Mikuni Spring Color & Popoff Pop Off Chart

[Shonuff]

http://i2.photobucket.com/albums/y32/dandbesales/Motor%20Stuff/Mikuni-fig4.jpg

115 gram = gold spring
95 gram = dull silver spring
80 gram = black spring
65 gram = shiny silver spring

115 - Mikuni Reference Number 730-03030
95 - Mikuni Reference Number 730-03033
80 - Mikuni Reference Number 730-03027-T
65 - Mikuni Reference Number 730-03027

Huge props to Greenhulk's RX951 (http://www.greenhulk.net/forums/member.php?u=26)

[DAG]

I took me a like 10 pictures to get one in focus but here they are...

Left to Right: 115g, 95g, 80g, 65g

All Genuine Mikuni

Two notes... seems the 115g are not gold anymore.....
The 95g are wound backwards as stated before

Hope this helps....

Buy lots of springs! they never read what they should..... grrrr!

spring w/pic thanks to 2lick

[Shonuff]

Awesome. Thanks Grif, thanks 2lick.

[Matt_E]

Urr....straight from the Mikuni manual?


*Damn, typing with banjo picks is hard.

[#ZERO]

Good post, this needs to go in the Tech FAQ section.

[Matt_E]

Indeed, it gets asked way too often.
I am tired of linking the manual.

Now I can just link the Tech FAQ.

:biggrin:

[Scorn800]

Just a FYI
I just got the new 115 gram springs & they are a new silver.
Got the springs from Tim at Novi

[michael950]

NOTE: It is recommended that you do not use too large a needle valve
for your application. Many tuners recommend using a 2.3 or 2.5 needle
valve in all cases. Actually, we recommended using the smallest needle
valve that gives you the correct pop-off pressure for your engine. A 1.5
needle valve can flow the maximum amount of fuel that the Super BN can
pump, so the only reason to use a large needle valve is to obtain the correct
needle valve and arm spring combination (pop-off) for your watercraft.

So, the manual states you want to use the smallest N/S to obtain the desired pop-off. Does that mean if the desired popoff was 32psi, you should use the 1.5 / 65g combo over the 2.0 / 115g combo?

[michael950]

One other questions, for what purpose would you use the Viton N/S?

[WFO Speedracer]

The reason for that is that the smaller needle valves have greater resistance to vibration,which in turn make the carbs easier to tune and stay in tune.

[SUPERTUNE]

I'd call the new 115 gram spring more like chrome color, not near as silver as the dull gray 95 gram spring or real silver 65 gram spring.

[michael950]

The reason for that is that the smaller needle valves have greater resistance to vibration,which in turn make the carbs easier to tune and stay in tune.

The reason for what, the smaller n/s (which I assume) or the use of the Viton tip?

[Matt_E]

The viton tip is on all newer N&S valves.

[michael950]

BTW:

Here is another copy of the chart from the Mikuni Watercraft Carburetor Owner's Manual (http://www.mikuni.com/pdf/sbn_manual.pdf)
Despite the page count, it is an easy and somewhat quick read.

You can use this info as a point of reference in the event you do not have a gauge.