Thread: 100% safe initial carb settings
06-20-2012, 10:03 PM #1
100% safe initial carb settings
Just about finished rebuilding my 2 sl650's and wanted to double check on here with my carb settings before i take them out on the lake.
1996 sl650std initial settings:
Main Jet = 87.5
Pilot = 77.5 or 82.5 for STD model
HS = 1-1/8M | 1/4C | 7/8P
LS = 1
POP = 10-18 psi
I turned all my LS screws 1/2 turn further out.
I turned all my HS screws 1/8 turn further out.
Will i be safe to go out on the water and what are the precautions.
What determines the prime setting for the LS adjuster, off the line performance?
I've read in the manual that the HS adjuster should be adjusted to achieve a medium brown spark plug color. Can't you also judge this by max rpms?
Also where does piston wash come into play and which adjuster/s determine the wash? Is it necessary to check wash after low and high rpm? Once you make an adjustment how long does it take to show? During this tuning period are you supposed to take it easy on your ski or just drive normal?
Another subject I have a question on is the idle screw. One of my skis is idling around 1000rpm, and the other about 2500rpm (estimate). Throttle screws are relatively the same position. However i did notice on the carbs that there is a 2nd idle screw by the MAG cylinder. Are you supposed to adjust them simultaneously? Only reason I ask is because that 2nd screw looks like its impossible to get to with the carbs installed.
06-20-2012, 10:31 PM #2
Post 5 second photo is what I follow when doing fresh carb or rebuild. Then go on checking piston wash after 1 tank of fuel.
A tad richer than factory should be safe, but I still wouldn't consider it a perfect safe guard against burning down your engine. Cautious riding on your first tank is your only safe guard IMHO. Just go easy on the throttle, don't do extended WOT, do short WOT bursts instead then ease off. In other words don't go all out till you have a chance checking your piston wash.
06-21-2012, 09:50 AM #3
Hope this helps
My experience with stock carbs and stock settings is very good. I do run 92 octane fuel. Almost all of these burn down from seal leaks, fuel pump or carb issues.
From my understanding (far from an expert) piston wash is created not just by the needle settings.
Here is some interesting reading. Keep in mind if everything is stock all of this should have been worked out by the factory.
I think the three outlet fuel pumps conversions are vey important as well.
06-21-2012, 03:52 PM #4
Thank you for both the links guys. Very helpful.
Any idea on the idle screws? Do all have 2? I only ask b/c i'd like to take the 2nd one out since adjusting it would be a PITA.
Is it safe to drive around with no FA while fine tuning?
06-21-2012, 06:31 PM #5
You only have one idle screw. the other one is probably your low speed adjuster. Your idle speed on the trailers should be in the 2k rpm range. In the water, different story. Have you sync'd your carbs yet? That will affect your performance and idle speed as will the idle screw setting and low speed jets.....
It will be easier to tune in my driveway......
06-21-2012, 06:33 PM #6
You can drive around without the FA, just need to make sure you don't have a lot of water slinging around. Performance and fuel air mix may change a little with and without the FAs on.
06-21-2012, 10:02 PM #7
haha! Yes synced the carbs with a 1/16" drill bit. No there are two idle screws. I have the main one where the cables attach, and then there's one between the CEN & PTO carbs. It seems likes it's maybe more of a "support" screw, but it serves the same purpose. The only reason I noticed the screw is b/c something was stopping the throttle blades after I turned the main idle screw out.
I thought it was on the bottom, but its on the top! Silly me and thank god!
Some observations i've noticed so far:
-one ski will idle a lot lower than the other before stalling.
-the higher idle ski has a lot more "snappier" or responsive throttle.
Time to get to the lake and start tuning! I'd like to hook up some tachometers for tunings sake.
06-28-2012, 12:27 AM #8
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