Ported Motor and flywheel weight

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#1
I purchased a 1996 '200 that has an FMF rev pipe and a ported cylinder (for top end).

I find I miss the bottom end pull a fair bit and was wondering whats the cheapest way of getting it (or some of it) back?

I was reading past posts about flywheel weights. Will one of these help me? Or should I shell out for a replacement (unported) cylinder?

Thanks in advance for any and all opinions !

Cheers

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Andrew
96 KDX200
remember: skin grows back!
 
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#2
My opinion is that a flywheel weight won't really "give" you more of anything except maybe traction. Now, you WILL be able to rev the bike a little more before the back tire breaks loose and THAT alone may cause you to THINK you've gained more torque. Their intended purpose is to keep the bike from building revs as quickly. To be honest with you, I've considered one for the 200. The Steahly is reasonably priced and you can easily take it off at any time. I had one on a CR250. I really think it's a great mod for big 2-strokes that ALREADY have a lot of torque and you just want to calm the "hit."

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Sage

dirtbike riding roadracer
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#3
a rad valve & 200 psi of cylinder pressure will get some bottom end out of it, if it has'nt got that already.

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Sage Wilkinson
sage@sagesdirtandstreet.com
 

fishhead

die you sycophant !
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#4
I've found the Boyesen power reeds(non carbon fiber)provide a noticable increase in bottom end. The flywheel weight will calm the hit as sage said and might prevent some stalling. But it doesent make more power it just absorbs and stores it in the form of inertia. I've ridden a kx with and without the weight and it did make quite a difference for woods riding.I would check the reeds, jetting and gearing before I plunked on a weight

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KelvinKDX

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#5
Yeah - what fishhead alluded to.

What gearing is the bike set up with?

Try a 12 tooth front sprocket. This will not cost you much and you will not have to change your chain length.

How is the jetting?

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'99 KDX200 (mine)
'01 TT-R125L (Wendy's)
 
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#6
Thanks for the replies fellas.
I neglected to say that I already do have Boysen reeds, and a trick looking aluminium intake tube instead of the original rubber one (Boysen product as well?)
Gearing is 13/48 which I find is a good combo for hills and fast fire trails.
Jetting is 155/45 which gives a darkish chocolate coloured plug.
Yeah, when I crack it open on flat ground I get a lot of wheel spin before finally getting traction (sometimes feels a bit like a slipping clutch, except that it's not !)
Also on steep hills I find it hard to lug it with low revs - once those powervalves open up, LOOK OUT!!
I realise flywheel weights won't increase bottom end power; I guess what I'm looking for is a way to redirect some of that power toward the low end of the rev range.

BTW Sage, my manual gives the max compression as 151 psi : how do you get 200 out of it? mill the bottom of the cylinder? If you do this, wouldn't that lower the port timing? and would that increase bottom end response??


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Andrew
96 KDX200
remember: skin grows back!

[This message has been edited by andrew (edited 04-16-2001).]
 
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#7
My 200 is ported for mostly top end, too and I did the following mods and got more low end than I know what to do with.

Torque ring from Fredette: $10
RAD valve: $160
RB carb mod: $160 Very worth it!
Answer SA: $? already had it on the 240.
48/13 or 14.

Hope this helps.

Brenda

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89, 92 KDX 200, 240
98 Montesa
94 ATK 250, 406
 

Canadian Dave

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#8
If you are looking for cheap then I'd consider:

1). Installing two extra copper gaskets between the pipe and cylinder or order a Fredette torque ring.

2). Play with your jetting including a different needle profile. Try richening your present needle one clip position and see how that helps as well.

3). Adjust your timing.

4). Have your cylinder head milled down for more compression and adjust the squish band.

5). Talk to a tuner with KDX experience and inquire about removing some material from the btm of the cylinder to lower the port timing a touch and increase compression. If they didn't originally do the work they'll likely need to measure up the cylinder before advising you.

I'd seriously consider having RB Designs mod. your carb. It sounds like exactly what you are looking for/need to improve throttle response at smaller throttle openings.

The silver intake is very likely a RAD valve.

David