Super Jet Prop advice

[swapmeet]

I have a ported, limited 701, single carb and running a 12/17 swirl. Feels like its loading up down low.

I've been jacking with my carb and nothing changes. What do ya'll reccomend?

 

[McDog]

That is a good prop for that setup. I would look elsewhere for problems. I guess it's a 61x single 44 carb? Did you change the jetting for the porting? or maybe B-pipe?

 

[swapmeet]

The engine was set up for a FX1 (only difference is the 144 pump now vs the 122 pump before.) by groupK, it had a 150main and 130 pilot when I first tore into it. I've tried 127.5, 125, 112 and 120 right now. I've upped the popoff to 30psi because I belive it was leaking at 26psi. None of these changes have helped resolve the issue.

I have two wear rings, to add capacity to the pump as well as pushing the pump to the back of the ski. Do you think that will effect the issue?

 

[Waternut]

Yep prop is good. Define loading up so that we have a better understanding of what's going on...

 

[swapmeet]

1/8th to just past 1/2 throttle its bogging. Its miserable, it feels like it has too much gas to me... then past half throttle the RPM's come up and it hits like a ton of bricks. (i.e. runs awesome)

I doesn't wind up... the RPM's stick in that 1/8th to 1/2 area and until it picks up RPM (what I thought was burn off the gas) it doesn't perform.

Also, i don't know if this helps but my buddy tried to ride my ski, hes about 80lbs heavier than I am and it the bogging condition was worse. He couldn't even get on plane.

BTW, I know this is a tough thing to diagnose, but i'm lost and really appreciate any advise/suggestions you can offer.

 

[McDog]

Was it a complete, well running setup before? If so put it back the way it was. It must be something else.

I had some similar issues and it ended up being fuel lines that had a slit in the inner diameter that allowed air in and made it lean.

 

[swapmeet]

Only way to truely put it back is to put it on a 122mm pump. Otherwise the only changes have been rebuilding the carb and adjusting jets etc. It has new tygon fuel line.

 

[McDog]

Have you talked to Group K? It seems they would know best.

 

[Big Kahuna]

I am going to say it is carb issues. May want to rebuild the carbs. May have a leaking needle and at low RPM's it is getting to much fuel, at higher RPM's it is able to burn through the excess.

 

[swapmeet]

I thought thats what it was doing too!!! I totally agree with you! I rebuilt the carb Sat night, complete rebuild, new everything that came in the Mukini kit. The N&S is maybe an hour of ride time old. I replaced the old one because it had a little wear on the rubber tip. Should I get another one and try it? Seems like I would get the same results but i'm willing to try anything.

I'm running the biggest spring on the smallest N&S... hence my frustrations.

 

[swapmeet]

Have you talked to Group K? It seems they would know best.

No... I hate calling Harry, I always feel like i'm bothering him. I bought the FX1 with the motor in it so since i didn't directly have it built I didn't think I should bother him.
Don't get me wrong, when I've talked to him in the past he's been helpful, but I always feel like i'm asking stupid questions.

 

[swapmeet]

Ok, called Larry. He had no idea LOL... FML.

He said he isn't sure, and didn't know what else to tell me without looking at it in person.

:banghead::banghead::banghead::banghead::banghead::banghead::banghead:


There is a local shop that charges $350 to tune your carb. I've avoided taking my ski there because I think its a stupid amount of money to tune a carb. I don't know if I have any other choice at this point. I'm so sick of working on this GD ski. I just want to ride. I'm the only person wrenching on thier ski all day at the lake. I got noobs to the left of me with stock skis that have no issues, but not a lot of power, and to my right I have the local 'pros' on AM hulls with bomber motors fully tuned out ripping it up.

 

[McDog]

You are assuming they will get right on it. It's the busy season. You are better off working through it yourself. I feel your frustration. We have all been there brother.

 

[swapmeet]

Yeah I just called the owner. He said he wasn't confidant what to do either. They charge $95/hour.

He suggested that I try a known good carb and see if it runs right. Trying to score one off a buddy just for a test.

 

[Waternut]

Sounds like the low jet is way off but you said you've tried various different jets with no change. At this point, I'd say either you have a crankcase leak or a leak between the carb and intake. Changing the jets should make some kind of difference whether better or worse. It's also possible that your timing is just way off but I think that's a long shot.

 

[swapmeet]

I did a pressure test about two weeks ago and it appeared to hold. I did not remove the flywheel cover, but I did take of the small billet cover which I assumed should allow any pressure to pass. I can do another one, but it seems redundant.

 

[Waternut]

Should be fine then. Might worth double checking with the mikuni manual to make sure that you have all the seals and diaphrams located in the right place for your carb. Replacing old seals with new seals in the exact same location isn't going to help you if the old location was bad to begin with.

 

[swapmeet]

I ordered 2 more 1.5 Needle and Seats to try out. I used the printed guide that comes with the rebuild kit, Its starting to look like something thats been faxed 5 times but I can make pretty much everything out.

So someone help me out. Can a engine run like i'm describing when its lean?

Am I correct that a lean condition should cause the ski to almost die?

 

[Big Kahuna]

why order 2 - 1.5's? it a single carb. If your running a 2.5, then try dropping down to a 2.0 N.S.

You may be dumping too much fuel in down low.

 

[Aircraftsalz]

I was running this basic setup, B pipe, 61x/61x, 180 compression, MSD E with 3 deg advance... Was running 120 pilot/145 main & the motor ripped, everyone that rode the ski never thought it had a 61x/61x 701 in it...

I had a 9/15 hooker, but the 12/17 is a great prop to...

If you think the prop is loading the pump to much on the bottom you can add a washer behind the prop to help unlaod the pump some... But I think its in your carb from the sound of things