New plug pics...

[Mark44]

I"m on stock carbs, on last question

where do you set the idle screw when your tuning the low speed

I have the idle set very very low.

 

[CarFanatic]

but where do you leave it when tuning, wont it bring down the rpms when your trying to tune?

 

[Matt_E]

You set it to a high enough idle that it will not die while you're adjusting the low mixture screw.
Do not touch the throttle.

 

[Mark44]

o

but where do you leave it when tuning, wont it bring down the rpms when your trying to tune?

I leave it low enough so I can see the RPM reading change on the meter.

Then after it is tuned by RPM. Turn the idle screw up or down for desired idle.

Mark44

 

[Matt_E]

but where do you leave it when tuning, wont it bring down the rpms when your trying to tune?

You turn it up for low mixture tuning. You do that ONLY because you do not want to touch the throttle and you don't want the engine dying.

 

[Mark44]

o

You turn it up for low mixture tuning. You do that ONLY because you do not want to touch the throttle and you don't want the engine dying.

Yep just enough to run and not die.

Mark44

 

[Matt_E]

Some clarification for RPMs:

For low mixture screw adustment, you want to get the highest RPM idling without touching the throttle.
Later, you will look for max RPM holding the throttle wide open, when tuning the main jet and high speed adjustment.

 

[CarFanatic]

I got it, so how high should I turn the idle screw at first? About how many turns? Then back it down once the low speed is tuned, and the move on to high speed.

 

[Philip Clemmons]

I find the easiest way to set the carbs is to ride!

The high is set with a good (fast reading) digital tach. Start out richer than you need (2 1/2) turns and make a run (glass water, ski is COMPLETELY warmed up and heat soaked). Note highest sustained reading. Turn screws in 1/8 to 1/4 and repeat. Rpms will increase if you are too rich. Continue this until you make an adjustment and no increase occurs, and back up to previous setting. This should be about as close as you can get on the high, although +/- 1/4 turn may RPM the same but have different midrange acceleration.

For the low, you can get it close on the trailer. It should rev (light touch of throttle) easily and cleanly. Ride the ski and let it idle for a minute or so and hit it. If its rich it will "gurgle", and if its too lean, it will "gasp". Make the appropriate adjustments. Note that the low speed screws (mixture) are VERY sensitive and require small increments, no more than 1/8 at a time.

I'm sure there are some other opinions on this but this method has worked for me and my customers for years..................

FTR, I have adjusted lows on the trailer or tied to a dock...........works also but is not as accurate IMO...........no water drag or added water pressure from the ski, but it will get you VERY close, and sometimes dead nuts perfect.

 

[Matt_E]

However much it takes for the ski not to die. There is no hard & fast rule. This isn't rocket science.

Turn it up enough so it will idle by itself.

 

[Mark44]

o

I got it, so how high should I turn the idle screw at first? About how many turns? Then back it down once the low speed is tuned, and the move on to high speed.

I put it just high enough to keep the ski running.

Mark44

 

[Matt_E]

I find the easiest way to set the carbs is to ride!


For the low, you can get it close on the trailer. It should rev (light touch of throttle) easily and cleanly. Ride the ski and let it idle for a minute or so and hit it. If its rich it will "gurgle", and if its too lean, it will "gasp". Make the appropriate adjustments. Note that the low speed screws (mixture) are VERY sensitive and require small increments, no more than 1/8 at a time.

I'm sure there are some other opinions on this but this method has worked for me and my customers for years..................

FTR, I have adjusted lows on the trailer or tied to a dock...........works also but is not as accurate IMO...........no water drag or added water pressure from the ski, but it will get you VERY close, and sometimes dead nuts perfect.

The low speed screw is for idle mix only, and is also the very first step in tuning the carb.
While your method may work, it is not ideal.
Why make it more difficult by riding it?
It is very very simple to adjust the low speed screw on the trailer (but in the water).

 

[CarFanatic]

so if I leave the idle where it is right now, I can still tune the lows and the ski will increase rpm. correct?

 

[Matt_E]

While you are turning the low speed mixture screw, you will inevitably hit spots where the idle will drop instead of increase.
So you need to have the idle stop screw high enough to keep the ski from dying even if RPMs drop a bit.

 

[CarFanatic]

got it! Thanks for the help!!

 

[Ericfox]

I would love to get a tiny tach for tuning. Can you do it on the trailer w/ no load?

Matt,
I have a pulse tachometer the 2100dx or something like that.... anyways its like the best one you can buy (or at least a really good one).... you can use it any time.... the lake I normally go to is really good for tuning... usually pretty calm and not too too many people. Let me know if you wanna use it.

 

[Philip Clemmons]

The low speed screw is for idle mix only, and is also the very first step in tuning the carb.
While your method may work, it is not ideal.
Why make it more difficult by riding it?
It is very very simple to adjust the low speed screw on the trailer (but in the water).

Matt,

I never said anything about what order to tune in, but now that you mention it, (and you are correct) starting with the low speed mixture is correct, followed by pop-off and then jetting............

I did mention the low speed screws were mixture screws..............maybe I should have clarified that they have the bulk of their effect at idle, and right off idle.

I also mentioned that I have tuned skis this way (your way) with success.

We can agree to disagree on the idle (low speed) screw adjusting method.

My method works better than the trailer method for me, and may or may not for others. I always start with the lows on the trailer to get it close, but where we ride we have over 1.5 or 2 miles of inlet to idle out of. I have found that setting that appear to be spot on on the trailer may need slight tweaking after these long idle zones. Once I adjust accordingly, they hit, start, and run perfect everywhere.

I dont just put something together and go ride............if I gave you that impression I'm sorry.

 

[Matt_E]

I've done it both ways before, and ended up liking adjusting low speed mix on the dock better.
But both work.