Carbed 2 stroke turbo guy's !!!

[canucklehead]

Also, Can the air screw be utilized to clean some of this up? How much does the air screw effect fuel flow at idle to say, 1/4 throttle? From what I understand, and please correct me if I'm wrong the air screw changes the air charge that is mixed with the fuel from the pilot? Or am I way off?

I have struggled to say the least with the tuning of this motor. Fat on the bottom, lean in the mid range and good on top. The lean midrange is a pita on the trail to the hills ( 2500' to 7500' elevation change), but it is good at elevation. The transition from say engagement to mid range is where this thing is the worst. I have seen a remote jet to richen the pilot jet somewhere on the internet, has anyone tried these in a turbo application?

Those are fuel screws on flatslides not airscrews like on roundslides, maybe you've been going the wrong way with them.

 

[zrt1]

Gus, I'm also new to the turbo scene. Cat 900 twin with mitsu, I'm running 40 pilots, is that way to big? Thanks and great read! also is there anyone that rides at 9k ft. That could point me in the right direction with clutching. I'm. Running stock gearing epi 180/320 primary 75 gram weights, cat green sec. With a 51 helix. It pulls good on top the bottom is a total lazy joke.

 

[devilrmk]

Todd, yes the airscrew and pilot are basically tied together. Rule of thumb is for every 1 turn on the air screw = 1 number on the pilots. So if you have your air screw out 3 turns, going from say a 5.0 to a 4.0 is going to put the same ratio at 2 turns on the air screw.
You want your airscrew in the 1-3 turns range. I would tune with your airscrew before changing your pilot and then see what it is telling you about your pilot. Turning it in richens, out leans.

On your mid range, raise your needle by one clip and see what it does. It might be too much.

Do you run powerjets? If so, at what point in the throttle do they hit?


Your Reeds are very suspect. Check them at minimum. V-force doesn't have a good rep with turbos, as canuck said.

 

[devilrmk]

Those are fuel screws on flatslides not airscrews like on roundslides, maybe you've been going the wrong way with them.

Unless the doo's flatsides are different, the ones at the back(closer to the motor) are fuel(thumb screws), the ones at the front that you use a screwdriver with are air screws.

 

[devilrmk]

Gus, I'm also new to the turbo scene. Cat 900 twin with mitsu, I'm running 40 pilots, is that way to big? Thanks and great read!

Whats stock?

Best way to tell is tune with your airscrew and read what its telling you.


My poo 800 stock runs 4.5's I am down to 3.0's Runs pretty crisp like that on the stand. Will find out how it does at elevation later today.

 

[Fack]

The doo flatslides don't have the air screw in them. That circuit was controlled by the DPM.

Todd H,
what is your system on? I had to grind the opening in the slides a little (.5mm) to get my bottom end to clean up. I had the same problem. Ran great at low elevation, but was rich on the bottom up higher.

-Fack

 

[devilrmk]

Thanks Fack, didn't know that.

So, I don't know what the fuel screw does. What does it control? never messed with that one.

 

[gus bohne]

DUMP THE V FARCE REEDS !!!!!!all your tuning issues will evaporate when you doo..

they have such low tension and leak around the petals so baddly that with a turbo it goes pig rich on low, then lean in mid..
bye bye v farce.

Gus

 

[Todd H]

The doo flatslides don't have the air screw in them. That circuit was controlled by the DPM.

Todd H,
what is your system on? I had to grind the opening in the slides a little (.5mm) to get my bottom end to clean up. I had the same problem. Ran great at low elevation, but was rich on the bottom up higher.

-Fack

900 Crankshop/ 800 doo bottom end. When you are refering to the opening in the slide can you be more specific. Not really what you would refer the "opening" as.

DUMP THE V FARCE REEDS !!!!!!all your tuning issues will evaporate when you doo..

they have such low tension and leak around the petals so baddly that with a turbo it goes pig rich on low, then lean in mid..
bye bye v farce.

Gus

Well if that is the case I will remove them. Any chance that the factory cages will fit the Crankshop cylinders? What should I do for petals for the factory cages?

Thanks for the help everyone...

 

[Todd H]

What do the fuel screws do? Are they changing how high or low the needle is sitting?

 

[Spaarky]

You use the fuel screws to get the bottom end close and the air screw to fine tune.

Devil.. I learned different than you... lets say your fuel screw is all the way open.. and you are still lean, then you need to go up on the pilots, if it is all the way closed, down on the pilots....

then the air screw is a fine adjustment within that..

 

[devilrmk]

Outlaw, I am used to tuning on the old round slides with no fuel screw.

So that answers what the fuel screw does. I have never touched the fuel screws.



Changed my exhaust valve bellows. My caps were warped. New caps and bellows my boost went from 8psi to 10psi. It was leaking oil so I knew it was probably leaking boost and it was.

Leaning out my pilots really cleaned up the low end. I need to change primary springs now and it should be pretty good.

 

[Tonysnoo]

I was surprized to get that much. I was on loose snow over ice/dirt with no real test space and absolutely no hookup........just a fancy snowblower.....LOL.

I assumed it was not a lot more load than being on the jackstand and that the real test would be on Sunday when I go up for a test tune ride.

Well, I assumed wrong!.............I had left the clip off of the actuator so the waste gate was flopping in the breeeeeze. Good catch!

Got my chance today to take it up and play. Wow! All the bottom end and slow speed response that I used to have and when it's on boost, time goes by too fast....LOL I got a chance to play around in a meadow with about two - three foot of new in and out of the drainages with no ill affects and if I hammered it....it walked.

I didn't even try to focus on the big end just a few burps of the throttle now and then for grins. I can see that my N/A settings(cruise and top end) are way too lean for the turbo. It was nice to have the side power jets on the CPC carbs. I did a lot of playing around with the mid range adjustment to see how much fuel I needed for cruisin between 5500 and 6500. This saved me from trying to yard carbs apart in a storm.

I have the power jets at 5 turns and it's obvious that I am still lean. I'm going to take the carbs apart this week and put in bigger mains.....prolly go from 450s to 500s, and raise the needles two or three steps. I wanna make this thing puke and then work back down.

Gus your fuel reg pressure source idea worked great. I set the pressure at 3-4psi at idle. By engagement I had 5, and with 7psi boost, I was reading around 14.....cool!

I was wondering about O2 readings. Can anyone tell me what they see at cruise speeds(5000-6500) and what do you see at WOT?

Thanks again, Gus! I'll give you a call.

 

[devilrmk]

Yea get on top of it then back it down. I am only out about 1.25 turns on my powerjets. Its nice knowing that you are fat. Mains are fat by a couple sizes for stock pipe, a little lean with my twins.

Some of the guys I have talked to like to turn out the powerjets a turn or so from just right to run on the trail. Not using much boost there anyway.

 

[Spaarky]

Some of the guys I have talked to like to turn out the powerjets a turn or so from just right to run on the trail. Not using much boost there anyway.

I always open mine up a couple turns past where I think they should be in the morning/ride in at night. We have big elevation change from where we stay to where we ride too. 6500ft to 9-10,000ft. Then when we get to the riding area, I take 5mns and get it tuned. I know they are a bit spendy, but that is a huge advantage of using Twisters remote adjusters. You can dial the power jets down in no time. Wish I could load video of him tuning my sled. You would be amazed how fast he can do it on a daily basis.

 

[devilrmk]

Yea I am really thinking about either trying to make something like that or just buying some from him.

My mag side is easy but the pto is a pain to get to.

 

[Spaarky]

He charges like 5$ more than he pays for the parts... so trying to put the RIGHT parts together, IMO isnt even worth the effort. I dont know, when I mentioned them before, I guess everyone flipped out on the price...... if you were around a sled that had em, you would write the check in a heartbeat..

I will even write instructions ....

 

[DWHalverson]

Ditto on the remotes!! You can even run them on your fuel screws to actually adjust them Worth every penny.


Dave

He charges like 5$ more than he pays for the parts... so trying to put the RIGHT parts together, IMO isnt even worth the effort. I dont know, when I mentioned them before, I guess everyone flipped out on the price...... if you were around a sled that had em, you would write the check in a heartbeat..

I will even write instructions ....

 

[devilrmk]

He charges like 5$ more than he pays for the parts... so trying to put the RIGHT parts together, IMO isnt even worth the effort. I dont know, when I mentioned them before, I guess everyone flipped out on the price...... if you were around a sled that had em, you would write the check in a heartbeat..

I will even write instructions ....

Yea, I am one of those guys that just likes to figure things out himself though. Not really about the cost more about the satisfaction of figuring it out myself. Not really a guy to step on others feet either so I don't talk much about stuff if I know someone else is trying to do something with it. I made my own powerjets.

I have not even seen them so not sure what he uses but I have a few ideas of what would work.

 

[esninak]

i have a 2001 non VES 700 polaris, seriouslly thinking about going with a turbo. got a few questions for you guys, any help would be great.

1. i was thinking about using a T25 turbo, 10psi max, is this a good choice?

2. this turbo is oil and water cooled, where should i plumb my water from? does it need a lot of flow.

3. what type of hose do you use for boost signal to wastegate, regulator, BOV, just worried about heat issues?

im sure i will have more questions, but this is where im at right now. AWSOME TREAD!!!!