Sync carbs on an '86

[garyS-NJ]

Finished some work and cleaned carbs on a stock '86 that's been sitting for a while. She really needs the airbox on sealed up to minimize pooping out carbs and let her rev. I think exhaust port temps could be closer.. Mixture needles set 2& 1/8 out. Gonna try syncing carbs. Anyone have a good link for syncing tips and otherwise method to best set idle mixture screws?

 

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[luvmy40]

The only "right" way to set the idle mixture is with an EGA. The next best would be with a Color Tune(my chosen method). Some have good luck tuning by ear, i.e to RPMs, I've never had much luck tuning multi carb banks by ear myself.

 

There are many Color Tune videos out there. It's a fairly simple procedure and easier on our liquid cooled bikes than on an air head. I found the extension tube and a small adjustable inspection mirror to work better than the mirror that comes with the Color Tune on the Venture engine. It's just not easy to get the plug extension wire and the Color Tune mirror situated in way that's visible and stable on these engines.

[bongobobny]

Yup! Either a CO Sniffer or a colortune plug...

[BlueSky]

[garyS-NJ]

I synced them with my home made gauge set (just four gauges and four tubes) but scratching around for a real tester to verify). And then did mixture screws seat of the pants. Leaned the fronts out till rough then back 1/2 turn (like doing a lawn mower). Then made the rears 1/2 turn richer. Pretty crisp now when warm but a total ***** to get it warm. Very lumpy like two cylinders coming in and out for a long time before warm. My '84 comes off choke real fast.. Oooo, idea, maybe the Tci is sketchy until she gets warmed!

 

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[garyS-NJ]

That's a fun video. I bet my girlfriend would like to watch it with me. Maybe we binge the whole series on a Saturday night. Anyway, gonna try swapping my ignetek for the Tci but if still no good, ill recheck my mixture settings. The video shows using a precision tach to set mixture. I only have the dash tach but wondering if I could use my 4 gauge vacuum sync to monitor. Then otherwise, I would have to look at choke circuit. Will I be able to remove the choke plungers without removing or splitting the carbs?

 

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[skydoc_17]

Hey Gary,

Since the "Idle Mixture Screws" only control the air/fuel ratio from idle to about 1800 RPMs, (and more turns out means less air, which means richer) set the idle mix screws at 2 1/2 turns on all four Carbs. Your bike spends most of it's time running at a much higher RPM. Then Re-Sync the Carbs at 3000 RPMs instead of 900. 3000 RPMs is the beginning of the "power band" for your bike, and where your motor is running a good amount of the time anyway. To verify your home made Manometer, (4 vacuum gauges) connect each vacuum gauge to the same cylinder (#2 cylinder) and note the difference in vacuum from gauge to gauge. Mark the gauge face with a magic marker where the needle lands and use that mark as your "Baseline". (Zero Reference) Then read all four cylinders with all 4 gauges and adjust from the zero reference line, NOT the zero vacuum point on the gauges. (the error will be much smaller doing the test this way) The difference in idle mix adjustment could be causing the difference in exhaust temps, but also consider that the front two exhaust pipes are fully exposed to air and the rear two are confined by the engine itself, the difference in length of the exhaust pipe from front to rear, and the frame. Being a bit of a perfectionist myself, (big time OCD!) I too like to have my mixture and Carb. Sync spot on, but it is relative. The engine in your bike spends very little time at idle in the grand scheme of things, I would spend my time tinkering with the Carb. Sliders and Diaphragms, checking for pin holes in the Diaphragms, cleaning out the slider bores, making sure the slider cap O'Rings are there, and are sealing the slider bore properly. This is the area of the Carbs. that controls the Cruse RPM of your motorcycle, and this is where my bike spends most of it's time...

CRUSING!

Earl

Edited November 16, 2016 by skydoc_17
at my age, most likely dementia!

[garyS-NJ]

Thanks Earl! You rock. That '86 cold start didn't get any better with my ignetek and then before pulling the carbs (everytime, and its been a few, I've had difficulty reinstalling the cables), I started looking for a temp sensitive ignition problem. I've had coils and pickups open (on other bikes) with temperature. The primary windings and pickups measured ok but the coil secondaries from power in at the Tci connector through to the plug caps measured avg 23k ohms on all four. About 10k high on all and I can't believe my meter (& can't imagine a failure mode on all four coils). Gonna try another meter. I sent the guy away with the bike (scratching my head) asking him to ride two tankfuls with strong sea foam hoping the choke paths might clear. Will reset his mixtures and recheck his sync but can't see that effecting his cold start much (I had started at 2 &1/8 turns out). But I am going to check sync and mixture on my '84 xvz 12 (& two '70's Suzi gs bikes I just bought). Btw, what range of exhaust temps on the port should I see?. Thanks again!

 

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[BlueSky]

Hey Gary,

Since the "Idle Mixture Screws" only control the air/fuel ratio from idle to about 1800 RPMs, (and more turns out means more air, which means leaner) set the idle mix screws at 2 1/2 turns on all four Carbs.

CRUSING!

Earl

 

skydoc, the yamaha video linked says turning the screw out richens the mixture.

[snyper316]

skydoc, the yamaha video linked says turning the screw out richens the mixture.

 

Thats um confusing because I have seen ppl say it leans it and some say it richens it grrr anyways. While we talking about carbs My number 2 cylinder Carburetor slide is saturated with gas. Just curious what would cause that to happen because up till tonight it was fine. I am actually trying to figure out how gas got up and around the slide like that. Unless my peg wasn't seated on the slide needle right. But correct me if I am wrong here but doesn't fuel come out the hole that the needle slides in. Also it goes peg washer, E Clip, Washer, Spring then plastic screw? Sorry for Hijacking your thread but just a little on the confused side. I really don't want to have to pull these carbs again.

[skydoc_17]

OK Blue Sky, post corrected. As far as the raw fuel in the #2 Carb. goes Snyper, I would be concerned about a sticking float. Here is the method I use to clear the float bowls on the Venture:

 

CleaningFirst Gen. Carbs. On The Bike

 

 

Iuse this cleaning method to unstick a float needle that is causingthe gas tank to drain when the bike is parked, or for a Carb. That ispassing raw gas out of the overflow tube when the bike is running.This on bike cleaning DOES NOT address the issue of a Carb. Setneeding a complete rebuild, (off the bike) and does not address theissue of AIR PASSAGES being blocked, and causing poor performance.These two issues require the Carbs. be removed from the bike.

 

 

Withthe bike on the center stand, and the engine off, I select the firstCarb. I want to clean. You will be looking for the Black PlasticCarb. Drain Tube, and the screw that opens that drain. (Phillips HeadScrew) You will need a small coffee can, or a coke can with the topcut off, (NO plastic containers) to catch the gas that will come outwhen you open the drain screw. Allow all of the gas to drain from theCarb. and have a look in the can for “floaters”. (Solidparticles) With a new can of Carb. Cleaner, insert the red straw inthe end of the drain tube. I wrap the junction of the red straw, andthe drain tube with a small piece of shop towel to slow the blow by.Press the button on the top of the can of Carb. Cleaner, and count to3. Remove the red straw and let the cleaner fluid run into the coffeecan. Move to the next Carb. and repeat. When you do Carb. #4, startover again, and do them again. I use up one can of Carb. Cleaner onthe four Carbs. When the can of Carb. Cleaner is gone, retighten allfour drain tube screws,

(CAUTIONDO NOT OVERTIGHTEN THE DRAIN SCREWS) Turn on the ignition switch, (donot start bike) listen for the fuel pump to fill the Carb. Bowles andstop pumping, check the drain tubes and the overflow tubes (down infront of rear tire) for fuel leakage, move the can with the Carb.Cleaner/Gas mixture away from the bike, (or better yet, roll the bikeout of the garage) and start the bike. (It may take a few shortbursts on the starter motor, and you may need to choke it as well) Gofor a ride and “blow the cobwebs out” (my personal FAV part) ifthis doesn’t solve your problem, then a “Carbs. Off Rebuild”may be in order. On a side note, I run 3 ounces of Seafoam in everytank of gas I put in my 87’and 89’VR because of the negativeeffects of the Ethanol in the fuel these days. Because of my shophere in South Central PA. I buy OEM parts direct from Yamaha, andshare my discount with the VR.ORG members. It would be my pleasure tohelp you with any project you have in mind for your First Gen. VR.

Earl(skydoc_17)

[snyper316]

@skydoc_17 All I know it was extremely weird. I went to gas station and when I went to start it back up it was running funky. It was also dark but when I got back home I was smelling gas. So I pulled the airbox and that is when I noticed it. But while I waited for an answer I litterally washed the airbox pieces and let me tell you that Dawn Dish Detergent works extremely well on ethanol and grease looks almost new, as far as ethanol goes I have this app on my phone that is called puregas and will tell me where the gas don't have ethanol. There is two gas stations here in town. The previous owner however didn't know you could get non ethanol gasoline anymore. So when the carbs were rebuilt they were caked with ethanol and other grime. He even emptied a bowl into a baby food jar which I can't find. There was some white looking fluid rust particals. They were just nasty. I am thinking about using a clear tube to check float levels to make sure of that. So with me having the access to the Non-Ethanol gas should I run Sea Foam in all my gas still? The other thing I would ask is what exactly is in Sea Foam Because everyone swears to the Sea Foam. What exactly does it do? I know it helps keep things flowing as it should, I'm just a little curious on how it works. @bongobobny thank you for the pointer on the slides It made them puppy's so much easier to put back in. There was no question that they were seated correctly, The next new slides I get I will definately be remembering that pointer.

[skydoc_17]

Hey Greg,

As far as the running of Seafoam in your fuel goes, even with the non ethanol fuel on board, you have in my opinion at least one stuck float. With that being said, Seafoam has high quality mineral spirits (lubrication) in it's make up as well as Naphtha. (cleaning agent) It also has an emoulsifier in it which keeps the petroieum from seperating from the Ethanol. (Alcohol) Running Seafoam in your gas is a personal choice. I for one would rather be proactive as far as the Carbs. go rather than reactive. In other words, I would rather put a splash of Seafoam in my tank, than pull the Carb. rack off...AGAIN! Because I now live in Pennsylvania, I have a relatively short riding season, and my bike sits for periods of time due to my work schedule. The Seafoam keeps the floats from sticking, and washes out crud that collects in the float bowls. When I lived in California, I rode all year round, and Carb. issues were minimal because I had fresh gas cycling thru the Carbs. regularly. For my climate conditions, and frequency of riding, the use of Seafoam works for me. It may work for you as well, and it may not. If you are riding every day, and use non E10 gas, then try cleaning the Carbs. as I have described above, and all should be well. If you ride your bike once or twice on the weekend, even with non E10 gas, and it sits for the rest of the week in a hot (or unheated) garage, then still clean the Carbs. like I have described above, get a shot glass from your bar, add 1 ounce of Seafoam to a tank of gas, and see what the results are. I had to add two "shots" of Seafoam to a tank of gas to get the results I wanted, you may not need to, OR you may need to add 3 shots. The point being careful experimentation with additives like Seafoam will net you the results you desire, as long as you are consistent, and don't go "crazy" with the stuff.

As far as the exhaust temps. from cylinder to cylinder goes, it's not the actual temp. that is important, it's the difference between the right front and left front, and the right rear and left rear that you are concerned with. Don't bother comparing front to rear cylinders, as they are exposed to different amounts of air, and are different lengths. If this were my bike, I would install 4 new plugs, and seriously consider changing out those 30 year old stock plug wires before I worried about exhaust temps, but that's just me. "Hard Parts" like plugs, and wires are easy to replace, and give you a reference, (items that you know are doing the job correctly). If you clean the Carbs., adjust the mix screws, Sync the Carbs., replace the plugs and wires, and run a little Seafoam, and you are still having an issue, then you now know that you need to look somewhere else! (Carb. rebuild, Gas filter replacement, coil replacement, TCI replacement, pickup replacement, etc.) Proactively addressing the issues in an organized manner will net you a bike that starts every time, runs well, and never leaves you stranded. This my friend, is the best you can hope for in a complex machine like the Venture that is 30 years old. Hell, I'm not nearly physically the man I was 30 years ago, but I'm a LOT smarter now then I was then. It's all relitive.

More questions, feel free!

Earl

[snyper316]

Done and done as far as the carbs went this time I got smart and wore safety googles. Last time I pulled my carbs I was like HEY!! I can do this who needs googles..... Well you can guess how that went and Holy Crap that stuff burns, I have already replaced my wires, spark plugs, and caps all new. I was a little concerned the flooding on that cylinder was from the choke. But after I did all that and started her up, Boy I bet the mesquitos are dead now if they weren't already, took it out for a ride and issue was gone. Pulled the TCI,Lid, and air filter out took a peak and dry as could be down in there. Well as it normally should be, Now being you said something about being able to get parts I will be going on a shopping spree in February. My goal is to finish putting new parts in the carbs. I have 1 new diaphragm in there I want to replace the other 3. I would also like to figure out what they call the engine to airbox snorkel and get a new one of those for her. I live in SWMO like today it got to 84, Tomorrow is supposed to be in the 70's, and as for Friday she can block the wind but I think 42 is a little cool to be riding. Our seasons here blend together but I don't ever remember being able to ride anything this late in the season. That being said I have still road at least 4-8 days a month during the winter even if it was short rides. If I still lived in Central Missouri I probably wouldn't be able to. I guess I did forget another new part that I haven't replaced would be the floats. Which I am not even sure it is possible to get them. Some people like my oldest son thinks I am trying to polish a turd persay, But I trully believe this bike really only has 17,000 on it. The other thing is How can one tell if these bikes had the 2nd gear issue fixed, I have seen someone mention a notch. Is it possible to locate this mark without opening the side up?

[bongobobny]

OK although there was no moisture observed in your TCI I strongly recommend you reposition it on top of the airbox as many of us have already done...

[snyper316]

Gary what bongo says not only helps your tci but make for alot easier access to it. I would rather spend 2 seconds changing it then spend 2 hours getting to it. If there was a way to move the coils to an easier access would be nice too, but those things are almost bullet proof. I don't know if the boost or whatever the little box is called but I would definatley check that vacuum line running to it. It could be dry rotted,hard, or brittle. Sorry for Hijacking your post, I will say that was about the oddest thing I have seen these carbs do other then that one post where the guy had a water fountain in his.