Other Mikuni sbn reverse jetting??

[849tigerbotkv1]

Motor : kawi sxr 849bb with wetpipe ,advent ,160 comp

Carb: sbn i40

 

[BMWtech]

I read all the posts and still don't know what engine or carbs you have. Here's a suggestion that works for dual 44 aftermarket (46 about same) used on a 700 -780 cc Yami: 2.3 n/s, 110 high, 115 low.

My jetting is almost identical to this. Going to be trying a 112.5 high and a 120 low. (110high/117.5 low currently)

 

[waxhead]

i would run a 120 -125 low and a 105-110 high.
bmwtech i would suspect you will lose torque when you change the jetting how you plan to

 

[Mark44]

All I can say is listen to Waxhead he knows what he is talking about.

 

[849tigerbotkv1]

i would run a 120 -125 low and a 105-110 high.
bmwtech i would suspect you will lose torque when you change the jetting how you plan to

Ill try that next time im out


Anybody wanna sell me couple of each :
120,122.5,125,127.5,130 low jets

And

105,107.5,110,112.5,115 high jets

 

[Scraggly]

Ill try that next time im out


Anybody wanna sell me couple of each :
120,122.5,125,127.5,130 low jets

And

105,107.5,110,112.5,115 high jets

jetmaniac has it all im sure and ships same day usually.

 

[BMWtech]

i would run a 120 -125 low and a 105-110 high.
bmwtech i would suspect you will lose torque when you change the jetting how you plan to

It bogs down low and then catches and rips my arms off (not literally) when the highs kick in. I have no torque at the moment. Plugs are a tad on the lean side, if anything.

I started with the 120 and had other issues...those issues were dealt with and I think I need to go back to the 120s. Chris had recommended the jetting specs.

I should probably check my pop off just to make sure it's where it should be.

 

[waxhead]

you just described a lean situation. Try even going to 125 low 110 high 20psi pop off or close to it
One turn out on high and low.

 

[kevbo]

Motor : kawi sxr 849bb with wetpipe ,advent ,160 comp

Carb: sbn i40

You can put larger pilots in first but be very careful with smaller mains. I-body carbs do not pull as hard on the main circuit as SBNs do so they need larger jets. Reverse jetting is just a phenomena that occures with stock and modded 44-46 SBNs set up for throttle blipping freestylers. It is not a rule that automatically applies to all setups.

 

[849tigerbotkv1]

I guess ill put my dual 46 in it. Where should i start with the jets on the dual 46?

 

[waxhead]

You can put larger pilots in first but be very careful with smaller mains. I-body carbs do not pull as hard on the main circuit as SBNs do so they need larger jets. Reverse jetting is just a phenomena that occures with stock and modded 44-46 SBNs set up for throttle blipping freestylers. It is not a rule that automatically applies to all setups.

I was runing 150 lows on my race hx and 100 highs as a race boat. It worked well enough.
The key to getting reverse jetting to work extremely well is in the timing curve. It makes them explode of the dock thats off the dock not on the dock lol ( stupid humour )

 

[BMWtech]

you just described a lean situation. Try even going to 125 low 110 high 20psi pop off or close to it
One turn out on high and low.

Thanks for your help! I'll try that for sure.

 

[849tigerbotkv1]

I guess ill put my dual 46 in it. Where should i start with the jets on the dual 46?

^^^

 

[High_Sun]

you just described a lean situation. Try even going to 125 low 110 high 20psi pop off or close to it
One turn out on high and low.

Very old thread, but thought I'd ask if this jetting would be a good place to begin for reverse jetting on set of 44 Buckshots..? Currently running 115L 120h 2.0 80gm 20-21 pop off. Feels like it lags until about 3/8ths throttle, then the power really pulls.
X2 750sp, Factory pipe, Blaster chamber, milled sxi head, sxr cdi (just installed, haven't used yet), Hooker 10/18.
Any advice would be appreciated.

 

[tntsuperjet]

Nope. I rejetted on my own...... 2 lessons learned.........

1. Dont trust someone who knows nothing about "your Setup".
2. See #1

BK, the lesson you should have learned is never go smaller on low speed without going bigger on high speed if your plug and piston wash say your top end fueling is good!
Remember low speed jets never turn off on a SBN, so it's always a combined of the two jets for wide open fueling. The low speed jets get there vacuum signal from the transition holes in side of the carb, main gets it vacuum from bomb site.
So your mistake wasn't going to 80 lows, as much as not increasing your high speed jets by same number you decreased your low jets!!
Basic rule.
If you have a heavy pump load reverse jetting brings in fuel down low adds tq to help pull big prop, or helps out a boat that struggles to get enough air into engine compartment.