KX Riders
Maintenance & Technical => KX250 / KX125 => Topic started by: eprovenzano on December 16, 2005, 04:45:42 AM
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I do mainly trail riding, and was wondering if anyone was using a flywheel weight. If so what size, and what did it do for you?
I'm looking for more low-end power. When I purchased the bike it came with a PC pipe and PC silencer. I do have the original pipe and silencer, and was thinking about trying them just to see what the difference would be. I'm also thinking of changing the sprockets, dropping a tooth on the front, and adding 1-2 on the rear.
Any advice would be appreciated.
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I have a 96 Kx-250 with stock flywheel that i trail ride also. I used to have a 91 Kx-250 that had a Stealy weight on it. Basically the extra weight will keep it from stalling as easy at low rpm and keeps it from spinning the rear tire as easy when the power band hits. I think the GNCC guys run around 8-10 ounces of extra weight on their 2 strokes.
I would try adding 1 or 2 teeth to rear sprocket first. I'm running a 50t
sprocket on my 96 now and it helped the hill climbing noticeably. Dropping the countershaft a tooth will lower gearing a lot. I guess if you
do a lot of steep hills that might be the way to go also.
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The P.C. pipe will probably rob you of low end. They are more of a peaky type m/x race setup. Try a FMF Gnarly, which will give you a good strong bottom end. Tradeoff is a slight loss of top end, but if your trailing it, its not gonna matter. Team the pipe with a VForce reed block for even more off a bottom end hit. You'll be sorted!
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I have an FMF Gnarly, VForce, Moose Spacer, Stealthy 16oz, and a Kenda Millville on a K5. The thing is a tractor!
My buddy on the other hand has a YZ 250 with a PC pipe VForce and Moose Spacer. That thing has a bundle of mid-range to top end but suffered on the bottom. He lives for weelies and wot, but is considering a stealthy for the woods because the excess weelspin is tearing the knobs off his tires, we have lots of roots. The tires really are a pain more than an expense cause my woman works with a guy whose kids race and gives her their old tires. A good tip for you guys who don't mind slightly worn tires for cheap.
Dale
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The reason I'm asking is I do a variety of riding types. For example back in mid November I went with a group to a local track. (This track had 2 full size MX tracks, one for the little kids, not to mention 400 acreages of trails.) I had a ball "pretending" to be and MX star... I then went riding with a friend through the wood. The week prior to our ride, a hare scramble was at this facility, so all of the markers were still up. Unfortunately after riding the track for several hours, I was pretty tired, and my friend races GNCC events. After about an hour, I told him to go do his thing and I'd see him back at the pits... (He was just tooooo quick through the woods.)
The following weekend I went with a different group (all quads) except for me on a 20-mile ride. The trails were ruff, very ruff. Even the detours around the deep stuff were very difficult. At one point we had to winch a 4-wheel drive out of the mud. The trails probably have not been used in years. I think I made it into 2nd gear twice in the trails, and up to 5th once on an open road.
Because I ride such a variety of terrain, I'm thinking of playing with the gearing. I?m planning on adding 2 teeth to the rear anyway. But if I know I'm going to the track/trails, I'd go with standard gearing, and If I know I'm going to be trail busting with quads, swap the front sprocket for one with one less tooth. I've never added weight to the flywheel, so I was wondering about the effect.
Any and all info greatly appreciated.
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Adding weight to the flywheel will help you if you ride really tight
trails. Like 1st or 2nd gear stuff that has you idling over obsticles
if you have a tendency to stall the bike here. Also on steep hills when you have to let off the gas for a second and then when you get back on the gas your bike wants to just spin instead of getting traction. Extra flywheel is good for this stuff. I hope this helps ya..
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OK. so the biggest advantage is the reduction of the wheel spin, reducing the "hit" of the band.
thanks guys, I now need to ponder my next move....
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Any suggestions as to weight size, and potential suppliers...
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Have a look in the reviews (http://www.pitbull-racing.com/modules.php?op=modload&name=Reviews&file=index&req=showcontent&id=16) . I am not sure you have that many choises. The Steahly ones comes in one weight only for the KX5.
//John
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My list shows 4 for a 99' @ $99.95 (a year old price)
7oz #619XL
9oz #619L
11oz #619
13oz #619h
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I have a 2004 KX 250 and i put a 51 tooth sprocket on the back and a 13oz. FWW. Where i live the trails are tight as heck and its 1-2nd gear all the time. The bike is alot easier to ride over roots,logs and technical stuff without stalling. Taming the hit from the powerband, i guess it did a bit but its no dog to ride it still has lots of punch.
There are only 2 brands to choose from that i know of, Steahly and SFB Racing. I got mine from SFB and it bolted on real easy with no set screws on the side like i think the steahly has.
Hope this helps ya.
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Thank you gentleman, (I use that term loosely... :wink: ) that's exactly what I needed to know.
I'll definitely add a flywheel weight to my winter purchases. Since I purchased my bikes used, I plan on placing the top end on both my KX, as well as my son's YZ. So I might as well throw on a flywheel as well....
Boys and their toys.... :roll:
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I took everyone's advice and purchased an 11oz flywheel weight. I was temped by the 13, but I don't want to lose the snap I love so much. I just need to make her a little more trail friendly. I'm also going to change the rear sproket, adding a few teeth.
I'm sure the gearing change will help, along the the addition of the flywheel weight, I'm ready for any type of trail or track...
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After some careful consideration, I replaced the front sprocket, dropping a tooth. I took her for a trail ride, and the difference was definitely noticeable. I was able top let her bog down, and with a twist of the throttle, get on it in a hurry.
I also purchased an 11oz flywheel weight. I'm having a tough time getting the nut off the crank. Any suggestions as to removing the nut.
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There is a special tool that holds the flywheel and you can use a impact driver to remove the nut with. It's hard to hold the flywheel and use a stand hand tools to remove it.
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Sometimes an oil filter wrench is the right size. I use a generic strap wrench. That nut should be normal thread (not left hand). Cam.
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Oil filter wrench is not a bad idea :-D . I was thinking of a c-clamp because that's kind of what the special tool looks like but with a handle.
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After some careful consideration, I replaced the front sprocket, dropping a tooth. I took her for a trail ride, and the difference was definitely noticeable. I was able top let her bog down, and with a twist of the throttle, get on it in a hurry.
I also purchased an 11oz flywheel weight. I'm having a tough time getting the nut off the crank. Any suggestions as to removing the nut.
My 2001 KX 250 is a woods bike, and I also changed my gearing....from 13/49 to 12/54. The change was dramatic and all for the better. I also have the Steahly 13 oz flywheel weight....another excellent purchase...no more stalling and the bike is far more manageable at the low rpm.
I removed my crank nut with an impact wrench. For installing and torquing the flywheel weight...I put my bike in 5th gear, and I crammed on both brakes while sitting on the bike and pulling on the torque wrench.....it was a little ungainly....but it worked.
I have also spent a fair bit of time getting the jetting just right...the bike starts first kick every time and it idles great....and has awesome throttle response too.
I still have the stock pipe with an FMF muffler [turbine-core]....once the pipe gathers a few more dents, I will be buying the FMF Gnarly.
Oh...almost forgot...I just put on a new rear tire.....it's amazing how the traction improves with some new rubber.
Ken
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The reason I'm asking is I do a variety of riding types. For example back in mid November I went with a group to a local track. (This track had 2 full size MX tracks, one for the little kids, not to mention 400 acreages of trails.) I had a ball "pretending" to be and MX star... I then went riding with a friend through the wood. The week prior to our ride, a hare scramble was at this facility, so all of the markers were still up. Unfortunately after riding the track for several hours, I was pretty tired, and my friend races GNCC events. After about an hour, I told him to go do his thing and I'd see him back at the pits... (He was just tooooo quick through the woods.)
The following weekend I went with a different group (all quads) except for me on a 20-mile ride. The trails were ruff, very ruff. Even the detours around the deep stuff were very difficult. At one point we had to winch a 4-wheel drive out of the mud. The trails probably have not been used in years. I think I made it into 2nd gear twice in the trails, and up to 5th once on an open road.
Because I ride such a variety of terrain, I'm thinking of playing with the gearing. I?m planning on adding 2 teeth to the rear anyway. But if I know I'm going to the track/trails, I'd go with standard gearing, and If I know I'm going to be trail busting with quads, swap the front sprocket for one with one less tooth. I've never added weight to the flywheel, so I was wondering about the effect.
Any and all info greatly appreciated.
I rode my KX500 stock for about a month. For the type of riding I do, which is varied trails, to casual MX'ing. I decided to try a flywheel weight. I added a Steahly 14 oz. weight. I must say what a HUGE improvement on ridibility and traction put to the dirt. My bike now "almost" feels like it has "4 stroke" like behavior. This is SO advantagious in slippery dirt and mud. Gone is the brutal voilent snap right off the bottome end. Contrary to when many people believe, you DON'T loose hp, you actually gain more upper rpm's because the engine is spinning so fast, the added weight prolongs the overrev on top end. I added 2 teeth to my rear sprocket, added the weight, a Moose torque spacer, and I have an FMF Gnarly pipe. My 500 is a fantastic woods bike now. (I wouldn't race a 500 in the woods, but at least now its fun, and manageable in technical trails) Itried the bike on an MX track with the weight also, and to my surprise, my bike was awesome, especially in the corners, the relaxed torque hit down low, allowed me to be so much smoother, and "chug" through the corners, rather than the typicall hard throttle "point-n-shoot" method.
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Does anyone have a 9oz they want to sell??
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Does anyone have a 9oz they want to sell??
Someone on Dirtrider.net has one for sale.
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Thanks! :-D