Need help in Idaho please

[BillyRok]

Back here after long but good day. Started slow as 5 miles up I-90 I crossed over into central standard time so according to the clock, I'm averaging 5 mph and will be home by Halloween did 580 miles today across two thirds of SD, all of MN, and into WI. Got about 34 mpg running 80 mph on a tank, got 44 on another tank running slower because of construction. Since cleaning the ignition switch and carbs it pulls better off idle in stop and go traffic...but still really hard to get moving first thing in the am after sitting all night. I leave the enriched on full til the rpms climb up to 2k or better, then close it down to half on and wait for rpms to climb again before turning it off. Still has that stumble, even warm, from 1-3k then smooths out. If I remember to, I'll pull the plugs in the am before starting and post a pic.

Last night at dinner a guy came over and asked if I owned the old Yamaha parked out front. He runs a bike shop along the MD/DE line and really loves the old bikes. We visited for a few minutes then he stopped by my camp site to take some pictures..."You don't see many of these old 1100's on the road, especially the mns and in this nice of shape." Reason I mention this is he heard me start it up this morning and came over and said he thought it sounds lean off idle. Commented that these bikes were pretty leaned out from the factory to begin with and today's gas with ethanol causes an even leaner condition. Suggested removing the mixture screw plugs and backing each one out a half turn to see if things improve...just food for thought.

I know I made the mistake of changing 2 things at once by blasting contact cleaner inside the ignition switch AND doing some cleaning on the carbs...which
made the difference in being smoother letting the clutch out in first and not wanting to bog down like before? I guess I'll leave things as is for now and check the other voltage points Scott mentioned when I get home...makes sense to verify all the electrical is good before opening up the carbs again right?

Thanks again to all of you for helping me along this trip. I've logged over 1900 miles with about 850 to go. Who knows where I'd be without this site! Probably home in my chair because I never would have been brave enough to attempt it without the expertise here that I knew I could access.

Now I just need to figure out why this IPad doesn't want to post pics I uploaded to Photo Bucket. Before I leave in the am I am going to try to get some up in the "Ride Report" section.

[MaximPhil]

Good going Billy, Looking forward to seeing the pictures.....but we can wait until you get home if too complicated on the road.
Phil

[motoman]

Glad to hear the bike is Rollin' as good as can be expected, specially considering some of the undertakings you have tackled while traveling......hats off to ya!.

[Bonz]

Good discussion guys!

In the grand scheme, Billy's got a pretty good running bike no matter what advice gets shot his way, and I can agree with you Brant that his pilot o-rings could be/are not resilient and adjusting the screws might undo what is already working pretty good. Leave well enough alone at 41 mpg and a mild annoyance in the low rpm range with an otherwise good running bike.

Hmmm... An old Yamaha guy thought it sounded lean off idle... Still has factory caps in place... What did I chime in about opening up the pilot screws...? Just had to get that in there, regardless of condition of tiny o-rings...

Brant, remember the rally and your screws were set to highest vacuum and your bike was choking itself running so rich? Where did you end up with them? Your carbs were otherwise in good shape, correct? We brought them in at least a full turn or maybe a turn and a half, and the bike responded very well for the good, with more turning in still to go in my estimation.

Keep in mind what a sync does... It gets the butterflies in concert with each other. Which more or less exposes the 3 tiny holes in the carb throat a similar amount, which the air from those holes mixes with fuel from the pilot jet.

Setting each to highest vacuum does so with the feed holes exposed as they are, and as soon as they are sync'd its for naught as the holes are now exposed differently. The carbs being in sync with each other is ultimately what we strive for and a few lines one way or the other on the sync sticks is immaterial with respect to steady idle and the like.

And at that, once past idle, sync doesn't play a lot. Been there, done that with a bike that won't idle well but runs like a raped ape at anything above idle. Should have sync'd at first opportunity was the lesson I learned from that, right CZ?

Set the pilot screws to the same turns, and the sync minutely or otherwise, adjusts the air to equalize the vacuum at each carb. If pilot screws are way out like yours were Brant (at highest vacuum I believe is what you said), no sync is gonna fix that so I would respectfully disagree with the highest vacuum method.

I really believe in the rationale that messing with each idle screw is not necessary when its already known, more or less, where they should be from literally 3+ decades of folks going before us. Put the screws in the ballpark when the carbs go on the bike, sync the carbs at the earliest possible point.

Then adjust main size if needed, get the needles adjusted correctly, the floats adjusted correctly if not already done, then fine tune the pilots in equal increments.

Pilot settings are the last thing to fine tune once all the rest is set correctly for your bike. Then finish up with a sync once the bike is like you want it.

I guess it can be termed rudimentary, however in my travels I have had great running bikes and never the issues that so many guys post about, when I follow an order of protocol for tuning carbs.

As an aside, I think many folks think they understand carbs, however really don't understand how all the circuits work together and chase stuff all over the place adjusting "this" when "that" isn't in order first.

Cheers fellas, good night!

[Bonz]

Dang nabbit, 10 minute rule... Who voted for that any way?

In my last post, when I talk about "carbs being in sync is what we ultimately strive for", what I meant to finish that with was "a few lines less on the sticks than highest vacuum when carbs are sync'd equally is immaterial when you have a steady idle and the like".

Also, Brant is the classic example of setting highest vacuum and being rich... BA80, did you mean to say highest vacuum -1/4 turn, because usually highest vacuum is richer than ideal to begin with.

[skids]

Howard, you hit the nail(s) on the head.

[BA80]

Good discussion guys!


Hmmm... An old Yamaha guy thought it sounded lean off idle...

What did I say about the pilot circuit off idle? Better go back and read.

BA80, did you mean to say highest vacuum -1/4 turn, because usually highest vacuum is richer than ideal to begin with.

No, The extra 1/4 turn out to slightly richen the closed throttle decel stopped the lean decel pop. It's too lean at highest vacuum.

But, I've only been working on carbs for 30 + years. I could be wrong.

[Bonz]

OK, I get my carbs set to best lean idle/highest vacuum on each cylinder, then sync the carbs.

Didn't I just undo everything that went into setting highest vacuum by adjusting the butterflies, thus the amount of air going in through the bleed holes?

Brants bike was set to highest vacuum and sloppy rich, that is my reason for the -1/4 turn question... Yeah, agreed that lean is where you go when setting highest vacuum. I withdraw that question you honor! And bow on my knees...

[BA80]

OK, I get my carbs set to best lean idle/highest vacuum on each cylinder, then sync the carbs.

Didn't I just undo everything that went into setting highest vacuum by adjusting the butterflies, thus the amount of air going in through the bleed holes?

That's why you need to go through the procedure several times until the vacuum readings are as high as can be across the board at the preferred idle setting.

Mix adjust, resync, mix adjust, resync, ect., ect., ect., .......................

Also, If the engine isn't at RUNNING TEMPERATURE and the carbs aren't PROPERLY cleaned it will all be for naught anyway.

[motoman]

Hi Howard,
Might read the 'carb issue' of my latest posting. In a nutshell, to low of fuel levels CAN cause a rich running issue at all rpm ranges. At this point, that IS the issue with mine(unless I can prove otherwise). Throttle plate opening determines fuel flow, not engine speed.

[WMarshy]

Hi Howard,
Might read the 'carb issue' of my latest posting. In a nutshell, to high of fuel levels CAN cause a rich running issue at all rpm ranges. At this point, that IS the issue with mine(unless I can prove otherwise). Throttle plate opening determines fuel flow, not engine speed.

There, I fixed it for ya.

[motoman]

There, I fixed it for ya.

No fix........was EXACTLY my point , if you'll read where the ACTUAL fuel levels were when I checked them the other day, on bike, not running. If you'll read it, a too LOW a fuel level can cause the same scenario. Since throttle plate opening determines DRAWN flow, not engine speed, what's happening if a to low a fuel level exists, more throttle plate opening is required, creating more venturi velocity in order to draw the lower than specified fuel level up thru circuit, which will also require the mixture screws to be opened more on the later model BS34 carbs, which is WAY more than the maiximan 'rule of thumb', no more than 2.5turns out or you've got either pilot jet sizing too small or bowl fuel level issues.
Same as blowing across a straw in a glass of water. Less blowing needed if glass is full as opposed to glass being LESS than full........ain't rocket science.
That throttle plate opening(venturi velocity), if not matched up correctly with fuel flow, IMO is gonna affect the overall performance, no matter what rpm range.........and 800+ miles to and from the rally, with some intermitant 'tweaking' of the idle mixtures proved that to be true, running some in the pilot circuit, and in the main circuit.......and is now confirmed finding low actual fuel levels. BTW, when things are off that much, you can actually 'feel' from motor response where that main circuit comes tottally into play, which is 3600rpm.
Also realize that is a static fuel level, not running. But with all the experimenting I've done in the past with these carbs, that static level of 9mm down from carb body isn't gonna come up near enough running to be even close to a 3mm number.
IMO, any continued discussion on this may wanna be carried to the 'carb issue' thread I started some time back, and this one left for the safe homeward bound of Billy Rok.

[cajun31]

I'm thinking

at this point in his trip weather is going to be more of a factor then problems with the bike. Sounds like mechanically he is going to get there but looking at the weather today he has probably encountered quite a bit of rain. Hopefully the tires he has on the bike presently are able to handle it.

[motoman]

What did I say about the pilot circuit off idle? Better go back and read.



No, The extra 1/4 turn out to slightly richen the closed throttle decel stopped the lean decel pop. It's too lean at highest vacuum.

But, I've only been working on carbs for 30 + years. I could be wrong.

BTW Greg, not my first rodeo associated with carbs either.
I didn't do them 'on occassion' in a work setting either.
In the performance automotive world, they became my forte, as a hobby, for over 30yrs.....on a daily bases.
Soon that led to folks litterally calling and knocking my door down to have their carbs rebuilt and set up for a variety of applications, the drag strip, off road and street.
Eventually that 'hobby' turned into 'work', so I quit doing it all together.......which would lead you to ask why I would be having these issues. Best answer I have is the Japanese do really wierd things inside carbs to reach their ultimate goal............ever rebuild a set of Hitachi's with the coolant ports for added cooling on late model 240Z's, then sync and set them up properly?......now there's your worst daymare for Japenese ingenuity.
Worst part.......I owned the car.

[BA80]

I'm not going to argue. The proof is in the puddin'.

See you next year, unless you think your bike can make it to XSSE.