Shop Tachometers

[Tek]

I am looking to buy some new tools for the garage, so I can avoid taking my bike to our local dealer's shop. I would like to know what you guys use for your tachometers when you're working on the bike (setting idle, TB sync, etc...). I noticed that the maintenance manual calls for a digital tach, but I wouldn't think that there would be much difference between the analog and the digitals for most applications....

I would appreciate any recommendations and pros and cons of the different tachs. Thanks a lot for your help.

Tek

 

[Silent]

I use the tach on the dash. If I want to be super anal, I'll hook the laptop into the PC3, but it's not going to make a difference in the way the bike runs imo. The difference between the two is negligable.

YMMV

 

[yamaholic]

+1

 

[charismaticmegafauna]

<snip>I noticed that the maintenance manual calls for a digital tach, but I wouldn't think that there would be much difference between the analog and the digitals for most applications....I would appreciate any recommendations and pros and cons of the different tachs. Thanks a lot for your help.

An auxiliary tachometer can be an effective tool (in a shop setting) for fine adjustment of fueling systems. The smallest adjustments will be noted by rpm change on tachometers that read to a finer scale (than the dash unit).

For years, before fuel injection, one of the ways to adjust the mixture of primary circuits on carburetted motorcycles (especially multiple carbs), and when exhaust sniffers aren't available -- was by using the "idle drop" method, whereby mixture adjustments would be 'set' by noting the specific drop in idle speed (referencing the manual) using a very accurate tachometer.

And..., it's easy to recco the acquisition of more tools.

 

[HaulinAshe]

+Gunny! on buying the PC-3. Tell the spousal unit it's a digital tachometer for the bike, with a laptop interface.

Works great!

 

[acat]

Could you elaborate on the " idle drop" method? I have a bike I need to adjust. Thanks

 

[Silent]

Could you elaborate on the " idle drop" method? I have a bike I need to adjust. Thanks

Turn the air screw untill the idle drops, then turn it the other way till it drops, then split the difference. Doesn't work on EFI tho.

 

[acat]

Do you think I will hear a rpm drop on a 6 cylinder engine or will I see it on the bikes tach? ( Valkyrie) That is why I thought I would need a shop tach.

 

[charismaticmegafauna]

"Idle Drop" is a way for factories to allow techs to approximate correct (EPA legal) idle mixture adjustment in the field -- without the benefit of exhaust analyzers. It's model specific and a detailed procedure that's best done with a shop manual for that model. It will, however, give you properly adjusted carburetors when expertly performed -- which should give you a bike that runs like the factory expects.

The speed differential is too little to notice without a more accurate tach than what's on the dash.

Here's a little bit from a Gold Wing manual: (omitting steps 1 ~ 4)

• 5. Start the engine and turn the idle adjust screw in or out to achieve the idle speed listed in Table 1.
• 6. Turn each pilot screw out 1/2 turn from the initial setting in step 1. If the engine speed increases 50 rpm or more, turn each pilot screw out by 1/2 turn at a time until engine speed drops by 50 rpm or less.

... and on thru step 14. And it's always 50 rpm more or less on through all the carbs.As you can see, it's a very exacting process -- but, it's the factory way to get it right. And a precise tachometer is a necessary tool. :huh: