I have a 98 KDX 200 with the air box lid removed, fmf fatty pipe and silencer,head Ported and Polished, KX front forks,shaved seat, and 12/48 sprockets. I want the bike to come alive on the bottom end. The guy who owned the bike before me turned this bike into a motocross bike, and I race hares scrambles. What is the best way to make the bottom end come alive. It is very flat and hard to work with in the woods. I was thinking maybe a frp torgue ring and new reeds, maybe even a reed spacer? Any suggestions? I need something that will make the bottom end come alive. Thnks
More Bottom end
- Thread starter 91KDX
- Start date
k first off u want to get an fmf gnarly pipe and turbine core 2 silencer you can sell the fatty pipe and silencer to some one.that will give you nice bottom end. next frp tourque ring, reed spacer, and moose tourqe reeds will make it even more down low, if u need any more i would suggest trading in ur 35mm carb for a 220's carb (33mm) many people with 220's will be more then happy to trade with u.
Jackpiner57
~SPONSOR~
- Aug 11, 2002
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You could go to a 12 or 13 tooth countershaft sprocket.
You could add a little weight to your flywheel.
You could you put in some low tension reeds.
You could add a little weight to your flywheel.
You could you put in some low tension reeds.
- Jan 8, 2000
- 3,331
- 1
You mention that the head is ported. Do you mean the cylinder is ported? Porting changes the way in which the power is delivered, especially if the port timing has been altered for top end. What kind of porting did you have done? I have RRP Stage II porting and my bike delivers power everywhere.
New reeds (Power Reeds) might help but it sould like you have done quite a bit to your engine at this point. You might want to experiemnt with your ignition timing. I believe retarding it by 1 to 2 degrees will increase low-end power at the expense of top-end power.
New reeds (Power Reeds) might help but it sould like you have done quite a bit to your engine at this point. You might want to experiemnt with your ignition timing. I believe retarding it by 1 to 2 degrees will increase low-end power at the expense of top-end power.
- Thread starter
- #5
I am not really sure what kind of porting was done to it. Like I said the guy who owned it before me raced motocross with it, and he sold it to Fredette Racing and I bought the bike from jeff and traded my old bike in to him. Jeff was going to scrap the bike for parts but I got before he got around to it. Jeff really couldn't tell me a whole lot about the bike because he can't remember everything about every bike he has in his shop (probably 250 to 300 bikes maybe, most of them scrapped for parts). So I take it the porting was done to improve top end. I have bought a 12 tooth sprocket, but haven't put it on yet. I will see about getting the gnarly pipe/turbine core silencer and the frp torgue ring. I have only owned the bike for 2 or 3 weeks now. I raced it the first sunday at the D. 17 hare scrambles in Morrison and did really bad because of the bad low end. Thanks for the help!
Ben
Ben
Canadian Dave
Super Power AssClown
- Apr 28, 1999
- 1,202
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Before you run out and buy a pipe have a look at the one you have. "Fatty" doesn't denote the profile of the pipe. Have a look at the mounting tab at the top of the pipe near the kick start. That numbers are stamped into it K_-30 is a rev pipe and K_-35 is a torque pipe. Torque is tuned for more bottom end.
Look for mechanical problems that may be causing you to loose bottom end. How the silencer's packing? Has it been replaced recently? What’s the compression like. Many factory shop manuals wrongly identify the left and right power valves. Pull the pipe and look up into the exhaust port. Both sub port valves (the side valves) should be closed when the bikes not running. Pull the plug off the clutch side of the kips system and insert an appropriate sized t-handle on the nut. Rev the engine and insure the kips system is working. You'll know it is if the t-handle rotates. Check you jetting and let us know what's in there. Could be the pilot circuit is a little lean or the transition between the pilot circuit and needle is a little lean. There's lots of things to check before you go out and spend your hard earned money.
It would be nice to have someone like Eric look at your cylinder and determine what kind of power it was ported for. Could be all you need is some head work to bump the compression and you’ll be back in business. Do you have the tools to measure the port heights etc? If so that info should go a long way to helping determine what kind of porting you’re dealing with. Ever had the top end off?
David
Look for mechanical problems that may be causing you to loose bottom end. How the silencer's packing? Has it been replaced recently? What’s the compression like. Many factory shop manuals wrongly identify the left and right power valves. Pull the pipe and look up into the exhaust port. Both sub port valves (the side valves) should be closed when the bikes not running. Pull the plug off the clutch side of the kips system and insert an appropriate sized t-handle on the nut. Rev the engine and insure the kips system is working. You'll know it is if the t-handle rotates. Check you jetting and let us know what's in there. Could be the pilot circuit is a little lean or the transition between the pilot circuit and needle is a little lean. There's lots of things to check before you go out and spend your hard earned money.
It would be nice to have someone like Eric look at your cylinder and determine what kind of power it was ported for. Could be all you need is some head work to bump the compression and you’ll be back in business. Do you have the tools to measure the port heights etc? If so that info should go a long way to helping determine what kind of porting you’re dealing with. Ever had the top end off?
David
canyncarvr
~SPONSOR~
- Oct 14, 1999
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Porting can ruin a two stroke, for one thing. It's only as good as the person that did it.
If it 'was' an mx(wannabe) and ported for that, it'll stink in the woods.
As CDave said....better to find out what you've GOT before you start trying to FIX it.
If it 'was' an mx(wannabe) and ported for that, it'll stink in the woods.
As CDave said....better to find out what you've GOT before you start trying to FIX it.
- Thread starter
- #10
Sorry about that, As I was trying to say, what am i supposed to be looking for with the kips? Take something off and insert a T-handle of the right size? Can you give me more information about that? I will look to see about the pipe and the Jetting. I will talk to jeff and see if he can give me the phone number of the guy who owned the bike before him. I am not really sure what I am looking for if I take the head off. I think I have the tools needed to measure, but if I don't I know I have a friend that does. If it is ported for motocross would it be easier to just trade Jeff for a head that isn't ported? I will look at my bike tomorrow to check and see about that other stuff. Thanks for all the help!
canyncarvr
~SPONSOR~
- Oct 14, 1999
- 4,005
- 0
1. You need a manual.
In lieu of, 'please observe the following'.
I don't understand the 'insert T-handle' part myself. T-handle means 'allen' to me, and it's not an allen. Your model (H4/1998) kdx has a nut (92015A) that attaches the actuating rod to the main shaft. What CDave is referring to is observation of this nut to ensure the activating spring assy is operating correctly when the engine is revved (+6000rpm). If the assy is not moving, the activating system isn't working.
Maybe he's looking at your nick (91kdx) with the t-handle ref? It's different from yours, but it still has a nut...I think. Anyway...I said I didn't get it.
IF it is being activated properly, 'please observe the following':
With a socket on the LH side of the KIPS, you can manually activate the KIPS. With the pipe off, looking up inside the exhaust port and with manual activation you can ensure the subport drums (12005/005a) and main valve (12005c) are moving as they should.
The subport drums should rotate in sync and come to rest in the same relative position (they rotate in opposite directions).
I'd hazard a guess that if you don't know what you're looking for, you won't be able to discern what shape your head is in as far as volume (cc), squish angle and such. Same for port heights.
***Miss the 'left hand thread' note (if you take the KIPS apart), and you will likely cause serious damage to your kdx!! Either immediately, or at some most inopportune time.
Howzthat!!??
In lieu of, 'please observe the following'.
I don't understand the 'insert T-handle' part myself. T-handle means 'allen' to me, and it's not an allen. Your model (H4/1998) kdx has a nut (92015A) that attaches the actuating rod to the main shaft. What CDave is referring to is observation of this nut to ensure the activating spring assy is operating correctly when the engine is revved (+6000rpm). If the assy is not moving, the activating system isn't working.
Maybe he's looking at your nick (91kdx) with the t-handle ref? It's different from yours, but it still has a nut...I think. Anyway...I said I didn't get it.
IF it is being activated properly, 'please observe the following':
With a socket on the LH side of the KIPS, you can manually activate the KIPS. With the pipe off, looking up inside the exhaust port and with manual activation you can ensure the subport drums (12005/005a) and main valve (12005c) are moving as they should.
The subport drums should rotate in sync and come to rest in the same relative position (they rotate in opposite directions).
I'd hazard a guess that if you don't know what you're looking for, you won't be able to discern what shape your head is in as far as volume (cc), squish angle and such. Same for port heights.
***Miss the 'left hand thread' note (if you take the KIPS apart), and you will likely cause serious damage to your kdx!! Either immediately, or at some most inopportune time.
Howzthat!!??
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- Thread starter
- #12
Maybe I should change my screen name to 98KDX? I checked my pipe and silencer. My pipe is a K-30, and the Silencer Packing is in fair shape. I would have checked the carb/jetting but I didn't have enough time between baseball practice and homework. I have a manual but it is for a 91 KDX 200. I think it will still work for the 98, there hasn't been any big change besides cosmetics. I put on a 12t sprocket, it gave me more power but I ran out of gears way to fast. Thanks for the help!
- Thread starter
- #14
Canyncarvr to manually activate the KIPS like you said, don't I have to take off the head to do that and then push the kick start with my hand and watch the drums 12005/a? Or can I look up the exhuast where the pipe connect to the cyclinder and do the same thing? Also your confusing me with your comment of taking apart the kips? How could I destroy/harm it? I haven't been able to get ahold of Fredette, he has been out of town for awhile. Thank you for all of the help, one day I hope to be able to take apart my KDX and know how to put it back together and fix it on my own.
91kdx, you first need to learn a little more about what these nice people are trying to tell you. First, read in your manual or on this websites home page under tech tips the section on KIPS power valve. You need to understand what the powervalve on your bike does and also how it does it. That information is all here.
Canyncarvr and Canadian Dave were trying to tell you how to check correct operation of your KIPS valve, both were offering different techniques, both will work well. Correct KIPS valve operation has everything to do with low end proformance. Its important to do these tests because the valves themselves become "carboned-up" with use and stop functioning resulting in additional damage to the KIPS drive system.
Good luck
Canyncarvr and Canadian Dave were trying to tell you how to check correct operation of your KIPS valve, both were offering different techniques, both will work well. Correct KIPS valve operation has everything to do with low end proformance. Its important to do these tests because the valves themselves become "carboned-up" with use and stop functioning resulting in additional damage to the KIPS drive system.
Good luck
Canadian Dave
Super Power AssClown
- Apr 28, 1999
- 1,202
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mudwalker is exactly right we are suggesting you check the operation and timing of your KIPS valves to ensure they are working properly. Let me explain both methods.
If you remove the pipe and look up into the exhaust port you'll be able to see (from left to right) a sub port valve that rotates in its bore much like your 91 did, the main valve sits on top the port and lifts up to expose more of the port at higher (above 6000) rpm and lastly on the right hand side you'll see another sub port valve. What should you see? The sub port valves should be closed i.e. rotated so that they are blocking the flow of exhaust gases from the cylinder to the exhaust port, and the main valve should be in the lowered position. While you still have the pipe off you can confirm they are operating smoothly and without binding by removing the cover from the actuating shaft which is located on the throttle side of the cylinder just above the rubber boot that's running at about a 45-degree angle from the clutch area. With the cover removed you'll see a shaft with a nut on top holding a gear in place. If you place a wrench on the nut and gently rotate it clock wise you should see both sub port valves rotate to expose the cylinder tothe exhaust port and the main valve lift up exposing more of the exhaust port to the cylinder. The main valve will often become carboned up and not be raised or lowered properly into position and will require disassembly and cleaning to make it work properly.
CC was cautioning you to treat the advancer shaft (with the nut on top) gently. The shaft is more than strong enough to last forever if the nut on top is properly removed and installed. If its not the shaft can snap off at the bottom and engine damage can occur. To remove the nut the shaft must be supported and you must remember that the nut uses a REVERSE THREAD. For more info on this check out the JustKDX web page.
How to confirm the KIPS system is operating - on 1995+ KDXs there is a large, about the size of a quarter, plug located on the cylinder just in front of the resonator chamber (that's the rectangular lump on the side of the cylinder) If you remove this plug (often removed using a quarter clamped in the vice grip) and look inside you'll see that there is a nut. If you take a T-handle, which is simply socket welded to a 10" long extension with a handle welded on the end to form a T shape, and install it on the nut, then rev the engine you should see the T-handle rotate as the KIPS valves rotate open. If you have a friend handy you can get them to look into the hole and confirm its rotating with out using a T-handle. The T-handle will allow you to perform the test by your self with out a helper. This will tell you if the system is operating i.e. if the KIPS shaft is rotating.
As for your cylinder I'd measure what you have before swapping it for another. A couple quick things to check would include measuring from the top to the bottom of the cylinder where the head gasket and base gasket sit then measure from the top of the cylinder where the head gasket sits to the top of the exhaust port. Also have a look at the transfer ports (the ports than run from the crankcase to the cylinder) and see if there is obvious machining there. Lastly look at the exhaust port and see if there is a notch etc ground into the top of the port or if there is any obvious machining there. Don't worry too much about measuring the cylinder head. Its going to be difficult to confirm the squish angle etc with out the proper tools. Also check to confirm if more than one base gasket has been used between the cylinder and case. If you can get back to me with this info we should be able to determine if its been ported and for what type of power delivery.
I'd pick up a 95+ KDX200 manual. The top end on your new bike is completely different than you 91 with a completely redesigned KIPS system.
If you remove the pipe and look up into the exhaust port you'll be able to see (from left to right) a sub port valve that rotates in its bore much like your 91 did, the main valve sits on top the port and lifts up to expose more of the port at higher (above 6000) rpm and lastly on the right hand side you'll see another sub port valve. What should you see? The sub port valves should be closed i.e. rotated so that they are blocking the flow of exhaust gases from the cylinder to the exhaust port, and the main valve should be in the lowered position. While you still have the pipe off you can confirm they are operating smoothly and without binding by removing the cover from the actuating shaft which is located on the throttle side of the cylinder just above the rubber boot that's running at about a 45-degree angle from the clutch area. With the cover removed you'll see a shaft with a nut on top holding a gear in place. If you place a wrench on the nut and gently rotate it clock wise you should see both sub port valves rotate to expose the cylinder tothe exhaust port and the main valve lift up exposing more of the exhaust port to the cylinder. The main valve will often become carboned up and not be raised or lowered properly into position and will require disassembly and cleaning to make it work properly.
CC was cautioning you to treat the advancer shaft (with the nut on top) gently. The shaft is more than strong enough to last forever if the nut on top is properly removed and installed. If its not the shaft can snap off at the bottom and engine damage can occur. To remove the nut the shaft must be supported and you must remember that the nut uses a REVERSE THREAD. For more info on this check out the JustKDX web page.
How to confirm the KIPS system is operating - on 1995+ KDXs there is a large, about the size of a quarter, plug located on the cylinder just in front of the resonator chamber (that's the rectangular lump on the side of the cylinder) If you remove this plug (often removed using a quarter clamped in the vice grip) and look inside you'll see that there is a nut. If you take a T-handle, which is simply socket welded to a 10" long extension with a handle welded on the end to form a T shape, and install it on the nut, then rev the engine you should see the T-handle rotate as the KIPS valves rotate open. If you have a friend handy you can get them to look into the hole and confirm its rotating with out using a T-handle. The T-handle will allow you to perform the test by your self with out a helper. This will tell you if the system is operating i.e. if the KIPS shaft is rotating.
As for your cylinder I'd measure what you have before swapping it for another. A couple quick things to check would include measuring from the top to the bottom of the cylinder where the head gasket and base gasket sit then measure from the top of the cylinder where the head gasket sits to the top of the exhaust port. Also have a look at the transfer ports (the ports than run from the crankcase to the cylinder) and see if there is obvious machining there. Lastly look at the exhaust port and see if there is a notch etc ground into the top of the port or if there is any obvious machining there. Don't worry too much about measuring the cylinder head. Its going to be difficult to confirm the squish angle etc with out the proper tools. Also check to confirm if more than one base gasket has been used between the cylinder and case. If you can get back to me with this info we should be able to determine if its been ported and for what type of power delivery.
I'd pick up a 95+ KDX200 manual. The top end on your new bike is completely different than you 91 with a completely redesigned KIPS system.
- Thread starter
- #17
Okay, Thanks for confirming everything for me! I wasn't sure what you guys were talking about with the Kips shaft rotating. I am not terribly worried about the bike being ported, it will just give me another reason to get another bike! I will have my dad help me with checking if that KIPS Bolt is turning. I will get back to you guys on that, and the jetting. Instead of taking the bike apart I am going to try and find the previous owners phone # and ask him. Jeff could have been wrong when he told me what was wrong with the bike. And if the bike was ported I can find out who did it and what kind of porting had been done. Thanks for all of the help, I appreciate it!
- Thread starter
- #18
The kips is working fine. I took that screw off with a quarter and I had my little brother start and rev the bike. That little gear and 10mm nut turned to the left when my brother reved the bike up and then when the revs went down the nut turned to the right again. It has got to be the K -30 pipe or the porting (if porting was done). Is there anything else I should check for? Thanks for the help, the way you guys taught me to check the KIPS is a lot easier than I thought it would be.
Ben
Ben
- Jan 8, 2000
- 3,331
- 1
Good job on checking the KIPS. Don't forget to check the jetting. Heck, just fool with the air screw, that might give you what you are looking for.
canyncarvr
~SPONSOR~
- Oct 14, 1999
- 4,005
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Well..there is one thing you could check....
... is the KIPS working????
The fact that the main shaft is rotating as you describe in your last post is not the final say-so that it's ok.
Re-read (read?) the post from CDave regarding the subport drums, how the rotate, what they look like @ different stages of KIPS operation. Now that you know the activation is taking place, check to see that all the stuff that is supposed to be moving is moving.
...........and that's all I have to say about that.........
... is the KIPS working????
The fact that the main shaft is rotating as you describe in your last post is not the final say-so that it's ok.
Re-read (read?) the post from CDave regarding the subport drums, how the rotate, what they look like @ different stages of KIPS operation. Now that you know the activation is taking place, check to see that all the stuff that is supposed to be moving is moving.
...........and that's all I have to say about that.........
- Thread starter
- #21
Will do! I have 20 more days of school or something like that, and all 20 of them are booked with baseball games. So I won't be able to check anything for awhile. I also just blew a fork seal so when I have the forks off I will check and see if the drums are operating smoothly. Thanks for all of the help!
Ben
Ben
canyncarvr
~SPONSOR~
- Oct 14, 1999
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Back to the basics of your question: An 'H' model kdx200 that you want more bottom end from.
Considering your bike to be mechanically sound, the first response from kdxmann is a big deal. The 200 won't have bottom end for diddle with the -30 (rev) pipe.
There are two choices from that point. Either off the -30 in preference for a -35 (torque pipe), or for a bit less money you could put in a deltaforceII reed cage system with the reeds set to low tension. That is the only setup I've come across that makes the -30 pipe useable in the woods on my 200.
AND, you get to keep the 'fun' factor of the rev pipe.
You get to have your cake and eat it too!
Considering your bike to be mechanically sound, the first response from kdxmann is a big deal. The 200 won't have bottom end for diddle with the -30 (rev) pipe.
There are two choices from that point. Either off the -30 in preference for a -35 (torque pipe), or for a bit less money you could put in a deltaforceII reed cage system with the reeds set to low tension. That is the only setup I've come across that makes the -30 pipe useable in the woods on my 200.
AND, you get to keep the 'fun' factor of the rev pipe.
You get to have your cake and eat it too!
canyncarvr, do you run the K-30, sounds like you do. Question, reed cage and keep the K-30 (how much $ for the reed cage) or go for the K-35)? Sounds like I answered my own question, oops. I'm looking into swapping my K-30 for a K-35 and it sounds like I may end up missing it.
canyncarvr
~SPONSOR~
- Oct 14, 1999
- 4,005
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Yes, I run the -30.
Yes, I run the -35.
I have both because it is worth the trouble changing them for different riding areas. Going to the sand (coast? glamis?). Rejet, strap on the -30, retard the ignition timing. Riding in the woods? Rejet, strap on the -35, change the timing back.
Last time back from the sand I figured I'd give the -30 another shot in the woods with my 'new' DFII. I was surprised to find that it worked! THEN I set the reeds to low tension......and it worked even better! I've got at least as much on the bottom as I had with the -35, and like I said, the -30 can be a blast!!
There are some tradeoffs (wow. THAT'S a surprise! ;) )
Woods riding with the -30 has a larger 'wear out' factor than the -35 does. Throttle control becomes very important. The hit of the -30 is substantial..even with a FWW. Your shoulders will likely feel like you've been trying to pull an arctic cat quad out of a ditch with a rope all day!
That's what they make advil for!
The DFII is less $$ than the pipe, given average retail, by about $30. The DFII is a great compliment to either pipe profile. Keep your -30 and give the DFII a shot, imo. If you don't like it, keep your -30 and buy a -35 so you'll be a good boy scout (prepared!).
...and repack your silencer (if you have a packable one) while you're at it!
Yes, I run the -35.
I have both because it is worth the trouble changing them for different riding areas. Going to the sand (coast? glamis?). Rejet, strap on the -30, retard the ignition timing. Riding in the woods? Rejet, strap on the -35, change the timing back.
Last time back from the sand I figured I'd give the -30 another shot in the woods with my 'new' DFII. I was surprised to find that it worked! THEN I set the reeds to low tension......and it worked even better! I've got at least as much on the bottom as I had with the -35, and like I said, the -30 can be a blast!!
There are some tradeoffs (wow. THAT'S a surprise! ;) )
Woods riding with the -30 has a larger 'wear out' factor than the -35 does. Throttle control becomes very important. The hit of the -30 is substantial..even with a FWW. Your shoulders will likely feel like you've been trying to pull an arctic cat quad out of a ditch with a rope all day!
That's what they make advil for!
The DFII is less $$ than the pipe, given average retail, by about $30. The DFII is a great compliment to either pipe profile. Keep your -30 and give the DFII a shot, imo. If you don't like it, keep your -30 and buy a -35 so you'll be a good boy scout (prepared!).
...and repack your silencer (if you have a packable one) while you're at it!
I have very limited experience on a dirt bike and the KDX200 I bought last fall is my 1st. It came equipped with a rev pipe (-30) which I found very usable in the tight rocky rooty trails, but I have nothing to compare it to... I did change from a 13 front sprocket to a 12, and left the stock 47 rear.
The origional pipe and silencer also came with the bike, might be neat to try that sometime...
I fear that if I put on the stock pipe or a torque pipe I would miss my top end, although I rarley get into the higher gears I like the power range I have now.
The origional pipe and silencer also came with the bike, might be neat to try that sometime...
I fear that if I put on the stock pipe or a torque pipe I would miss my top end, although I rarley get into the higher gears I like the power range I have now.
