I found out proper adjusting of these mixture screws with a color tune is crucial. In my case they were set too lean, thus it was causing problems with idle and the rpm hang after cracking the throttle.
thanks so much just bought an xj650, cleaned the carbs and is still running like shit. Just assumed that you couldn't adjust these carbs I never would've found the location of these adjustment screws.
I'm glad you found it useful! I'm a hobbyist, and I'm learning so much along the way. I did a full restoration on my carbs, with a bench sync and float bowl test. If you get stuck on something, I can try to help.
@@lilandmadsmoto6235 Just patched up some vacuum leeks on my 650 with new gaskets. Have all my needles at 3 turns out now. Wondering if theres a more accurate way to sync the carbs without a gauge (too poor to get one) or if tuning all carbs to the same setting is enough
@@bengearhart4613 Without a carb sync, you can opt for a 'bench sync' at zero cost for tools. Matt has a good video on how to do this. th-cam.com/video/oVlLitzF38I/w-d-xo.html
@@bengearhart4613 You will never get it right without taking actual readings on the bike. Old dogs can get close by sound, but if you are new to syncing 4 carbs you will just frustrate yourself into circles and end up with a rough running bike waaay out of tune. You can start with a pair of $16.00 vacuum gauges from Harbor Freight,.Then find the carb without an adjustment as your base #1. Hook up #1 and #2, match the readings by adjusting #2. Then on to 1-3, and 1-4 off of that base # one - one at a time. You will still need the proper adapters at the carb side. If it is a YICS engine you should get and use the temporary tool to block the secondary ports, until all 4 are synced (or find a friendly Yamaha mechanic and borrow one). As for getting the mixture right - that alone is a mystery religion without using the proper tools. Unless you know what a 14.8 - 15:1 mixture feels and sounds like. Another variable with OLD bikes (besides rusting tanks and such) is now we have "green approved" corn crap gasoline. That alone means re-jetting a little richer to get back the original power. Or stopping by the airport for some 100 octane low lead gas. For your home "generator," not road bike. That would be illegal.
When I set the screws, I screwed them all the way in and then backed them out 3 full turns. (360 degrees x 3) This seemed to work well. However, this was after I had fully restored the carbs. I knew the float settings were identical, the butterfly values were set identically, and everything was dialed in - these carbs were better than new. If you are starting with the carbs on the bike and they are in unknown condition, a color tune as Mr. Thomas points out in this thread, might be the best way to go. I've never done it myself, but it seems legit. Post back and let us know how it goes. Good luck!
Can start by screwing them al the way in, then backing out 3 full turns, then making fine adjustments after... But a colortune kit takes all the guesswork out of it
Seriously!! From what I've read online, it was an emissions thing. I think they had to make the bike run lean and not make it adjustable by the end consumer so that the bike qualified for import. I guess they weren't thinking these things would be around for years and years.
A reverse bit should be used to prevent the last 2 rounds, bottoming and braking the screw in the port.
I found out proper adjusting of these mixture screws with a color tune is crucial. In my case they were set too lean, thus it was causing problems with idle and the rpm hang after cracking the throttle.
yes, these were set at the factory too lean (US govt regs). 1 extra turn out (counter clockwise) give you a better mixture for cold starts.
This was an amazing video just to let you know.
Thanks!
thanks so much just bought an xj650, cleaned the carbs and is still running like shit. Just assumed that you couldn't adjust these carbs I never would've found the location of these adjustment screws.
I'm glad you found it useful! I'm a hobbyist, and I'm learning so much along the way. I did a full restoration on my carbs, with a bench sync and float bowl test. If you get stuck on something, I can try to help.
@@lilandmadsmoto6235 Just patched up some vacuum leeks on my 650 with new gaskets. Have all my needles at 3 turns out now. Wondering if theres a more accurate way to sync the carbs without a gauge (too poor to get one) or if tuning all carbs to the same setting is enough
@@bengearhart4613 Without a carb sync, you can opt for a 'bench sync' at zero cost for tools. Matt has a good video on how to do this. th-cam.com/video/oVlLitzF38I/w-d-xo.html
@@bengearhart4613 You will never get it right without taking actual readings on the bike. Old dogs can get close by sound, but if you are new to syncing 4 carbs you will just frustrate yourself into circles and end up with a rough running bike waaay out of tune. You can start with a pair of $16.00 vacuum gauges from Harbor Freight,.Then find the carb without an adjustment as your base #1. Hook up #1 and #2, match the readings by adjusting #2. Then on to 1-3, and 1-4 off of that base # one - one at a time. You will still need the proper adapters at the carb side. If it is a YICS engine you should get and use the temporary tool to block the secondary ports, until all 4 are synced (or find a friendly Yamaha mechanic and borrow one).
As for getting the mixture right - that alone is a mystery religion without using the proper tools. Unless you know what a 14.8 - 15:1 mixture feels and sounds like.
Another variable with OLD bikes (besides rusting tanks and such) is now we have "green approved" corn crap gasoline. That alone means re-jetting a little richer to get back the original power. Or stopping by the airport for some 100 octane low lead gas. For your home "generator," not road bike. That would be illegal.
Great video ladies, very informative thank you 👍🏻🇦🇺
Isn't that set at factory?
Did you recover the screw with a replacement plug when you were done or did you leave it open?
great job
Thank u for the help
Do you know how to set them. Someone in the past has been messing with them and now I need to get them balanced again
When I set the screws, I screwed them all the way in and then backed them out 3 full turns. (360 degrees x 3) This seemed to work well. However, this was after I had fully restored the carbs. I knew the float settings were identical, the butterfly values were set identically, and everything was dialed in - these carbs were better than new. If you are starting with the carbs on the bike and they are in unknown condition, a color tune as Mr. Thomas points out in this thread, might be the best way to go. I've never done it myself, but it seems legit. Post back and let us know how it goes. Good luck!
Also, a carb sync gauge will help, too.
Lil and Mads Moto ok and thanks for getting back to me. I’ll definitely let you know how I get on. Thanks again
Can start by screwing them al the way in, then backing out 3 full turns, then making fine adjustments after...
But a colortune kit takes all the guesswork out of it
Why did they hide that screw that make us so hard to adjust it?
Seriously!! From what I've read online, it was an emissions thing. I think they had to make the bike run lean and not make it adjustable by the end consumer so that the bike qualified for import. I guess they weren't thinking these things would be around for years and years.
That is NOT the idle adjustment, that's the fuel/air mixture..there's ONLY One idle adjustment I'm the center
idle jet, idle screw...