990 / 1010 Cat teck info

[76FoMoCo]

Mike,

Just for fun lets set up some info for the bb cat 1M guys.
I will start with the first question, I'm running a turbotators ported 990 with jaws D's with twin stingers, cpc 48mm carbs and pods with stock hood and mesh hood. I have the pipes chocked to 33mm the carbs have a 30 pilot and a cpc ti #5 needle in the middle clip with a cc0 nozzle. Power jets at 3 turns out and ride 5-9K and -10 to 20 deg.

what is the starting point for jetting?

and I know each is different.

Thanks,
Shane

[HOBB-Z]

Originally Posted by 76FoMoCo

Mike,

Just for fun lets set up some info for the bb cat 1M guys.
I will start with the first question, I'm running a turbotators ported 990 with jaws D's with twin stingers, cpc 48mm carbs and pods with stock hood and mesh hood. I have the pipes chocked to 33mm the carbs have a 30 pilot and a cpc ti #5 needle in the middle clip with a cc0 nozzle. Power jets at 3 turns out and ride 5-9K and -10 to 20 deg.

what is the starting point for jetting?

and I know each is different.

Thanks,
Shane

Are all the power jets out 3 turns??? Thats alot of fuel.........

The big carbs don't have the fuel signal/ or draw that the smaller carbs do, I would start at 680s with the power jets closed and work down opening the power jets a little until it settles to some where around a 560 main and 1.5 out on the power jets.


On my 1200 I run the 48s, custom Jaws and straight race fuel

720 mains, 45 pilot, ti needle...forget the nossle size and the power jets out 1.5 to get up the trail, once at elevation I'd shut the bottom 2 power jets and turn the main power jet to 1/2 turn

I jetted for elevation and used the power jets to ride at a lower elevation


Where are you at?

Dale Cutler was only off 24 jets sizes on the low side when I asked about were to start. Thats going 10s, after 600 you go in 20s

.

[76FoMoCo]

I'm in boise and start out at 4500 a lot but most of the riding is at 6-8.
all the other power jets are only out about 1.5 and the top power jet is about 3.
I started with 620 and was rich on top even at -12 so stepping down to 580. I have the low and mid running good but just to much fuel still at the top.

[HOBB-Z]

The power jets make these carbs so tunable its crazy what can be done, how much jet you run totally depends on how the power jets are set.

Once you get them perfect the fuel mileage should come back to about were it was with the smaller carbs as well.

Is it making good power for you yet?

[76FoMoCo]

thats half my battle is the too many knobs to turn.
It is starting to come a live when i went from 620 to just 600 made a good gain so I know i have to be getting close. I had it running good with the tm40 but after the jump to the 48 had to learn how to tune a real carb.
I'm close on the gears and clutch they stay cooler better than ever this year.
looks like we will be getting some snow this coming week

[rdr99]

FoMoCo, I am running the same motor and pipes as you, but with bored stock carbs and 3 degree timing key. How much of a difference did the bigger carbs make? What RPM do you run at? You run premium, av, 110 or a mix?

[76FoMoCo]

i think you get another 10-15 hp but just seat of the pants so far, i'm running a 2 deg key in mine. only running 50/50 100ll and pump and no det yet 8150 but i think jaws target is 7900