Thread: 780 carb and oil questions
08-02-2012, 04:21 AM #1
780 carb and oil questions
Okay...looking for the top dogs to chime in. You know who you are...BFC,K4,XL,etc.
I was putting some OP flame arrestors from a 95 780SLX on my 96 780 and ran the studs down too far...broke the ear off the carb. No worries; plenty of extras. Just grabbed the carbs off the 95 SLX and went to town rebuilding them. I actually decided to video it because some people think this is such a complicated task, so I thought I'd show how easy it actually it (I'll post it once I'm done).
So then I get stuck. "Why did this parts motor I have burn down?" Being a mechanical engineer I'm constantly killing myself with those questions. As the veterans on here know, the 780 setup FINALLY moved the oil injection nippers onto the carbs instead of the intake manifold or the FA. So I hit the pause button on the camera and think, "I should really check to make sure I'm getting oil through these little nips." I think the standard is that 3 PSI should pop the check valve, so I blew on one of them like a street corner hooker, and I got nothing. Now I'm scared. I pulled another setup off the shelf from...whatever year it might have been, and I could actually blow through the nips. The last thing I want to do is light this thing up and not have any oil. So...what would you do at this point?
I've done my due diligence in searching and I have a huge headache from it. OP Vortex FA, hitting 19 PSI on pop-off, 105 HS jets. Is this fkr going to burn up on me, or am I sitting okay. Summer's running out FAST and I need to spend more time on the lake than in the garage (I know; we've all been there).
Thanks, guys. You've all successfully been enablers to my addiction.
...and yeah....I searched my ass off for answers. I think I just get distracted by shiny things.
08-02-2012, 06:17 AM #2
I do not run direct injection so cannot comment on the oil fittings issue. As far as issue #2 goes, if you take care of issue #1, and ensure the ski is getting oil, you just need to watch your piston wash and make sure it looks right. You can throw all kinds of Vortex this n that 105 hs jets etc out there, but no one is going to say you are good to go with that setup. There are so many variables including air temp, humidity, etc. that at the end of the day you just need to run it, check wash, adjust, run it, check wash, adjust, etc......
08-02-2012, 11:52 AM #3
lol...give yourself a little more credit.
I know I'll have to tune, check wash, etc...pretty used to that after 6 skis. The first 5 were all the same, but this one's just a tad different. Just want to make sure I have a decent starting point while I still have them on the bench.
08-02-2012, 12:11 PM #4
Issue #1. On my 780 black carbs... off an engine that threw a MAG rod due to lack of oil. I could blow threw the oil injection nipples on the PTO and CEN with some pressure... but could not suck anything back threw them. On the suspect MAG nipple... I could blow threw it with less pressure AND I could suck back threw it. Turns out this MAG nipple came loose from the press fit into the injector screw-in base part and was sucking air and leaking oil... robbing this cylinder of oil. I converted to premix after rebuild.
So, I think you should be able to blow (with some pressure) threw the oil injection nipple on a 780 carb... but not suck. So if you can't... I'd investigate further.
08-04-2012, 12:04 AM #5
#1: I used my pop-off tester with an 1/8" adapter on it. Pumped up the oil fittings and they worked fine. Nice peace of mind to have, and never thought to check them on all of the boats I've gone through.
#2: Ran for about 2-1/2 hours today on the lake. Very happy with this ski. Checked the wash when I got home. Experts, PLEASE chime in.
I'm thinking PTO=tits; C= turn in just a hair; M= turn in about 2 hairs. Am I close?
lol...just looked at the pics after I posted them. Looks like a frog got smashed in my PTO.
08-04-2012, 07:31 AM #6
- Join Date
- Oct 2006
- Cleveland OH
PTO good. CEN in about 1/8 on the highs MAG, need a better pic to show details. (if you can, bring the piston to TDC when taking pics please)
08-04-2012, 05:10 PM #7
08-04-2012, 05:16 PM #8
That looks to be Just before TDC. Adjust it to exactly at TDC and retake the photo.... haha
08-04-2012, 05:21 PM #9
08-04-2012, 05:24 PM #10
Hey - gotta add some fun to the frustration!
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