Using a Digital Tach to Sync Carbs

[GolfVenture]

I'm looking for a write up on how to use a digital tach to fine tune the carb sync up process. I read it about a year ago and now can't seem to find where I read it.

[etcswjoe]

I bought the one from Harbor Fright and could not get it to work.

[GolfVenture]

I bought the one from Harbor Fright and could not get it to work.

 

 

Oh great...thats the one I got with a 20% coupon. I'll have to try it soon to make sure it works.

[etcswjoe]

Oh great...thats the one I got with a 20% coupon. I'll have to try it soon to make sure it works.

 

 

I tried it on both bikes and it was all over the place. I am thinking about putting in a plug and using a cheap in dash tach when I need it.

[XV1100SE]

Think this is the one I picked up last year. Pretty sure the tach reads 2x the actual rpm (plug fires 2x per cycle) so I just divide by 2.

http://www.harborfreight.com/lcd-automotive-multimeter-with-tachometer-kit-95670.html

 

Make sure you are on cylinder 1. Think you are supposed to be a certain distance from the plug on the wire too.

[Snaggletooth]

Brian,

 

This is the one I was talking about. Very simple. Ground and spark sensor wire.

 

Included the directions.

Edited April 8, 2013 by Snaggletooth

[etcswjoe]

I think I will have to give that a shot.

[V7Goose]

A Tach is useful for many things, but not much for sync. It does let you set proper idle speed, but that's is not too important for a sync. To sync the carbs you need to set all VACUUM readings equal, regardless of RPM.

Goose

Edited April 8, 2013 by V7Goose
fix auto- correction typo

[MiCarl]

A Tach is useful for many things, but not much for sync. It does let you set proper idle speed, but that's is not too important for a sync. To sync the carbs you need to set all VACUUM readings equal, regardless of RPM.

Goose

 

The existing tach is plenty accurate for judging idle speed.

[mbrood]

The analog tach is fine for basic RPM. You want a digital tach when the differences you are looking for are in the 3rd or 4th digit of the reading. This is particularly true when optimizing the settings on the idle mixture screw. You tune each one for overall peak rpm and then do a vacuum sync to insure they are all pulling equally. Then I go around once more insuring the idle mixture is peaked and then I back it OUT 1/16th or 1/8th turn to insure I'm JUST toward the rich side of the setting.

 

For almost anything else you will do for basic maintenance, the analog tach is quite satisfactory.

[playboy]

Brian,

 

This is the one I was talking about. Very simple. Ground and spark sensor wire.

 

Included the directions.

 

 

I have one of those so how do you turn it off ?

[Snaggletooth]

I have one of those so how do you turn it off ?

 

I don't think you do. Mine has had a display showing since the day I got it. I just zero it out and forget about it.

[etcswjoe]

Brian,

 

This is the one I was talking about. Very simple. Ground and spark sensor wire.

 

Included the directions.

 

 

Is this the same one?

 

http://www.northerntool.com/shop/tools/product_524744_524744

[Condor]

A Tach is useful for many things, but not much for sync. It does let you set proper idle speed, but that's is not too important for a sync. To sync the carbs you need to set all VACUUM readings equal, regardless of RPM.

 

 

Goose

 

 

 

I was going to say that. Thanks for beating me to it Goose....

[Snaggletooth]

Is this the same one?

 

http://www.northerntool.com/shop/tools/product_524744_524744

 

Yep, same one.

[BigBoyinMS]

We did a group buy on those type a few years ago and got instructions on how to turn them off. There may still be a link if you can find the old post.

 

EDIT: I found it. Dingy did the group buy and they sent him the info on turning it off... no file to copy.

 

Here's the info:

"Press and hold down S1 button, will show 01-05 (do not release S1 at this time), when display 05, release S1.

 

After 8-10 seconds(at this time, the meter will flash), the meter will return to total hours, will display 0.0 hours (the meter will not flash).

 

Then press and hold down S1 and S2 buttons, the meter will display 01-09 (don't release S1 and S2 buttons), after showing 00000, release S1 and S2 buttons, the meter will show 00000 to 99999, then return to 0.0.

 

Now the meter is reset, after 5 seconds or so, the meter will become blank display, 0.0 will disappear."

Edited April 8, 2013 by BigBoyinMS

[playboy]

Thanks for the info on the tach.

 

Another question about the tach ?

 

When using this tach to adjust the pilot jets is it necessary to move the pick up wire to the cylinder being adjusted or will any one of the four work?

[V7Goose]

Since you are only looking for a change in engine speed, any kind of tach and pickup is fine. It doesn't even matter if it displays the correct rpm.

Goose