Help..want to know more about popoff pressure

[ISeeWetPeople]

Back again..

i just get new set of engine mounts.. and now my engine run smooth.. so that is fixed.. but no i have new set reeds VForce3 and tauceti flame arrestors. today i tryed to adjust my carbs and i have to open my low screw about 3 turns.. is it possible that vforce is that much better airflow than R&D M16 but it still fealt less powerfull than M-16?
any tips for jetting and pop-off for my setup now..

and can someone clear me out and tell me how do you know when your pop-off is either too high or low. not sure if i get it..

 

[Fro Diesel]

Read the manual again and remember popoff pressure is only part of the five part equation. Pop off is 33 to 66% of throttle response depending on carb.

I have only used dual 38s in a 701 max.. whats the advatage of these novi 48s builder recommended? Insane deal?

Try a variety of popoffs even when you think you have it. It is a combo of spring and low jet.

 

[Vumad]

whats the advatage of these novi 48s builder recommended? Insane deal?

Should be a second thread titled, "Help..want to know more about carb signal"

 

[Vumad]

Back again..

i just get new set of engine mounts.. and now my engine run smooth.. so that is fixed.. but no i have new set reeds VForce3 and tauceti flame arrestors. today i tryed to adjust my carbs and i have to open my low screw about 3 turns.. is it possible that vforce is that much better airflow than R&D M16 but it still fealt less powerfull than M-16?
any tips for jetting and pop-off for my setup now..

and can someone clear me out and tell me how do you know when your pop-off is either too high or low. not sure if i get it..

No one can give you exact specs for your set up. Every motor wants something different even if it has the same parts. Also, lots of people have poor tuning even if they believe their ski runs wonderful. Any specs you are given are just a starting point.

Any small bolt on changes you make can result in a need to change the jetting. They should be minimal changes, excluding a pipe which is often a huge change. So basically, you already have your starting point, and you need to fine tune from there.

How to know your popoff is wrong...

if you are about 1500-2000 RPM, and you stab it, and it falls on its face, lean hesitation, you need to go bigger on your low jet or lower on your popoff.

if it sputters and bogs, you need to go leaner on your low or higher on your pop.

It's also important to note that you could be transiting onto your high speed circuit, and the problem is there. The only way to know that is from experience of changing settings and seeing what happened. Your probably is likely not from your high circut.

As for your pop-off, your carb signal is likely so low it will never work right. My popoff is at 18 with a stock airbox on stock 38s, and I have excellent throttle response for my setup. You may not be able to get your carbs dialed in, as they may be wrong for the rest of your setup. Bigger is not better. It's unlikely that anyone can provide you specs, because it's doubtful many people are running bigger than dual 44s on a 701.

 

[speedysprocket]

Going from a fast idle to wide open throttle can sometimes blow right by your mid range tuning issue. Using Vumad's procedure, try again going quickly from approximately 1/3 throttle to 2/3 throttle. With boats not tuned properly in the pilot jet/pop off area, I've seen the issue more easily to diagnose that way. A proper high speed setting can mask your mid range tuning proplem that you feel during normal riding.

 

[ISeeWetPeople]

Read the manual again and remember popoff pressure is only part of the five part equation. Pop off is 33 to 66% of throttle response depending on carb.

I have only used dual 38s in a 701 max.. whats the advatage of these novi 48s builder recommended? Insane deal?

Try a variety of popoffs even when you think you have it. It is a combo of spring and low jet.

i just blow my bigger engine and thats why i run 701 with big carbs. Not sure but i think the msd total loss helps with that because the spark is so strong that it can ignite bigger amount of fuel.
and my crankcase is ported and mod so it can take more fuel

 

[ISeeWetPeople]

Thanks for your replys guys=)

i went to lake and about 5hours i was testing everything..

my biggest jets were 130high 130Low so i only had it wor somehow with lowest possible pop-of. but i get more jets this weekend so i can put biggers..

 

[speedysprocket]

These are the "D" shaped booster Novi carbs, right? I want to say I run mine around 115/125 jets and 20 psi pop off. And changing displacement engines for me never had a dramatic affect on jetting... I'd advise trying these settings, or whatever your bigger engine used. When you say your pop off is as low as possible and jets are as big as possible, that sounds like a very rich combination. Low pop off means richer mixture while a high jet size is a richer mixture.

 

[ISeeWetPeople]

i have two of these 48..

so you suggest that i put smaller needle stronger spring and smaller jets?

 

[speedysprocket]

One thing at a time! State your symptoms again and where your current setting are.
I'd start with a stronger spring first, and see if it's better or worse, and then keep going from there.