More Down Low on a 200?

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Mayor Brap Brap
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More Down Low on a 200?

Post by Mayor Brap Brap »

Is there a way to get more down low grunt on the 200? I love the way it runs, and I think the jetting is good, but when I hop on my friend's 220, it's like a rocket throttle. The 200 is awesome in the mid and top ranges, but I favor the grunt for tight technical trails.

I have a Gnarly Woods with Turbinecore, stock gearing, and that's all I know. I haven't touched the carb or looked at the reeds yet because it runs so nicely. I'm just questing for the oomph at the crack of the throttle.
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More Down Low on a 200?

Post by offshoretitan »

I have a 2004 KDX 220 with FMF Gnarly Woods pipe and TurbineCore 2 silencer. I recently had the Ron Black head and carb mods and installed the Vforce 3 reed block. It is an Amazing bike after these mods. I also used that opportunity to service all the bearings outside the engine (yes every single one); convert the front end to USD forks sprung and valved for my weight and riding style; and installed new tires. Tires I learned should be replaced every two - three years regardless of mileage or tread. My front tire was date coded to Feb 2003 and hard as a rock. You might want to consider these details as you contemplate improving your bike's performance and handling.

From reading this forum for some time, I think the RB mods for the 200 would help you achieve some of the same performance upgrades for your woods riding - especially your desire to have more 'down low'. There is a ton of information on this site. Search for terms relevant to your interest in the 200 and you'll find tons of information. Lastly, this site has no advertising. [Thank you Julien, Jason and others who make this site possible!] If you find this site valuable, make a generous contribution to support its presence on the web.
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More Down Low on a 200?

Post by B737driver »

:wink:
offshoretitan wrote:I have a 2004 KDX 220 with FMF Gnarly Woods pipe and TurbineCore 2 silencer. I recently had the Ron Black head and carb mods and installed the Vforce 3 reed block. It is an Amazing bike after these mods. I also used that opportunity to service all the bearings outside the engine (yes every single one); convert the front end to USD forks sprung and valved for my weight and riding style; and installed new tires. Tires I learned should be replaced every two - three years regardless of mileage or tread. My front tire was date coded to Feb 2003 and hard as a rock. You might want to consider these details as you contemplate improving your bike's performance and handling.

From reading this forum for some time, I think the RB mods for the 200 would help you achieve some of the same performance upgrades for your woods riding - especially your desire to have more 'down low'. There is a ton of information on this site. Search for terms relevant to your interest in the 200 and you'll find tons of information. Lastly, this site has no advertising. [Thank you Julien, Jason and others who make this site possible!] If you find this site valuable, make a generous contribution to support its presence on the web.


+1 on all of this...especially the last part... :yawinkle:
This was my setup for a long time. You will get more down low. The next level IMHO is the Eric Gorr 225 kit. This added more to every range ( low, mid, top) but it was most noticable in the low to mid range. Now my bike powers through the low end with no hesitation or stalling. I can ride a gear higher than before. This combined with the RB carb mods forms an awesome machine....exactly what I was looking for.

PS.....this is not meant to stir up a RB vs EG debate or a 200 vs 220 debate. Both RB and EG have done wonders to keep the mighty KDX competitive far beyond it's years. This is simply my opinion. :wink:
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Re: More Down Low on a 200?

Post by Mayor Brap Brap »

What's really throwing me for a loop is that my friend had a '95 200 that was hell on wheels. I don't think he ever touched the engine, but played with the gearing. That thing was almost too much.

His '01 220 on the other hand is perfect. It pulls instantly from the snap of the throttle, but does not overwhelm you.

My '06 200 is great, don't get me wrong. Mid and top end is beautiful, but it lacks that punch. My question is how is it that his '95 200 was the fiercest one of them all? I don't think he did any major mods aside from being piped. He did say it was a 'tired engine.'
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More Down Low on a 200?

Post by cornishwrecker220 »

You could just `deck` the cylinder , machine the head ( squish ) fit a `woods` pipe ......

or just buy a decent 220 ! :lol:
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Re: More Down Low on a 200?

Post by Jaguar »

the pipe sets the powerband.
I'd rather lathe some off the bottom of the cylinder (so that there is 1mm * squish clearance still) to lower the ports than have RB lathe the head down for the same clearance.

*I'm just guessing at the minimal acceptable squish clearance. If anyone knows what it is then please step in. Probably it is what RB leaves it at after lathing down the head.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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Re: More Down Low on a 200?

Post by Jaguar »

let me explain a little more...
the height of the ports cause the engine to favor an rpm range for its best power output the higher the ports, the higher the favored rpm.
But the pipe has a powerband, usually around 2000 rpm wide, that is determined by the pipe length and also its design determines if the power is spread out or is more peaky.
the pipe and the porting should agree.
the KDX comes with high ports and so putting a woods pipe on it gives a lot better down low power but could even be much better if the ports were lowered to match.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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More Down Low on a 200?

Post by pumpguy »

Interesting thread.

Can anyone chime in on what this revised port timing would be in terms of degrees of open duration?

Standard port timing for an H series 200 is, transfer 120 degrees, 60 degrees either side of BDC. Exhaust is , low speed 157.6 degrees, 78.8 degrees either side of BDC. High speed, KIPS open, is 185.4 degrees, 92.7 degrees either side of BDC. This is as published in my Service Manual.

Anyone have any actual experience with an H series 200 using a faced off cylinder base?
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Re: More Down Low on a 200?

Post by Mayor Brap Brap »

Man, this stuff is way over my head. No one has addressed the fact that I've ridden a 200 with minimal mods that's been faster and scarier than a 220.
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More Down Low on a 200?

Post by pumpguy »

The fundamental difference between the 200 and 220 is it's port timing. Other factors come into play including the carb size, cylinder cc displacement, head combustion chamber shape, and other things too. You would need to do some research to learn all the differences.

The 220 has less degrees of open duration for both the transfer and exhaust port timing. This results in better low end performance at the expense of top end. For specific cases, your mileage may vary.

To decrease the port timing of a 200 to the same timing as a 220, you would have to make the top of the exhaust and transfer ports lower. Adding metal to the 200's ports to make them lower is a difficult thing to do. I am sure there are people out there, and hopefully here too, that can answer your initial question and offer other suggestions.

You should be able to fit a complete 220 top end to your 200 lower. This would include a cylinder, piston, head, and I believe some KIPS parts too. You would need to check individual part numbers for their interchangeability.

The PO of my bike went the other way, converting the 220 to a 200. I assume this was due to an exploded 220 piston. Wish he had stayed with the 220, but it is what it is. Still tinkering with it, so can't comment on its performance.
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Re: More Down Low on a 200?

Post by Jaguar »

here's a good port duration calculator to know how many degrees you will decrease the duration by lowering the cylinder:
http://lambretta-images.com/archive/porttiming.php
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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More Down Low on a 200?

Post by pumpguy »

Great link! Thanks for posting. These calculations don't take KIPS into account for exhaust.

Need to enter numbers with KIPS closed and open to get exhaust duration for low and high speed.

Inlet can be ignored since KDX is reed valve while Lambretta is piston ported inlet.

Getting back to OP original question, I too would be interested in knowing what others have done to improve low speed performance of H Series 200. Anyone have any other ideas or experience besides torque pipe and smaller carb?
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More Down Low on a 200?

Post by cornishwrecker220 »

Jeff fredette makes a 'torque ring' that. Slips inside the exhaust port....it's supposed to aid with low end power with a small sacrifice on top end, perhaps someone on here has fitted one, if so then I'm sure they'll be able to give a little input?
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More Down Low on a 200?

Post by Tioli »

I made one and took it a bit further because of the sound wrap (Tioli's Soundwrap, still developing) the wrap kept the heat in the pipe and made my desert pipe even higher. Would make a woods pipe higher and stelfi.
The spacer did what I wanted plus some but I lost that really low near on staling sharp singal bang you get with the RB kit and a few touches. It's still good but not quite the same there are a lot of other things going on that I will sort my way throu to get it back. Feels like a easy fix would be to look for the SSS.
On a desert pipe without the sound wrap I'd say good way to change the nature of your pipe.

It starts a few pictures down
http://www.trials.com.au/forum/viewtopi ... &start=400

Answer to another question.
I use to set my squish at .8 mm. 6mm for rod stretch and .2 for safety. 2 degree angle. This is very much old technology.
2001 KX125 with a 1997 KDX Tioli Hp motor

My KDX journey starts at the bottom of this page:
http://www.trials.com.au/forum/viewtopi ... &start=160

Trials.com.au / Forum / All about...me! / My long time friend the prancing horse / page 9
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