yuk, yuk, yuk

[Crazcnuk]

Heh, i can still turn the throttle, just there is no more power.

Passing on the highway is the same on my xs or in the neon.


I got outrun by a Ford p/u the other night. I can max out about 100mph tops.

[Crazcnuk]

I set my floats back to stock (23mm), dropped the needles one notch and put the 115 mains back in.

Low end bog is gone, bike runs smooth from idle to ~6000rpm.

After that, there is litte or nothing. I can hold the throttle wide open and it will hit 8000rpm in 1st and 2nd, then 3rd takes about 10 seconds to go from 6500-8000, and 4th would take several minutes, 5th will not accellerate at anything over 5000rpm. I have to drop a gear to pick up any speed.

About 1/3 to 1/2 my throttle opening (wrist twist) does nothing.

Dropping the needles actually made the top end worse. If I understand these carbs at all, it is my belief that at some point the needles have to clear the emulsion tubes.

IF the needles didn't get 'out of the way' so to speak, then changing mains would do nothing, as even wide open throttle would be then controlled by needle position, or in effect, the mains would never be on thier own.

That is what my bike seems to be doing. I can go from 110's to 120s and it makes NO difference in how the bike runs. The plugs still show lean even going up that far in main size, and my bike should run fine on the stock jets.

Earlier in this thread it was pointed out that the needles I have are longer than any on record for the xs1100.

Is it possible that my needles are just never coming fully out of the tubes?

[egsols]

Is it possible that my needles are just never coming fully out of the tubes?

That's what I've been thinking. I also think that the needles you have aren't a good match for the tubes. That's based on my comparison between the '79 5 step needles in my kit to the stock needles in my 81 carbs.

Problem is I don't how you could change what you've got. As far as I know the slides are different for the adjustable needles and the fixed ones, although I think its possible to interchange them between carbs, I almost did that with an older set that had torn diaphragms. (i.e. stick good 79 diaphragms and needles into 81 carbs), but I don't think you can stick the later needles into the earlier slides.

[thewiz]

I like a good ...

'head scratcher' as much as the next guy, Craz, and this thread has got to be the grandaddy of all head scratchers. If I had a functional set of extra carbs, I'd gladly ship 'em to ya' to try on just for laughs .... BUT .... some one on this forum must have a good tested rack layin' around that they'd lend ya'... and that thought leads to a story ....

Once upon a long time ago, while I was working at the Mercedes dealer in Colo. Spgs., a brand new 190E came in running like $hit with less than a thousand miles on it. The RO was given to Artie Shaw, a seasoned Benz wrench in his 60s even back then.

I was working in the bay next to him and watched with great interest as he systematically tore it down til he found the problem ... a couple of flat cam lobes. I remember leaning over the fender and musing out loud, "Now why and how could that have happened to such a new car?"

Artie replied, "It's not WHY , it's WHAT and then we fix that".

And sometimes that's what it boils down to, my friend .... my 2cents.

[psycoreefer]

I've been kind of following along but I can't remember,
Have you tried the following combination:
stock size idle jets
Stock float height
Stock main jet
needles one or two clip positions down - Richer?

That may tell you if your needles are too long. Sure it might run like crap at idle and mid range but if it gives you your top end back then you know your on the right track.

Here's the theory, PO got the wrong needles, increased the Pilot size to get the low end back and called it close enough.

If you want I have a set of adjustable needles that came with a rebuild kit I got for my 79. I'm not using them and don't intend to use them in the future, I'll ship em to you for postage if you want to try different needles.

[egsols]

Hey psyco,

I think craz tried going back to all stock and said it was still rich so he went to a leaner setting on the needle and it fixed the low end but made the top end worse.

I think that the needle and diaphragms are wrong for the carbs, I know MikeXS says that the Canadian BS34's used the adjustable needles in 80 but they also show a YO 366 series tube to match the needle, and they say the needle/tube combo are richer then stock. I have searched but can't find any specs for the 11's that has anything other then the X2 tubes for all years of the BS34's. Were the ones made for the 650's slightly different?

[Crazcnuk]

Yes, Psyco I put it all back to 'stock', except for the needles, as I don't know where they come from.

I was thinking the same thing, raising the needles, just to see.
I just can't see the .5mm making that big of a difference, but who knows.

I bought the MikesXS emulsion tubes, for the 1980 Canadian models, a while back, not realizing they are different than the stock X-2.

Last night, I got to thinking, if those tubes are supposed to be for these carbs, why don't I just buy the matching needles to go with them?

So I did that. I ordered the needles that match these tubes. According to Mikes, they are richer than the stock Y-0 tubes.

Not sure where that puts them against our X-2s but at least they would be matched. I can't see there being that much difference when these carbs are on an XS650.

[psycoreefer]

You opened a can of worms...
650 = one 325cc cylinder per carb
1100 = one 275cc cylinder per carb

I'd say thats a significant difference, more then going to the big bore kit. You'll for sure have to play some more with the jetting but I bet your getting real good at taking those carbs on and off aren't ya.

If you change your mind and want to try my needles PM me.


As far as X-2 vs Y-0 the Y-0 is going to be significantly richer then your stock X-2. And if the tubes you got are richer then Y-0 then I'm guessing your going to be rich in the mid and high range. Aren't carbs fun.

I think I posted the link to a site that tells what the letter code means somewhere in your thread.

[thewiz]

"...that the needle and diaphragms are wrong for the carbs.."

think Ernie's onto something here ... diaphram/carb mismatch issue perhaps. Not lifting the needles far enough for some reason.

[Crazcnuk]

If there was some way to SEE the slides move under load, it would be easy to check. But there is no reason that they shouldn't be lifting. They are stock, no holes, and they pass the leak down test.

As for the 275cc to 325cc change, I have been told that increased volume makes no difference to how you jet. It still has to put the same air/fuel ratio.

However, rejetting is not a big deal. I was more curious to see IF the MikesXS needle/valve combo works, since I already bought the expensive half of the combo.

We are also not sure what needles they are selling as they use thier own numbering system.

[Montreux_Blue]

Originally posted by Crazcnuk
If there was some way to SEE the slides move under load, it would be easy to check.

Like this - XS1100 Carbs Vacuum Slides UNDER LOAD

[Crazcnuk]

Thats very nice, now to see MINE!