Thread: My jetting-SL 750
06-29-2007, 08:24 AM #1
My jetting-SL 750
Since my ski seems to disregard all commonly held knowledge, I figured I'd post my jetting and set up. When I installed flame arrestors, Most said that all I needed to do was open the needles 1/2-1 turn more than stock. That didn't work for me.
Maybe it will help someone not blow up there motor this holiday weekend.
+1mm sbt jugs and pistons
pentagon triple fuel pump
boyesen pro reeds
tau ceti F/A's
injected with Amsoil HP injector, non variable pump.
I had no wash and melted a piston!
I was at:
80P 1/2 turn
110M 2+ turns
until I checked wash last night. Mid and rear cylinders just have a pinky nail sized wash on some ports, MAG had a tiny, tiny bit of wash on 1 port.
I re jetted last night to:
My low speed is fine. Idles cleanly and accelerated hard at 1/2 turn out. with the stock pilot jet I was at 2 1/4 out. I am hoping that the 115's are too big, and that I will be more than safe when the cold weather arrives, even If I need to keep the HS needle closed in the summer.
Maybe I ended up with some kind of ported cylinders from SBT? I don't know, but the F/As yielded alot of RPM's for me, but it needed a whole lot more gas. Also, the plugs looked rich the whole time
Moral of the story. . . Don't believe your plugs, believe your wash, and give that thing as much gas as it needs. Jets are cheaper than pistons.
06-29-2007, 11:17 AM #2
AMEN!! Piston wash works for me. Have you checked tuning on the ground strap(for lack of better term)?
Did you by any chance see what your fuel pressure was before the restictor? I'm curious as I'm thinking if the pressure is low maybe we wind up with tuning issues. This is just a guess on my part but I'm going to check it out next week. I think the magic number is supposed to be 6 pounds or tuning issues arise? I know this works for the Novi set up and it may not even apply in this case nor the Keihins but I want to play with it just the same.
06-29-2007, 11:25 AM #3
Hi there sorry to kind of jack your thread but how do you check piston wash and what am I looking for? I did a search but only came up with a tool to look inside.
06-29-2007, 11:28 AM #4
06-29-2007, 11:45 AM #5
Thank you he had a great article there. I always used the old check the plugs after running it hard method.
06-29-2007, 01:04 PM #6
06-29-2007, 01:06 PM #7
06-29-2007, 11:14 PM #8
- Join Date
- Oct 2006
- Cleveland OH
You always know when I'm about to PM you Addicted. I was looking for your carb adjustments again. 94 SL 650/750 conversion .25mm OverSize. I too added the reed spacers, V Force II reeds, and Vortex F/A's. 70 lows (going to go bigger on lows with premix)100 mains were still too lean. Jumped to 112.5 (that's what I had on hand) and was coming up with too rich. I think I'm looking at 105 to 110 mains. But, stupid me had to replace the crank seals, so I just threw in the PSI dry pipe and a 12/18 impeller instead of the 13/18. I'm gonna see what happens with that pipe and screw before I change the jets. I'm hoping it will require a little more fuel and be perfect were she's at. Hey Addicted, any chance of me getting that speed sensor you offered up? Thanks
06-29-2007, 11:36 PM #9
X, 75 lows are stock for a 750. I would raise those up ASAP. As I understand it, you want to jet the carbs so that the needles are right around 1 turn out. With the dry pipe and added rpm's, you probably want to go way up on the jetting to be safe. you are going by your wash and not the plugs, right?
PM me your address again and I will try to get the speed sensor pickup out tomorrow or early next week. Work is going to be crazy Monday.
06-29-2007, 11:44 PM #10
- Join Date
- Oct 2006
- Cleveland OH
I was going by plugs only, until I get close enough to inspect wash. No sense in removing heads when I know I've been lean until last test run with 112.5's. Then my crank seal went bad, now I'm almost ready to try again.
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