Backie Chan 850 BB need help bad....

d_moss

d_moss

Location
Rexburg, ID
Best I could get was 135 pilot 115 main one turn out on the screws.

Still runs mostly crappy. If I Brap Brap Brap it's like it loads up some times it's ok some times it FLOGGS!

Off idle. pintch throttle. flogggg.
Motor runs but it won't rev up. But if you run it quarter throttle for 15 seconds and pintch it it goes wfo like it should. But if you go wo then let off then go wo most times it flogggggs. It's like a donkey. Hehaaa.

I have added another flap to the anti siphon valve didn't really change anything.

Should I just put some 38s on it and see if it runs?
 
CRJ

CRJ

Hibernating
Location
Toronto
d_moss said:
If I put a 140 pilot in wouldn't I need to put a smaller main jet in it? A lot of setups I see have smaller main jets and bigger pilots. Two 140 jets per carb seems like a lot of fuel for an 850.
Click to expand...
im running a 155m 125p on my 762, you'd be surprised how much fuel these things want!

ride at 1/4 throttle for 1 minute, then punch it. if it bogs, its lean, if it hesitates, its loaded up. it should rip out of your hands if its perfect.
 
CRJ

CRJ

Hibernating
Location
Toronto
d_moss said:
Best I could get was 135 pilot 115 main one turn out on the screws.

Still runs mostly crappy. If I Brap Brap Brap it's like it loads up some times it's ok some times it FLOGGS!

Off idle. pintch throttle. flogggg.
Motor runs but it won't rev up. But if you run it quarter throttle for 15 seconds and pintch it it goes wfo like it should. But if you go wo then let off then go wo most times it flogggggs. It's like a donkey. Hehaaa.
Click to expand...

this is a twin carb 44 right? id run a 135M and a 115P in each carb, making sure its clean inside. you should be 1-1.5 turns out. if your further out, jet up, if your further in, jet down.

have you read the SBN carb tuning manual yet?
 
d_moss

d_moss

Location
Rexburg, ID
So this afternoon I had a 132.5 pilot and 120 main. Was running crappy thought I would try a stock 115. Pretty much no change it ran the same. I have spent over $100 on jets for these carbs.

I supprised no one has dual 44 carbs on a big bore 850.

Nuclear chuck I think has had this setup.

Would I have bad crank seals?
 
Harbor

Harbor

Location
Stockton
If you didn't get the programming cable and software do you have a known good enhancer or stock Cdi you throw in and re-test ?.....

Did you get that hissing noise you mentioned isolated ?

image.jpg This portion before the hit gives a poopy sort of thud bog down low before the hit

image.jpg Here is the enhancer curve it's much more snappy and very clean sounding down low, great throttle response.. the other curve I softened some to help with the poopy sort of bog thud down low, it helps but doesn't eliminate it

These curves have huge effects on how the ski runs and sounds, what's your curve look like ????????????

What symptoms is your curve giving you??
 
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d_moss

d_moss

Location
Rexburg, ID
Hissing turned out to be the flow control valve as the water drained out of the cooling line.

I am running the blue curve in the first picture. Ski really does sound like crap down low. Runs really rough. Like a top fuel dragster pulling up to the line. I will order a tuning cable today.
 
Harbor

Harbor

Location
Stockton
You may want to get the rotary switch with your software so you'll have the ability to switch between curve A & B if desired. Otherwise you can only access one curve and you would have to hook up to your computer again and upload curves one at a time.

The Enhancer curve is MSD's, I called the tech and they gave me the curve. I also emailed AirTime and they gave me the enhancer pmd file, also the MSD enhancer curves are on this site
image.jpg
 
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