idle mixture

MattK

Joined
Jul 28, 2016
Messages
52
Location
CHICAGO
Ive read how to adjust theses screws.. did it by ear, problem is the manual says to be more precice with an electric tach!! i dont really want to spend alot of money, but i also want to do a good job! has any body bought elec tach for this job? thanks
 
I assume you are referring to either the idle drop procedure or carb synch procedure. You can do neither by ear alone. You have a very good question though, what kind of affordable tachometer is any one using for the idle drop procedure on the ST 1100?? I would like to know as well, I just purchased the idle mixture screw adjustment tool, so now I need a decent tach. I would like to hear from John O....
 
hotrod1 said:
I would like to hear from John O..
Click to expand...

My ST1100 runs pretty damn well with the occasional carb sync with my merc sticks. Frankly I decided quite some time ago that I won't be buying the special idle drop tool and tachometer because of the cost benefit ratio. I can't justify the big bucks for a quality meter (e.g. Fluke) that can accurately measure the 50 rpm drop. JMHO

Maybe I'll road-trip out to my friend Adam Frymoyer's some day and do the deed. :)

John
 
You can't tune 4 individual carbs "by ear" and have it accurate. I've not used an inexpensive meter, so I can't help you with a proper selection. I use our shop's top of the line OTC meter which reads down to 1 rpm. It's still a very tricky and time consuming procedure. Send me a PM and I'll help you set them up for your area.

We could have a CARB-stoc and use John's bike as a guinea pig...:) Just bring fresh carb boots. I've got everything else in stock. :):):)
 
A Carb Stock actually sounds good. I have a long adjustment tool and a basic snorkel vacuum gauge I could ad to the mix..
 
hotrod1 said:
I assume you are referring to either the idle drop procedure or carb synch procedure. You can do neither by ear alone. You have a very good question though, what kind of affordable tachometer is any one using for the idle drop procedure on the ST 1100?? I would like to know as well, I just purchased the idle mixture screw adjustment tool, so now I need a decent tach. I would like to hear from John O....
Click to expand...
I also need to do this idle mixture adjustment on my 1996 Honda ST1100. I bought the special 90 degree screw driver, but I still need the D shaped driver bit and the super accurate tachometer (hard to find).
How do you plan to accomplish this task?
 
question on st1100 vac/sync, on vac ports for sync procedure #2 and #4 vacuum are connected with a tee that also feeds the pair valves. Why don't the also tee together the right side (1 &3 ) or all 4 together? It seems to me that the current configuration would not balance correctly. Do pre pair valve engines cap off the ports individually?
 
Al st1100 said:
question on st1100 vac/sync, on vac ports for sync procedure #2 and #4 vacuum are connected with a tee that also feeds the pair valves. Why don't the also tee together the right side (1 &3 ) or all 4 together? It seems to me that the current configuration would not balance correctly. Do pre pair valve engines cap off the ports individually?
Click to expand...

I think the vacuum created by the airflow through each carb is sufficient enough that the small differences in air volume in each of the various hose configurations can be ignored.
 
Basically what are the turns most people have adjusted their pilot jets to beyond the 2.5/8 turns out, I have a 98 ST1100 with 38K miles on it
 
Does this careful idle adjustment work affect the engine's performance when accelerating, or are the small differences irrelevant?
 
Larry Fine said:
Does this careful idle adjustment work affect the engine's performance when accelerating, or are the small differences irrelevant?
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I feel the idle adjustments makes it easy on the gear box from neutral, but your performance is based on how the butterfly are adjusted after a good synch, these bike have a quick throttle response and when revving it, the fuel mixture has got to be right which I am having a problem with dealing with performance.
 
I have never yet adjusted the idle mixture screws on my ST1100 - I know, me very, very bad.

Still would like to know where to buy the special "D" shaped tool to adjust the mixture screws - hint, hint.

Is there a starting point ( "X" number of turns out ) for the idle mixture screws ?
 
Jim Van said:
I have never yet adjusted the idle mixture screws on my ST1100 - I know, me very, very bad.

Still would like to know where to buy the special "D" shaped tool to adjust the mixture screws - hint, hint.

Is there a starting point ( "X" number of turns out ) for the idle mixture screws ?
Click to expand...
What year, 49 state, California, or Canadian?
 
afrymoyer said:
You can't tune 4 individual carbs "by ear" and have it accurate. I've not used an inexpensive meter, so I can't help you with a proper selection. I use our shop's top of the line OTC meter which reads down to 1 rpm. It's still a very tricky and time consuming procedure. Send me a PM and I'll help you set them up for your area.

We could have a CARB-stoc and use John's bike as a guinea pig...:) Just bring fresh carb boots. I've got everything else in stock. :):):)
Click to expand...
I did find a less expensive meter on eBay that had a spec good enough to work, but it was a closeout kind of deal. With Afrymoyer's help, I went through the whole procedure using the Honda tool (I don't think you could do it with anything else, the adjustments are not easy to get to) and arrived at a pretty good place. (my bike is a 2000 CA bike though, and I changed the idle jets up a step richer). The bottom line is this: set them to what afrymoyer says....he is very close. His prediction was very close to where I ended up.
I did notice when doing the procedure, that adjusting them didn't seem to make much difference, until you turned them in enough to have the slight drop. (with my CA carbs jetted rich, that was at about 1 turn, then the manual said to back out 7/8 turn from that...thus a setting of 1 7/8 for me). I think I could have set them a bit leaner for better gas mileage on my bike (instead of the factory CA 7/8 turn backout, say maybe 3/4 or 5/8) (please note this does not apply to 49 state bikes) without hurting performance. (the factory 7/8 was premised on the factory jetting).
Having said all that, my bike runs great....hardly uses the choke. Mileage is not great at about 43. I think if I did it again I would probably just keep the stock idle jets and tune it that way for the gas mileage. Again, whatever setting Afrymoyer tells you will be close.
I did note one other thing going thru the whole carb cleanout/tuning process. When syncing carbs, there was a difference between pairs of cylinders caused by the linkage between the carb sides....if I had a lot of time I would have tried to deal with that linkage to dial in the carb syncing better. That is why the sync changes off idle on my bike. I will say it didn't seem to make much difference in that this bike really takes off above 4K and will zip right up to 7K and beyond. On my old V65 bike, with a similar carb set up, I could dial them in tighter on sync.
Thank you again for all your help, Afrymoyer!

PS...Took my first long trip and it ran like a champ. Rode 690 miles up to my sister's house and back a different day. On a nice stretch of highway, I opened it up and it zoomed up to 105 before my front end acted like the tire was out of balance (?) and I backed off. The bike could have easily gone a lot faster. I'm getting due for new rubber, so I'll see if that fixes it.
All the maintenance work was worth it. I can go anywhere now without worries.
 
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