Where is the jetting on your Bender turbo?

[BigDog05]

Had the sled out again today.

2800 elevation
32 F
pitot jet 300
mains 135
pilot 2 turns off seat
needles, c clip in top groove, with a washer above the c clip and the white spacer and washer below the c clip.

The sled ran great under boost with the needles stock position, but had bad gruggling etc when not under boost.

Would like to drop the needles even further for off boost running, but I think I am going to run out of pitot jet adjustment when under boost.

When the needles were in the stock position, the sled ran great under boost with a 600 pitot jet.

Any suggestions? Thanks, I do not like the way this thing sounds when not under boost.

 

[spray25]

FYI you can get hex jets over 800.

It sounds to me like you need to go down on the mains though.

 

[RX-1 Moose]

9,000 ft and up
127.5 mains
Neddle dropped all the way
stock pilots
320 pitot on the trail 5 to 600 on the hills
Seems to work pretty good. Cannot run more than 320 pitot down the trail because my temp rises pretty fast. On the hill 10,500 and up 5 to 600 works great.

 

[spray25]

Hey moose is there a particular throttle position, rpm, or boost level where your temps seem to rise the most?

 

[RX-1 Moose]

Mid range was alittle scary. I had my needles buried then moved them back to stock all the way dropped using the washer. Full throttle not a problem, just going down the trail at a steady pace. With the larger pitot I would use my choke alittle to dump some fuel to cool down but going up mountains the temps are great. 320 pitot would work great all day long but I was just playing and the larger pitot on the Mountain made the sled sound better while climbing, not alot of poping if you know what I mean.

 

[hlmrx1]

Excuse my ignorance, but can someone explain what the pitot is?

 

[BigDog05]

Spray 25, I'll try next size smaller mains. The sled ran great under boost with all settings stock, and a 600 pitot jet @ 9 F.

Yesterday at same location @2800 ft and 32 F the sled ran great under boost with needles dropped 2 notches and 300 pitot jet.

The sled always runs great under boost, no matter which setting it was at.

It just sounds like S??? at low speed around 4500-7000RPM. Trying to go around a groomer yesterday @ 10-15 MPH it sounded like Sh&&. You can not cruise at 10-30 MPH without it snapping, popping etc.

I even gave it a little choke thinking it was too lean and it made it worse.

 

[BigDog05]

Another thought. I'm going to put a fuel pressure guage on it tonight or tomorrow. Could it be pushing too much pressure @ low speed and low RPM causing it to be way rich when off boost?

What about float setting? It is good as long as you bypass 1/8 to 1/4 throttle position. You just cannot let it hang in that area. Thanks

 

[RX-1 Moose]

hlmrx1,
The pitot is a air jet found on the Bender Turbo's charge tube to help with your fine tuning. The jet is located on the right side by the chain case on the under side of the charge tube. The pitot gives you the opportunity to richen or lean your sled by adjusting the amount of air without tearing the carbs apart. You must be pretty close and have zero, no air leaks or air problems for it to work properly.
I hope this helps and I believe Bender is the only Turbo that offers this cool feature.

 

[spray25]

BigDog,

Do NOT take my earlier advise of changing the mains!!!!

The problem you just described is the exact problem I am having. I have a lean spot at about 1/4 throttle. If I go just above or below 1/4 everything is fine. This is why I was asking Moose where exactly he was running hot.

Your description of popping is more likely a lean spot than a rich spot. Crisp, somewhat loud popping is lean, a dull muffled gurgle sound is rich. I'm thinking you do not have an air fuel gauge. If you did I bet you would see what I do. The gauge reads rich, or even stoich, but when you hold it at 1/4 throttle (which also equates to about 8,000 rpm and 3.5 lbs of boost for me) all of a sudden the gauge drops like a rock to lean!!

I need to go up on my pitot to clean up the areas above 1/4 but when I do it makes that lean spot bigger.

I have been chasing this problem for a while. I have tried smaller and smaller mains, moving the needles all over, softer and stiffer slide springs, and playing with the fuel screw. None of that has cured it although richening the fuel screw helped.

I then ran accros this: http://66.47.68.116/tech/pilot%20jet,%2 ... ruise.html

I am going to try larger pilots. At part throttle higher rpm riding most of the fuel is actually supplied by the pilots. Richening the screws helped, but they only control 25% of the pilot's fuel flow when the throttle is cracked and 100% of the pilots fuel flow at idle. Continuing to turn the screws will likely help somewhat, but at some point the idle quality is going to suffer.

I am starting to learn about a number of sleds that have this problem. A lot of people are running without gauges so they only see it as an annoying popping, instead of what it really is... an EXTREME lean condition.

 

[BigDog05]

spray25: I am running a EGT but it is way back behind the turbo. When going slow nearly off boost it reads 800-900 degrees.

When on boost, with the needles on the top groove and a 300 pitot tube at 32 F and 2800 ft it reads 1150-1225 degrees. Plugs look real good at that temp on racing gas. Possibly a tad lean but no detonation showing on plugs. This is on a 1/2 mile run varing between 1/2 to 2/3 throttle.

I'm going to leave the mains where they are as you suggested, and move the EGT sensor up to where the 2 pipes go into one to get closer to engine.

My yard is approx 2 acres and before dropping the needles, if I would ride around the yard for a while, the plugs would be black and exhaust very black.

By dropping the needles I've lost all of the black.

As I stated in an earlier post, I think my boost guage is bad. Bender is sending me a new transducer. Was getting 11 peak and showing 9lbs on steady pull. Put new activator and readjusted wastegate and still got same readings. never put it on high boost because I was only running 93 octane Sunoco. But yesterday I put in 9 gal of 110 and hit the high boost switch, it showed 22lbs peak and running boost of 17lbs. No way this turbo can do that. Shut it down from high boost at approx 100ft. Guage has to be bad.

I'm afraid to get to close on the EGT because it is so far back.

 

[kip]

rx... nothing worse than breaking stuff for the wrong reason.... what seems strange is that the pito tube does nothing but transfer presure.... that is the presure in the charge tube is greater than in the intercooler.... with the right set up you have no more than 1 to 1.5 pound drop in presure.... so the job of the pito is to take advantage of higher presure to apply to the vents, offering higher or a richer mixture under boost,,, one should not need to find the magic spont in the tube, as your are not looking for air speed, you are looking for presure.... on top of that unless the charge tube system was to large, that would be the only way you have a smaller differential between the tube and the intercooler..

 

[kip]

rx... nothing worse than breaking stuff for the wrong reason.... what seems strange is that the pito tube does nothing but transfer presure.... that is the presure in the charge tube is greater than in the intercooler.... with the right set up you have no more than 1 to 1.5 pound drop in presure.... so the job of the pito is to take advantage of higher presure to apply to the vents, offering higher or a richer mixture under boost,,, one should not need to find the magic spont in the tube, as your are not looking for air speed, you are looking for presure.... on top of that unless the charge tube system was to large, that would be the only way you have a smaller differential between the tube and the intercooler..

 

[BigDog05]

Found my problem, I hope. #1 carb not right.

Put back of sled on cherry picker and let run until warm. While running between 4500 and 6500 RPM, sled was popping thru exhaust. Added choke and sled would smooth out for 10-15 seconds, then load up from too much choke.

Did this 3 times with same results. Pulled plugs. #1 plug was showing very white and clean. Plugs 2-4 were starting to color from too much choke.

Will take carbs off tonight. What am I looking for ? Dirty pilot jet?

 

[spray25]

Will take carbs off tonight. What am I looking for ? Dirty pilot jet?

Most likey plugged jets, but could be a sticky float, stuck slide, etc.....