Carbed 2 stroke turbo guy's !!!

[Summit Guy]

I have an 09 rev xp that I turboed myself and just wanted to share some knowledge that I learned from it here. Run on! I could not get rid of it, I tried balance lines to the top of the slides, dynamic and static, no luck and actually the dynamic made the problem worse! I tried big and small lines to the top of the carbes, no luck. Tightened the spring on the throttle, no luck and a sore thumb! So I searched and searched until I found some information on a drag bike forum that was of interest and makes complete sense,

Run on is caused from too much air getting into the engine when the throttle is closed correct? so why are we putting air to the top of the slides? Here is what is happening:
we let off the throttle
the slides close
the turbo is still spinning and increases pressure in the airbox until the turbo stalls, and the air goes back out the compressor (without a bov)
but during the high pressure spike when the slides shut you are forcing air into the engine past the slides just like you would have a hole in the intake boot, only worse because of the pressure in the airbox. To make things worse because you are pushing air around the slide and not past the mainjet your mixture is lean which we all know makes a 2 stroke rev higher! this goes on until the the pressure bleeds down in the airbox and charge tubes or until all fuel is burned in the cases.
To solve this problem is simple, don't put pressure to the top of the slides. It IS that easy! If you look at the slides there is plenty of room for the pressure in the carb to equalize and also pressure cannot push the slide up into the carb because there is no flow there, if the pressure is equalized on top which is is without any mods the slide cannot open. If it could then this would happen to guys at sea level where atmosphere pressure is higher, just like boost does to your engine, makes it think it at a lower than sea level elevation. I now have my spring on my slides loosened up one revolution and my throttle is as light if not lighter than an efi sled, which rocks! No more sore thumb. In and out of the throttle all day long without a hint of run on, the thing runs like a stock 220hp sled!

For a blow off valve I use a Tial 50mm bov but with a soft spring so it opens at idle, the spring I used is from a automotive thermostat, i believe an eagle talon actually, but any standard thermostat will work, very soft and no leaks and very responsive action of the bov.

Very interesting, I wish we had some snow to test out the options.

Anybody else have XP turbos with run on issues, like the turboboys kits.

 

[gus bohne]

Sorry guys,
I have asked this person to remove this as it has ONE good point but all the rest is BAD information.

Whether you apply pressure to the slides or do NOT apply it, will NOT affect your hanging issue IF you are having them.

Hanging throttles are not wives tales, I've first hand been heading for a stone wall with stuck open throttles,, Its no fun !!

Why SOME have the issue while others do not is a weird thing, but is treatable !! lol

Gus

 

[Summit Guy]

Sorry guys,
I have asked this person to remove this as it has ONE good point but all the rest is BAD information.

Whether you apply pressure to the slides or do NOT apply it, will NOT affect your hanging issue IF you are having them.

Hanging throttles are not wives tales, I've first hand been heading for a stone wall with stuck open throttles,, Its no fun !!

Why SOME have the issue while others do not is a weird thing, but is treatable !! lol

Gus

Thanks for the clarification

 

[mattymac]

rode my cat 900 turbo for 2 years, 1 year with a BOV and the first year without. Top caps vented to airbox.

It hangs either way but only if the throttle posistion, boost, RPM, load are in just the right spots (pretty much on the flat trail with less load). A quick tap of the brake and it idles right down.

With the BOV this year it will drop the slides (when they hang up) but only if im 100% off the throttle, if I let off leaving 1/4 throttle or more it still hangs up (under the right conditions). Let completly off and you can hear the BOV dump and the throttle slides drop. Its an improvement but it doesnt hang up bad enough to even make me worry, on the hill I cant make it do it because of the load aginst the motor makes it idle down naturally.

I have my BOV tapped into the upper half of both my reed/carb boots into a "Y" and into my turbosmart BOV.

 

[10001110101]

Sorry guys,
I have asked this person to remove this as it has ONE good point but all the rest is BAD information.

Whether you apply pressure to the slides or do NOT apply it, will NOT affect your hanging issue IF you are having them.

Hanging throttles are not wives tales, I've first hand been heading for a stone wall with stuck open throttles,, Its no fun !!

Why SOME have the issue while others do not is a weird thing, but is treatable !! lol

Gus

I guess i should have asked for you to verify if indeed your slides are sticking open or just experiencing run-on from air bypassing the slides. you can verify this if you have a throttle position sensor, measure the voltage coming out of the sensor and verify it drops when you close the throttle and the sled runs on. If they indeed do stick simply round the slides where it catches in the grooves of the carb the slides and then polish to a mirror finish and test them on the bench using pressure with your fingers to make sure they slide smoothly.
I definatly wasnt posting false information, just a solution the problem I was having and what I learned from experimenting to find a solution. I also premix my gas 100-1 for saftey sake so maybe the oil in the gas helps the slides close as well?
cheers!

 

[RIDECATS]

Anyone uisng E-85 in carb 2 stroke turbo? I saw that Sibler was on the dragon kit he sells.

Tell us a bit about it if you are.

1. How is the cold starting
2. How hard on the plastics is it
3. Must be hugely detonation prone, you agree?
4. Did you run gas setup before - how did it comparre?
5. How far can you get on say...10 gallons

Thanks

 

[ExtremB]

Hi GUS

My summer projet is put a turbo in my 800r XP 2008 and I have a couple of questions ,

1- what about the DPM system ,just unplug it or ?

2- I will build an oill tank for the turbo which model of oil pump to use and which PSI range for a Garrett GT25 ?

3- on turbine it have two cooling system ,one oil and one water ,I think for water cooling ,use the carb heater system to relocated to the turbine .?

 

[Silber]

Anyone uisng E-85 in carb 2 stroke turbo? I saw that Sibler was on the dragon kit he sells.

Tell us a bit about it if you are.

1. How is the cold starting
2. How hard on the plastics is it
3. Must be hugely detonation prone, you agree?
4. Did you run gas setup before - how did it comparre?
5. How far can you get on say...10 gallons

Thanks

E85 has worked great in the polaris application. No issue with cold starting maybe and extra pull or two. Sleds are designed to run on 10% anyways so and extra 75 % wont hurt anything. Performance wise its great, You can run it supper rich and sleds still pull hard, but you can also run it way lean without deto. Gas milegas does go down abit, usally used around an extra two gallons when I headed to the pump. Its all on how you ride, When did most of our testing with e85 with really rode the chit out of the sleds so It was hard to compare. I feel it would work great in a carb two stroke application, Just start rich and you should be fine, You will probally have to adjust your needles alot richer as thats where we seemed to have to add the most fuel was in the midrange with the polaris's. Thanks Justin

 

[lords88]

Anyone uisng E-85 in carb 2 stroke turbo? I saw that Sibler was on the dragon kit he sells.

Tell us a bit about it if you are.

1. How is the cold starting
2. How hard on the plastics is it
3. Must be hugely detonation prone, you agree?
4. Did you run gas setup before - how did it comparre?
5. How far can you get on say...10 gallons

Thanks

First off correct me if I am wrong.

1.) You shouldn't notice any cold start difference on a two stroke engine with E85.
2.) Ethanol is highly corrosive, so all of your fuel lines should be upgraded to a flex fuel lines. Also E85 is a filter killer, so you will have to check and replace any inline filters often.
3.) E85 is more knock resistant than regular gasoline due to having a higher octane rating
4.) You're going to need more fuel with E85 approximately 20-30% more fuel compared to regular unleaded gasoline due to Ethanol's lower energy value.
5.) I would estimate you're only going to be able to go about 65% as far on E85 again due to its lower energy output.

 

[Snocross 100]

I want to turbo my 2003 700 144 getting streched to a 162 and wondering who has the best set up, how hard of an install and most importantly how much it would cost!! Any help is grately appresheated!

 

[gus bohne]

There really is NO best set up.

ALL the sytems on the market are EXCELLENT, the END users abilities, experience with tuning clutchs and jetting are paramount as well as the small details in the assembly..


Follow the instructions to the letter, make no shortcuts please.

be patient, your first ride out will show any little leaks or installations you did wrong, its sometimes slightly frustrating but in the end, a day is spent tunign for years of unequaled fun !!!!!

My most important criteria for anyone contemplating a turbo is MONEY !!
If you can't afford the CORRECT FUEL and ALL the tuning parts then SKIP IT !

You will be unhappy ,, turbos will get a black eye from you jumping in over your head...and another O.T. will be born..!!ARGH !!!

Gus

 

[00kitty]

after reading this ive realized i might be in over my head but there is no better way to learn! Im building a zr500 turbo using a garrett GT17 out of a saab. im trying to figure out a parts list. i bought koso dual egts, but thats it so far. i know i need a fuel pump and regulator, battery, BOV, boost controler, and a scavange pump for the turbo. i made the air box for the carbs and am working on the oil tank res. my questions are how many quarts should i make the res, where can i find all of these parts, and most important of all fuel delivery. i was thinking of power jets? and i have no idea how much boost i am going to be making so how do i know what fuel pressure to run. next i have 155 compression in both cylinders with wiseco pistons, am i going to have to take them out and get them milled to lower comp. My friend said use a thinker base gasket but i dont want to mess with port timing. thanks for all your help i have more questions but this will be a good start since im just starting the build

 

[Snocross 100]

O have the money just wanted to know about what the initial install will cost me?

 

[mattymac]

after reading this ive realized i might be in over my head but there is no better way to learn! Im building a zr500 turbo using a garrett GT17 out of a saab. im trying to figure out a parts list. i bought koso dual egts, but thats it so far. i know i need a fuel pump and regulator, battery, BOV, boost controler, and a scavange pump for the turbo. i made the air box for the carbs and am working on the oil tank res. my questions are how many quarts should i make the res, where can i find all of these parts, and most important of all fuel delivery. i was thinking of power jets? and i have no idea how much boost i am going to be making so how do i know what fuel pressure to run. next i have 155 compression in both cylinders with wiseco pistons, am i going to have to take them out and get them milled to lower comp. My friend said use a thinker base gasket but i dont want to mess with port timing. thanks for all your help i have more questions but this will be a good start since im just starting the build

Not trying to hyjack this thread with a swapmeet ad to sell my stuff but on my cat I have a parted it out with a detailed list of most of the big stuff to do a kit that for me has worked well some people may see this and get a better idea of some of the stuff it takes to do one of these! Pix and details...

http://www.snowest.com/forum/showthread.php?t=150036

 

[00kitty]

here is a thought about eliminating run on. say you have the BOV on the turbo side of the charge tube and then in the middle of the charge tube you have a butterfly that opens and closes in relation to the carbs. would that cause a vacum on the carb side of the intake circuit? this would be the order how things are laid out under the hood: turbo, bov, butterfly, air box, carbs. then have a line running from the air box to the bov to activate the bov. just a thought

 

[DWHalverson]

Run on is not an issue if the carbs are setup properly and the BOV is installed and setup correct too. Most Greedy Type RS BOV's have two springs and the light tension one is the one used and with very little, to zero preload on the spring. No need to over engineer things and make them complex.

 

[triple7]

Im not super sure on a turbo setup but run-on on a NA setup is many times caused from overfueling the motor. I would be suspicious that it is the same thing with turbo motors. Run-on and carb hang are two entirely different issues that can have a similar effect. Different cures are needed.

 

[mattymac]

Im not super sure on a turbo setup but run-on on a NA setup is many times caused from overfueling the motor. I would be suspicious that it is the same thing with turbo motors. Run-on and carb hang are two entirely different issues that can have a similar effect. Different cures are needed.

When mine would do it like I had posted on before, you could easily tell by the way the throttle would feel when the slides would hang.

 

[libbresse]

gus: What are your experience with turbo on triples ? I'm thinking about putting a turbo on my wc 1425.

-Anders

 

[gus bohne]

gus: What are your experience with turbo on triples ? I'm thinking about putting a turbo on my wc 1425.

-Anders

Thats what I cut my teeth on ,, triples...

Its really ironic, when these all came about in the 80's a piston port twin was so small and so weak that turboing one was a waste of effort...

Now the bmep of the twins has made them very popular and effective..

None the less, a triple will still , done correctly make you respect it.


Gus

pm me for all the details and results to date. I have 2 more watercraft triples in the works..