Air box lid
#61
12-13-2004, 09:31 AM
Air box lid
Originally posted by: Freez
I have a question to those of you that ride a DS and have a buddy with a Predator.
Can you check if the holes in the sliders are the same size and shape between the carb in the DS and the one in the Predator? It’s the same carb, but they might be using a different slider and spring.
If there is a difference it might be worth trying the predator slider to see what it does on the DS? If it works great, you might just be able to buy a predator slider and spring, maybe even the needle to give you that extra bit of kick over the stock DS configuration.
I forgot to add the last way to increase the slider opening. I mentioned this before, but this might be another way to increase airflow into the motor.
Since there is a vacuum, small without a lid and large with the lid in place, between the carb and the air cleaner, it might be possible to get the slider to open a bit larger by removing the breather hose of the carb and connect it to its own little filter. PS, block the hole in the rubber intake. The slider is opened by the vacuum above the slider diaphragm and the normal setup will cause a vacuum under the slider diaphragm by means of the vent being connected to the air intake hose between the carb and air cleaner. The more vacuum above the slider diaphragm the larger it will open. If you take the vacuum underneath the slider away, then the slider should be able to use the same vacuum to open much larger.
Since you are running less vacuum inside the intake, thanks to the open airbox, the less vacuum under the diagram the more the slider will open, since the two vacuums are not competing against each other. With some luck we might be able to get the same slider openings as with stock setup and this means we can use the stock needle even if you are running no lid. Anyone going to test it this weekend? I will try it in my buddies DS tomorrow.
I have a question to those of you that ride a DS and have a buddy with a Predator.
Can you check if the holes in the sliders are the same size and shape between the carb in the DS and the one in the Predator? It’s the same carb, but they might be using a different slider and spring.
If there is a difference it might be worth trying the predator slider to see what it does on the DS? If it works great, you might just be able to buy a predator slider and spring, maybe even the needle to give you that extra bit of kick over the stock DS configuration.
I forgot to add the last way to increase the slider opening. I mentioned this before, but this might be another way to increase airflow into the motor.
Since there is a vacuum, small without a lid and large with the lid in place, between the carb and the air cleaner, it might be possible to get the slider to open a bit larger by removing the breather hose of the carb and connect it to its own little filter. PS, block the hole in the rubber intake. The slider is opened by the vacuum above the slider diaphragm and the normal setup will cause a vacuum under the slider diaphragm by means of the vent being connected to the air intake hose between the carb and air cleaner. The more vacuum above the slider diaphragm the larger it will open. If you take the vacuum underneath the slider away, then the slider should be able to use the same vacuum to open much larger.
Since you are running less vacuum inside the intake, thanks to the open airbox, the less vacuum under the diagram the more the slider will open, since the two vacuums are not competing against each other. With some luck we might be able to get the same slider openings as with stock setup and this means we can use the stock needle even if you are running no lid. Anyone going to test it this weekend? I will try it in my buddies DS tomorrow.
I was also thinking about drilling the slide on mine. If I were to just drill the slide hole to the next size up. It would have to be closer to working corectly than the stock hole/holes with the lid off. right? even though it might not be exact. it would be closer than just taking the lid off alone. I remember doing this to a 86 yamaha 600 radian street bike. the jet kit came with the drill bit. from what I remember. it was just barely big enough to shave the stock slide holes out a little. I put direct mount K&Ns on it. it had a dead spot down low. but, by moveing the needle clips one spot at a time I was able to find a happy medium. lost a little top end power. but, got rid of the the dead spot down low.
#62
12-13-2004, 10:51 AM
Air box lid
busmechanic. I hear what you are saying about putting a restrictor in place, but it will also cause another potential problem.
The following will happen if you install a breather filter for the carb vent. The area below the slider will have a temporary vacuum under the slider while the slider is moving up. Once the slider reaches the top, the vacuum goes away, since the air from the outside will flow into the passage. When the throttle is closed the slider moves down and the air under the diaphragm will have a positive pressure. The vent then acts as a hole for that positive pressure to escape. Installing a restrictor will slow down the upwards and downward movement of the slider. You might fix the upwards slide with a restrictor, but when you close the throttle the slider will take time to close, causing very rich running conditions. I personally think that you should have no limitation of the breathing potential of that hole. That hole under the slider diaphragm is massive and it was designed to give very good flow in and out of that passage. I did dyno runs on my raptor with and without a restrictor. Between 3000 and 5000 RPM without the restrictor the power output was much better compared to the restricted vents. If you pick up bad mixtures with the vent "open" you should address it my changing the needle position or the hole size in the slider, but don’t limit the hole size of the breather
Now, I know of a couple of DS's running modified sliders. One of them has 3 holes slightly bigger than the single stock hole. Think of a clock. Put the stock hole at 12, then the one holes is at 2 and the other at 10. Before drilling the slider, check inside to see where the supports are. You need to drill the holes so that they don't mess up the support inside the slider. This modified slider DS is running without the lid. Both the owner and the Dyno said it made more power and added much better acceleration.
The other DS has 3 holes the same size as the stock hole. Same positions as above. This works well and the owner is running with the lid on. He did not notice any loss of power without the lid. The reason he runs with the lid on is to keep water out.
The airbox intakes on both these above quads are much larger than the stock intake pipes to the airbox, so they are not running a stock intake. The one without the lid will flow much more than the stocker.
On the dyno the mixtures are perfect with the dynojet kits and needles. The mixture is nearly constant from bottom to top. They where set to run at 14:1 air to fuel ratio and the mixture will not change by more than 0.5 anywhere in the RPM range. That takes some doing and is not easy to get 100% perfect. The bikes are running the dynojet needles and clip position recommended by dynojet and 185 dynojet main jets. We are 5000 ft above sea level. At sea level you might have to run 190 to 195 mains.
If you like and want to experiment, you can start by drilling the stock holes slightly larger. See what it does, then add one smaller hole and keep going till it’s the same as the other one, then add the 3rd. See what works for you. If you don't like it, you can close the hole with a drop of glue.
Like I said before, the holes on the raptor carb is about 4 times the size of a DS carb. Same make, different model carb. Here they use a hole shaped like a half moon.
With the lid on and the vacuum under the slider diaphragm, the slider will take longer to open. When you close the throttle the slider will close much quicker, since the vacuum under the slider is sucking it closed. This cause slow up and very fast down.
In a mount or so I will be doing extensive testing about the effect of the bigger holes and what works and what don't. If you like to wait, I migth be able to give you more advice early next year. I will also be abel to show dyno runs before and after each mod.
The following will happen if you install a breather filter for the carb vent. The area below the slider will have a temporary vacuum under the slider while the slider is moving up. Once the slider reaches the top, the vacuum goes away, since the air from the outside will flow into the passage. When the throttle is closed the slider moves down and the air under the diaphragm will have a positive pressure. The vent then acts as a hole for that positive pressure to escape. Installing a restrictor will slow down the upwards and downward movement of the slider. You might fix the upwards slide with a restrictor, but when you close the throttle the slider will take time to close, causing very rich running conditions. I personally think that you should have no limitation of the breathing potential of that hole. That hole under the slider diaphragm is massive and it was designed to give very good flow in and out of that passage. I did dyno runs on my raptor with and without a restrictor. Between 3000 and 5000 RPM without the restrictor the power output was much better compared to the restricted vents. If you pick up bad mixtures with the vent "open" you should address it my changing the needle position or the hole size in the slider, but don’t limit the hole size of the breather
Now, I know of a couple of DS's running modified sliders. One of them has 3 holes slightly bigger than the single stock hole. Think of a clock. Put the stock hole at 12, then the one holes is at 2 and the other at 10. Before drilling the slider, check inside to see where the supports are. You need to drill the holes so that they don't mess up the support inside the slider. This modified slider DS is running without the lid. Both the owner and the Dyno said it made more power and added much better acceleration.
The other DS has 3 holes the same size as the stock hole. Same positions as above. This works well and the owner is running with the lid on. He did not notice any loss of power without the lid. The reason he runs with the lid on is to keep water out.
The airbox intakes on both these above quads are much larger than the stock intake pipes to the airbox, so they are not running a stock intake. The one without the lid will flow much more than the stocker.
On the dyno the mixtures are perfect with the dynojet kits and needles. The mixture is nearly constant from bottom to top. They where set to run at 14:1 air to fuel ratio and the mixture will not change by more than 0.5 anywhere in the RPM range. That takes some doing and is not easy to get 100% perfect. The bikes are running the dynojet needles and clip position recommended by dynojet and 185 dynojet main jets. We are 5000 ft above sea level. At sea level you might have to run 190 to 195 mains.
If you like and want to experiment, you can start by drilling the stock holes slightly larger. See what it does, then add one smaller hole and keep going till it’s the same as the other one, then add the 3rd. See what works for you. If you don't like it, you can close the hole with a drop of glue.
Like I said before, the holes on the raptor carb is about 4 times the size of a DS carb. Same make, different model carb. Here they use a hole shaped like a half moon.
With the lid on and the vacuum under the slider diaphragm, the slider will take longer to open. When you close the throttle the slider will close much quicker, since the vacuum under the slider is sucking it closed. This cause slow up and very fast down.
In a mount or so I will be doing extensive testing about the effect of the bigger holes and what works and what don't. If you like to wait, I migth be able to give you more advice early next year. I will also be abel to show dyno runs before and after each mod.
#64
12-13-2004, 12:12 PM
#65
12-13-2004, 03:19 PM
Air box lid
Is there someone in So Cal that understands this CV carb intimately? I will supply all the Dyno time necessary to come up with a solution. Either on their DS or mine, doesn't matter to me. This way we could get a basic assembly together, then people would just have to jet according to their specific elevation, mods, etc. If anyone is interested E-mail me. Dave " TriSum1@aol.com"
#67
12-13-2004, 09:23 PM
Air box lid
Originally posted by: Freez
busmechanic. I hear what you are saying about putting a restrictor in place, but it will also cause another potential problem.
The following will happen if you install a breather filter for the carb vent. The area below the slider will have a temporary vacuum under the slider while the slider is moving up. Once the slider reaches the top, the vacuum goes away, since the air from the outside will flow into the passage. When the throttle is closed the slider moves down and the air under the diaphragm will have a positive pressure. The vent then acts as a hole for that positive pressure to escape. Installing a restrictor will slow down the upwards and downward movement of the slider. You might fix the upwards slide with a restrictor, but when you close the throttle the slider will take time to close, causing very rich running conditions. I personally think that you should have no limitation of the breathing potential of that hole. That hole under the slider diaphragm is massive and it was designed to give very good flow in and out of that passage. I did dyno runs on my raptor with and without a restrictor. Between 3000 and 5000 RPM without the restrictor the power output was much better compared to the restricted vents. If you pick up bad mixtures with the vent "open" you should address it my changing the needle position or the hole size in the slider, but don’t limit the hole size of the breather
Now, I know of a couple of DS's running modified sliders. One of them has 3 holes slightly bigger than the single stock hole. Think of a clock. Put the stock hole at 12, then the one holes is at 2 and the other at 10. Before drilling the slider, check inside to see where the supports are. You need to drill the holes so that they don't mess up the support inside the slider. This modified slider DS is running without the lid. Both the owner and the Dyno said it made more power and added much better acceleration.
The other DS has 3 holes the same size as the stock hole. Same positions as above. This works well and the owner is running with the lid on. He did not notice any loss of power without the lid. The reason he runs with the lid on is to keep water out.
The airbox intakes on both these above quads are much larger than the stock intake pipes to the airbox, so they are not running a stock intake. The one without the lid will flow much more than the stocker.
On the dyno the mixtures are perfect with the dynojet kits and needles. The mixture is nearly constant from bottom to top. They where set to run at 14:1 air to fuel ratio and the mixture will not change by more than 0.5 anywhere in the RPM range. That takes some doing and is not easy to get 100% perfect. The bikes are running the dynojet needles and clip position recommended by dynojet and 185 dynojet main jets. We are 5000 ft above sea level. At sea level you might have to run 190 to 195 mains.
If you like and want to experiment, you can start by drilling the stock holes slightly larger. See what it does, then add one smaller hole and keep going till it’s the same as the other one, then add the 3rd. See what works for you. If you don't like it, you can close the hole with a drop of glue.
Like I said before, the holes on the raptor carb is about 4 times the size of a DS carb. Same make, different model carb. Here they use a hole shaped like a half moon.
With the lid on and the vacuum under the slider diaphragm, the slider will take longer to open. When you close the throttle the slider will close much quicker, since the vacuum under the slider is sucking it closed. This cause slow up and very fast down.
In a mount or so I will be doing extensive testing about the effect of the bigger holes and what works and what don't. If you like to wait, I migth be able to give you more advice early next year. I will also be abel to show dyno runs before and after each mod.
busmechanic. I hear what you are saying about putting a restrictor in place, but it will also cause another potential problem.
The following will happen if you install a breather filter for the carb vent. The area below the slider will have a temporary vacuum under the slider while the slider is moving up. Once the slider reaches the top, the vacuum goes away, since the air from the outside will flow into the passage. When the throttle is closed the slider moves down and the air under the diaphragm will have a positive pressure. The vent then acts as a hole for that positive pressure to escape. Installing a restrictor will slow down the upwards and downward movement of the slider. You might fix the upwards slide with a restrictor, but when you close the throttle the slider will take time to close, causing very rich running conditions. I personally think that you should have no limitation of the breathing potential of that hole. That hole under the slider diaphragm is massive and it was designed to give very good flow in and out of that passage. I did dyno runs on my raptor with and without a restrictor. Between 3000 and 5000 RPM without the restrictor the power output was much better compared to the restricted vents. If you pick up bad mixtures with the vent "open" you should address it my changing the needle position or the hole size in the slider, but don’t limit the hole size of the breather
Now, I know of a couple of DS's running modified sliders. One of them has 3 holes slightly bigger than the single stock hole. Think of a clock. Put the stock hole at 12, then the one holes is at 2 and the other at 10. Before drilling the slider, check inside to see where the supports are. You need to drill the holes so that they don't mess up the support inside the slider. This modified slider DS is running without the lid. Both the owner and the Dyno said it made more power and added much better acceleration.
The other DS has 3 holes the same size as the stock hole. Same positions as above. This works well and the owner is running with the lid on. He did not notice any loss of power without the lid. The reason he runs with the lid on is to keep water out.
The airbox intakes on both these above quads are much larger than the stock intake pipes to the airbox, so they are not running a stock intake. The one without the lid will flow much more than the stocker.
On the dyno the mixtures are perfect with the dynojet kits and needles. The mixture is nearly constant from bottom to top. They where set to run at 14:1 air to fuel ratio and the mixture will not change by more than 0.5 anywhere in the RPM range. That takes some doing and is not easy to get 100% perfect. The bikes are running the dynojet needles and clip position recommended by dynojet and 185 dynojet main jets. We are 5000 ft above sea level. At sea level you might have to run 190 to 195 mains.
If you like and want to experiment, you can start by drilling the stock holes slightly larger. See what it does, then add one smaller hole and keep going till it’s the same as the other one, then add the 3rd. See what works for you. If you don't like it, you can close the hole with a drop of glue.
Like I said before, the holes on the raptor carb is about 4 times the size of a DS carb. Same make, different model carb. Here they use a hole shaped like a half moon.
With the lid on and the vacuum under the slider diaphragm, the slider will take longer to open. When you close the throttle the slider will close much quicker, since the vacuum under the slider is sucking it closed. This cause slow up and very fast down.
In a mount or so I will be doing extensive testing about the effect of the bigger holes and what works and what don't. If you like to wait, I migth be able to give you more advice early next year. I will also be abel to show dyno runs before and after each mod.
#68
12-13-2004, 09:24 PM
#69
12-13-2004, 09:26 PM
Air box lid
Originally posted by: TriSum
Is there someone in So Cal that understands this CV carb intimately? I will supply all the Dyno time necessary to come up with a solution. Either on their DS or mine, doesn't matter to me. This way we could get a basic assembly together, then people would just have to jet according to their specific elevation, mods, etc. If anyone is interested E-mail me. Dave " TriSum1@aol.com"
Is there someone in So Cal that understands this CV carb intimately? I will supply all the Dyno time necessary to come up with a solution. Either on their DS or mine, doesn't matter to me. This way we could get a basic assembly together, then people would just have to jet according to their specific elevation, mods, etc. If anyone is interested E-mail me. Dave " TriSum1@aol.com"
#70
12-13-2004, 09:30 PM
Air box lid
bus mechanic
Keep us posted on how the hole drilling goes and take plenty of photos so if it works i wil know what to do on mine[img]i/expressions/face-icon-small-smile.gif[/img] and if it doesnt i will know what not to do to mine Theres no point both of us buying new slides is there[img]i/expressions/face-icon-small-wink.gif[/img] LOL
Keep us posted on how the hole drilling goes and take plenty of photos so if it works i wil know what to do on mine[img]i/expressions/face-icon-small-smile.gif[/img] and if it doesnt i will know what not to do to mine Theres no point both of us buying new slides is there[img]i/expressions/face-icon-small-wink.gif[/img] LOL