08-26-2009, 11:26 AM #1
Jetting for Flame arrestors and milled head 787ccJust want to confirm this setup
I pulled this off the website from the shop that's milling my head. Does it sound right? Need to confirm before I go buy some new parts.
One this there is no mention of pop of pressure?
(jet kit includes 90 pilot & 170 main jets & (2) 2.3 needle & seat)(lows 1 & 1/4 turn out on both)(mag high 1/4 turn out / pto high 1/2 turn out / add 1/4 turn on both for 175 psi)(all settings tuned for outside temp of 72 F / warmer and humid air requires less fuel so turn adjusters in slightly)
08-26-2009, 11:34 AM #2
- Join Date
- Mar 2006
75 piolets, 145 mains, 2.0 N/S, 65 gram springs, 1 1/4 LS, HS PTO 5/8, HS MAG 1/2-- perfection for Michigan-- others down south recommend 80 gram springs and 142.5 mains-- try both...
08-26-2009, 01:53 PM #3
I run 75 ls 145hs mag, 147.5pto. HS adjusters closed. I use stock needle and seat with 65g springs. I have aftermarket flame arrestors, and 170psi compression. Jetting is great for my set up.
08-26-2009, 02:31 PM #4
What is your guys altitude? I'm at around 500ft.
If I could run stock needle and seat then that would save some money but I really haven't heard of people doing that, most seem to run 2.0
So does the pop off stay the same as stock then?
08-26-2009, 02:46 PM #5
I have been running the stock needle and seat for 4 years. The jetting in your original post, was for the 951 motor.
08-26-2009, 02:57 PM #6
If you read the website closer, that is his recommendation for a 951, go down the page a little lower for the 787:
(jet kit for just F/As are 80 pilot jets/stock 142.5 main jets/2.0 needle & seat with 3/4 turn out on both lows & 1/2turn out on the MAG highs & 3/4 turn out on the PTO highs)(warm/humid climates above 72F could require 75 pilots with an additioanl 1 half turn out on all adjusters)
08-26-2009, 03:13 PM #7
On my wife's 787 GTX, I am using 75 pilots, 2.0 needles and seats and 3/4 turn out on both lows & 3/4 turn out on the MAG highs & 7/8 turn out on the PTO high.
Now I haven't had a chance to test it in flat water yet and do some plug chops. Hopefully before the end of the summer.
Now on my 1996 XP, I had them set up by a well known Seadoo engine builder back in 1997. We started off using the 80 pilots that R&D recommended but they didn't work. I know we didn't change the needles and seat, but I think he made some other adjustments. Back then I trusted him to set it up and I have been happy with it since so I haven't even had it apart. I am running the R&D Power Plenum on it.
08-27-2009, 07:52 AM #8
08-27-2009, 08:13 AM #9
You should be fine, but make sure you do a plug chop and inspect the color of the plugs.
Have you changed your internal carb fuel filters and fuel lines yet? You want to make sure you have a good flow of fuel to get proper readings.
Thinking about it, I can't remember if I changed the springs in the GTX as well. Maybe someone else can comment on this setup.
08-27-2009, 08:19 AM #10
Thanks for the quick reply, I'm going to ask him about the pop off pressure when I get there. I already cleaned the fuel system and replaced the fuel lines. Carbs where stopless basically, alittle bit of junk in the filters though. I think I messed something though after cleaning because I lost 150/200rpm topend. When I put the jets in I'll check everything over ones again to make sure.
And I'll forsure check the plugs, just have to make sure its a calm day.
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