what can you tell me about reading these plugs?

[Matt_E]

No trimming the spring.

The article has a table that tells you what combination of n&s valve and spring gives what popoff pressure.

 

[CarFanatic]

unless I read it wrong though, the springs offer a range of pop off pressure?

 

[Matt_E]

Two components that make up popoff pressure - spring and needle & seat valve.


Look at the table in the document. There are four springs, four valves, 16 combinations.

 

[WB1994]

Two components that make up popoff pressure - spring and needle & seat valve.


Look at the table in the document. There are four springs, four valves, 16 combinations.

Low jet also contributes to popoff presure. Change the low jet and the popoff will change.

 

[Matt_E]

That's news to me.

Why?

And why doesn't Mikuni state this?

 

[WB1994]

That's news to me.

Why?

And why doesn't Mikuni state this?

Read page 14 of your Mikuni bible again ...........:deal:

http://www.mikuni.com/pdf/sbn_manual.pdf

It couldnt be any clearer ..........

The spring / needle/ seat chart is just for refrence , There are many variables that can change that value besides the low jet size. Kawi 650's are known for a low intake volume preasure while yamaha's have a higher intake volume preasure which has everything to do with popoff. There are not just 16 combinations. Its infinite depending on motor and intake mods and needle/seat/spring/low jet combo's. No need to split hairs though .....

 

[Matt_E]

If you are referring to the text under "Popoff Pressure and Low Speed Jet", then I think you are misreading what's stated. That paragraph simply states that popoff and low speed overlap and can be compensated for with each other.
The fuel delivery of the popoff circuit and the low speed jet overlap, very true.
But the actual popoff pressure is not influenced by that jet.

Am I missing something? :dunno:

 

[WB1994]

Its a little hard to understand it the way they word it but if you do more-research, others explain it better. Here's what group K says about it.

Like I said before.... no nead to split hairs but it does effect it. I was also told to believe 1/2 of what I read so....

Or maybe thats stating that changing the low speed means a need for a popoff readjustment for the more/less fuel consumption ....

you could very well be right....

 

[Mile9c1]

The Low speed jet has NO affect on the value of the pop-off pressure. The only thing that affects the actual popoff pressure is the size of the needle/seat and the spring.

When it comes to jetting however, the pop-off pressure and the low speed jet somewhat overlap in function. Lowering the popoff has a similar effect as installing a larger low jet. And vice versa.

 

[CarFanatic]

so if it all relates to pop off pressure, my question is how do you adjust that? Its not like a low speed needle where you can move it in and out. right?

 

[WB1994]

The Low speed jet has NO affect on the value of the pop-off pressure. The only thing that affects the actual popoff pressure is the size of the needle/seat and the spring.

When it comes to jetting however, the pop-off pressure and the low speed jet somewhat overlap in function. Lowering the popoff has a similar effect as installing a larger low jet. And vice versa.

:beerchug: I will stand corrected of my misinterpretation of the lawyer wording.

I like the way you worded That.:Eyecrazy:

 

[Matt_E]

:biggthumpup:

Which is what I tried to say all along. The physical "pressure" it takes to "pop off" has nothing to do with the pilot.
:cheers:

 

[Matt_E]

so if it all relates to pop off pressure, my question is how do you adjust that? Its not like a low speed needle where you can move it in and out. right?

You adjust by changing the spring, or the needle & seat valve, or both.
You can also make small adjustments by bending the needle arm.

 

[CarFanatic]

bending the needle are eh.. man I got alot to learn...