Thread: tuning the carbs 97slt 780
05-31-2014, 10:54 AM #1
- Join Date
- Feb 2014
tuning the carbs 97slt 780
I decided to take the step and adjust the carbs on my ski even though the guy i bought it from was extremely knowledgeable on the two stroke motor, I felt as if he had dialed the carbs to there maximum potential. When viewing the plugs after riding they where clean as a whistle with a tiny bit of grey splatter on the white electrode not chocolate brown by any means, also running like a bat out of hell just zip zip zip everywhere you go. Of course this was not at a plug chop situation so doesn't mean anything except it's lean at an idle right, so i twisted some knobs"like a knob" and been playing hell trying to get it right.
I found the specs finally for the turn outs on high and low, noticing that it had three different settings for the high
M 1 1/8, C7/8, P1 1/4, assuming this is because of technical things such as fuel tank, lines, feed, and setup.
Now for the question. can I tune these skis without the air box on so I can get to the screws easier, or does this mess up the air flow which gives me a bad reading and when I put the air box back on will it restrict the air flow and have it all out of whack?
And can anyone give me any tips on how to smooth the idle out having three carburetors turning an low speed adjustment on one with the motor shaking doesn't help the other two from shaking so how do I listen for the smoothness? Or am i looking at plugs to dial the idle in?
Also holy crap haves you ever googled chocolate brown...that color can be anything.haha lol. I noticed when dialed in like a race ski the fuel economy was exceptional. after I dialed it back and got yes chocolate brown for sure the fuel economy went way down, burned off 15 gallons in one day real quick. Can i dail it to where it's not a clean plugs but more like tan for fuel economy and be safe.I'm looking for longevity here kids and wife don't desire to go much faster than 35-40 anyway.
Any input would be great. I think i got the routine down on how to adjust now but any "deadly watch out fors" so i don't kill my ski would be nice. Thanks
05-31-2014, 11:06 AM #2
- Join Date
- May 2008
- Elephant Butte New Mexico
anything that changes the air flow characteristicwill chang the arb performance.
you can buy a special tool for adjust carbs..it's a flexible screwdrive with a 90 degree bend, so you can get to the carb screws with the flame arrestor on.
Unless you are tuning the engine with the ski in water, you can make some simpleMINOR screw adjustments and get it dialed in that way.
there are plenty of pictures describing plug colors, but seldom a substitute for experience
you should check that the thottle plates are snycronized and that requires a vaccum gauge to do it "right" or a very good eye.
the real question I have is why you might undertake adjusting when you come out of the gate saying the seller seemed to know what he was doing?
Givent he color situation, the MOST i'd go is 1/8 to 1/4 turn richer on l/h speeds and then a few days of run time until you see a little color on the plugs.
Plenty of info here on tuning, checking piston wash to see what might really be going on and so forth.
Make sure the engine cooling system is flowign freely the thermostats tend to go bad after ac ouple of years and restrict water flow, which makes for a hotter running motor.
05-31-2014, 11:21 AM #3
- Join Date
- Feb 2014
Thanks for the input much appreciated.
I got a little nervous about the settings cause the guy had nothing but racing equipment in his garage and was selling it cause it wasn't providing enough speed and power for him then after seeing the plugs and the plugs on my other ski the drastic difference in color plus all the chocolate brown talk i come to the assumption it wasn't set up right for my purposes. Not downing the previous owner in any way just some ride to win and some ride to float.
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