Stock Carb Mods
Nov 22, 2005 | 09:48 AM
#81
Pro Rider
Joined: Aug 2003
Posts: 391
Likes: 0
Stock Carb Mods
Same Holiday wishes to all you guys.
Mind you, you have more "practise time" than me on these mods, so it takes a "team effort" to do all the testing and come up with the goods and ideas. So you have a bigger input into these mods than me.
I am glad some people are willing to take up the ideas and put them into practice and reap the benefit, especially since these mods are dirt cheap.
I hope I can get some dyno time soon, to see what the dyno and Air fuel ratio meter say about all the mods and different setups. If all works out fine, I soon, hope to be the lucky owner of my own personal Dynojet dyno, at my house. I just need to figure out how to keep it busy, so I can get money to pay for the thing. It should not be a problem though, since the other dynos in the area will not have the capability to do the testing a Dynojet dyno does, plus map EFI bikes and quads. I also qualify to get Dynojet kits, and all their other products at a much better price, so I should have a price advantage on the other guys.
A while back, people jokingly thought I had a dyno in my living room, from all the testing I done on other quads. Soon, that might not be a joke anymore…lol
Now… the only burning questions I would like to know, is how the modified stock carb compares to an aftermarket carb on a stock to slightly modified DS.
Mind you, you have more "practise time" than me on these mods, so it takes a "team effort" to do all the testing and come up with the goods and ideas. So you have a bigger input into these mods than me.
I am glad some people are willing to take up the ideas and put them into practice and reap the benefit, especially since these mods are dirt cheap.
I hope I can get some dyno time soon, to see what the dyno and Air fuel ratio meter say about all the mods and different setups. If all works out fine, I soon, hope to be the lucky owner of my own personal Dynojet dyno, at my house. I just need to figure out how to keep it busy, so I can get money to pay for the thing. It should not be a problem though, since the other dynos in the area will not have the capability to do the testing a Dynojet dyno does, plus map EFI bikes and quads. I also qualify to get Dynojet kits, and all their other products at a much better price, so I should have a price advantage on the other guys.
A while back, people jokingly thought I had a dyno in my living room, from all the testing I done on other quads. Soon, that might not be a joke anymore…lol
Now… the only burning questions I would like to know, is how the modified stock carb compares to an aftermarket carb on a stock to slightly modified DS.
Jan 4, 2006 | 11:20 PM
#82
Thread Starter
|
Pro Rider
Joined: Dec 2001
Posts: 400
Likes: 0
Stock Carb Mods
Needle Assembly Into Slide:
The injection molding of the vacuum slide sometimes had a slight mismatch in its production.
With the needle and washers removed from slide, look down with good light and where the washer will rest, does your bottom look round or can you see a slight flat lip that is raised and thus looks like like the bottom is D shaped. Many slides seem to have a D shaped bottom.
If you have a D bottom:
Take the thick metal washer and grind a flat. Usually about half the width to the inner hole is find.
Install the thick washer first to align in the D.
Then install thick nylon washer.
Then needle with clip in 4th or 5th(stock needle) or 2nd or 3rd(DJ needle) from top groove, and thinner washer on top of clip.
Press in plunger with small spring attached.
When assembled and you turn the slide over and look at the needle going into the slide, you will notice that the needle is positioned in the middle and has equal space around the needle. This is important otherwise the needle will be dragging in jet needle and wear out of round. Also the better it is positioned, the better fuel will be drawn up the jet needle and the fuel will atomize better.
Final Check:
Push needle lightly up into slide body. There should be a slight movement. Spring will return needle when released. If running in the 5th(Stock) or 5th/6th(DJ), you may find that there is no movement.
Warning: If no movement, the assembly may come apart while riding.
Fix: Grind 1/32-1/16 off top of needle and re-assemble. Check again for movement.
I have found that the slide length varies. Excess shinkage is the issue.
The injection molding of the vacuum slide sometimes had a slight mismatch in its production.
With the needle and washers removed from slide, look down with good light and where the washer will rest, does your bottom look round or can you see a slight flat lip that is raised and thus looks like like the bottom is D shaped. Many slides seem to have a D shaped bottom.
If you have a D bottom:
Take the thick metal washer and grind a flat. Usually about half the width to the inner hole is find.
Install the thick washer first to align in the D.
Then install thick nylon washer.
Then needle with clip in 4th or 5th(stock needle) or 2nd or 3rd(DJ needle) from top groove, and thinner washer on top of clip.
Press in plunger with small spring attached.
When assembled and you turn the slide over and look at the needle going into the slide, you will notice that the needle is positioned in the middle and has equal space around the needle. This is important otherwise the needle will be dragging in jet needle and wear out of round. Also the better it is positioned, the better fuel will be drawn up the jet needle and the fuel will atomize better.
Final Check:
Push needle lightly up into slide body. There should be a slight movement. Spring will return needle when released. If running in the 5th(Stock) or 5th/6th(DJ), you may find that there is no movement.
Warning: If no movement, the assembly may come apart while riding.
Fix: Grind 1/32-1/16 off top of needle and re-assemble. Check again for movement.
I have found that the slide length varies. Excess shinkage is the issue.
Jan 18, 2006 | 10:47 PM
#83
Weekend Warrior
Joined: Dec 2005
Posts: 2
Likes: 0
Stock Carb Mods
Oldmanracing is a pure genius. I did the carb mods just like you said and it worked great. My throttle responce is greatlly improoved and is pulls alot harder. I'm a big boy and now I can get 2nd gear wheelies when before there was now way it could do it. For everyone out there thinking about doing the mods, stop thinking. Its like having a new machine. My thanks to you Oldmanracing and please keep posting more great ideas!
Jan 19, 2006 | 03:55 PM
#84
Pro Rider
Joined: Jan 2004
Posts: 396
Likes: 1
Stock Carb Mods
Originally posted by: meatman
Oldmanracing is a pure genius. I did the carb mods just like you said and it worked great. My throttle responce is greatlly improoved and is pulls alot harder. I'm a big boy and now I can get 2nd gear wheelies when before there was now way it could do it. For everyone out there thinking about doing the mods, stop thinking. Its like having a new machine. My thanks to you Oldmanracing and please keep posting more great ideas!
Oldmanracing is a pure genius. I did the carb mods just like you said and it worked great. My throttle responce is greatlly improoved and is pulls alot harder. I'm a big boy and now I can get 2nd gear wheelies when before there was now way it could do it. For everyone out there thinking about doing the mods, stop thinking. Its like having a new machine. My thanks to you Oldmanracing and please keep posting more great ideas!
May 25, 2006 | 11:28 PM
#87
Pro Rider
Is Oldmanracing! Also the inventor on the DS650 carb Mod!
Is Oldmanracing! Also the inventor on the DS650 carb Mod!
Joined: Jan 2006
Posts: 408
Likes: 0
Stock Carb Mods
My son moved 120 miles away so testing has been slow.
We made some final changes last weekend and this weekend he will do alot of riding to validate that the power is trail rideable. All around power and good throttle response is my goal. Our setup with new emulsion tube was great for drags but not as good as I wanted for trails. If you hooked up too fast at launch and the rpm's dropped, it fell off power too much. Needed to keep velocity higher. New spring, with different rate was developed. Bottom is now great and to maintain top, front two vacuum ports were increased to .140. Rears are still at .125.
If all goes well I will get quotes for emulsion tubes and springs. Then if anyone would like one, I will be able to have a price.
Latest Airbox Mod:
I did not like the way air enters the box. I felt that the air caused too much disturbance in mid-range. As the air on each side of the filter, enters the filter, they are crashing together, some air is pushed into the carb and some is pushed to the rear. This caused negative pressure to vary too much. Not good for cv carb.
Solution:
Since I have the airbox adapters mounted already backwards for the sump-pump hose, I took the stock inlet hoses and cut them from adapter end, up 20 rings. I then installed them into the inside of the airbox. Air now travels to the rear of airbox and all the crushing now forwards air only towards the carb. Mid range even sounds different and hits harder. With new spring and this mod we had so much more mid range velocity that we had to raise the DJ needle to the 6th(lowest groove). Popping wheelies is very easy now. Note: To run in the 6th groove, you have to cut off the top of needle to the 1st groove. Top of needle will hit the retainer plug and not allow good seating. Thus with needle shortened slightly, everything fits correctly.
Tubes mounted inside the airbox is what the ducati's use in their racing machines.
OMR
We made some final changes last weekend and this weekend he will do alot of riding to validate that the power is trail rideable. All around power and good throttle response is my goal. Our setup with new emulsion tube was great for drags but not as good as I wanted for trails. If you hooked up too fast at launch and the rpm's dropped, it fell off power too much. Needed to keep velocity higher. New spring, with different rate was developed. Bottom is now great and to maintain top, front two vacuum ports were increased to .140. Rears are still at .125.
If all goes well I will get quotes for emulsion tubes and springs. Then if anyone would like one, I will be able to have a price.
Latest Airbox Mod:
I did not like the way air enters the box. I felt that the air caused too much disturbance in mid-range. As the air on each side of the filter, enters the filter, they are crashing together, some air is pushed into the carb and some is pushed to the rear. This caused negative pressure to vary too much. Not good for cv carb.
Solution:
Since I have the airbox adapters mounted already backwards for the sump-pump hose, I took the stock inlet hoses and cut them from adapter end, up 20 rings. I then installed them into the inside of the airbox. Air now travels to the rear of airbox and all the crushing now forwards air only towards the carb. Mid range even sounds different and hits harder. With new spring and this mod we had so much more mid range velocity that we had to raise the DJ needle to the 6th(lowest groove). Popping wheelies is very easy now. Note: To run in the 6th groove, you have to cut off the top of needle to the 1st groove. Top of needle will hit the retainer plug and not allow good seating. Thus with needle shortened slightly, everything fits correctly.
Tubes mounted inside the airbox is what the ducati's use in their racing machines.
OMR
May 26, 2006 | 01:26 AM
#88
Pro Rider
Joined: Aug 2003
Posts: 444
Likes: 0
Stock Carb Mods
Just curious, how can a Predator owner with Nicholas Cycle carb mods..same carb, run no airbox and a direct mount air filter..with great results. No worries about top end power suffering because of no vacuum on the slide. Is it as simple as different motors providing more top end vacuum or are we missing something? How nice would it be to just do similar mods to the stock carb and be able to get rid of the air-box all together or at least the lid? My buddies Predator flat out flies!
