Connecting a tach

[kerryb]

I want to hook up an electronic tachometer to set my idle mixture screws. With my other bikes I use the signal wire from the points, but the '83 interstate has the electronic ignition with igniters so I'm hesitant to go hooking clips up willy-nilly, hate to break something and the factory service manual doesn't say where to make connections.
It would be helpful if I don't have to remove the shelter too, it is a pain on this bike.

Suggestions appreciated.

 

[desertrefugee]

Tachs just run from a pulse feeding the coil primary. Voltage is still 12'ish VDC and points or electronic switching won't matter. But, you'll need a "programmable" or "configurable" tach that will double the RPM since there are only two coils and a wasted spark config. That would make the tach run at half speed if not compensated.

 

[kerryb]

Thanks, I'll hook it to the coil primary then. I just need to see small increases, actual tach speed vs engine speed doesn't seem necessary. FSM calls for rise and fall of engine speed to adjust mixture screws. If I remember correctly, the concensus these days is to adjust for the best rise in engine rpm and leave it there.
Another question: does it matter which one comes first, carb synch or mixture screws? I'm thinking carb synch should be first because it can have such influence on idle speed. Do I have this right?

 

[desertrefugee]

You’ll have better results with the mixture screw adjustment after synchronizing. But, in reality neither one has any effect on the other. It’ll just be running smoother after a synch. That’ll make it easier to detect changes with the idle mixture.

 

[kerryb]

Thanks, I'm looking forward to it running smoother. It's good now, but I detect a rythmic change compared to my other '83 that is much smoother (singer-like). I think that smoothnes is "synch" related.
I got my first fuel usage results yesterday...45.6mpg over 160 miles of mixed riding. Mixture screws are 3 turns out from closed as per the manual. Unfortunately my pilot and main jets are not keihin brand, so I don't have confidence in their precision. Carbs are very, very clean,with no leaks, but it will only run w/ full choke for the first 20 seconds before settling in to a nice idle after a minute of run time. Re-starts when hot could not be any better! ( the temps here are 50's & 60's, not what I call hot!).
I'm looking forward to finding out if "adjusting" gears on the mixture screws make the process as easy as I hope.

 

[desertrefugee]

kerryb » Fri Jan 15, 2021 6:45 am[/url]":36iu1x3c]
... Re-starts when hot could not be any better! ( the temps here are 50's & 60's, not what I call hot!).

:headscratch:

Wha - wha - wha - whaaattt???

50 and 60s in Buffalo in mid-January? That does not compute!

 

[kerryb]

desertrefugee » Fri Jan 15, 2021 11:01 am[/url]":aa8qrp9z]

kerryb » Fri Jan 15, 2021 6:45 am[/url]":aa8qrp9z]
... Re-starts when hot could not be any better! ( the temps here are 50's & 60's, not what I call hot!).

:headscratch:

Wha - wha - wha - whaaattt???

50 and 60s in Buffalo in mid-January? That does not compute!

Ha, ha, no, I'm currently hiding from the cold (and missing my workshop) in florida. The wing is the perfect florida bike, plenty of plastic to hide behind on a 50 degree day, and enough power to get out on the I95 when I want to. The '76 cb550f from last year was too small to be comfortable in high-speed traffic and the lack of a fairing made it pretty chilly on some days. So when I found the '83 interstate with low miles I figured that would be a good choice for this location.

 

[desertrefugee]

Ah, that's right. I'd forgotten you were a snowbird. (I lived in Ocala for 12 years between '84 and '96).

Miss Florida.

 

[D-50Dave]

desertrefugee » Yesterday, 2:31 pm[/url]":3detlnuq]
... (I lived in Ocala for 12 years between '84 and '96).

Miss Florida.

You were Miss Florida from '84 thru '96? :headscratch:
That's quite the run. :smilie_happy:

 

[desertrefugee]

 

[kerryb]

I just love it when I get my carb synch done...smoother...more singer-like :clapping:

I really should take notes on which way to turn the screws though, I would save a lot of time!

 

[kerryb]

A thousand miles and no hiccups!

(Rotated pic, DF)

 

[desertrefugee]

The smell of success. A clean burning exhaust.

 

[joedrum]

Good deal ...nice bike

 

[julimike54]

Cool to hear!