How to eliminate Rev Limiter on Predator?
#14
03-03-2003 | 09:44 PM
Trailblazer
Joined: Jan 2003
Posts: 65
Likes: 0
How to eliminate Rev Limiter on Predator?
Hi everyone,
I just installed the Dynojet kit on my Predator, and here's the results:
I used the stage III kit, which is for a slip-on K&N filter (RU-1770, plus an Outerwear cover {check my photos if you want to see the mounting}). The DJ kit uses a new needle, and their DJ main jets. The DJ needle is on the 2nd from the top slot (out of six slots available), the DJ main jet for this set-up is a 170. The air mixture screw is approximately what mine was stock, 3 1/2 +/- turns out. The pilot jet is stock at 45. They DO NOT modify the slide or the slide spring. I have a W/B slip-on exhaust, currrently with the spark arrestor baffle only and the open end cap. For stage III, DJ tested with 12-16 discs, with and without USFS plates, and found the more open the better. It starts very easily and idles great. Appears to be no need for any other low speed jetting changes.
The quad literally hauls butt!! It is so much stronger through the low, mid, and top, that it reaches the rev limiter very quickly. The rev limiter kicks in at about 8800 rpm, on most Predators. This is about where I am getting popping. The peak power is at 8000 rpm, on the DJ dyno, with stock tires at 10 psi. It now makes perfectly good sense to me that you need a tach to establish your best shift points, and where your limiter kicks in. It has been hard to guess with a quick revving motor, and a rev limiter that is so unforgiving. I am also mounting a high quality tach this week so I can set my best, fastest shift points. I am guessing that wil be at about 8300-8500 rpm.
The Stage III kit is making 43.5 h.p. at the rear wheels, and just over 30 ft lbs of torque. The stage I number are about 2 h.p. lower across the board. These numbers tested out the same +/- on 5 different Preds, all of which had their rev limiters kick in at 8800 rpm. I am able to literally leap the Predator through berms and banked sand trails where I ride (sea level near Palm Springs, CA). I did not run my paddles on it yet, but it was literally digging holes in the sand/dirt here with the stock tires. It is making so much more power now that I am considering going back to the stock 37 tooth rear so it will rev a bit longer in each gear.
For a long time I was not sure if it was the W/B pipe, my jetting attempts, or what???, but now I feel pretty sure the popping is just the built in rev limiter for the Predator. If I can get a new CDI with a slightly higher rev limiter setting, it may help eliminate the popping. I am working on obtaining one now, but not sure re: applicability and availability. Also, learning the shift points and realizing that I need to shift a bit sooner is a learning curve, for me anyway, as an old 2-stroke TRX250R guy.
All in all, I'm happy with the performance. I hope everyone elses Air Force kits are working well, too. I believe that Gary at the Superbike Shop has made an great effort to pull performance out of this machine, and the initiial feedback I am seeing on his Air Force jetting/airbox kit is very good. I will be able to run against a few buddies with that kit pretty soon, to compare the overall performance gains/differences...that may be very telling! I may end up switching to an air box set-up after all, who knows??
Sorry for the long posting, but I know this has been, and still is, a very hot topic for alot of us...
I wish you all good luck with your efforts...I'll update later as I test further...
Take Care,
JJ
I just installed the Dynojet kit on my Predator, and here's the results:
I used the stage III kit, which is for a slip-on K&N filter (RU-1770, plus an Outerwear cover {check my photos if you want to see the mounting}). The DJ kit uses a new needle, and their DJ main jets. The DJ needle is on the 2nd from the top slot (out of six slots available), the DJ main jet for this set-up is a 170. The air mixture screw is approximately what mine was stock, 3 1/2 +/- turns out. The pilot jet is stock at 45. They DO NOT modify the slide or the slide spring. I have a W/B slip-on exhaust, currrently with the spark arrestor baffle only and the open end cap. For stage III, DJ tested with 12-16 discs, with and without USFS plates, and found the more open the better. It starts very easily and idles great. Appears to be no need for any other low speed jetting changes.
The quad literally hauls butt!! It is so much stronger through the low, mid, and top, that it reaches the rev limiter very quickly. The rev limiter kicks in at about 8800 rpm, on most Predators. This is about where I am getting popping. The peak power is at 8000 rpm, on the DJ dyno, with stock tires at 10 psi. It now makes perfectly good sense to me that you need a tach to establish your best shift points, and where your limiter kicks in. It has been hard to guess with a quick revving motor, and a rev limiter that is so unforgiving. I am also mounting a high quality tach this week so I can set my best, fastest shift points. I am guessing that wil be at about 8300-8500 rpm.
The Stage III kit is making 43.5 h.p. at the rear wheels, and just over 30 ft lbs of torque. The stage I number are about 2 h.p. lower across the board. These numbers tested out the same +/- on 5 different Preds, all of which had their rev limiters kick in at 8800 rpm. I am able to literally leap the Predator through berms and banked sand trails where I ride (sea level near Palm Springs, CA). I did not run my paddles on it yet, but it was literally digging holes in the sand/dirt here with the stock tires. It is making so much more power now that I am considering going back to the stock 37 tooth rear so it will rev a bit longer in each gear.
For a long time I was not sure if it was the W/B pipe, my jetting attempts, or what???, but now I feel pretty sure the popping is just the built in rev limiter for the Predator. If I can get a new CDI with a slightly higher rev limiter setting, it may help eliminate the popping. I am working on obtaining one now, but not sure re: applicability and availability. Also, learning the shift points and realizing that I need to shift a bit sooner is a learning curve, for me anyway, as an old 2-stroke TRX250R guy.
All in all, I'm happy with the performance. I hope everyone elses Air Force kits are working well, too. I believe that Gary at the Superbike Shop has made an great effort to pull performance out of this machine, and the initiial feedback I am seeing on his Air Force jetting/airbox kit is very good. I will be able to run against a few buddies with that kit pretty soon, to compare the overall performance gains/differences...that may be very telling! I may end up switching to an air box set-up after all, who knows??
Sorry for the long posting, but I know this has been, and still is, a very hot topic for alot of us...
I wish you all good luck with your efforts...I'll update later as I test further...
Take Care,
JJ
#15
03-03-2003 | 11:05 PM
Trailblazer
Joined: Feb 2003
Posts: 43
Likes: 0
#16
03-03-2003 | 11:15 PM
Thread Starter
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Pro Rider
Joined: Jul 1999
Posts: 629
Likes: 0
How to eliminate Rev Limiter on Predator?
JJ:
Excellent response! Thanks!
I have owned a Banshee for the past six years and am begining to wonder if the popping I am experiencing is normal.
Basically, the popping occurs when it reaches the end of each gear during a hard acceleration. I can also make it occur when I am sitting in neutral and I rev the engine real high. Does yours pop then also?
I have a WB Slip-on, a 50 Pilot Jet and have jetted my main from 150 (stock) all the way up to 175 and the popping is still there, no changes.
After the above carb mods, can you make yours pop if you are in neutral and rev it high? Could you please try it and then describe to me what occurs?
You say you are hitting your Rev Limiter now. What does the engine sound like when it hits the limiter? I always thought the engine would simply cut out when you hit the Rev Limiter and not begin popping like mine does.
Help!
Excellent response! Thanks!
I have owned a Banshee for the past six years and am begining to wonder if the popping I am experiencing is normal.
Basically, the popping occurs when it reaches the end of each gear during a hard acceleration. I can also make it occur when I am sitting in neutral and I rev the engine real high. Does yours pop then also?
I have a WB Slip-on, a 50 Pilot Jet and have jetted my main from 150 (stock) all the way up to 175 and the popping is still there, no changes.
After the above carb mods, can you make yours pop if you are in neutral and rev it high? Could you please try it and then describe to me what occurs?
You say you are hitting your Rev Limiter now. What does the engine sound like when it hits the limiter? I always thought the engine would simply cut out when you hit the Rev Limiter and not begin popping like mine does.
Help!
#17
03-03-2003 | 11:24 PM
Thread Starter
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Pro Rider
Joined: Jul 1999
Posts: 629
Likes: 0
How to eliminate Rev Limiter on Predator?
More stuff for JJ:
Kewl photos!
Regarding your shifter. I had the same problem. The fix is real easy. The shifter is aluminum. I simply took a dremel tool and ground a small area out of the bottom of the shifter so it would no longer hit the frame.
I also began wearing a hole in the top of my airbox where my tool kit was hitting. I simply glued a peice of thick rubber pad (like the kind you get for furniture so it doesn'r scratch your wooden floor) and stuck it to the top of the airbox where it was hitting. Now it just rubs into the rubber pad.
How much was the K and N kit, what did it come with and where did you get it? Can the carb intake rubber boot hold the weight of the carb and air filter without the rear support of the airbox? I did a similar mod to my Banshee years ago and the boot broke open due to the lack of support on the rear of the clamp-on air filter. The boot couldn't take the constant pounding of a hard ride and eventually split open.
Also, could you please look at my post before this one and answer the questions if possible???
Thanks!
Kewl photos!
Regarding your shifter. I had the same problem. The fix is real easy. The shifter is aluminum. I simply took a dremel tool and ground a small area out of the bottom of the shifter so it would no longer hit the frame.
I also began wearing a hole in the top of my airbox where my tool kit was hitting. I simply glued a peice of thick rubber pad (like the kind you get for furniture so it doesn'r scratch your wooden floor) and stuck it to the top of the airbox where it was hitting. Now it just rubs into the rubber pad.
How much was the K and N kit, what did it come with and where did you get it? Can the carb intake rubber boot hold the weight of the carb and air filter without the rear support of the airbox? I did a similar mod to my Banshee years ago and the boot broke open due to the lack of support on the rear of the clamp-on air filter. The boot couldn't take the constant pounding of a hard ride and eventually split open.
Also, could you please look at my post before this one and answer the questions if possible???
Thanks!
#18
03-04-2003 | 02:21 PM
Trailblazer
Joined: Jan 2003
Posts: 65
Likes: 0
How to eliminate Rev Limiter on Predator?
Hi Rob4092,
The K&N slip-on RU1770 fits without much weight on the carb throat. I don't see it ever being a problem as far as the weight causing stress to the boot mount. If anything, it would rest slightly on the cross bar...I would suggest Rocky Moutain ATV on the net for the best prices. They should have the jet kits and the filters...and are about the best prices I have found...I paid $57.00 for my Dynojet kit directly from DJ, and I think RM ATV sells the kits for mid $40.00 range. I think about it was $40.00 for the K&N slip-on. The DJ kit has about 15 different jets, instructions for stage I and stage III, a new needle, and a drill bit to drill out the air mixture screw cap. Yeah, their instructions are very basic, I guess they assume you won't try to be jetting unless you know what you are doing. Read some of their jetting basics on their we site.
In my years of past experience in jetting (mostly street bikes with 4 carbs and 2-stroke dirt bikes), I have found, that most jetting problems are specific to a particular jet, ie; the main jet, or the needle jet, or the pilot. In your case, if you bike is idling well, and not stumbling, but pulling strong in the mid range, then the only issue left is the main jet, or maybe the needle jet clip position, or the rev limiter.
I have a tach enroute to me, should be here today or tomorrow. That is really the only way I see to tell accurately the rpm where my rev limiter hits. I suspect it will be right at 8500 to 8800, as it was with all the bikes Dynojet tested. I have not really revved the motor to the rev limiter just sitting, I have never advocated doing that, as I feel it doesn't give an accurate representation of what the motor will do under a load. I really believe that any jet kit/air box fix or combo will still hit the rev limiter, no matter what changes those fixes make. After all, that is what the rev limiter is designed to do. It will interrupt the spark to the plug, and that can and most often will cause popping/backfiring as the combustion process is not completed. It is more audible when you have a loud, open exhaust pipe. The fact that you have gone all the way to a 175 main and still have popping is to me a very good clue that you are hitting the rev limiter.
If my set up is popping at a good step before 8500-8800 rpm, then I still have some main jet or maybe needle clip adjusting to do. Sunday, when testing my set-up in the local desert, I heard a totally stock brand new predator go by at warp 9. His motor was popping off the rev limiter with the stock exhaust. It was very quiet compared to my more open W/B pipe, but it was still there. Three weeks ago when Tres and I were at Glamis, there was a guy there with his Predator, supposedly all dialed in by a shop in the Phoenix area. He was racing up Olds Hill against other quads, and doing quite well. When we spoke to him, he said he did not know the jetting setup his dealer had done, but he didn't have any popping. Well, Tres and I stood directly behind him at the base of Olds Hill while he raced, and we could CLEARLY hear the bike popping at the top end. I don't think the guy was trying to mislead us, he just did hear what was really happening.
I believe that the factory rev limiter kicks in a tad too soon on our Preds to allow for some over-rev, and eliminate the popping. I am working on obtaining a new cdi that will eliminate this issue. I feel the motor is safe to 9300 rpm or thereabouts, without any damage. I like this quad so much though, that even if the motor takes a crap tomorrow and grenades, I will keep the quad and just figure out a way to fit a Honda CR500 2-stroke in the chassis! That's a motor I am very familiar with, and am very comfortable working on. Hey, it's all fun and it's only money!
Hope this helps,,,I am by no means an expert, and I hope you carefully evaluate your situation before spending money on fixes. I have spent some money I wish I would have saved...There will be more kits, pipes, and other stuff out there soon. But I can tell you that my set-up now is running very strong. It has a killer mid range and pulls strong from the bottom to the rev limiter.
Take care, and good luck...
JJ
The K&N slip-on RU1770 fits without much weight on the carb throat. I don't see it ever being a problem as far as the weight causing stress to the boot mount. If anything, it would rest slightly on the cross bar...I would suggest Rocky Moutain ATV on the net for the best prices. They should have the jet kits and the filters...and are about the best prices I have found...I paid $57.00 for my Dynojet kit directly from DJ, and I think RM ATV sells the kits for mid $40.00 range. I think about it was $40.00 for the K&N slip-on. The DJ kit has about 15 different jets, instructions for stage I and stage III, a new needle, and a drill bit to drill out the air mixture screw cap. Yeah, their instructions are very basic, I guess they assume you won't try to be jetting unless you know what you are doing. Read some of their jetting basics on their we site.
In my years of past experience in jetting (mostly street bikes with 4 carbs and 2-stroke dirt bikes), I have found, that most jetting problems are specific to a particular jet, ie; the main jet, or the needle jet, or the pilot. In your case, if you bike is idling well, and not stumbling, but pulling strong in the mid range, then the only issue left is the main jet, or maybe the needle jet clip position, or the rev limiter.
I have a tach enroute to me, should be here today or tomorrow. That is really the only way I see to tell accurately the rpm where my rev limiter hits. I suspect it will be right at 8500 to 8800, as it was with all the bikes Dynojet tested. I have not really revved the motor to the rev limiter just sitting, I have never advocated doing that, as I feel it doesn't give an accurate representation of what the motor will do under a load. I really believe that any jet kit/air box fix or combo will still hit the rev limiter, no matter what changes those fixes make. After all, that is what the rev limiter is designed to do. It will interrupt the spark to the plug, and that can and most often will cause popping/backfiring as the combustion process is not completed. It is more audible when you have a loud, open exhaust pipe. The fact that you have gone all the way to a 175 main and still have popping is to me a very good clue that you are hitting the rev limiter.
If my set up is popping at a good step before 8500-8800 rpm, then I still have some main jet or maybe needle clip adjusting to do. Sunday, when testing my set-up in the local desert, I heard a totally stock brand new predator go by at warp 9. His motor was popping off the rev limiter with the stock exhaust. It was very quiet compared to my more open W/B pipe, but it was still there. Three weeks ago when Tres and I were at Glamis, there was a guy there with his Predator, supposedly all dialed in by a shop in the Phoenix area. He was racing up Olds Hill against other quads, and doing quite well. When we spoke to him, he said he did not know the jetting setup his dealer had done, but he didn't have any popping. Well, Tres and I stood directly behind him at the base of Olds Hill while he raced, and we could CLEARLY hear the bike popping at the top end. I don't think the guy was trying to mislead us, he just did hear what was really happening.
I believe that the factory rev limiter kicks in a tad too soon on our Preds to allow for some over-rev, and eliminate the popping. I am working on obtaining a new cdi that will eliminate this issue. I feel the motor is safe to 9300 rpm or thereabouts, without any damage. I like this quad so much though, that even if the motor takes a crap tomorrow and grenades, I will keep the quad and just figure out a way to fit a Honda CR500 2-stroke in the chassis! That's a motor I am very familiar with, and am very comfortable working on. Hey, it's all fun and it's only money!
Hope this helps,,,I am by no means an expert, and I hope you carefully evaluate your situation before spending money on fixes. I have spent some money I wish I would have saved...There will be more kits, pipes, and other stuff out there soon. But I can tell you that my set-up now is running very strong. It has a killer mid range and pulls strong from the bottom to the rev limiter.
Take care, and good luck...
JJ
#19
03-04-2003 | 06:29 PM
Thread Starter
|
Pro Rider
Joined: Jul 1999
Posts: 629
Likes: 0
How to eliminate Rev Limiter on Predator?
JJ:
I just ordered a kit called the Air Force Kit from Gary at Superbike Shop in Indiana. I found out about it through a message board on the Internet.
Everyone on this Predator message board says this kit will fix the popping problems with the Predator due to the fact that the issue revolves around an inadequate air/fuel mixture at high rpms. I have faith that everyone's comments are honest simply due to the fact that the folks who made them live throughout the world (not just the US). It would be pretty difficult to set up a scam with folks from all over.
Please go this message board and review the comments. Let me know what you think as there are dozens of Predator owners who swear by this fix. They swear that once this kit is installed, there is no popping whatsoever. This makes me think that the popping we are all experiencing is not the rev limiter kicking in.
The message board is located at:
http://www.esuperbikeshop.com/Servic...age_board.html
Please let us all know what you think after you go to this site and review the messages.
Rob
I just ordered a kit called the Air Force Kit from Gary at Superbike Shop in Indiana. I found out about it through a message board on the Internet.
Everyone on this Predator message board says this kit will fix the popping problems with the Predator due to the fact that the issue revolves around an inadequate air/fuel mixture at high rpms. I have faith that everyone's comments are honest simply due to the fact that the folks who made them live throughout the world (not just the US). It would be pretty difficult to set up a scam with folks from all over.
Please go this message board and review the comments. Let me know what you think as there are dozens of Predator owners who swear by this fix. They swear that once this kit is installed, there is no popping whatsoever. This makes me think that the popping we are all experiencing is not the rev limiter kicking in.
The message board is located at:
http://www.esuperbikeshop.com/Servic...age_board.html
Please let us all know what you think after you go to this site and review the messages.
Rob
#20
03-04-2003 | 07:34 PM
Trailblazer
Joined: Jan 2003
Posts: 65
Likes: 0
How to eliminate Rev Limiter on Predator?
Rob4092,
I have been on all these boards since I got my Predator, and followed all the postings. I believe that Gary's Air Force kit will work...He uses a lot of reasonable, seasoned, tuning tips and tricks that have been around for quite a long time. Advancing the slide speed by drilling additional slide holes and softening the slide spring, more air to the carb by extra airbox venting, and larger jets to match the new flow are all basic good long standing tuning methods that I have used myself for many years. From all the postings on that board, I believe Gary is a very knowledgable guy with a very honest and ethical business operation. I don't think you will go wrong with his kit. If it works out that I have missed something here and my popping is still a jetting problem, rather than the rev limiter, then I may also order his kit to try.
Right now I see the biggest issue about this popping problem is the individual quad owner deternining if the popping is rev limiter induced or jetting. Everyone on all the web sites and forums have acknowledged that the physical/mechanical redline of the motor is about 9005 rpm, and the rev limiter kicks in at 8800+/-. Once you determine that on your quad, you can then adjust around it accordingly.
I spent a lot of time messing with various 'fixes' on my own, and at the advice of others on the net...a very frustrating experience that an old "mod dog" like me couldn't find a quick and easy answer to the problem. The factory air box is very sensitive to changes. Both Gary and Dynojet agree on this. I wish I would have just bought my tach first, and then started the modification process...It would have taken a lot of guessing out of the equation. When I hear more than just one bone stock Predator popping at the top end, it tells me the rev limiter is there and working.
I will post my findings about this issue as soon as I get the tach mounted and going. I know I was used to a higher revving 250R motor, that did not need a tach, as it would rev to the moon. This quad wants to do the same, but has the limitations of a valve train that sets a farily rigid rev limit. Valve train damage can occur if it's over-revved. I feel pretty sure that Polaris did not want to have reports of blown top ends on their new sport quad...hence an earlier, more rigid rev limit. I'll bet that Rath is not running a stock CDI on his race predator. I wonder if DYNA or other companies in the ignition industry are seeing a good, new market here?
As I said before, I may also join Gary's "Air Force," I just want to know what MY QUAD"S current upper limit is. With Gary's kit, unless they mod the CDI, or by some other means bypass the rev limiter, every Predator will have ignition cut out at the factory pre-set limit.......or those quads would grenade their top ends, that's just physics...
Good luck, let me know when your kit is in and running...I'm waiting for Tres to return from Chicago so he can finish his install and test his ride, if he doesn't break another partl!!!!...I think we are going to try and hook up this weekend and do some testing.....
Later,
JJ
I have been on all these boards since I got my Predator, and followed all the postings. I believe that Gary's Air Force kit will work...He uses a lot of reasonable, seasoned, tuning tips and tricks that have been around for quite a long time. Advancing the slide speed by drilling additional slide holes and softening the slide spring, more air to the carb by extra airbox venting, and larger jets to match the new flow are all basic good long standing tuning methods that I have used myself for many years. From all the postings on that board, I believe Gary is a very knowledgable guy with a very honest and ethical business operation. I don't think you will go wrong with his kit. If it works out that I have missed something here and my popping is still a jetting problem, rather than the rev limiter, then I may also order his kit to try.
Right now I see the biggest issue about this popping problem is the individual quad owner deternining if the popping is rev limiter induced or jetting. Everyone on all the web sites and forums have acknowledged that the physical/mechanical redline of the motor is about 9005 rpm, and the rev limiter kicks in at 8800+/-. Once you determine that on your quad, you can then adjust around it accordingly.
I spent a lot of time messing with various 'fixes' on my own, and at the advice of others on the net...a very frustrating experience that an old "mod dog" like me couldn't find a quick and easy answer to the problem. The factory air box is very sensitive to changes. Both Gary and Dynojet agree on this. I wish I would have just bought my tach first, and then started the modification process...It would have taken a lot of guessing out of the equation. When I hear more than just one bone stock Predator popping at the top end, it tells me the rev limiter is there and working.
I will post my findings about this issue as soon as I get the tach mounted and going. I know I was used to a higher revving 250R motor, that did not need a tach, as it would rev to the moon. This quad wants to do the same, but has the limitations of a valve train that sets a farily rigid rev limit. Valve train damage can occur if it's over-revved. I feel pretty sure that Polaris did not want to have reports of blown top ends on their new sport quad...hence an earlier, more rigid rev limit. I'll bet that Rath is not running a stock CDI on his race predator. I wonder if DYNA or other companies in the ignition industry are seeing a good, new market here?
As I said before, I may also join Gary's "Air Force," I just want to know what MY QUAD"S current upper limit is. With Gary's kit, unless they mod the CDI, or by some other means bypass the rev limiter, every Predator will have ignition cut out at the factory pre-set limit.......or those quads would grenade their top ends, that's just physics...
Good luck, let me know when your kit is in and running...I'm waiting for Tres to return from Chicago so he can finish his install and test his ride, if he doesn't break another partl!!!!...I think we are going to try and hook up this weekend and do some testing.....
Later,
JJ