Another dual 44's tuning question

[x-jetter]

I'm still having some tuning issues. It's really hard to start when it's cold (has to idle for a loooonnnngg time, if i touch the gas it dies) and after it's warm i have to throttle it up a lot to get it to start. then when i'm riding it, it bogs only sometimes, and sometimes it's bad enough where it dies. i know that this is a lean condition, and it only happens on the very low end. the low speed screws don't seem to be helping much in either direction, so do i need to change the popoff (2.3 ns/115g spring) or change the low jet (120)?

motor setup:
magoo ported 735
lightened flywheel
ada head (195 psi)
b pipe
enhancer
jet works valve
mikuni 44's (silver)

 

[Matt_E]

The low speed screw adjusts mostly your idle - it has little effect on the low end acceleration.
The popoff should be right around 22 psi - you may want to verify that with a popoff gauge.
Make sure your primer line isn't leaking fuel into the carbs. That makes tuning difficult.
As for the jetting, I don't know....Paul's recommendations are pretty conservative, I have a hard time imagining you're lean on the bottom.
Go up one size on the low speed and see if it improves things. I think you may end up with a 117.5 or 115 pilot instead.

 

[Mark44]

What are your jets at now? 120 low what about high? Do you have to hold the throttle open to start it? Your pop would not effect the starting.

Mark44

 

[Mark44]

a

The low speed screw adjusts mostly your idle - it has little effect on the low end acceleration.
The popoff should be right around 22 psi - you may want to verify that with a popoff gauge.
Make sure your primer line isn't leaking fuel into the carbs. That makes tuning difficult.
As for the jetting, I don't know....Paul's recommendations are pretty conservative, I have a hard time imagining you're lean on the bottom.
Go up one size on the low speed and see if it improves things. I think you may end up with a 117.5 or 115 pilot instead.

Matt,
Thats what I ended up with on my magoo 117.5M 115P 2.0 NS 95G 24PSI pop

Mark44

 

[x-jetter]

i have the primer hooked up to the fuel return line, so can that leak fuel into the carbs? my lows are 120's and my highs are 115's i think. they may be 117.5 but i think they're 115. when i cold start it, i can't touch the throttle or it won't start, but when the engine's heated up, i HAVE to give it throttle, and it runs real bad for a second then it's fine. it seems like a rich condition when starting, but when riding it feels like a lean condition because it dies sometimes like it's out of gas. i don't have a popoff gauge or even an air tank, so i can't measure the actual numbers unfortunately.

 

[Matt_E]

If your primer is hooked up to the return line, I wouldn't worry about the primer leaking.
Do you prime before you start (for the first time that day)? It should start right up, but may take a couple of seconds to have enough fuel in the carb & lines in order to run right - that may be why you can't give it throttle or it dies. Now, the carb & lines should stay full of fuel, though.
If you're having an issue with bottom end, your high speed jets are more than likely okay - concentrate on the low speed circuits.
I have to give my ski throttle to start it once it's hot, but that's because my idle is turned low, so I consider that normal - but what do I know.
Seriously, go up on the pilot, but I think you'll find you need to go smaller.

 

[x-jetter]

well i only have smaller jets, so i'll probably just try that. the idle is definately turned up enough, so that's not why i have to give it throttle. i didn't actually use the primer today, and thats when it would only idle for a while so that's probably normal. the only thing that worries me is that the idle is faster sometimes and slower at other times, leading me to believe i may have a small airleak or something. it may just be because i've been messing with the low speed screw though.

 

[waxhead]

your pop off is to high
thats the next circuit straight after the low speed adjuster
put a 95 gram spring in there go ride

 

[Matt_E]

It's not necessarily too high...it's only 22 psi.

 

[waxhead]

if its dieing as soon as he hit the throttle i would say its to high
But each to there own setup

 

[Matt_E]

There are a few different reasons it may do that. I agree, too high a popoff is one possibility, but it could also be a too small/too large pilot jet.
You can make anything from 15-35 psi work if you try hard enough.

 

[waxhead]

i agree you can get both to work like that
and with a larger jet you can make it come clean off the bottom
but in my op the ski will never be as crisp as if it had the pop off lower

In all my testing with the 44s i found that the bigger pop off and larger ls made for a softer midrange than the lower pop off smaller ls jet

The high speed jet size i found was just a result of tacho tunning the engine

 

[Matt_E]

Very interesting point about the midrange Jared....when I was trying different combos, I went for the crispest bottom end - which turned out to be at 25 psi (ON MY SKI!). YMMV

 

[waxhead]

Like i said each to there own setups
I find if you have to big a high speed it will also give you the same effect

 

[x-jetter]

alright i have some 95 gram springs (i think, what color are they again?) so i'll try that first, then i'll mess with the jets after that if i have to. the ski was seemingly running pretty good before i put in my primer and jet works FC valve, so could it be the valve that's maybe causing this? it's definately acting like a fuel issue, but you never know?

 

[Matt_E]

Just for giggles, disconnect the primer line and cap the fittings and run it.

 

[x-jetter]

lol i was just looking at my vacuum caps thinking the same thing. i'll give that a try before everything else.

 

[Mile9c1]

I would ditch the JW valve and try 115 lows, 25-30psi popoff, 120 highs. The low screw around 1.25 out and the high maybe 1-1.25 out.

Then only open the top screw on your B pipe, and open it about 5/8 turn.

I can't say it'll be perfect, but I bet that would work NICE :biggthumpup:

 

[x-jetter]

I would ditch the JW valve and try 115 lows, 25-30psi popoff, 120 highs. The low screw around 1.25 out and the high maybe 1-1.25 out.

Then only open the top screw on your B pipe, and open it about 5/8 turn.

I can't say it'll be perfect, but I bet that would work NICE :biggthumpup:

what's wrong with the JW valve? that sounds like a pretty good setup so i'll keep that in mind. i already setup my pipe how you suggested a couple weeks ago and it made a HUGE difference. thanks!

 

[Freestyleriverrat]

I have about the same motor set up as you x-jetter and Paul reccomended 110M, 117.5 P and 2.0 w/ 95g spring. Thats should get you very close. My pop offs were sitting at like 23-24psi.