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I had the pleasure of cleaning the carbs on my 83 last weekend and found that someone had already been into them before, removing the blind plugs to expose the idle mixture screws. The mixture screws were all at different settings. I had one a 2 turns out, another at 2 3/4 turns, another at 3 truns, and the last one at 4 turns out. I'm betting someone has been messing with these in the bikes history and at least a couple of these are no longer at the factory setting. Now for my real question. Given that 2 -2.5 turns is suppose to be the magic number on the idle mixture screws, and the fact that these have already been messed with and I cannot return them to their orignal settings. What are your thoughts moving forward? I'm thinking set them all to 2.25 turns and then try to tune each one individually using max vacuum readings like I do on a car. Any other ideas on how to properly tune each carb? -
Last weekend, I pulled the carbs to clean the jets (both sets). Pilots were clogged, mains were fine. Started the mixture screws at 3 turns out from seated. Question: Is there a recommendation on WHICH CARB to begin the mixture adjustment process? I've review numerous threads regarding the adjustment process, but no mention of which carb to begin with. Does it matter? Question: Does the idle adjustment affect all four carbs? Or does turning the idle adjustment screw adjust one carb, then the others "synch-up" to it?
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I have posted on this in the past, but thought I would update the info with a fresh post since I just revisited the settings on QuickSilver. Factory settings on the mixture screws seem to always be extra lean - somewhere around 2.5 - 3 turns out, if I remember correctly (I always check this and write it down for the carbs I work on, but then I give the notes to the owner and do not keep them myself for reference!). This lean setting is not too surprising with the current state of emission regulations, but I do find it strange that Yamaha's published spec for CO on this engine is MUCH richer than they come set from the factory. I have a tendancy to believe that a manufacturer should actually set up the machine to match their own published specs, but Yamahaha both sets their floats WAY higher than the spec and the mixture leaner than the spec. Although I do have an exhaust gas CO analyzer, I rarely use it because it is tedious and a PIA. I have found that I can get excellent results by simply tuning each carb for max RPM. I have also tried the Colortune, but I find that tool a sad joke. The published CO% for this engine is: #1 & #3 = 2.5-3.5% #2 & #4 = 3.5-4.5% For reference, here are the settings I have found on my RSV - Using the max RPM method, I still end up with settings that are slightly too lean, especially for the front cylinders. Typically this method leaves the screw about 3.5 turns out, and that is what I would recommend as a starting point for someone looking for that info. Using the CO analyzer, I get about 3% with the screws set somewhere between 4 and 5 turns out, and pushing the front cylinders all the way up to 4% CO requires a full SIX turns out! Six turns out seems like a huge amount, but I have used the analyzer on this bike twice (two years apart), and the settings I ended up with are the same today as they were back at the beginning of 2009, so I am getting consistent results. Although the bike has been running perfectly for the past two years at the midpoint CO settings, I think I'll probably reset the front two jugs for the minimum of 3.5%, just so I'll feel better about the screws not being so danged far out! But for the majority of carb setup and tuning for 2nd gens, I think I will continue just setting for max RPM + 1/4 turn on each carb. Even without a tach on every bike, I find it pretty simple to do it by ear. I used to actually leave the screws a tad more IN from max, but in light of the settings required to reach the published CO numbers, I've decided to set them 1/4 turn richer. If you feel the need to adjust your carbs for any reason, here is the process I think will produce good results for just about anyone. First, sync the carbs and make sure the idle RPM is set properly. If you do not have a tach, just realize the idle spec of 1,000 RPM is probably a little faster than the idle sound you prefer. Just leave the sync gauges connected while you do the mixture screws, since you will want to double check the sync setting when you get done. I'd start with each mixture screw about 3.5 out, then the first thing is to start turning it IN to verify you get a drop in RPM (which proves your idle jets and circuit in that carb are actually working) - no point in trying to tune a carb that already has problems with plugged idle jets, right? Now slowly turn the screw out to the point where the RPM no longer increase. Select the final setting by turning the screw back in to just where you first detect any drop in RPM, then back out 1/4 turn. Repeat that with each carb, then verify the sync is good, and you are done. If you have problems getting a good setting on any specific cylinder, I'd start looking for other carb issues there, such as plugged jets, bad o-rings on the mixture screw, diaphragm holes, etc. Goose
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Ok!! so now that my dog has been sprayed by a skunk for about the eleventh time, :bang head: I thought for those of you that own dogs, I would post the recipe that I use ( and have found to be the best non-commercial wash I have used so far) to de-skunk my dogs. I have done the tomato juice,yuk thing. I have done the coke and pepsi thing (a little better), but none so far have worked as well. NOTE ! I usually find that mixing 1/4 of the amount seems to be enough for an average size 50-60 lb dog. 1 quart of 3% hydrogen peroxide ¼ cup baking soda 1 teaspoon of strong liquid soap such as dishwashing detergent. (polmolive or sunlight work well here) Mix the ingredients in an open bucket or bowl. The mixture will fizz. Wet your dog and thoroughly massage the solution into the coat. Be sure to keep the mixture out of the dogs eyes, nose and mouth. If it is necessary to apply it to the dogs face, very carefully use a washcloth or a sponge. After applying the mixture to all parts of your dog that may have been sprayed, rinse the dog thoroughly. *Warning* This mixture can be explosive, as it will fizz and creates pressure if it is enclosed in a seal tight container. Never store unused portion, always discard. Be sure to only mix in an open container and do not try to store or cover it in any way. Do not get the mixture into the dog's eyes, nose or mouth.
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Yes, sometimes the problem you are trying to slay is caused by the most simple cause, but even then it can be a REAL PITA to find! Been having a surge in my idle speed for the past few weeks, so today I decided to check it all out, re-set the carb mixture screws, and actually compare the screw settings I get when just using a tach compared to my exhaust gas analyzer in preparation for Maintenance day. Shoulda been pretty simple, right? But it was anything but! When I checked the mixture screws on #1 and #2, they made almost no difference in the idle speed. In fact, the bike actually picked up a bit and ran BETTER with the mixture screws for either of those two jugs ALL THE WAY IN!! Now that was weird. In contrast, the two right side jugs acted perfectly normal. So I hooked up the gas analyzer to check the CO% - no problem dialing in the right two, but those damned left two wouldn't get below 6% even with the mixture screws closed, and if I set them out around 3 turns, it was pumping 15% CO!!!! Plugs were not that old (about 12,000 miles), but I decided to put new ones in, just in case. Those left two were real black and sooty - either running mucho rich or lots of problems firing. Seemed unlikely I would have two bad plugs at once, but I crossed my fingers and fired it up again with the new ones - no joy. So now I am really stumped trying to figure out what coud be affecting just the left bank. Decided to check the sync - seemed unlikely, but I could imagine that something had gone haywire with the linkage. Got the gauges on there and sure enough, both left carbs were pulling a couple of inches of mercury less than the right. Aha! says I, now I'm on the track. But alas, no. It was not the sync. OK, this is long enough, so I'll jump to the end. While I'm futzing around and starting to get really annoyed, I happen to grab the choke knob and push it in, AND IT MOVES!!!! Simultaneously, the bike settles down to a perfect idle! And the carbs come right back into perfect sync too. That is all it was - choke just a tad out and hung up. Nine freaking hours later, and now all I gotta do is finally reset all the mixture screws that were probably just freakin' perfect to start with!. No moral here, just had to share my pain. Hope it helps someone to stop and think about their problem and get back to basics a little faster than I did! Goose -
I have never worked on 2ed gen ventures so I need a little help. Some one has pulled the brass plugs on the Carburetor and adjusted the mixture and the owner wants me to help him make an adjustment. I have to admit that I have no Idea where the mixture screws are on the Carburetor. Can some one tell me where to look? Fred
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I have a 1996 Royal Star and am getting some popping on deceleration. I want to set the mixture screws and have been reading some posts on the site. I read the write up by Goose and the 3 methods he knows. I am familiar with the "drop idle method" but I think it requires a tachometer that can read in 50 rpm increments, which I don't have. My question is... Has anybody tried setting the mixture screws using a vacuum guage and adjusting for maximum vacuum like we used to do on automobile carburators ? Also, do I sync the carbs and then adjust mixture or adjust and then sync ? Enjoying the site, lots of good information and knowledgable people. Thanks Doug
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I seem to be noticing a rich running issue recently. It appears to me it is at idle conditions. Fuel mileage seems ok...similar to what i always get. Around 40 mpg. At idle i notice a strong fuel/rich mixture smell...if it idles for any length of time....some 'smoke' from right pipe (fuel?)...accompanied by strong fuel/rich mixture odour. I pulled and checked plugs. Right front cyl. seems to 'foul' badly...wet with fuel. If i pull vacuum barb cap on that cyl...notice some raw fuel...but no external fuel leakage otherwise. Right rear plug looks somewhat rich too.... but better than front cyl plug. Left side plugs look perfect. If i try to adjust mixture.... left side carbs will lean out and stall out engine...right side makes very little difference as screws are adjusted. Bike runs decent starts well...no issues otherwise. Bike hasn't been sitting. Have changed plugs several times. Brand new set right now. Have run seafoam in the past...late last year....just as a 'maintenance' thing. Just changed diaphragms(only because of age...was running ok)...seems problem surfaced or more noticeable then...or coincidental??? 3 of 4 diaphragms had a small pinhole each. Synched carbs several times. Any thoughts/suggestions?
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OK since all technicians are lazy. Does any one have a pic of the covers for the PMS (pilot mixture screws) I am hoping that I won't have to pull the carbs to get the anti tamper plugs. I just picked up a set of Shogun pipes and the K&N's are on order so I'm going to have to fatten her up a tad. I haven't even looked for them yet so you can go ahead and laugh at me if it is obvious where they are. Like I said I'M lazy
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Hello everyone, I made the mistake of having a friend adjust my carbs a few months ago. I have an '03 MRSV, running with K&Ns and all the pollution stuff plugged and rolled up. I also have the four tits stemming from the carbs plugged. I checked the spark plugs today and the bike is running extremely lean. My buddy does not remember where the mixture screws were at when he started turning them out a few months ago. I have been getting popping on decel too. So I turned out the mixture screws a complete 360 turn and the popping persists. I need to ride it for a while and check the plugs again. Can anyone tell me a good setting, for these screws, FROM BEING BOTTOMED OUT, while running with K&Ns and with the all the air polution stuff plugged? Many thanks in advance - Ponz
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I wrote last fall about how unimpressed I was with the Colortune to set the fuel mixture, and I promised then to report back on how my exhaust gas analyzer compared - well, here it is. Sorry it took so long. Most exhaust gas analyzers are quite expensive - $2,000 to $5,000! And my research shows that there are not a bunch of Cheap types, then a bunch of expensive one, they are virtually ALL expensive. So when I found one that I might actually think of buying, the Gunson Gastester, about $230, I had to think long and hard about just how good this thing might be. The few reviews I found on the web were contradictory - some said it worked well, others said it was junk. I took the chance, and I am glad I did. Before I go there, however, let's talk about the three ways I know of to approach this task. First is by ear and a tach. You simply turn out the mixture screw until the engine reaches the highest RPM, then back in just enough so the RPM begins to drop off. I am never comfortable with this method, since it seems so danged imprecise, but when I have used it and then compared it to instrument measurements, I have always gotten it quite close. Second is to use the Colortune - a device with a glass window in the spark plug so you can see the color of the flame. I only tried mine once, and I was unimpressed by how far you could turn the mixture screw in either direction before seeing ANY change in the color of the flame. That one time, when I got done - just guessing where to leave the screw, it turned out to be almost the exact right setting. I can't imagine it was anything but luck. So I think the Colortune is good only if you have a carb so far out of whack ANYTHING you do might be better. Real exhaust gas analyzer, where you can actually know how a change affects the combustion. The Gunson Gastester only measures CO%. This is not everything that a quality instrument would measure, but CO% is a good indicator of the combustion efficiency. The biggest problem I have with using a CO meter is that I have not been able to find any published spec from Yamaha on the CO setting for this engine, so I just have to use general engine info. Basically, CO% in free air is about 2%, so CO in exhaust at 2% is about as perfect as you can get - less is too lean, more too rich. Generally, an engine running anywhere between 2% and 4% CO is good. The Gastester is very cheaply made - seems like flimsy plastic, and the part that actualy reads the CO is just held on with double sided tape that falls off. This does NOT give one confidence. Most important to know, when the instructions tell you that this device cannot be moved after the 10 minute calibration, they ain't kidding! Any movement at all will send the numbers out the window! It is slow and tedious, with lots of waiting for calibration and readings to stabilize. But it DOES work. I don't have time to do a proper writeup with pictures right now before my trip, but I will when I return. I found that the setting of the mixture screws is fairly sensitive, with as little as 1/4 turn making a noticeable change in the CO%. This is particularly important when I contrast it to the Colortune, where turning the screw TWO or THREE entire turns did not seem to change the color of the flame at all! Hope that info is of value. Ride Safe! Goose
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Hi all. I just synched my carbs today(first time!!) thanks to the article in the tech section!! And I was wondering if theres any way to check/adjust the Fuel mixture... The reason I ask is it "smells" rich to me at idle,maybe thats normal...I don't know.... Thanks in advance.
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Hey guys, I know some of you own multiple types of bikes and was wondering if you could give me a hand. I have been working on my girlfriends 04 883 Sportster and it's about to drive me nuts. It has been backfiring through the carb. I adjusted the mixture screw to richen it up and that didn't help. I upped the slow jet one size bigger and played with the mixture now it's running more on the rich side. But it still backfires thru the carb. Carb backfire is usually a sign of lean but it does it running rich as well. Really don't want to take it to the dealership. Wallet is already on the light side as it is. Any help you might could give would be appreciated. Thanks!
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Hi, My bike been running perfect for a long time until #4 cyl suddenly became a bit rough. A check of the exhaust temps confirmed the weak cylinder (not hot compared to other cyls). Problem seems to be from the idle mixture circuit, which was not responding to any adjustment. Avoiding to pull down the carbs, I sprayed carb cleaner on both the pilot jet and idle mixture orifice hoping to get lucky. It improved and the cylinder started firing again. Just to be sure, I used colortune and confirmed the correct mixture was there. Unfortunately that was good for about 15 miles only and the problem came back . Note that the basics checked out : compression, ignition, fuel, vac leaks. Would appreciate any input on this. Thanks. -
Help!,:starz: I am trying to adjust my idle mixture settings on my carbs on my 99 blvd. 4 piper and I can"t get the brass looking caps off?? What is the best method, I'm a little scared to drill em out and so far I'm having no luck. Also are the pilot screws flat head or phillips? I am doing this to try to eliminate some backfire on decel . Thanks -
Hi everyone, I have a 2006 RSTD and have read several posts (and Freebird's excellent detailed step-by-step picture show - Thanks!) regarding 17.5 pilots and going up one size on all main jets. I have a question about altitude. I am at 3500 feet in Calgary, AB and often travel the Rockies at 6000 ft plus... I have K&Ns, BUB slipons and the Dyna ignition module. Has anyone with similar equipment run for long periods at 3500 - 6000 feet? If so, how did the richer mixture work out? I'm for anything that adds smooth and more HPs but don't want to go the wrong direction and end up too rich.... Oh and I pull an Aspen Classic which is large as trailers go - probably 500 pounds loaded -
Hi, this is my first attemp at this so please bear with me? My wife, Claudia Ann and i have 2 of the 1st Gen XVZs, a 1984 and a 1990. I have purchased shop manuals for each but find nothing in the manuals about either setting the idle mixture screws or how to find them on the carbs. I've read other threads that talk about the proper setting being 2 - 2 1/4 turns CCW from very carefully closed position. That's great, but i've looked at the carbs on both bikes several times and have not found what would even seem to me to be 'idle mixture screws'. I have even purchased parts manuals for both bikes and the exploded parts diagrams of the carbs and accompanying parts list does not list 'idle mixture screws' anywhere so i cannot tell even looking at these diagrams where they might be. Does anyone know what Yamaha calls these screws if it is something different than 'idle mixture screws'? It might be less confusing for those of us that new to this sort of thing if in the threads everyone would use Yamaha's term/names for parts and what is being discussed. How about a few pics to show where they are located? Anyway, thanks in advance for any help offered! fmandcac -
Greetings. Can anybody tell me where the idle mixture screws are located on the 28mm Mikuni carbs (1998 Tour Classic)? Just cant seem to find these little buggers. I am having the exhaust popping and would really like to get rid of it. Have already run through a full tank of new fuel with cleaning additives (carb and injector cleaner) and it still pops. No holes in or around the Y pipe weld and all exhaust gaskets seem to seal perfectly. I plan to install the Dyna 3000 module in the near future but not at the moment. Any help or/and advice would be very much apreciated.
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83 Mixture Screw Source???
zagger posted a topic in Venture and Venture Royale Tech Talk ('83 - '93)
I finally found the reason why a couple of cylinders were idling super rich - the tips of two idle mixture screws were missing, busted off by some previous owner! In looking at the carb exploded diagram it doesn't seem that these screws have a part number and I am guessing that they aren't available from the dealer (I'll check tomorrow morning). Anyone know a source for these little stinkers? Anyone have a couple of old carbs they might like to sell? Feeling a little gloomy right now. zag -
While at Vogal, I had my carbs synced by the professionals and it ran better and smoother on the hand grips. But, I knew my carbs needed to have the air mixture setting adjusted because at idle the richness would bring tears to your eyes. Without starting the bike, I started around the carbs and found two was about two turns out and one about one turn out. When I got to the front carb on the right side, I tried to turn it and it was pretty tight, but moved a little. When I bottomed out, it would not move and in the process of trying to make it move, I broke off the two raised edges that are on each side of the slot, therefore no more slot. I have another set of carbs I bought cheap off ebay, so I knew at worst, it would take pulling the carbs off and breaking them apart and cleaning them all and putting a spare on. So, if I really screwed the carb up on the bike, it would be ok. What I ended up doing was I used a drill bit that fit the hole with minimal slop and drilled a dimple in the head of the screw. I then used a small drill bit that fit the easyout, or screw extractor as some would know. I was able to drill deep enough to get a hole without drilling so deep that I drilled to where it shanked down to the step area. By tapping the easyout and seating it, I was able to unscrew the adjustment screw. I used a piece of rubber hose on my shopvac to pull out any debris. I was then able to put in one of the spare mixture screws from the other carbs and I was back in business. I then hooked up my son's carb syncing outfit and synced them myself. It took a few minutes, but I got them all the same. Now the bike is again running good and don't bring you to tears when idleing. randya
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