Fine tuning Carbs and Idle after installing a new/used set.

Update.New isolators are in.I am using Adam's write-up as a guide to cleaning and rebuilding the carbs while I have them out.From a look at the insides,I don't think they were the problem,pretty clean but I'll give them a proper refreshing since theyr'e on the kitchen table. New main jets,float/slide needles,#40 slow jets ,Re-using Pilot screws as replacements were slot headed and I have the factory wrench so will clean and re-use those at 17/8 turns out.Once in I'll do an Idle drop and carb sync procedure.Didn't check calibration on carb sync dials last time so I'll check that before I proceed,...
 
Last edited:
OK, if I read the unit's manual correctly
http://manuals.harborfreight.com/manuals/95000-95999/95670.pdf
the 50 rpm drop will be shown during the idle drop procedure when the meter reading drops from 120 to 115. IOW, it reads in increments of 10 rpm. I'm very interested in the accuracy of the unit in actual use.

image.jpg

I wonder if the ST1100's wasted spark needs to be adjusted for...?

John
 
Last edited:
***UPDATE***,....Carbs back in.Cleaned out as per Adam's write-up with #40 Pilot jets.Started right up and felt like butter and revved up and down without drama.Also held it's idle steady.All this BEFORE I have touched carb sync and Idle drop which will have to wait a few days,...report later in the week,...:D
 
Great news Michael. Happy to hear she's all back together and running good. Thanks for the follow-up.

It's a shame that we'll be putting the bikes away soon for their winter slumber. Don't forget to drain those fresh carbs for storage....
 
Absolutely great news Michael. Just love when it all comes together.


afrymoyer said:
It's a shame that we'll be putting the bikes away soon for their winter slumber. Don't forget to drain those fresh carbs for storage....
Click to expand...

But Adam, what's this about 'we'll be putting the bikes away soon' as it's just getting riding season here.
 
Michael and I are in Upstate NY (the other NY). Our days are numbered.... :snow1:

No need to rub our noses in your fair "Texass" weather Gary! :D
 
afrymoyer said:
Michael and I are in Upstate NY (the other NY). Our days are numbered.... :snow1:

No need to rub our noses in your fair "Texass" weather Gary! :D
Click to expand...
Ha,ha.I live much farther south and east of Adam so we have a more temperate clime.Should be able to ride well into November and possible Dec if the snows hold off as we usually(on average) don't have a white Christmas.
With my new 40 amper heated grips and a power outlet for my heated vest should be no problemo.

Heading down to garage today so should have a report tonight on how she's running after carb sync/idle drop procedures.
 
Ok.Got it synced and pilot screws adjusted.(boy is that hard to feel for the #1 screw).running nicely,put the airbox back on tomorrow and hopefully a road test!
 
John OoSTerhuis said:
Good news, Michael. But details (and pictures?) about the idle drop procedure and the rpm meter you bought, please!

John
Click to expand...

I didn't take pics John but will take a few staged shots before I button it up.Won't do road test till tomorrow,so not done yet.

The Idle Drop was done per the Honda shop manual using the Harbor Freight DMM.Worked pretty well,just clamp it to a spark plug wire,set it to 4cyl mode and watch reading.You want to keep the idle within a 50rpm +/- range depending where you are in the procedure, you are turning the screws in or out.The idle will always be going up or down without any input by you(ie;turning pilot screws or idle adjuster) but you wouldn't normally see that on the tach because the measurement is so small,hear it or feel it.Hence the reason for a tach reader that will show 10ths.Your trying to keep the idle within that 50rpm constantly fluctuating, imperceptible spec with the tach reader and the pilot screw adjust.
 
So the meter does read '120' and drops to '115', or with the wasted spark '240' and drops to '230'? With your recommendation I'll probably buy that meter and Honda special tool for a new STOC loaner tool kit...

Also, shouldn't the idle drop procedure be done with the air cleaner buttoned up?

John
 
John OoSTerhuis said:
So the meter does read '120' and drops to '115', or with the wasted spark '240' and drops to '230'? With your recommendation I'll probably buy that meter and Honda special tool for a new STOC loaner tool kit...

Also, shouldn't the idle drop procedure be done with the air cleaner buttoned up?

John
Click to expand...

Good question about the wasted spark. A lot of current automotive ignition systems also have a wasted spark, but I'm not aware if any used that system before FI - I think all the carbureted auto engines back in the day still used distributors. I also wondered the same thing when I saw your previous post related to the wasted spark question, and wondered if the meter would need to be set to the 8-cylinder setting rather than 4, to give the correct reading.
 
Don B said:
Good question about the wasted spark. A lot of current automotive ignition systems also have a wasted spark, but I'm not aware if any used that system before FI - I think all the carbureted auto engines back in the day still used distributors. I also wondered the same thing when I saw your previous post related to the wasted spark question, and wondered if the meter would need to be set to the 8-cylinder setting rather than 4, to give the correct reading.
Click to expand...

Two coils.......four cylinders= wasted spark. Majority of 4cyl. bikes are like that.....nothin' new, and no association with FI;).
 
John OoSTerhuis said:
So the meter does read '120' and drops to '115', or with the wasted spark '240' and drops to '230'? With your recommendation I'll probably buy that meter and Honda special tool for a new STOC loaner tool kit...

Also, shouldn't the idle drop procedure be done with the air cleaner buttoned up?

John
Click to expand...
I left the air box off as per Adam's procedure.Asked him that question to confirm that was correct and he said it was.

Not sure what "wasted spark" is.

The display will give you 2 digits.X 100,so 57 is 570 rpm.You'll be concerned with the second number.If it's going from 49(0)-58(0),a 90 rpm fluctuation,that's more than a 50rpm change,if it's going from 52(0)-56(0),that's a 40 rpm fluctuation,your within spec .The actual idle setting isn't as important as the fluctuation.You will be affecting the reading on the bikes tach so you have to adjust to keep that in spec as you would during a carb sync,which you will have to do again after the ID procedure.
Your target is to keep that fluctuation within the 50rpm +/- goal.
You have a guide on the carb bodies to help get the tool in,you just have to get a feel for it.#1 is the most difficult to see.
Until the bike is on the road,I can't say it's fixed but she is running sweet on the lift.The HF DDM is well-built and at $35 on sale it's a good deal even if you don't end up using it for the ID procedure.

Someone more familiar with procedure could probably explain this more thoroughly or correctly,just my initial thoughts from doing this the first time.
I would think using an exhaust sniffer would be more effective.I have a Gunnson and plan on doing this at the former PAIR ports by using a homemade attachment from the PAIR piping.Would like to see the CO output and how it's affected by the P.mixture screws
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom