Carb pop-off Adjustment

[arhaney]

I've been out adjusting my carbs today and found that I have a problem. (97 SLT 780)
Could not get # 1 lean enough on the low side.(1/8 turn out would not cure problem)
Then it hit me!! Pop off pressure was off.
Just rebuilt carbs with kits from SBT. I installed silver springs in kit to lower pop off a bit. (book says 20-24 psi) I just pulled off carbs and found the following:
#1 1/8 turn out on low needle 15 psi pop off.
#2 7/8 turn out on low needle 17 psi pop off
#3 1 turn out on low needle 18 psi pop off
The carbs had the reverse turned springs at first. When I replaced # 1 with original spring, pop off came back up to 20 PSI.
Now the questions. Should I bump all carbs back to 20 PSI? Also, how do you make small
adjustments on pop off pressure? Later this week I will be installing Boyesen Pro Power
Reeds and a waterbox, how will this affect the need to make pop off pressure adjustments. Your help would be greatly appreciated!

[Bryan Glynn]

You ALWAYS need to take measurements when installing new springs - they are NOT the same out of the box. I don't know why some people or instructions spread the myth that certain springs are allways a certain spec...anyway, you can cut the coils, go in 1/4 or 1/2 coil increments to get the pressure down in 1 psi increments until you have them all the same. Lightly stretch the center coils to raise the pressure - and I mean LIGHTLY. It doesn't take much - then cut coils to work back down. Set them all to 20.

[arhaney]

Thanks for the advice, guess I'll head out to the shop for some late night adjusting.
I checked all pressures when I assembled the carbs, but I think I got in too big a hurry.
Have a good eve. One other CRAZY question When I was out on the water today, the only way to get the RPM's up over 5000 was to make right hand turns in light chop. Whenever it finally took hold it would scream right up to 6400. Seems like it was when the exhaust was under
water good that it took off.

[Bryan Glynn]

Your high circuit(s) may be too rich.

[arhaney]

Just got back in, now have all carbs at 20 PSI, checked a number of times to be sure.
I will readjust low and high at the waterway on Monday.
I'm trying to go easy on the high side, perhaps I'll be able to get it set better this time out. You were right about barely
stretching the springs, a little goes a long way. Thanks, Alan

[arhaney]

Hit the water at 6:20 this AM, it seems that
the ski still hangs up about 5000 RPM's.
I leaned it out and checked plugs several times. After making right hand turns in the chop the thing will take off (6400 RPM's).
I leaned until it backed off to 6370 RPM's.
Help!!!!!!!!!

[arhaney]

Okay, I need some help! I've checked everything that I know to check. Carbs are on the money. Checked timing. Spark plugs and gap. Fuel/Water Sep. Still will not get past 5000 RPM's until I turn right and hit some chop. It screams up to 6400 at that time (51 MPH). Strange Please someone point me in the right direction before I go crazy

[Bryan Glynn]

CLosely inspect your reeds for chips/gaps/cracks. You could also have a damaged waterbox, with a partially clogged baffle, or a baffle that broken and swinging, it will clog the system.

[ July 16, 2001: Message edited by: Bryan Glynn - SBT Webmaster ]

[arhaney]

Thanks Bryan, just happens to be that I have
ordered a set of Boyesen Reeds and a water box.
I think that I will go ahead and tear down tonight. I visited with my local Polaris dealer here in Amory and we came up with almost the same ideas. Let me run this one off you, could the fuel pump be weak or a fuel problem. I really don't think so since it will run up to 6400 RPM's. My dealer suggested that. He also thought that there
could be a bullentin on this??? (turning or leaning causing a change in RPM's.

[arhaney]

Just pulled off the thermostat and cooling system pop off valve, pop off valve was broken and wedged in the bore, is this the problem?

[Bryan Glynn]

I don't think that could effect RPMs like that, but I'm not 100% sure.

[arhaney]

I meant to let you know, waterbox looks OK other than a lot of carbon. Reeds are not broken and I am about to measure the clearances. Does anyone else out there know about the coooling system pop off valve.

[SeaLion]

I don't the history on your ski but try this and let me know what happens. Ride the ski and do a few bunny hops to unhook the pump while going straight. If it wants to bite and rev to higher rpms then it sounds like an over loaded engine from too tall of an impeller pitch. If it is the stock impeller in there then you have some carb issues. I know you stated that you went through them but most likely they are not dialed in right.

[tomv]

Hey, check the black exhaust hose that goes from the water box to the through hull exhaust at the back of the boat. if the inside of this hose is blistering an becoming delaminated this can cause a similar problem to what your having, when the hose starts falling apart internally it restricts the exiting exhaust and boggs down the motor at high rpm's, But you still may have a carb issue you haven't solved.

[mcbare]

I have the exact same problem with my 96 SLX. If I break the pump loose in a right turn I get 6400 rpm. Left turn and I lose 500 rpm. It's driving me crazy! It will do 6400 in my drive way anytime (instantaneous duration). Any thoughts?