Dual 44 Mikuni observations

[x-jetter]

when mine was acting like yours is, i thought it was a n/s problem too. turns out a very small screw went through the rear cylinder and there was minor detonation. it wasn't enough to make it run real bad, but it made it seem like a carb issue. have you inspected the pistons/cylinders just to be safe?

 

[Matt_E]

It's a very intermittent problem. It occurs only after rough landings, and after high speed chops and restarts after that.
I am suspecting bad one-way valves.

It's definetely a rich condition.
Besides, I am not missing any screws on the engine, reed cages, or intake tract.
Compression is perfect.

 

[sjetrider]

It's a very intermittent problem. It occurs only after rough landings, and after high speed chops and restarts after that

I assume you have checked to make sure all is tight on throttle spring and shafts? Had same problem w/ 44's when the spring and shafts needed replaced. Hard landings and rough water conditions

 

[Matt_E]

Interesting!
But why would a worn throttle shaft (or both) cause that? It would only allow some additional air through - that shouldn't cause a rich condition.
Same with the throttle springs?

I'll check it tonight, though.

 

[x-jetter]

yea that's pretty much EXACTLY what mine was doing. my compression was good too. you may not have detonation or anything, but i'd bet you anything it's being caused by something other than jets/ns

 

[Matt_E]

I know for a fact it's not jetting or N&S. Ski runs great most of the time, and N&S are in brand-new condition.
It's not due to a too-low popoff pressure. 32psi is not low enough to be shaking loose.

It's also not caused by the atmospheric pressure hole on the jet side of the carb being covered up (they are mounted pump side outwards).

The throttle shafts may be worn, I'll check into it. I just cannot see it having that effect.

 

[waxhead]

the n&s may be new
but do they pop off real clean

 

[Matt_E]

Yes. Clean as they should (when wet). I have no good way to verify it at 32psi due to my gauge, but at 25 psi they popped cleanly and repeatably at 25psi (as long as they were wet!).

The problem occured at both popoff pressures the same.

 

[Mark44]

Wax,
Finally got to test the ski with the filled crossover and wow this helped 100 %. I actually had to go in with the pilot jet a 1/8 turn. The ski felt like it loaded up just a tad after a stab. I also feel the motor doesn’t have enough snap on the bottom end although everyone tells me it rips I still feel like I am missing something. I still want to play with the carbs to see I can get some more snap out of it. I believe I may also just be use to the feel of the motor now and wanting more possibly a mental thing? Who knows………Hmmm what to try next? Any ideas?

Again here is what I have.
44mm Mikuni’s
120P
105M
2.3 NS
80 gram
15 pop
Limited pipe duel cool
Jet works valve
Magoo port stock bore
Boysen glass reeds with stuffers R&D intake filled
180 Psi comp
MSD enhancer
13/15 Solas cut back 3mm & Wet wolf cone

Mark44 Brap!

 

[waxhead]

remove the stuffers from the intake for a start
this will make a huge difference

how is the limited pipe set up

what rpm are you pulling up top

also you could try 17psi pop off
but first of all dump those stuffers

 

[Mark44]

The pipe is set up as followed. Bottom screw is aprox 1 turn out the center screw is in all the way and top screw is aprox 1 ½ turn out I am not running the pipe got enough to sizzle water but feels quite warm.

I will take out the stuffers I remember you saying this to someone in another thread but I didn’t want to remove them and fill the cross over at the same time. I will remove and post outcome.


Mark44

 

[waxhead]

close top screw as well

 

[Mark44]

f

I am on it!

Also I do not have a recording on my peak rpm due to my tach. going under the car tire. :banghead: I need to purchase another.


Mark44

 

[waxhead]

yes its a good idea to use a tach to tune

 

[freestylegeek]

Wax,
Finally got to test the ski with the filled crossover and wow this helped 100 %. I actually had to go in with the pilot jet a 1/8 turn. The ski felt like it loaded up just a tad after a stab. I also feel the motor doesn’t have enough snap on the bottom end although everyone tells me it rips I still feel like I am missing something. I still want to play with the carbs to see I can get some more snap out of it. I believe I may also just be use to the feel of the motor now and wanting more possibly a mental thing? Who knows………Hmmm what to try next? Any ideas?

Again here is what I have.
44mm Mikuni’s
120P
105M
2.3 NS
80 gram
15 pop
Limited pipe duel cool
Jet works valve
Magoo port stock bore
Boysen glass reeds with stuffers R&D intake filled
180 Psi comp
MSD enhancer
13/15 Solas cut back 3mm & Wet wolf cone

Mark44 Brap!

Wow, after all of this, and you and I are basically RIGHT where Wax told us to go from the beginning...

 

[Mark44]

f

Wow, after all of this, and you and I are basically RIGHT where Wax told us to go from the beginning...

You know how I feel don't you. :banghead: :banghead:

But all is good and it makes me stronger.....right? :biggthumpup:

Mark44

 

[butti]

:banghead: this is exactly why i run a single on my surf ski^

 

[JonnyB]

I have a 96 superjet with a waverader 760 NO PORTING, B-pipe, riva head, dual 44s right now I am running

120P
105M
2.0N/S
95G

I was tuning it last weekend and started at 2 turns out on the highs and it hit 5740RPM at the end 6480RPM with the high out 1/4 turns I am running too rich up top and haven't had a chance to take it out because pump shoe broke and now waiting for the 5200 to dry. I will update soon

 

[robertg]

I almost have mine set up perfect. I am running 14.5 psi pop off, 112.5 pilots and 100 mains. It doesn't have any hesitation anywhere but it's slightly rich at 1/3 throttle. My only problem is it still loads up when I tilt it to the right side. My 46mm Novi carbs did this also but my 38mm carbs didn't. I think the low pop off pressure is causing this.

 

[waxhead]

have a look at your pivot arm make sure its not worn or lose on the pin
this sometimes does this as well when it shakes

make sure its poping off clean as well