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KDX rev limiter?

P455

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#1
Hi all. Noob here.

I'm coming to the world of KDX from musclecars, street bikes and dualsports... all of the above being 4-strokes with tachometers, so bear with me.

I've just gotten my '04 200 broken in, and am having an obscene amount of fun learning dirt riding. I'm not used to riding 2-stroke bikes, but I love the "hit".

My question is, does the KDX have a rev limiter? I've only gotten it up "on the pipe" a couple times, and it feels great, but I'm afraid of overrevving the engine. Is that even possible on a 2-stroke? Should I worry about how high I'm revving it? Am I being overly paranoid? (probably). Any help/advice welcome.

Mike
 

Smit-Dog

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#2
As long as the bike has been broken in properly, jetted correctly, and you're using the correct pre-mix ratio, don't worry about it.

There is not a rev-limiter, other than the size of your conjones....
 

canyncarvr

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#3
The kdx does not have an electronically controlled spark governor (read: rev limiter). The upper rev limit comes from a combination of things....port timing, scavenging/ramming effect of the exhaust, carb tuning etc.

While it's unlikely you are going to cause any damage to a (otherwise mechanically sound, properly tuned) 200 running it at WOT, it's always given me severe heartburn when someone twists it wide open in neutral and just sits there for awhile under the guise of 'clearing' something out. Or they think they're 'checking the main.'

Sheesh...just tune the thing right in the first place and that won't be an issue (you won't 'have to' do it).

The only time you should be concerned about an overreving situation is when you're breaking the bike in, or after a rebuild. Which is to say, don't put a new top-end in it...take it out and run it pinned.
 
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#4
Hey dude! As long as you have tranny oil, the proper fuel mixture, and not too lean a pilot---assuming everything is in good working order, ie. no crank air leaks etc..., you should be able to give it all you want under a load. That doesn't mean pegged wide open in 2nd---please upshift when you run out of revs. I cringe when some folks start their bikes cold and hold 'em wide open "to blow the cobwebs out??"---you wouldn't do that with your old four stroke toy, would you?? Don't worry---a little common sense goes a long way!! Jay
 

P455

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#5
Thanks for the reassurance! I would never free-rev the engine with no load on it, I just wanted to make sure I wasn't gonna blow something up by winding it up a little. Looking at the "carb tuning" article, it says to run it WOT for 20-30 seconds then do a plug chop... I was just worried about overrevving it.

thanks again!
 

canyncarvr

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#7
Whoa there...

For best results you should accelerate up a slight up hill section to place additional load on the engine. Continue to run the engine at WOT for 20 to 30 seconds longer if there is not fear the engine is running lean. If you suspect the engine is running lean 15 to 20 seconds to give you an indication. At the end of your full throttle run simultaneously push the kill button, chop the throttle and pull in the clutch. This procedure is often refereed to as a " plug chop". It is important to perform a plug chop exactly as described.
The WOT is part of the plug chop/main jet check process. It's not 'run it WOT', THEN do a plug chop. You're running WOT under load.

Right?

With your earlier post it's easy (well, for me!) to infer that there's a misunderstanding? Maybe?
 

P455

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#8
No no, it's cool. I would NOT run without a load... I bracket race and build my own engines, I know how to do a plug chop and plug check :) I also know what free-revving an engine can do to it. :0

I was just wondering how many revs I'd pull while doing that WOT for 30 seconds in 4th gear, NOT while parked along the trail.
 
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#9
methinks you should run out of revs between 10 & 11,000 rpm. unlike an
mx bike, this thing ain't crackin' 12,000 any time soon!
 

canyncarvr

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#10
If you get too many revs...make it 5th gear!

It's not the revs..it's the throttle position that matters.

You're on the right track, sounds like.

Have fun! These things are a blast, huh?
 
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#11
I have heard / read that at WOT you should run for 5-6miles before chopping the engine to get an accurate main jet reading from the plug!

Just my 2 cents worth.......