would it be possible to "t" into the vacume line that goes to the carb. check vacume with a manometer. lid on. this would give you a base line to shoot for. then remove lid. tap into the snorkle between the filter and carb. there will be alot more vacume there. so you would have to determine how small of restricted fitting it would take to acheive the same vacume that the box has with the lid on. then move the vacume line to the snorkle with the restricted fitting in place. and , leave your lid off.I have not tried this. so, I do not know if it will work. but, I think it could save a lot of dyno $, slide drilling and spring changing. the one thing that comes to mind is, would the vacume remain consistent with a load on the engine between the box and snorkle. the vacume in the snorkle will also increase as filter gets dirtier. so you would want to keep a clean filter.

 

The "vacuum pipe" you are talking about is not a vacuum pipe at all. Its actually a breather pipe! The vacuum that operates the slider is generated by the hole in the slider and the area above the slider diaphragm. The "breather pipe" connects to a area under the slider. The vacuum that pulls the slider open is above the slider. Creating another vacuum under the slider is going to cause a clash. The two vacuums will compete with each other, preventing the slider to react quickly to the motors demand and causing all kinds of problems.

There is very little vacuum between the carb and the air cleaner. The air cleaner is not that restrictive and will result in a very small vacuum if it is flowing correctly. If there is a vacuum, for example at high RPM, when it sucks the rubber intake hose to deform, it is caused by the lack of flow by the airbox intakes and running with the lid on. It is not caused by the air cleaner restriction. Remove the lid and you will never suck that intake hose to deform. It blows my mind how people go out and try and stop the hose from deforming. They put on clamps or use the new intakes hoses from the 2003 models. Does this not ring bells in your head that there is a MASSIVE vacuum inside the intake hose? This robs power people!!! Vacuums are NOT good for power, yet people follow the wrong advice blindly. Vacuum means the motor is NOT getting the air it needs. Fix the vacuum. The carb does not need vacuum to work! Don’t try and overcome the problem by addressing the WORNG thing. The motor needs air. Give it all the air it needs and you will not have vacuum problems and deforming intake hoses and the best of all, you will get more power. It’s that simple. Think logically here. Why are people still running with the lids on? It does not make any sense.

Now some more info. The breather connection on the carb connects to the rubber intake at a 90 degree angle. Connecting hoses like that will cause a vacuum in the breather hose, due to the flow of air going into the motor.

Do this simple test. Get yourself a pipe, cut it into 3 peaces and connect it to a "T" peace hose fitting. Make a "T" with the pipes. Connect the one side of the pipes, you can see thru, to a hose of water and open the tap. Stick the other 90 degree end into a glass of water and you will see it sucks the glass dry. 90 degree angled pipe fitting causes a vacuum.

The best is to remove the breather from the air intake and give it a little breather filter. Block the hole in the rubber intake. Remove that stupid lid and keep it for when you are going to run in lots of water. With an open lid and a little breather on the carb vent, the slider is free to move as fast as it likes, since there is no competing vacuum under the slider diaphragm. You might need to rethink the needle position or try another needle to get the right mixture.

This alone will make a nice difference in throttle response and you will pick up good acceleration.

This story of needing a vacuum inside the breather is the biggest load of bull!!!.

PS.

Next time you see a predator have a look at the carb. It uses the exact same carb as the DS. They use a breather filter on the carb vent. Somebody at Polaris seems to know what they are doing.

People always run and get themselves a new carb in the hope it will give them more power. They never get the stocker to perform correctly, since they never understand how the CV carb actually works.

 

ok, I was given the wrong impression of what that hose was for. I was way out in left field. thanks for clearing that up for me.

 

Sorry if I sounded a bit direct or upset. It was not my intensions to hit on you busmechanic .

Lots of people here have been fed the wrong information. They follow advice blindly without question. If it comes from a well known person, they believe it must be correct. Some advice is incorrect and other is correct. This lid must be on is wrong!

I said this already but it all starts with guys messing around and not thinking about what they are doing. Some assume things and then try and justify their incorrect assumptions.

Think of it this way. Everything on the motor is matched. Compression, cam profiles, valve sizes, intake and exhaust ports and the intake and exhaust system. All form a unit and the manufacturer spends hundreds of hours getting the balance right.

Now the stock DS has a very restrictive intake and exhaust system. So, what do the power junkies do, they add new exhaust systems and try and improve the intake. Then they find that there are power increases, but some things don't work like it should. Removing the lid is so obvious. Getting deformed intakes under high RPM loads is a sure indicator that the intake is not working correctly. When they remove the lid they found that they lost power. Now they are faced with two problems. Logic say that the no lid should work better, but the dyno say the opposite. They might try a couple of things, but in the end they go back to running the lid on, because it works better. The light never came on that the problem is with the slider and carb setup. Instead of fixing the carb to make use of the better airflow, the went the other route. Restrict the airflow to fix the carb "problem"

Then they go further. They add a new cam and upgrade the piston. This demands more air. With the lid on the problem gets worse as there is more vacuum now. There might be more power, but the motor is not performing like it should. So, what is next, new carb. The stocker is cr@p. With the new carb, do they still run with the lid on???????? Chances are no, since the new carbs are not CV carbs. Hell now they get power and it is contributed to the new carb and all those extra mods.

If they fixed the carb problem right in the beginning they might have had similar HP as the new carb, camed and pistoned motor.

Each time they add a new part and leave the other things stock, the more mismatching you will get. Sure you get more power, but you are NOT getting the most out of the motor. Instead of making 100% use of potential of the new part they might only be able to make 80% use of the potential power due to mismatching with other components.

It really bugs me that there is a massive amount of misinformation about the DS. So many posts have been added to this forum relating to tuning the stock carbs, fixing the deformed rubber intake and running with the lid in place. 90% of it is the biggest load of bull and is based on incorrect trail and error. In this process people are following others "experiments" blindly, even if it makes no sense at all.

Making power is not about bolting more things on. It’s about making the stuff that is there to match and work together. Change one thing and ALL others must be matched to the new part.

 

no problem. I acually apriciate the feadback. I have went back to my stock carb. I want it to be running to its fullist potential. so all this info is great.

 

these claps keep the intake from vibrating as well turbulance robs Hp to so it only makes sence
did you ever stop to think that this vacume is causing velocity? packing more air in than just some free flowing free for all. Bombardier knows air flow we all know this. I think Bombardier w/ all their experiance in lear jets ect. broke the mold w/ the DS in the stock fourm. I hate to drag MR Hp in to this but he didnt win all those State Stock Championships on his DS on a fluke Im almost positive all those runs were w/ the lid ON. Championships dont lie either. By the way some of us actuly own a DS and have spent countless hours/ years testing our Ds and passing it along to others to help them out. they have a choice of using it , improve on it or leaving it. take it for what its worth.

Sam

 

If you want to limit vibration, you need to strap the whole tube down, not just put rings around it. For vibration to affect airflow you need to bend that pipe is such a way that it will pop off. Airflow only gets affected when the curve of the tube gets around 30 degrees or more. That pipe cannot bend to have an angle of more than 30 degrees. Small vibrations are not going to make any real impact on the performance.

Now, velocity is one very important factor in producing HP. But, the velocity will not cause such a vacuum that it will suck a pipe to deform. To deform that pipe you need one thing. Vacuum, and lots of it.

High velocity flow thru the carb will actually cause a higher pressure before the carb because the air is punched up and compressed. The rubber intake starts out big and gets smaller as it gets closer to the carb. This will compress the air and cause higher pressures before the carb. This bunched up air causes higher velocity thru the small carb opening, since the air before the carb is actually pressing itself thru the hole. The vacuum is between the carb and the head, not between the carb and the air cleaner. If this was true the vacuum before the carb will actually suck the air out of the head, back where it came from in the 1st place. Vacuum created by higher velocity is not correct, it’s actually the opposite.

Vacuum in the intake is bad, that’s a FACT!

A high flow air cleaner and intake will cause very little vacuum between the carb and the air cleaner. A good air cleaner will have very little restriction to airflow. For a vacuum to form between the carb and the air cleaner you need an extremely bad flowing filter, OR, you need the airbox around the air cleaner to flow very poorly. The air pressure between a good flowing cabr and air cleaner will be very close to normal atmospheric pressure, since the air has very little restriction to move thru the air cleaner. The less vacuum, the better the intake is working and the more power can be made.

Now restrictive air intakes can help to increase low RPM power, but it is very bad for high RPM power output.

I am not here to attack MisterHP, so I am not going down that trip again. I am not disputing how well he did when he raced DS's. It's a simple fact that the best tuner will win.

Could it not be the case of a one eyed man is king in the land of the blind?

I check all the quads I work on to see how well their volumetric efficiency is. On all the dynos I used the DS's with pipes, new air cleaners and jet kits produce a VE value of 85% A VE of 100% is what you need to get. This means there is 15% lack of airflow. 15% less is equal to around 8HP less than it should be producing if it had a VE of 100%. There are big mismatches with the intake and exhaust and that is something than needs to be solved before the DS will have 100% VE.

I might not ride a DS, but I ride with about 6 other guys that have them. Then I also spend lots of time on the dyno with these quads. I don't use seat in the pants. It check HP, torque and acceleration on the dyno, and only with the dyno. In all my tests the open lid works better.

I work on Suzuki, Honda, Yamaha, Kawasaki and Bombardier. I spent more time at the dyno than most of the dyno time of people on here put together.

I will be doing massive testing on the DS early next year and I will post my findings. I will be testing 3 DS's at the same time and I will get the real facts behind this.

I don't understand how not riding one of these quads make what I say false?

 

So why did the Bombardier engineers go with the firmer intake shorkel on the newer models than stick with the softer snorkel?

 

Freez, some of us appreciate any and all info that we can get on here. Some may be incorrect, some not so. Its up to the end user to determine what he thinks is correct or not. I for one appreciate your input, keep it up will ya. And didnt you all know its sleddin season now![img]i/expressions/face-icon-small-wink.gif[/img] Jed

 

Im not saying its false. what Im saying is owning one give you more credit. If you look at any of the builders, or parts MFGs that people use on these fourms they own there own Machines they put countless hrs on what works they go out and ride it tweek it and ride again. The Bomb, Mr HP , TVI , AZSAND and others, they all own there machines and seem to have the best results w/ there set ups vs manufactures that dont.

now having fellow riders that ride Ds that back up your findings is better than knowing you own a rapter and trying to give us bomb riders advice when you dont even own one.

Im very curious on your findings in the future, of course you will need to post dynos w/ times or race results or some way to prove your findings.

my findings were simple. I get my results like alot of guys here seat of the pants we dont have dynos to go back to we race if we lose we tweek if we win we tweek. I jetted it accordingly and I lost in a race every time to the DS w/ the lid on. the stock carb slide just does not open all the way w/ the lid off.
I run a tm45 now and dont have this worry any more in fact I leave the air box off most of the year.

I just wanted to ad that we prob. just need to agree to disagree and let the info flow. thats what the fourms are for[img]i/expressions/face-icon-small-cool.gif[/img]