Venturer Running/stalling dilemna

[motoman]

Changed oil and filter as it had a hint of fuel smell from carbs flooding over being mothballed under cover in the man-cave the past year.

After pulling carb bank and fuel bowls, it looked like a science project in there with a couple of floats not pivoting from the fuel seperation that left a sticky substance on EVERYTHING. The enricher circuit and mains were plugged solid and a bit of black lookin' stuff in different locations inside carb body. 3Phase looked like the mad scientist sittin at the medical roll-around tray with a can of carb spray, toothpic, and fine little wire in surgical mode.

Rode it after changing oil, fresh fuel with a shot of Berryman's in tank. Smooth as silk up to 4800rpm on the slab, then acts like starvin for fuel. Left idle mix and sync as it was when I parked it a year ago, as this was just a test ride for some thirty miles. Starts cold instantly with no enricher and idles smoothly down at 500rpm, so sync is still close, but sure idle mix is off since I also replaced the tired old Yammy coils(ohmed@2.3-4ohms) with a set of Honda VF coils that checked out at 2.9 and 3.1ohms. Now a good hot spark at those lower R's, and 3Phase found the 1.5V of missing all important smoke at the kill switch. Dis-assembled and pieces all cleaned after soaking pieces in EvapoRust.

Likely at this point just have to chase a carb/fueling issue, and the no-enricher with a cold start says idle mixes are at a too rich level, fuel levels a tad high or both.
Either way, with Scott's surgical procedures of the carbs and electrical and me getting rid of the tired coils, it's back smoother than its been in some 5+yrs.(easy to just park and forget about when having the other scoot that is always trouble-free).
Any and all suggestions welcome at this point to eliminate the above 5Krpm where it just goes 'flat' and into felt starvation mode.

[BA80]

Have you checked to make sure the gascap vent isn't plugged up moto?

Also. did Scott take the needle jets (emulsion tubes) out and clean them and the wells they fit into? If the crud was thick as you say those are gonna be gummed up too.

[motoman]

Have you checked to make sure the gascap vent isn't plugged up moto?

Also. did Scott take the needle jets (emulsion tubes) out and clean them and the wells they fit into? If the crud was thick as you say those are gonna be gummed up too.

Yup, stripped 'em down to body castings and even pulled the seats out as I had a new set of O-rings that Yahman had sent me a couple years back, along with the teeny-tiny idle-mix O-rings, as the others had grown up to adult O-rings from the nasty fuel.
Tank vent is also open and clear. ALL jets are GenuineMikuni, re-cleaned up of course. Idle circuit just purrs perfectly up to the 4800rpm range with absolutely no stumble anywhere now, which it DID have when I got peod at it and parked it last Sept.

BTW, so as not to hijack this section, any input I'll see if put where it normally belongs. Never had this sort of scenario happen before, so it DOES kinda have me a bit stumped at this point. I'm sure the fix is right next to the snake-bite kit.

[BA80]

Ok, if it's been cleaned as well as you say it's time to direct your attention to the ignition.

How old are the plugs, are the plug caps making good contact with the pug wires, are the plug caps good, is your vacuum advance moving freely and working properly? Ect. ect.

My bike actually started having a stumble when a pickup coil wire started going bad. Felt just like a carb issue.

[motoman]

Plugs are new(have several sets), as well as wires(7mm high temp solid core) since I just put the VF coils on. With these, had the convenience of making up new wires.

The annoying ever so slight stumble dissapeared that it had for the past few yrs. It pulls smoothly now from idle up to the 5K in fifth gear and can't even make it stumble cruising, with an ever so slight throttle application like it used to. Pick-up coil wire issue was resolved a couple yrs. back and all checked out good threre as far as current. May have to pull the carb bank and double check circuits as it seems to be in the main circuit somwhere.
But hey, appreciate all the ideas and keep throwin' stuff at me, as I'm sure it's something simple I've missed........right near that snake bite kit.

I know from experience, rule of thumb 'old school' is ignition before fueling whether it be automotive or bikes, but obviously something is crew-cutting me. I know,..the ole' Bentley will step it up a notch just to make smoke come out of my ears taxing whats left of my brain just cause it can. Thanks for all the input Greg.......and keep it comin as I'll take no offense as you well know.

Anyone else........feel free to jump in with some thoughts as I know at this point it's gotta be obvious as chit.

[BA80]

If it's in the carbs it's highly unlikely that it will be the same thing in all 4. It will probably be in 1 or possibly 2 if it's a fuel feed problem from one side of the tank. Seems it would show up on the plugs.

A couple other thoughts are a pinhole in a diaphragm or one or more that isn't sealing in the groove properly.

Seems to me that Nate had a similar problem and it turned out that the needles were improperly installed in the slides.

Just throwing stuff out there man.

You got someone close by that might let you swap out carbs just as a test to be certain your barking up the right tree?

[TopCatGr58]

Hey there Brant,

Okay, had to wrap my head around what you have, an 81H, so it has the 4R1/4RO ignition black box which has the cent. adv. curve built in/programmed into the TCI. I'm going to assume that you have an OEM airbox, can't recall whether you've stated in past threads if you have Pods. Just replaced the OEM coils with Hi output 3 ohm Honda VF coils, wires, caps and new plugs.

Thoroughly cleaned the carbs, floats may be a little high, but that would as you said, contribute to a slightly rich condition, however your bike falls flat at ~5k rpm like it's running out of fuel, so it's not the slightly rich float height causing that.

81H standard, vac. controlled petcocks....if running low on fuel, then turning petcocks to PRIME would bypass the petcock vac. function and feed the carbs easily, so a test run with Prime would be in order, and then if still hitting the 5k wall, then can rule out the petcocks/vac. lines and possible cracks.

Next, would suggest putting a timing light on it and see if you can see the timing advance indication with the vac. adv. removed to see IF the TCI is doing it's job creating the cent. adv. curve. IF not, then you may be in need of a replacement TCI.?

Those are a few ideas that I can think of.

T.C.

[motoman]

Hey there Brant,

Okay, had to wrap my head around what you have, an 81H, so it has the 4R1/4RO ignition black box which has the cent. adv. curve built in/programmed into the TCI. I'm going to assume that you have an OEM airbox, can't recall whether you've stated in past threads if you have Pods. Just replaced the OEM coils with Hi output 3 ohm Honda VF coils, wires, caps and new plugs.

Thoroughly cleaned the carbs, floats may be a little high, but that would as you said, contribute to a slightly rich condition, however your bike falls flat at ~5k rpm like it's running out of fuel, so it's not the slightly rich float height causing that.

81H standard, vac. controlled petcocks....if running low on fuel, then turning petcocks to PRIME would bypass the petcock vac. function and feed the carbs easily, so a test run with Prime would be in order, and then if still hitting the 5k wall, then can rule out the petcocks/vac. lines and possible cracks.

Next, would suggest putting a timing light on it and see if you can see the timing advance indication with the vac. adv. removed to see IF the TCI is doing it's job creating the cent. adv. curve. IF not, then you may be in need of a replacement TCI.?

Those are a few ideas that I can think of.

T.C.

All excellent suggestions T.C.! Would you be able to transfer your post in the XS discussion at this point as Venturer dileamma or whatever as this is gonna' have some more input and responses. Could of stopped at the oil change thing, but didn't think of that. My bad. BTW, no pods allowed on the this scoot.

[Ken Talbot]

...The enricher circuit and mains were plugged solid and a bit of black lookin' stuff in different locations inside carb body...

... Starts cold instantly with no enricher and idles smoothly down at 500rpm...

Makes me think you got the enricher circuit, including the critical spooge hole in the float bowls, cleaner than its ever been, and now you're actually dealing with an overly rich situation at the low end. I would say go in and drop the floats a mm or two (i.e. raise them when looking at them upside down) to bring down the fuel level in the bowls. Follow up with a fresh sync, tweaking of the pilot screws, and another sync.

Sound reasonable to you?

[motoman]

Having approx. 4-4 1/2gal. of fresh fuel(drained all the old out) with a couple ounces of Berryman's added, low fuel should'nt be a problem........but flipping to prime for any possible change is gonna' be my next step since it's back up and runnin'. FYI, the bike ran perfect in the mains with plugs showing that when I parked it last fall. Back then I found smoke missin' from the ignition switch(system was at 9.5V unknowingly at the time). Spray cleaned switch assembly from underside without removing(Iknow....removal and disasembly the better option, but answered that question mark for me). Got back to 10.5V thru whole system, but still had blackened plugs 3000rpm and under. Runnin' in the main circuit out on the road, it was happy,happy, and would always twist up to 8K and above extremely quick.......before I mothballed it a year ago out of disgust.

Forward to now, Replacing the old tired malfunctioning coils, 3Phase going thru the carb mess, maticuoulsly BTW, and finding the missing 1.5V hiding at the kill switch, pretty much figured short of a fine tune, this scoot was gonna rip as it used to. But no joy hitting the 'wall' at 5K. Couldn't ask for more perfect running under that rpm though even though idle mix needs re-adjusted to the now good spark along with synced. Can't be far off on sync itself with a smooth 500rpm idle. So we'll 'call it good' for the moment till I resolve the 5K 'wall'. Any re-tuning at this point is an exercise in futility IMO.

Tomorrow afternoon I'll ride it and try the PRIME on the petcocks so that can be eliminated as an issue along with taking the ignition cover off and watch that vacuum advance while riding just to be sure there's movment going on still. The assembly itself IS floppy free. Next, as U suggested would be timing lite on things with vacuum advance didconnected. I DO have another, maybe two 4RO transister ignition boxes could try if mechanical advance went wacky(possible with previous low voltage issue).

I'll report back tomorrow how far I followed up on checks. I would'nt want this to turn into actual work with a deadline.
BA80 and T.C........thanks for all the input so far.......helps the light to come back on. A huge THANKS goes out to Scott(3Phase) for helping me get this scoot back to this point! He spent several hours in MikuniLand

[motoman]

Makes me think you got the enricher circuit, including the critical spooge hole in the float bowls, cleaner than its ever been, and now you're actually dealing with an overly rich situation at the low end. I would say go in and drop the floats a mm or two (i.e. raise them when looking at them upside down) to bring down the fuel level in the bowls. Follow up with a fresh sync, tweaking of the pilot screws, and another sync.

Sound reasonable to you?

Good thoughts Ken. If I end up pulling the carb bank again for a final 'look over', I'll be double checking those float levels. Just a quick check prior to re-assembly by 3Phase, I saw a couple that had a sliver of daylite between the float and slide-rule. I previously, a couple yrs. ago had them meticulously al lset at 23.5mm which gave me a running fuel level of 3mm down from carb casting at operating temerature. Just had to watch closely and not spill fuel from hose moving from one carb to the other while running.

Good thoughts Greg. The tank is 3/4 full, but follow what your getting at.
No holes in diaphrams and the metering rods didn't need to be removed from slides.
Like I said, other than the rich cond. at lower rpm's, now knowing it was from low primary ignition voltage and weak secondary voltage to plugs, it flat ripped from 3800rpm past redline extremely quick when I parked it. So, whatever happened I'm pretty sure is either carb related or fuel supply related. Only thing that makes sense at this point, but these ole' XS eleven's WILL throw you a curve just 'cause they can. They can almost be as evil as the No.3 master carb .

[DGXSER]

Have you done a plug chop test at the higher RPMs? Might actually be to much fuel. my thinking is if you jetted, tuned, and synched to run as well as it did with the electrical issues you had, it would need retuned now. Did the floats get set at 23.5? I know you had advised me in the past that setting did not work for you. Just some thoughts.

[skids]

Should you really be tuning while the fuel system cleaner is still in the mix? I would run all of that through before making adjustments.

[motoman]

Have you done a plug chop test at the higher RPMs? Might actually be to much fuel. my thinking is if you jetted, tuned, and synched to run as well as it did with the electrical issues you had, it would need retuned now. Did the floats get set at 23.5? I know you had advised me in the past that setting did not work for you. Just some thoughts.

Hi there DGXSER,
Thanks, realize in the final stretch, will have to re-tune to the now correct hotter spark. CRS, so can't remember any advising I may have done, but seem to remember something along those lines. IIRC, a tad lower setting was creating issues a few yrs. back. But yes, 23.5mm gave me a 3mm down from carb casting across the board of all carbs while running, and at operating temperature. Crossed my mind of getting too much fuel, but no actual float changes from when I parked it a year ago, and it running and pulling hard up and past reline easily at that time, still leads me in the direction of actual fuel flow somewhere between the petcocks(which flowed fine on PRIME draining the old fuel out), and metering system in the main circuit. Idle circuit is happy enough, least at this point in the game with almost instant light color on plugs, even idleing for a bit with fresh cleaned plugs in it. Prior to this the past few yrs., plugs would blacken once rpm's dropped into the idle circuit(under 3800rpm). They would whiten up once in the main circuit previously. Now at least plugs have hint of color not only running in idle circuit(remember, no crossover for transintion like the early carbs), but runnin' in the mains. Least it's on the lower end of main circuit before 'hitting the wall' at 5K rpm, just like if starting to run out of fuel before flipping to reserve. Will be giving it a short test on prime here soon this afternoon and report back of any change.

Hi Sid,
Definitely a good thought, and the final thing I'll be doing of course once I get it all back to normal above 5K rpm. Once getting it back to normal in the upper rpm range and then giving it that initial tune matching fueling and sync fairly equal in all four cyls., I'll definitely be having to re-adjust things with just 'corn-squezzins' from the staion pumps. Thanks for the reminder though.

As a side note, the Bentley really oughta just give it up, as I always win in the end no matter what games it trys to play.

[motoman]

Just now fired it up and rode it. Initially, starting it up cold, i used no enricher(choke). It fired up instantly with hardly a tick-over and idled being cold at 500rpm perfectly. Having good voltages and the VFcoils attribute to this I'm sure. Even signals and indicators are bright and cycle perfectly at this low 500rpm.

Ran the bike on a straight stretch near my house, rotating petcocks from ON to PRIME for a bit and then back to ON. No change, but I did notice that it would falter a bit at the 5K range instad of just 'hitting a wall', but now would pull gradually up to 7K with the faltering going on, whether enricher was pulled or not under full throttle applied at 5K rpm(in second or third gear of course).
One thing I did fail to mention initially was, when Scott was here and it faltered at the 3K range, was we backed out the idle mixes from the approx. 2 3/8 turns from seated that I had previously done a year ago using my known lean-drop method to a static setting of 3 1/4 turns out thinking possibly that my previous setting was on the lean side with the weak voltage weak spark issue at the lower rpm range, and definitely at an idle.
DGXSER may be on to something here at his point, so am gonna pull the seat and tank when it cools a bit, flip tank around, and actually set idle mixes running, get mercury even across all four carbs, re-tweak the mixes a bit and tweak the mercury to even again, and go ride the the bi, see what happens.(applying the 'one change at a time' thing)

BTW, for what it's worth, those with the later carbs that have those idle mixes out some 3.5-4 turns with a totally stock intake/exhaust set-up, have other issues goin on in the idle circuit IMO. That 2 1/2 turn out range limit for fuel screws holds true for most all your bike carbs. From what I've found, also holds true for these later BS34 Mikunis also.

Will report back the results, whether it be joy or no joy. Figure if nothing else, all this may help a few others here with gremlin diagnosis in the future.