Lighter flywheel for an h series 200?

Actionman · Post by **Actionman** » 10:53 pm Dec 23 2013

Is there a kx125 flywheel that'll fit my ole 02 200? I'm mostly riding wide open spaces and I'd like to try a lighter flywheel just for the heck of it. I love the stock engine but I'd like to collect a cadre of differing parts to tailor the power for different uses.

ecojbr · Post by **ecojbr** » 11:40 pm Dec 23 2013

The only option you have is lightening yours. The best I have been able to get off of mine is 8.3oz. Noticable difference, but really wish I could get more.

Marky360 · Post by **Marky360** » 07:42 am Dec 24 2013

I got 230 grams taken off mine real big difference head shaved, carby bored, ported was a great motorcross bike

cornishwrecker220 · Post by **cornishwrecker220** » 09:23 am Dec 24 2013

All a lightened flywheel will do is make your bike rev quicker ( more like an mx bike )....no real performance gains as such...it will also make it stall quicker too....kdx is just a play bike, enjoy it as it is or sell up for something more competitive.

ecojbr · Post by **ecojbr** » 11:59 am Dec 24 2013

IF YOU HAVE NEVER TRIED A LIGHTER FLYWHEEL, DON'T KNOCK IT. The KDX has such a heavy flywheel to start withb. 43.32 oz on my scale. the KX 250 is 22.62. That's alot. 8oz less is nice on the DX but it could really use more. The hard to stall is not noticed at 8 oz. I would like to see 14 come off the DX, just can't find where to get it at. Even Jeff Freddette likes the lighter weight!!!

Actionman · Post by **Actionman** » 12:49 pm Dec 24 2013

cornishwrecker220 wrote:All a lightened flywheel will do is make your bike rev quicker ( more like an mx bike )....no real performance gains as such...it will also make it stall quicker too....kdx is just a play bike, enjoy it as it is or sell up for something more competitive.

I understand the use and limitations if the kdx. I'm keeping the stock flywheel as well. This kdx reminds me if the 88 kx125, which a few of my friends had back in the day. I ride 98% strip job roads so it would be fun to set it up as a faux mx'er for when I feel like goofing around. Believe me, the heavy flywheel is a marvel in the tight woods because I've never been able to stall this thing out! But like I said, it would be cool to have different options for whatever mood strikes me. Ill order an ebay flywheel and proceed from there.

ecojbr · Post by **ecojbr** » 01:10 pm Dec 24 2013

Had an 88 myself. I also ride with guys who add 10 to there 220's. Sounds crazy but I am gonna ride one before I say it's stupid. I don't think you could stall a DX with 15oz off the wheel. They are just to trail friendly. Porting has so much to do with it.With the 8 off of mine it will still lug down to the point of chattering and recover from it which tells me more off would give it more zing.

cornishwrecker220 · Post by **cornishwrecker220** » 01:28 pm Dec 24 2013

Instead of messing around with the flywheel why not just send the head & carb off to be modified, or just go the whole hog & get the ports done too which will transform your kdx beyond belief....you will then have a bike that's great in the woods & also a ripper on the open tracks, sure it will cost you more $$ than a replacement flywheel but you will have a great little bike that I`m sure you will want to keep for a very very long time.

Actionman · Post by **Actionman** » 01:57 pm Dec 24 2013

Actually, next on my list is a total engine rebuild. I jumped the gun last night and ordered all new plastics, so I'm put off on the rebuild by a few months. While the rebuild is happening I'm picking up a fmf pipe and getting RB to work my head. Then it's new rims and spokes and front/ rear springs for the suspension. Believe me, I'm in it wayyy too much money wise to sell it now lol. I'm checking ebay as I speak for a flywheel and I'll have it lightened as well just for kicks. I'd love to have a 220 piston installed and may go that route on my 200 cylinder as well as a 220 head( with rb work) and the required power valve to fit the 220 cylinder. I want it to be right where I'd like it power wise since I'm keeping it. I feel like another 4-5 horsepower would be beyond perfect and wouldn't hurt the positive aspects of the kdx powerband. I just enjoy light tinkering- the kind that can easily be reversed. Btw: what exactly is the list of parts I need to make the jump to the 220 piston? Piston, head and center valve only? Thanks!

Actionman · Post by **Actionman** » 02:00 pm Dec 24 2013

ecojbr wrote:Had an 88 myself. I also ride with guys who add 10 to there 220's. Sounds crazy but I am gonna ride one before I say it's stupid. I don't think you could stall a DX with 15oz off the wheel. They are just to trail friendly. Porting has so much to do with it.With the 8 off of mine it will still lug down to the point of chattering and recover from it which tells me more off would give it more zing.

I literally climb almost verticle hills lugging at what feels like 200 rpm! It amazes me the torque of this little bike!

Actionman · Post by **Actionman** » 02:07 pm Dec 24 2013

cornishwrecker220 wrote:Instead of messing around with the flywheel why not just send the head & carb off to be modified, or just go the whole hog & get the ports done too which will transform your kdx beyond belief....you will then have a bike that's great in the woods & also a ripper on the open tracks, sure it will cost you more $$ than a replacement flywheel but you will have a great little bike that I`m sure you will want to keep for a very very long time.

I plan on performing a port cleanup on mine as well. As a 17 year old, I cleaned and matched the ports on my old 86 rm250 and the difference in power was extremely noticible. It gave a nice increase in torque more than hp, but it also cleaned up the low rpm response. I'd never grind ports wider or raise/ lower them, but I'd bet that stock kdx cylinders have a big room for improvement just on matching and removing burrs and flashing from the tunnel surfaces. A good mirror polish on the exhaust for carbon buildup purposes can't hurt either. I think I just got real lucky on that rm by not messing it up! I know what NOT to do now just in case. There's probably always a hidden 1/2 to 2 horsepower in every motor if they were blueprinted correctly I'd assume. I'm no expert though, do I don't plan on trying to be pro-circuit on my cylinder lol. Just a port match to the gasket surfaces and light cleanup.

ecojbr · Post by **ecojbr** » 02:22 pm Dec 24 2013

If you are going the 220 route. You will need a complete top end, cylinder, head, powervalves. It is a nice improvement. I did some port work to mine when I changed over to the 220. But I have a slight advantage as I used to build outboards and have all the porting tools and some of the knowledge. The 220 can be opened up quite a bit and still have it's stump pulling power. Couple that to a 200 carb, a tighter head and it becomes an amazing motor, that will like a lighter flywheel.

Actionman · Post by **Actionman** » 03:38 pm Dec 24 2013

ecojbr wrote:If you are going the 220 route. You will need a complete top end, cylinder, head, powervalves. It is a nice improvement. I did some port work to mine when I changed over to the 220. But I have a slight advantage as I used to build outboards and have all the porting tools and some of the knowledge. The 220 can be opened up quite a bit and still have it's stump pulling power. Couple that to a 200 carb, a tighter head and it becomes an amazing motor, that will like a lighter flywheel.

I'm thinking more of an overbore in my 200 cylinder. It looks like the center valve and a few smaller parts need replacing as well. I don't know; that's kind of back burner as far as what I'm going to do anyway. I'll decide when I send my cylinder off to have it recoated as to my decision. I may even do the 225cc "big bore" route if I've got $500 to spare. Who knows lol.

ecojbr · Post by **ecojbr** » 04:36 pm Dec 24 2013

Careful with big bores. On some bikes, the trade off of a bigger bore and loss of port volumes doesn't work so well. I have never spent much time with big bores as I have with port/head/piston combinations to have any real facts. But on some engines the loss of port volume can be a bigger loss than the gain of cylinder volume.

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