Air/Fuel Adjustment for the 2nd Gen Virago...prep tips and why sometimes they just won’t dial in

[@StevesDIYs]

If you are looking for the custom adjustment tool I made and used in the video, I listed some out on eBay under my Steve’s DIYs listings. Here’s the link if interested: www.ebay.com/itm/226120064166?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=sfmcIdagSM-&sssrc=2051273&ssuid=sfmcIdagSM-&var=&widget_ver=artemis&media=COPY Thanks and all the best !

[@vicnickerson5474]

AaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaAaaaaaaaaaaaaaàaaaaaaàaaaaaaaaaaAaaàaaaaaààaaaaaaaaaaaAAaaaaaaaaaaaaaaaaaaaaaaàaàaaàaaàaaàaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaàaaàààaaaaaaaaaaAaaaaaaaaaaAaaaaaaaaaaaaaaaaaàaaàaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa mp

[@ferssfree]

Excelente herramienta. Puedes enviar a México?

[@marekbrodowicz8950]

Świetne objaśnienia,jak szybko wyregulować skład mieszanki i synchronizować gaźniki bez dużego nakładu kosztów i pracy! Właśnie to samo muszę zrobić w moim xv 1100, Twój film jest bardzo pomocny LwG

[@StevesDIYs]

Thanks and glad the video helped some 👍. All the best ! Steve

[@nikpellinen2010]

This helped me so much, I couldn't find in the manual or anywhere online a clear image of where the air/fuel mixture screw was on second gen Viragos. My 750 is backfiring like crazy when I coast and sometimes when idling, hopefully making that adjustment is the solution

[@StevesDIYs]

Thanks man ! Yep, I would guess that either the sync between the two carbs or the air/fuel mix is off on one of the carbs a bit. From what I’ve seen, the more in-tune cylinder over powers the other one so it’s making it rotate faster than it’s adjustment prefers…then it just pops and randomly hits on decel or no load when the amount of air and fuel get close enough to ignite in the cylinder. Thanks again and all the best ! Steve

[@yarekk]

Hi. I had a similar problem and it was a vacuum leak. I used a propane torch (not ignited) to blow a little stream of propane around the engine while it was running, and when the propane gets sucked into the vacuum leak, the rpms drop. That allows you to quickly find the leak. That's where I would start. Sync'ing stuff and adjusting the mixture is good, only if the engine isn't getting extra air elsewhere. Awesome video Steve!

[@kdsowen2882]

That's a slick-little tool, very handy . Dave NZ

[@StevesDIYs]

Thanks man 👍. Yep, I hated having to remove the seat and tank to adjust the carbs for sure. You know something is annoying when you’ll actually design a custom angled tool just to avoid the aggravation, LOL !

[@CreatingExcellence]

You my friend are a genius. The one cylinder at a time PMS adjustment is just what I needed! I have a Vstar 1100 and Cobra 2 in 1 exhaust so it’s difficult to do a lean drop plus it’s just a pain in the ass to do each side and try to do them equally. Your way allows to really dial in each carb for maximum fine tuning. Thank you for this video! After you do the lean drop for each cylinder separately, what do you do to further dial them in together or do you do nothing (I’m talking with the air mixture screws)?

[@StevesDIYs]

Thanks and glad the video helped some 👍. Yep, running them on one cylinder makes it much easier to hear when the rpms drop for sure…especially with the uneven firing these do from the angle between the two cylinders. For the final adjustments after setting them at about 1/8 to 1/4 turn out from where the idle drops, I’ll usually run the bike around a bit keeping the rpms up, then pull the plugs to see how they look. I purposely run these old air cooled motors just a bit rich as I’ve blued many a chrome pipe when I was younger lol. I also run Iridium plugs as they don’t seem to soot up as bad so as long as the plugs aren’t sooted up when I pull them, I call it good. Thanks again and all the best ! Steve

[@wparsley04]

Also im having a issue with my pilot screw needles.....the old had just a spring....the new is longer with a oring and spacer...97 1100

[@StevesDIYs]

Hey again, if you still have the original carbs on it, there should be a small flat washer and an oring below the spring that seals off on the bigger shaft of the needle. If a tiny little washer didn’t come out when you pulled the needles, it is still stuck in the hole as well as the oring underneath. I get a small piece of wire and make a small hook on the end so I can pull the washer out and then the oring when I do mine. Not sure about why the replacement ones are longer, but they should look just like the original ones if they are the correct ones. There were some different needles used for different motorcycle manufacturers using the Mikunis so they did different needles to either allow more fuel in (making them a bit harder to adjust unfortunately) or restricting the amount of fuel flow to the idle circuit for smaller Mikuni carbs. The ones for the 2nd Gen Viragos should have a double taper on them I believe…the small tapered tip and then a second tapered area (I’m away from the shop right now or I’d check to be sure). If those two tapers look different to the original ones, I would not use them as they are probably for some other carb. If the tips of the old ones are not damaged (bent or eroded from years of fuel going by them), I would just replace the washers and orings with the new ones and reuse the original needles. If they are damaged, you may have to get another set. Hope this helps a bit and all the best ! Steve

[@Mikeironwheel]

Thank you! I followed Everything Fantastic info!

[@StevesDIYs]

Thanks man ! Glad the video helped some 👍. All the best ! Steve

[@mikkomansikka5704]

I started wondering.. On air fuel adjust we run engine with one cylinder only. Why carbs need to be synced for that? Would it be better if air fuel ratio is done first and then sync them?

[@StevesDIYs]

Hello, yes, if adjusting the mix needle for one carb with the other cylinder’s pressure plug removed, the carbs don’t need to be synced so the mix can be adjusted prior. The reason for the bench sync is to get them close so that the idle can be adjusted for both to make adjusting the mix easier…then once the mix is close and both cylinders running, the sync is checked to dial it in. Then with both cylinders firing, the mix is adjusted again to maximize the rpms at idle (since both are firing and need to be balanced so they help each other vs. one slowing the other down.

[@seniorrider9337]

Steve, I thought you may have an opinion on the octane of the gas you use in your Viragos. I have been using 87 octane non-ethanol, but the station I was using now only has 93 octane in non-ethanol. A bit more expensive but not too bad. I have been searching the internet but come up with conflicting views on this. What is your take on running 93 octane in a 8.3 to 1 compression engine? Thanks man. I can always but 87 octane ethanol and remove the ethanol, but what a pain.

[@StevesDIYs]

Hey man ! From what I know about octane ratings (my BMW is super finicky about the gas put into it and will actually throw codes if I use suspect gas), the higher octane rating defines the fuel’s resistance to pre-detonate or ignite from the pressure and heat that builds up in the cylinder vs. the actual spark from the plug. Since these motors aren’t higher compression, we get to use the lower octane stuff as there is hardly any risk of the fuel igniting before the cylinder gets past TDC which is what causes the engine damage if it does it over and over for each stroke. I’d say running the higher octane non-ethanol wouldn’t be an issue at all if the lower octane fuel wasn’t available anymore (I too run 87 non-ethanol). The biggest reason I always stick to non-ethanol is that the ethanol in the gas absorbs more water and also seems to swell rubber parts that aren’t rated for it. A car’s fuel system is mostly sealed up and well controlled to reduce pollution so there’s not much of a way for moisture to get absorbed into the fuel when sitting, but older bikes, boat motors, lawnmowers, etc…tend to have non sealed fuel systems so the moisture happily finds the ethanol and gets absorbed. In a pinch I’ll run gas with ethanol, but I always be sure to run it on out and refill with the ethanol free before letting the bike sit for very long. The 2nd Gen I got at the 1st of the year is a good example of the effects of the ethanol added fuel. Apparently the previous owner ran ethanol added fuel in it so all was well initially when I first got the bike running, but because I switched it to non-ethanol, after a few tanks, the float needle stopped sealing off anymore since the ethanol wasn’t there to swell the little rubber tips on the shut offs…thus the hydro locked cylinder that made the lovely fire ball in the video a few months ago, lol. The ethanol also seems to make rubber (not rated for it) harden faster so things like the petcocks on my 1st Gens would stop sealing off as well if the ethanol was in the gas. Switching back and forth between non-ethanol and ethanol really upsets things on seals and stuff for sure it seems. Anyway, long story, lol, but my take is that it would be much better to run higher octane non-ethanol than any form of ethanol fuel in these as the parts and fuel system just weren’t made to handle it very well. The higher octane would mainly just reduce the chances of pre-detonation that wasn’t much of a worry with these if lower octane is used. It might run just a hair smoother if the cylinders had buildup in them as sometimes the little pieces of crud stuck to the head near the valves will actually pre-detonate the fuel, but they usually get incinerated little by little when it does it and blow out the exhaust, lol. Hope this helped and all the best ! Steve

[@seniorrider9337]

@@StevesDIYs Thanks man. That makes me feel a lot better about using the higher octane. I need it in my old 76 pick up also. I find that ethanol causes a white powdery corrosion on aluminum. I recently had to rebuild my carter AFB on the truck. Same as in my Virago carbs, white corrosion build up. Yep, the rubber hoses we used for non ethanol get soft when one uses ethanol based fuels. Funny thing is, my research is finding that using ethanol causes MPG to fall about 10-15%. Kind of funny as most regular 87 ethanol fuels are in the 10-15% range. I miss the good old days when gas was gas! Thanks again Steve and have a good one.

[@TheMontagGarage]

What about the adjustment screw on the bottom

[@StevesDIYs]

Hey ! For the Mikuni carbs on these 2nd Gen Viragos, there isn’t an individual adjustment for each carb, but there is one in between the carbs that is used to synchronize them so they are pulling vacuum equally (thus both cylinders are balanced and not fighting each other). Some of these 2nd Gen Mikuni carbs did have a port on the bottom of the bowl just below the main fuel jet, but I think this was for an optional fuel bowl heater if the carbs were used on a snowmobile or something.

[@boxer71c55]

I’m at this point in my virago journey, do I need to adjust my valve timing before this procedure? Thanks

[@StevesDIYs]

Hey man, yep, if you haven’t checked the valve gap, it would be worth while to check just to confirm they are set properly before firing one up. If the bike was running prior to having to clean or adjust the carbs, the valve gaps would probably be fine, but I usually check just to be sure if it’s a “new to me” bike.

[@boxer71c55]

@@StevesDIYs You have been a big help. Thank you!

[@محمدشاكر-ق7ف]

Video of the reason for cutting off the electricity to the spark plug of a Yamaha Virago 535 motorcycle

[@MrScaniamanden]

Hey Steve will you get a falls reading if you just pull out det plug and dont got a spare

[@StevesDIYs]

Hello, sorry but I’m not sure if I understand the question. If you are thinking to try to tune one carburetor, with the plug removed from the other cylinder, you for sure can do that to tune each carburetor, but you would need both cylinders firing in order to synchronize them for the final adjustment. If this is not what you are referring to, just let me know, Steve

[@bahaanaji7823]

Can you please tell me what makes the fuel go to the intake manifold?

[@StevesDIYs]

Hey man ! I may be misunderstanding the question…if so just let me know, but these carbs use the vacuum generated by the draw of the air being pulled into the cylinder to pull fuel in as well through both the pilot (idle) fuel circuit as well as the the running (main) fuel circuit. As the butterflies are opened by the throttle, it allows more air in, which also allows more air to come into the air pilots which pushed fuel up from the bowl. There is also an emulsion tube that has small air holes in the sides that mixes air into the fuel as it is being drawn up through the main fuel jet. The fuel pump on these 2nd Gen Viragos (the 1st Gens don’t even have a fuel pump) only fills up the bowls and keeps them full so it does not actually force fuel into the manifold. There is a small deceleration pumper on the 2nd Gens, but its job is mainly to add fuel in when the butterflies close on deceleration to prevent the lean popping some bikes do.

[@bahaanaji7823]

@StevesDIYs I've checked the L shape rubber air hose, and I found that it has fuel inside. What is the problem?

[@StevesDIYs]

@bahaanaji7823 for fuel getting back into the rubber intake elbows that are before the carb, these old carbs pop back from time to time if they are really well tuned and they will blow fuel back up into the carbs. It think the biggest reason for this is when the two carbs aren’t sync’d very good so one is getting too much fuel and then backfiring up through the carb which blows fuel backward.

[@bahaanaji7823]

@StevesDIYs OMG, that's really what happening right now. Thank you.

[@alexanderramosn1428]

Would this work on my 83 750? The problem that's happening is after getting it running the moment I give it a bit of throttle it shoots up really high and stays there and sometimes when I start it, it automatically starts going up on its own?

[@StevesDIYs]

Hey man, it definitely sounds like a carb issue, but several things can cause the idle to accelerate up uncontrollably. Most times, when the float is sticking or it’s set too high, the motor will foul the plugs and the cylinder will stop firing vs. accelerating up when the throttle is closed back. If the motor is running very lean, it will throttle up uncontrollably and will hang with the rpms up even when the throttle is released. I’d pull the carbs and check to be sure the screens aren’t blocked up in behind the float needle seats, then recheck the float heights. Since the 1st Gens don’t have a fuel pump, you might need to check the screens in the tank to be sure fuel is flowing good as well.

[@TalFulano_]

Hey, im rebuilding a 1988 virago. By any chance do you know if mechanical partss can be replaced with 1986-1999 virago parts?

[@StevesDIYs]

Hey man ! Yes, I believe most everything on the motors are interchangeable on the ‘86 through the end of production of the Viragos as these are all 2nd Gen bikes (the xv750 and xv1100 anyway). The ‘81-‘83 750 and 920 were the 1st Gens, then the ‘84 and ‘85 are a bit of a mix of parts so they are part like the 1st Gen and part like the 2nd Gen. As far as the frames shaft drive, etc…I believe they are the same as well for the ‘86 through end of the production for the Viragos as well.

[@JAllen-db2kv]

Any info on where to get one of those fancy screwdrivers??

[@StevesDIYs]

Hey ! I actually made that as it aggravated me that I couldn’t get to the adjustment screw on the 2nd Gen (I got spoiled by my easy to access 1st Gens, Lol). I made about 20 of them when I made mine since several of the parts came in a pack of 20, but they all sold a bit ago. Several more folks have asked for one so It sounds like I need to makes some more 👍. I have an eBay account that I set up (stevesdiys) so once I make some more I’ll put them out there for sale…might be a few weeks though as I’ll need to order up the materials.

[@mikkomansikka5704]

I missed the thing, where to attach nanometer on carb sides?

[@StevesDIYs]

Hello, if you still have the MCV system in the motor, you’ll have to tee into the small tube that connects to the carb boots for the front and rear. If the MCV system has been removed already, there should be a couple of small rubber caps on the ports on the carb boots that you would connect to.

[@xxnx.o]

Smart guy

[@StevesDIYs]

👍

[@danikagarcon8467]

What about ‘97 Yamaha virago? Bike starts does not idle, shuts off right after

[@StevesDIYs]

Hey ! Usually if they will fire up, but then die quick, it’s an issue with the fuel coming to the carb or a dirty carbs. Does the fuel pump prime the carbs and then stops clicking within a few seconds or does it keep clicking? If it continues to click then it may not be pumping fuel (bad pump, stopped up filter, etc…). If it is pumping fuel, but the carbs are dirty, sometimes you can squirt a little fuel into the carbs (elbows removed) and keep it running long enough that they well clear out a bit and start running.

[@Churr_boi]

What size clear hose did you use?

[@StevesDIYs]

Hey man ! I use some 1/4 OD clear tubing…you can get it at the big box hardware stores like Lowes over in the plumbing section. It’s the same stuff like what is used for refrigerator ice maker water lines. Hope this helps and all the best ! Steve.

[@staffannielsen7719]

I dont get reading on rear cylinder vacuum but it runs whats wrong

[@StevesDIYs]

Hello, are you not seeing any vacuum when the gage is hooked directly to the fitting in the carb boot? If so, and it’s running fine, there must be something blocking the port in the boot as they have to be pulling some level of vacuum to pull fuel in from the carbs.

[@wparsley04]

Whats that red cut-off for.....

[@StevesDIYs]

Hey man ! I put the red 1/4 turn fuel shutoffs on most if my bikes so I can turn them off and run some of the fuel out of the bowls. With 5 or so running bikes, I don’t get to ride each one enough so draining the bowls down seems to help with the floats sticking and also swelling of the rubber float needle ends. All the best ! Steve

[@wolfgarmountbatten1576]

This guy is 👍

[@StevesDIYs]

Thanks man 👍. All the best ! Steve

[@mikkomansikka5704]

Which ones are 1st gen and 2nd gen?

[@StevesDIYs]

Hey again, the 1st Gens were the xv750 and xv920 from 1981 through 1983. In ‘84 and ‘85, the xv700 was more like a 1st Gen motor on a 2nd Gen frame and the xv1000 was almost like the ‘86 and up 2nd Gens. The ‘86 through the end of production of the xv750 and xv1100 Viragos are called the 2nd Gens. Some folks call the ‘84 and ‘85 a 2nd Gen as well, since the frames changed from the mono shock to a dual shock setup, but the motors are a mix of both it seems.

[@dameanbible1694]

How can i sync up carbs at home

[@StevesDIYs]

Hey man ! Are they on the bike and both cylinders firing or are you rebuilding the carbs and want to bench sync them prior to installing? If you are doing the final sync on the bike, here’s a video of how to setup a simple manometer sync that works great for twin cylinder bikes. It’s for my 1st Gen, but the process is very similar for the 2nd Gens and is actually easier since the adjustment screw between the carbs is accessible from the bottom vs. having to remove the seat and lift the tank to get to the sync screw. Here’s a link to that if it helps some: kzbin.info/www/bejne/goGkYoGgbZWSbKs . If the bike is not running yet and you have the carbs off to do a bench sync, just let me know as there’s another 1st Gen video on the channel that would show roughly how to do that on the 2nd Gen carbs as well. Thanks and all the best ! Steve

[@dameanbible1694]

@@StevesDIYs dude you are awesome, I've never seen a KZbin reply so extensively. Its a 96 I got for free that runs on spray but the carbs probably need a good cleaning. I'm gonna run gas through them today to see if they need it before I take them off. Do you know where the air fuel adjustment is on these carbs. I can't find it

[@StevesDIYs]

@@dameanbible1694 thanks man…I do tend to get too detailed on the responses sometimes lol, but I figure if someone goes to the trouble to make a comment, I figure I should try to answer the best I can 👍. For the air/fuel mix needle location, it’s up top on the carbs for the 2nd Gens. I’ll add another reply in just a second with a link to another video on the channel that shows me adjusting mine.

[@StevesDIYs]

@@dameanbible1694 hey again, here’s the link to the other video….it actually shows how to sync the carbs as well…I forgot I had that part in there, lol ! kzbin.info/www/bejne/o4mtgJmJrcqXfLc . Hope it helps and all the best ! Steve

[@dameanbible1694]

@@StevesDIYs ok thanks, ill check them out. Other people kept telling me you have to drill out the bottom of the carbs and I was like that doesn't sound right

[@jameslaine2472]

Where to get that tool?

[@StevesDIYs]

Hey man, I actually just made another batch the other day so I listed them again it on eBay. Here’s the link to them: www.ebay.com/itm/225577145995?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=sfmcIdagSM-&sssrc=2051273&ssuid=sfmcIdagSM-&var=&widget_ver=artemis&media=COPY . I’m away from the shop for a week so I have the time away turned on right now, but if you add it to your eBay watchlist, I think it will notify you once I return. Thanks and all the best ! Steve

[@godworden2768]

Isn’t the right side the rear cylinder?

[@StevesDIYs]

Hey ! Actually the carb to the rear cylinder would be the one in the left side of the bike as the carb boot bolts up to the rear cylinder from the left one. The left side reference is relative to when sitting on the seat of the bike.

[@godworden2768]

@@StevesDIYs I just figured carb and spark plug would be the same each side and left spark plug is on rear cylinder

[@StevesDIYs]

@@godworden2768 yep, does make sense 👍. I think because of how they offset the cylinders on these they ended up lining up the carbs opposite to keep the motor slimmer on the width.

[@godworden2768]

@@StevesDIYs No I just mean that you think the side carb you adjust air/fuel mixture screw on would be for the cylinder with its spark plug on same side. Like when I take the plug out of one side to run on one cylinder I dont then go adjust the screw on the other side?

[@StevesDIYs]

@@godworden2768 Hey again. I watched the video again to check to see how I showed the process. When I pull the plug wire on the left side that goes to the front cylinder and substitute the extra spark plug, that effectively deadens the front cylinder so it’s only running on the rear at that point. Since the carb for the rear cylinder is also on the left side, it’s the one I’m adjusting to dial in the highest rpms of the rear cylinder since it’s the one running. When I switch to the right side, I put the front plug wire back on and then remove the wire to the rear so it’s no longer running. The adjustment for the front cylinder is on the right so then it is adjusted (or in this case I tried, but it wouldn’t adjust since the float wasn’t shutting off). The cylinder getting the air/fuel adjusted is the one that is running so the rear cylinder gets adjusted with the left side carb….the front with the right side carb. Hopefully this explains the process a bit better 👍.