Matching Mixture levels 4-5K RPM

[nzemke]

So I have been having a hell of a time trying to get these things synced because of the over drilled mixture screw pin hole on the third carb. Because of this she typically runs rich. I tried using the ear method of listening to it but I have two young kids that scream at each other a lot, and a wife that believes that I have very selective hearing. So after throwing a patch on the third one I still couldn't find the point where it went from being to lean to too rich.

As I was messing with it I tend to occasionally give it a little rap on the throttle when it seems like its going to die. That's where I noticed with the vacuum carb sync tool that even with them at level at idle that when I rap it quickly to 4-5 grand and letting off that they would never bounce up to the same height on the gauges. So I decided to adjust the mixture screw then rap it out again. And low and behold it moved from where it was before. I had one that was a little high, and the third one that was really low. So I adjusted a little at a time, rapping it up a little to watch the bounce.

Now the power has returned at cruising speed and coming off of idle and she sounds the best she has since I brought life back to her. I'm not sure how helpful this is, or how accurate this is at getting things properly tuned but it took ALL of the hesitation out of the bike at cruising speeds. I'm hoping that someone else can use this information to benefit them.

[BA80]

You just kinda reinforced that counting turns ain't the way to adjust the mixture screws. It has to be done with the vacuum gauges to get it right.

[IanDMacDonald]

I wish I could learn that way of adjusting. Read post after post on how to do it, and just don't have the gift. Plug chop method and Carb Tune are my friends.

[nzemke]

I'll make a video this weekend for you.

[BA80]

Plug chop is only good for jet sizing or needle adjustments. The carbtune I've never used personally because I could never get it to work properly but if you can it would need to be used in conjunction with the sync gauges because adjusting the mixture screws will change your sync and when you change your sync it will affect your mixture adjustment.

It takes a while to bring it all together but when your done you'll have an engine that is as close to perfectly tuned as you can get with old beat up carbs.

Just regular old fashioned spring type gauges work the best because they can be adjusted and synchronized to all read the same from a single vacuum source and all of them reading the same is very important.

If I can get the time and the assistance I might make a video sometime. It's really quite easy once you begin to understand how it works.

[IanDMacDonald]

The carbtune I've never used personally because I could never get it to work properly

The Carbtune is the sync tool, Color/ColourTune is the mixture tool. I know u knew that though.

And, if u could do that video Greg, that would be great!

[BA80]

Yup, my bad. I did have them confused. That happens a lot the older I get.

However, I never could get a carbtune to work right either.

Take your carbtune and hook all the hoses together and run it to a single vacuum source and see if they all read the same.

I've used a carbtune a couple of times that belonged to somoneelse and had to fix my bike with my gauges when I got home because it ran like crap.

Not saying they are all bad, just my experience.

[BillyRok]

Is this what you are referring to Greg?

http://www.ebay.com/itm/New-Vacuum-C..._Tools&vxp=mtr

What are the Yamaha 6mm adapters they talk about and where do you find them?

I've wondered about the accuracy of the Carbtune I bought, #4 always seems a bit "sticky" in the tube.

[mack]

idle adjustments

I had a broken tip in the #4 carb on my SF. After removal the hole was slighly altered. If found that setting that carb was just as described and after finally getting good plug colour and sync, that it is only a 1/4 turn out now. Once you mess with those holes, all bets are off as to the number of turns.

[BA80]

Is this what you are referring to Greg?

http://www.ebay.com/itm/New-Vacuum-C..._Tools&vxp=mtr

What are the Yamaha 6mm adapters they talk about and where do you find them?

I've wondered about the accuracy of the Carbtune I bought, #4 always seems a bit "sticky" in the tube.

That's exactly like what I have but I didn't get a nice case and mine cost a little more.

[BillyRok]

So where did you get the 6mm adapters?

[skids]

The Carbtune is the sync tool, Color/ColourTune is the mixture tool. I know u knew that though.

And, if u could do that video Greg, that would be great!

You took the words right out of my fingers Ian.

[skids]

I had a broken tip in the #4 carb on my SF. After removal the hole was slighly altered. If found that setting that carb was just as described and after finally getting good plug colour and sync, that it is only a 1/4 turn out now. Once you mess with those holes, all bets are off as to the number of turns.

The other thing about the larger pilot hole is, you may get popping on deceleration when you get it running right. At least that is the way mine was. I don't think it "mists" to fuel properly and is more of a drip. With mine, I cared more about getting the idle right, than the midrange when I adjusted pilot screws (and vacuum synched of course).

[nzemke]

After messing with it again today. I have found that this works only if you some how messed up the hole its self...otherwise your stuck with the other two options for mixture levels.

[BA80]

So where did you get the 6mm adapters?