I bought an '81 xv1000 (TR1) in '83. Had trouble from the get-go with backfiring, actually blowing the carbs off on one occasion. Asked questions and the consensus was *piss it off* (The mixture control) I did, and no more trouble (with mixture) for the 26yrs I owned it!. Currently have an '82 750 which of course had the mixture control removed before I got it. Runs fine.
Hey man ! Yep, if the MCV goes bad or starts letting air in, it will “lean pop” the carbs right out of the boots since many if the Virago models don’t have the metal surrounds that go around the rubber on the boots lol. One of mine would pop the small vacuum lines off of it even with the wire clamps on them.
Just found this video and can’t thank you enough. I’ve been tearing my hair out re-tuning the carbs over and over using your other videos, and my front cylinder kept dropping out and fouling. I’m hoping this is the answer for my old UK XV750SE. Great job Steve!
Hey man ! Yep, if the MCV goes bad (or even the vacuum lines that go to it) it will cause issues for sure. Another thing often missed that can cause the cylinders to drop out (after warming up if the rings are a little worn) is if a lot of fuel has gotten down in the oil over time from periodic stuck floats. They will fire up and run great when cold (since the oil with fuel in it is just a bit thicker), but then the oil thins out so bad as it warms up that the compression starts to drop and the plugs will foul. Let me know how it goes and all the best ! Steve
@@StevesDIYs Yet again; great info! In the end I tested the MCV & hoses and found they were ok. I replaced the vacuum line wire clip fasteners with more robust ‘collar’ clips to prevent any vacuum leak. Sprayed the MCV with WD40 and then tried to do the fuel mix etc. according to your other videos. It was then I discovered that the front fuel / air mix needle was way too far out. I’d replaced the needle during rebuild and the new rubber ring must’ve made it more stiff to turn. I had been too cautious doing the ‘soft seating’ and once I had wound the needle in another two turns suddenly the front was running sweetly on it’s own. I completed the synch process and then had a wonderful test ride which felt absolutely great as I’d been struggling to get it right for a while. I had finally made them behave!!! I have to say it’s all thanks to your videos and info which are done so well. You are a legend mate!! I still have the annoying tick and I will definitely need a clip clip someday but for now I am just happy to have a working ride for the summer! I’ll send a link at some point with pics of my totally all original restored Yamaha 1980 XV750SE with only 5000 miles on the clock. It must be the last one left in the UK! Thanks once again Steve! YAMAHA CLASSIC LEGEND!!!
@@thepenningtons17 hey man ! That’s awesome you were able to get it figured out and glad the videos on the channel helped some 👍. It’s always frustrating when they are being grumpy for sure, but when they finally come to life it’s the best feeling in the world ! For me, part of the fun on getting one running again is the challenge to see if I can figure out what the issues are, lol. I’m at an advantage though as I have a couple of bikes so when things get really frustrating on a resurrection, I can just go hop on one of the running bikes and go for a ride to clear my mind, ha,ha. Thanks again for the update…I’m always excited to hear when folks take on the challenge of getting one running again vs. just sending them off to a repair shop (or even worse, just giving up and abandoning it). It will be great if you send me a little video clip once you are all done…I’d love to see it 👍. My channel’s email address is Stevesdiys@gmail.com if you wanted to send me the link there. Best safe out there and all the best ! Steve
Very well done video. Thanks. Incredible amount of information in it and your comments. I’ll add these notes into to do pile of wrecks restoration. Hope the license plate gets to wave before winter. Been waiting 43 years to ride again.
Thanks man 👍. Yep, some of these little emissions things cause a lot of problems when they finally go bad. Best of luck on getting yours going again ! I’m sure you’ll be heading down the road in no time on it 👍
I used some WD -40 to free up the valve , it also has an adjustment under the silicone you can use to help free up the valve (count turns ) . Nothing to lose by trying it . Worked for me .
👍. Yep, some folks like to leave them on the bikes as they do help some with the popping on decel. If they are still functioning I too just leave them on the bike, but if they go bad I bypass them and remove since it doesn’t really hurt much for them not to be in the system.
@@StevesDIYs I was trying to remove it (MCV) but for a reason I don't understand, it doesn't work. For some reason, the front cylinder need extra air from that MCV. other wise it fail ! I though my problem was solved but i'm still have issue at 2000-4000 RPM. On idle, it's working fine with the ajustment of the screw on the MCV. Look like it missing air and running lean. Do you have any advise on what could it be ? Thank you
Thanks for the vid. I've just bought a 96 1100 here in the uk with the entire left side missing. all i have is the two large rubber pipes sticking horizonatally from the bike......Can't find any info so far on what it's all for and how necessary it might be? Bike runs great!
Thanks man 👍. Yep, the 2nd Gen Viragos had something sort of like the MCV for the first Gens. It is called an AIS system (Air Induction System) and supposedly helped with emissions compliance. It doesn’t do anything for the motor and just causes trouble when it goes bad. If the AIS valve has been removed, most likely the two lines that were connected beside the exhaust ports on each cylinder are capped off as well since they were part of this system also. The 2nd Gen I picked up last year (‘89 1100) also had all of this stuff removed prior to me getting it so I think it’s pretty common to remove it as long as there aren’t super strict emissions laws in the area (like California, USA…those folks in that state can’t get away with any modification to the emissions system on anything if I remember right, lol). After going through my ‘89 1100 to see if there are any special things attached that actually do something, the only thing I noticed was that there is a small vacuum line that goes up to a vacuum switch sitting on top of the coils under the plastic cover in the front. That little guy is a boost sensor of some sort that changes the timing when the throttle opens up and the vacuum changes (kind of like a vacuum advance for old cars and trucks with a distributor ignition system). If this is not hooked up, it seems to affect the higher rpm range, but for normal cruising around I couldn’t tell much of a difference with it connected or not…maybe a little on the fuel economy. Glad to hear another one of these old school bikes is back on the road and all the best from Nashville Tennessee, USA ! Steve
@@StevesDIYs Cheers Steve, that's put my mind at ease.......I'll take a closer look at the vacuum to see if there's an issue with the upper rev range. But for now, it's back on the road with it. Sun shining here in the UK, but the wind getting up a bit. Take care.
Hello, the valve doesn’t really change the tuning of the carbs…it’s just there to help with the sudden vacuum increase when the throttle is closed back quickly when decelerating. There shouldn’t be any rejetting of the carbs required if the valve is removed.
Hola ! To eliminate the MCV on the 1st Gen xv750 or xv920, you just need to cap off the ports on the carb boots where the small rubber vacuum lines connect the MCV to the boots.
@juaniitocast 👍. Since the MCV valve is just being eliminated, there should not be any need to change anything on the carburetors (jetting or even the air/fuel mix adjustment). The valve normally stays closed so it does not affect the system…it only opens on deceleration. When I removed them on my motorcycles, I did not have to make any adjustments to the carburetors…I just capped off the fittings that are on the carb boots so no air can enter into the ports where the vacuum lines were connected.
@@StevesDIYs Thank you very much my dear friend, thank you for sharing your experience, your knowledge helped me a lot now I will go to eliminate the system, I myself do the repairs on my motorcycle, I am completely restoring it, greetings from Guatemala. 🫡
In one of your videos I believe you mentioned using an Iridium spark plus. Would your recommend a change from an NGK BP7ES for my stock 1982 920 Virago? Also, how do you take a resistor plug and make it a non resistor plug.
Hey man ! I’ve found that the Iridium version of the plug (NGK BPR7EIX) doesn’t foul near as fast (if at all) compared to the regular plug. I’m guessing it has something to do with the tiny little iridium tip that can clean itself off better, but actually not sure. I’d say give it a try next time you change plugs to see if it was me...they cost a little more, but it’s not so bad since there’s only two. For switching over to resistor plugs, you can take a flat head screwdriver and take the contact out of the plug boot where the plug goes into the boot (for NGK plug wires...not sure for others). When you unscrew it, there will be a little resistor that comes out. I just get a piece of copper that’s roughly the same diameter and replace the resistor with it then put it back together. The little resistor should have metal ends then a ceramic center part. It’s pretty easy to take them out and you can always swap them back in if you change back to a non resistor type plug. All the best and happy holidays ! Steve
Hello, yep, the MCV smaller hose (the control one) should tee off of the line that goes to the petcock down to the carb boot. To remove it, you just have to copy the way the rear cylinder is setup but running the petcock hose straight down to the carb boot. Then the bigger hose connector on the carb boot is just capped off (be sure to put a little clamp on the cap and hoses that holds them securely 👍). All the best and happy holidays ! Steve
Steve, how does this affect your gas mileage by removing the MCV and tuning your carbs by ear to run richer on the front cylinder? I have a 1983 Virago 750 that needs torn down and replace the valve stem seals and a gasket kit. On trips my gas mileage was 39 MPG or 78 miles before running out of gas and walking. I wouldn't want to get less gas mileage unless were talking about 1 mpg. Great video and great demo and explanation. You know your older Yamaha 750 bikes thru and thru. I hope at some point to be able to go thru my engine using your prior videos that were done first rate. Thank You!!!!
Thanks man ! I still get 80 to 90 miles before hitting the reserve on mine even without the MCV. Seems like I put about 2 gallons in it when I’ve hit the reserve level so that would be 40 to 45 mpg. I’ve rebuilt all three of my bike’s motors in the past few years so I’d say that has a lot to do with it the economy since my compression is back high again and the carbs are all cleaned up and adjusted. It doesn’t take much extra to get the front carb happy and not poppy...once I adjust it to what would be close to factory, I then just turn the mix needle out about 1/8 turn to add just a bit more fuel...if it still pops a bit on the next cold start I give it another 1/16 or so turn. There’s only a small window of being too rich or too lean and then the plugs foul or burn so it’s a very small amount of additional fuel needed so they don’t hiccup back into the carbs 👍. Another thing that helps to reduce the hiccups seems to be the type of plug. I switched over to NGK Iridiums a few years back (I had to take the resistors out of the plug caps as I can’t find iridiums without the resistor version), and noticed immediately that it took less warm up time for the motor before it would throttle up smoothly in the cooler months (I live in TN so I’m actually still riding this year as the afternoons are nice).
@@StevesDIYs Thank you very much Steve for the valuable information, your videos and all your time and work. Your experience and intelligence are appreciated. 😊
Thanks man ! I do find it interesting looking back in time (so to speak) and seeing what the engineers came up with for issue resolutions on the 1st Gens. They had some interesting ideas for sure…some (like the starting system in these), were not so good, lol. But hey, these old bikes are still on the road after 40 years so that does speak to how well they were designed and built. All the best ! Steve
I keep having issues with my 1st gen virago 750, can this valve be the issue? A couple of weeks ago the bike started to loose its overall power/speed and later when I would try to give it speed in 1st gear, I would stall easily on a red light light turning green. It would spit/sputter but wouldn't get up to good speed even having high rpms. I changed the plugs and it actually fixed the issue for a day or two and now I'm experiencing the same issue. The bike doesnt get up to speed as easily anymore, its really easy to stall it when in 1st gear. So far the carb was cleaned and tuned, new plugs, new air filter, petcocks are supplying fuel normally, I'm loosing my mind here. Any suggestions?
Hey man ! It could be this little valve if you are having issues on the front cylinder…an easy way to check is to just disconnect the small hose that goes to the front boot that goes to it and then cap off the port that’s on the boot. If it starts running good again then the MCV valve would be bad. Other things to check would be that the carbs are sync’d good (if you haven’t already done that). When you cleaned the carbs, did you notice any small black particles up above the diaphragms? If so, the vent tube foam filters may be finally started disintegrating and it will keep stopping up until those are removed and cleaned out. One other item would be the float height in the carbs (if you also didn’t check them when cleaning the carbs). If the fuel level in the bowls is too high, it will foul the plugs really fast as it’s pulling too much fuel into the motor. It does sound like something to do with the air/fuel mix though like you are thinking.
Good day my good sir, I have a new problem on my 84 xv750. At low rpm or throttle, the bike bogs, but when I full throttle or raise to high rpm, the bike runs great. What do you think is doing that?
Hey man ! I would first suspect that the idle circuit jet may be getting clogged up so the air/fuel mix is getting thrown off. If not that, there may have been some particles that have gotten into the idle mix needle hole and is preventing fuel from getting pulled up at idle. Could also be that the floats are not sealing off and it is getting too much fuel, but usually they won’t run many months if that is the case since eventually it will foul the plugs. Might be time to pull the carbs and give them a good cleaning as a first step 👍. Hope this helps and all the best ! Steve
@@StevesDIYs my plugs foul when low throttle, but full throttle the spark plug looks brown. About the floats, the carb doesn't flood. What do you think Steve sir?
@@anthonyarmstrong9508 hey again, I’d say if the bike is not hard to start or smells really rich when first started, then the floats are probably set ok. It might just be that the carbs need to be cleaned and the air/fuel adjusted again to get it running right again. Most times, when the motor runs good when throttled up, but not very good when idling, it’s something to do with the carbs (or the p,Gus are very fouled and will only spark when the rpms are up causing more voltage to be made by the stator). You could also check the voltage being put out by the stator when idling and at higher rpms…at idle it should be at least putting out around 12.5 volts. When throttled up, it should go up in to the 13+ volts.
Lol thank you for this wonderful information sir. That device sounds like fart sounds, I could imagine that sound happening while on the bike, my biker friends might ask what is that?
Thanks man ! Yep, I’d say if the bike wasn’t running when it gulped or burped, folks would wonder what the heck that noise was 🤣🤣. If you still have it on your bike, you’ll probably hear it now if the front cylinder hiccups when you try to throttle up too fast without letting it warm up a bit in the cooler months, lol
A vast majority of folks who alter their air cleaners for more Harley-esque type of look for K&N filter systems just try and gut the system without taking any account for capping off or making some provision for balancing the scale and go chasing their tails like a dog trying to figure out why their bike doesn't run right anymore. In the groups and forum's there is an immense amount of ignorance about how to solve the issue after they chop the channel the bug-eyes for esthetic reasons. I just picked an 85' Virago with the hack, and no one on eBay even has one I can buy. As many as get tossed you would think everyone would have one? Not the case though. Guess I'll keep looking since I don't mind the bug-eyes or the mixture control valve living in that little shiney mouse house.
Yep, if not done properly, taking away an original part will cause all kinds of issues. As long as they are working they don’t bother anything and actually help with back fires back into the carb it seems…once they go bad though it can be really tough to track down why the cylinder won’t fire due to the extra air getting in. Someone had already removed the one in the chrome cover on the 2nd Gen I recently got as well unfortunately.
I bought an '81 xv1000 (TR1) in '83. Had trouble from the get-go with backfiring, actually blowing the carbs off on one occasion. Asked questions and the consensus was *piss it off* (The mixture control) I did, and no more trouble (with mixture) for the 26yrs I owned it!. Currently have an '82 750 which of course had the mixture control removed before I got it. Runs fine.
Hey man ! Yep, if the MCV goes bad or starts letting air in, it will “lean pop” the carbs right out of the boots since many if the Virago models don’t have the metal surrounds that go around the rubber on the boots lol. One of mine would pop the small vacuum lines off of it even with the wire clamps on them.
Just found this video and can’t thank you enough. I’ve been tearing my hair out re-tuning the carbs over and over using your other videos, and my front cylinder kept dropping out and fouling. I’m hoping this is the answer for my old UK XV750SE. Great job Steve!
Hey man ! Yep, if the MCV goes bad (or even the vacuum lines that go to it) it will cause issues for sure. Another thing often missed that can cause the cylinders to drop out (after warming up if the rings are a little worn) is if a lot of fuel has gotten down in the oil over time from periodic stuck floats. They will fire up and run great when cold (since the oil with fuel in it is just a bit thicker), but then the oil thins out so bad as it warms up that the compression starts to drop and the plugs will foul. Let me know how it goes and all the best ! Steve
@@StevesDIYs Yet again; great info! In the end I tested the MCV & hoses and found they were ok. I replaced the vacuum line wire clip fasteners with more robust ‘collar’ clips to prevent any vacuum leak. Sprayed the MCV with WD40 and then tried to do the fuel mix etc. according to your other videos. It was then I discovered that the front fuel / air mix needle was way too far out. I’d replaced the needle during rebuild and the new rubber ring must’ve made it more stiff to turn. I had been too cautious doing the ‘soft seating’ and once I had wound the needle in another two turns suddenly the front was running sweetly on it’s own. I completed the synch process and then had a wonderful test ride which felt absolutely great as I’d been struggling to get it right for a while. I had finally made them behave!!! I have to say it’s all thanks to your videos and info which are done so well. You are a legend mate!! I still have the annoying tick and I will definitely need a clip clip someday but for now I am just happy to have a working ride for the summer! I’ll send a link at some point with pics of my totally all original restored Yamaha 1980 XV750SE with only 5000 miles on the clock. It must be the last one left in the UK!
Thanks once again Steve! YAMAHA CLASSIC LEGEND!!!
@@StevesDIYs Here’s my XV!
th-cam.com/video/4OgMhmGtWMk/w-d-xo.html
@@thepenningtons17 hey man ! That’s awesome you were able to get it figured out and glad the videos on the channel helped some 👍. It’s always frustrating when they are being grumpy for sure, but when they finally come to life it’s the best feeling in the world ! For me, part of the fun on getting one running again is the challenge to see if I can figure out what the issues are, lol. I’m at an advantage though as I have a couple of bikes so when things get really frustrating on a resurrection, I can just go hop on one of the running bikes and go for a ride to clear my mind, ha,ha.
Thanks again for the update…I’m always excited to hear when folks take on the challenge of getting one running again vs. just sending them off to a repair shop (or even worse, just giving up and abandoning it). It will be great if you send me a little video clip once you are all done…I’d love to see it 👍. My channel’s email address is Stevesdiys@gmail.com if you wanted to send me the link there. Best safe out there and all the best ! Steve
Very well done video. Thanks. Incredible amount of information in it and your comments. I’ll add these notes into to do pile of wrecks restoration. Hope the license plate gets to wave before winter. Been waiting 43 years to ride again.
Thanks man 👍. Yep, some of these little emissions things cause a lot of problems when they finally go bad. Best of luck on getting yours going again ! I’m sure you’ll be heading down the road in no time on it 👍
I used some WD -40 to free up the valve , it also has an adjustment under the silicone you can use to help free up the valve (count turns ) . Nothing to lose by trying it . Worked for me .
👍. Yep, some folks like to leave them on the bikes as they do help some with the popping on decel. If they are still functioning I too just leave them on the bike, but if they go bad I bypass them and remove since it doesn’t really hurt much for them not to be in the system.
If I can add one point. In my case, I only adjusted the small screw behind the small rubber portion.
👍. Yep, I just usually remove them if they start causing an issue, but seems they can be adjusted as well. All the best ! Steve
@@StevesDIYs I was trying to remove it (MCV) but for a reason I don't understand, it doesn't work. For some reason, the front cylinder need extra air from that MCV. other wise it fail ! I though my problem was solved but i'm still have issue at 2000-4000 RPM. On idle, it's working fine with the ajustment of the screw on the MCV. Look like it missing air and running lean. Do you have any advise on what could it be ? Thank you
Thanks for the vid. I've just bought a 96 1100 here in the uk with the entire left side missing. all i have is the two large rubber pipes sticking horizonatally from the bike......Can't find any info so far on what it's all for and how necessary it might be? Bike runs great!
Thanks man 👍. Yep, the 2nd Gen Viragos had something sort of like the MCV for the first Gens. It is called an AIS system (Air Induction System) and supposedly helped with emissions compliance. It doesn’t do anything for the motor and just causes trouble when it goes bad. If the AIS valve has been removed, most likely the two lines that were connected beside the exhaust ports on each cylinder are capped off as well since they were part of this system also. The 2nd Gen I picked up last year (‘89 1100) also had all of this stuff removed prior to me getting it so I think it’s pretty common to remove it as long as there aren’t super strict emissions laws in the area (like California, USA…those folks in that state can’t get away with any modification to the emissions system on anything if I remember right, lol).
After going through my ‘89 1100 to see if there are any special things attached that actually do something, the only thing I noticed was that there is a small vacuum line that goes up to a vacuum switch sitting on top of the coils under the plastic cover in the front. That little guy is a boost sensor of some sort that changes the timing when the throttle opens up and the vacuum changes (kind of like a vacuum advance for old cars and trucks with a distributor ignition system). If this is not hooked up, it seems to affect the higher rpm range, but for normal cruising around I couldn’t tell much of a difference with it connected or not…maybe a little on the fuel economy.
Glad to hear another one of these old school bikes is back on the road and all the best from Nashville Tennessee, USA ! Steve
@@StevesDIYs Cheers Steve, that's put my mind at ease.......I'll take a closer look at the vacuum to see if there's an issue with the upper rev range. But for now, it's back on the road with it. Sun shining here in the UK, but the wind getting up a bit.
Take care.
Oops, logged on with my other profile. Same Paul. :D
When you remove the valve, are you jetting both carbs according to the front or to the rear carb?
Hello, the valve doesn’t really change the tuning of the carbs…it’s just there to help with the sudden vacuum increase when the throttle is closed back quickly when decelerating. There shouldn’t be any rejetting of the carbs required if the valve is removed.
Amigo. Que se debe hacer para eliminar este componente y que trabajen bien los carburadores?
Hola ! To eliminate the MCV on the 1st Gen xv750 or xv920, you just need to cap off the ports on the carb boots where the small rubber vacuum lines connect the MCV to the boots.
Thank you very much friend for your kind help! Apart from that, do you have to modify anything in the carburetors? like injectors or needles?
greetings from Guatemala
@juaniitocast 👍. Since the MCV valve is just being eliminated, there should not be any need to change anything on the carburetors (jetting or even the air/fuel mix adjustment). The valve normally stays closed so it does not affect the system…it only opens on deceleration. When I removed them on my motorcycles, I did not have to make any adjustments to the carburetors…I just capped off the fittings that are on the carb boots so no air can enter into the ports where the vacuum lines were connected.
@@StevesDIYs Thank you very much my dear friend, thank you for sharing your experience, your knowledge helped me a lot now I will go to eliminate the system, I myself do the repairs on my motorcycle, I am completely restoring it, greetings from Guatemala. 🫡
In one of your videos I believe you mentioned using an Iridium spark plus. Would your recommend a change from an NGK BP7ES for my stock 1982 920 Virago? Also, how do you take a resistor plug and make it a non resistor plug.
Hey man ! I’ve found that the Iridium version of the plug (NGK BPR7EIX) doesn’t foul near as fast (if at all) compared to the regular plug. I’m guessing it has something to do with the tiny little iridium tip that can clean itself off better, but actually not sure. I’d say give it a try next time you change plugs to see if it was me...they cost a little more, but it’s not so bad since there’s only two. For switching over to resistor plugs, you can take a flat head screwdriver and take the contact out of the plug boot where the plug goes into the boot (for NGK plug wires...not sure for others). When you unscrew it, there will be a little resistor that comes out. I just get a piece of copper that’s roughly the same diameter and replace the resistor with it then put it back together. The little resistor should have metal ends then a ceramic center part. It’s pretty easy to take them out and you can always swap them back in if you change back to a non resistor type plug. All the best and happy holidays ! Steve
I want to delete my MCV as well. Is the mcv vacuum hose connected to the petcock. Because that also has a vacuum hose connected to it?
Hello, yep, the MCV smaller hose (the control one) should tee off of the line that goes to the petcock down to the carb boot. To remove it, you just have to copy the way the rear cylinder is setup but running the petcock hose straight down to the carb boot. Then the bigger hose connector on the carb boot is just capped off (be sure to put a little clamp on the cap and hoses that holds them securely 👍). All the best and happy holidays ! Steve
Steve, how does this affect your gas mileage by removing the MCV and tuning your carbs by ear to run richer on the front cylinder? I have a 1983 Virago 750 that needs torn down and replace the valve stem seals and a gasket kit. On trips my gas mileage was 39 MPG or 78 miles before running out of gas and walking. I wouldn't want to get less gas mileage unless were talking about 1 mpg. Great video and great demo and explanation. You know your older Yamaha 750 bikes thru and thru. I hope at some point to be able to go thru my engine using your prior videos that were done first rate. Thank You!!!!
Thanks man ! I still get 80 to 90 miles before hitting the reserve on mine even without the MCV. Seems like I put about 2 gallons in it when I’ve hit the reserve level so that would be 40 to 45 mpg. I’ve rebuilt all three of my bike’s motors in the past few years so I’d say that has a lot to do with it the economy since my compression is back high again and the carbs are all cleaned up and adjusted.
It doesn’t take much extra to get the front carb happy and not poppy...once I adjust it to what would be close to factory, I then just turn the mix needle out about 1/8 turn to add just a bit more fuel...if it still pops a bit on the next cold start I give it another 1/16 or so turn. There’s only a small window of being too rich or too lean and then the plugs foul or burn so it’s a very small amount of additional fuel needed so they don’t hiccup back into the carbs 👍. Another thing that helps to reduce the hiccups seems to be the type of plug. I switched over to NGK Iridiums a few years back (I had to take the resistors out of the plug caps as I can’t find iridiums without the resistor version), and noticed immediately that it took less warm up time for the motor before it would throttle up smoothly in the cooler months (I live in TN so I’m actually still riding this year as the afternoons are nice).
@@StevesDIYs Thank you very much Steve for the valuable information, your videos and all your time and work. Your experience and intelligence are appreciated. 😊
Thanks man ! I do find it interesting looking back in time (so to speak) and seeing what the engineers came up with for issue resolutions on the 1st Gens. They had some interesting ideas for sure…some (like the starting system in these), were not so good, lol. But hey, these old bikes are still on the road after 40 years so that does speak to how well they were designed and built. All the best ! Steve
I keep having issues with my 1st gen virago 750, can this valve be the issue? A couple of weeks ago the bike started to loose its overall power/speed and later when I would try to give it speed in 1st gear, I would stall easily on a red light light turning green. It would spit/sputter but wouldn't get up to good speed even having high rpms.
I changed the plugs and it actually fixed the issue for a day or two and now I'm experiencing the same issue. The bike doesnt get up to speed as easily anymore, its really easy to stall it when in 1st gear.
So far the carb was cleaned and tuned, new plugs, new air filter, petcocks are supplying fuel normally, I'm loosing my mind here.
Any suggestions?
Hey man ! It could be this little valve if you are having issues on the front cylinder…an easy way to check is to just disconnect the small hose that goes to the front boot that goes to it and then cap off the port that’s on the boot. If it starts running good again then the MCV valve would be bad. Other things to check would be that the carbs are sync’d good (if you haven’t already done that). When you cleaned the carbs, did you notice any small black particles up above the diaphragms? If so, the vent tube foam filters may be finally started disintegrating and it will keep stopping up until those are removed and cleaned out. One other item would be the float height in the carbs (if you also didn’t check them when cleaning the carbs). If the fuel level in the bowls is too high, it will foul the plugs really fast as it’s pulling too much fuel into the motor. It does sound like something to do with the air/fuel mix though like you are thinking.
Good day my good sir, I have a new problem on my 84 xv750. At low rpm or throttle, the bike bogs, but when I full throttle or raise to high rpm, the bike runs great. What do you think is doing that?
Hey man ! I would first suspect that the idle circuit jet may be getting clogged up so the air/fuel mix is getting thrown off. If not that, there may have been some particles that have gotten into the idle mix needle hole and is preventing fuel from getting pulled up at idle. Could also be that the floats are not sealing off and it is getting too much fuel, but usually they won’t run many months if that is the case since eventually it will foul the plugs. Might be time to pull the carbs and give them a good cleaning as a first step 👍. Hope this helps and all the best ! Steve
@@StevesDIYs thank you for sharing your wisdom Steve sir. I will go look into it and see what's up.☺👍💯
@@StevesDIYs my plugs foul when low throttle, but full throttle the spark plug looks brown. About the floats, the carb doesn't flood. What do you think Steve sir?
@@anthonyarmstrong9508 hey again, I’d say if the bike is not hard to start or smells really rich when first started, then the floats are probably set ok. It might just be that the carbs need to be cleaned and the air/fuel adjusted again to get it running right again. Most times, when the motor runs good when throttled up, but not very good when idling, it’s something to do with the carbs (or the p,Gus are very fouled and will only spark when the rpms are up causing more voltage to be made by the stator). You could also check the voltage being put out by the stator when idling and at higher rpms…at idle it should be at least putting out around 12.5 volts. When throttled up, it should go up in to the 13+ volts.
@@StevesDIYs thank you soo much Steve sir, I will look into it first thing in the morning please God.😁👍💯
Lol thank you for this wonderful information sir. That device sounds like fart sounds, I could imagine that sound happening while on the bike, my biker friends might ask what is that?
Thanks man ! Yep, I’d say if the bike wasn’t running when it gulped or burped, folks would wonder what the heck that noise was 🤣🤣. If you still have it on your bike, you’ll probably hear it now if the front cylinder hiccups when you try to throttle up too fast without letting it warm up a bit in the cooler months, lol
@@StevesDIYs 😂
A vast majority of folks who alter their air cleaners for more Harley-esque type of look for K&N filter systems just try and gut the system without taking any account for capping off or making some provision for balancing the scale and go chasing their tails like a dog trying to figure out why their bike doesn't run right anymore. In the groups and forum's there is an immense amount of ignorance about how to solve the issue after they chop the channel the bug-eyes for esthetic reasons. I just picked an 85' Virago with the hack, and no one on eBay even has one I can buy. As many as get tossed you would think everyone would have one? Not the case though. Guess I'll keep looking since I don't mind the bug-eyes or the mixture control valve living in that little shiney mouse house.
Yep, if not done properly, taking away an original part will cause all kinds of issues. As long as they are working they don’t bother anything and actually help with back fires back into the carb it seems…once they go bad though it can be really tough to track down why the cylinder won’t fire due to the extra air getting in. Someone had already removed the one in the chrome cover on the 2nd Gen I recently got as well unfortunately.
That’s a fart valve
Lol, yep I sure sounds like that when it actuates. I guess, it does actually function the same way…releasing excess gas when it builds up 🤣.