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two stroke performance mods?

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new here and i apologise as this shit has been covered countless times and im proberbly going to get told to use the search bar (people say it on every single forum and you can never find s**t with them lol) so anyway....
basically iv had my 07 kx250 since new and recently started spending a bit of money on it and now looking into engine performance, besides the obvious pipe/reeds/jetting (which iv ordered) what else is there which can make a difference? dont fancy getting into porting just yet. 

read this site last night

http://yz250-horsepower.700hp.com/

few things on there interested me....

 

aftermarket coils....will they actualy make a difference? 

 

castor oil?...... the site claims they gained 3.5hp on a cr 500 by using it which seems quite a bold claim 

 

also what do people rekon of using atf fluid in the gearbox

 

 

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Aftermarket coils won't fix a problem unless there is one.  If you have spark hot enough to ignite the fuel charge reliably and on time as it stands, there's nothing that increasing the strength of the spark can accomplish.

 

ATF works OK in most 2-Stroke transmissions, and the clutch will get along with it, but you won't get a lot of free power from it.

 

Castor oil is very simply the best engine oil that exists, looking only at its lubricating abilities and its tolerance for heat.  The claim of 3 HP is a little suspect, however.  The thing is that you would need to compare both the oil and the mix ratios to get any clearer picture of their findings.  The other thing is that 3 is a smaller percentage of probably something like 60 that the CR500 may have had than of the 40 or so your KX has.   Castor is also messy.  It leaves a stubborn gummy scum on everything it touches, and has been know to gum up power valves.  Excellent oil, nevertheless.

 

If you aren't interested in porting, about the only way to gain much of any significance is through the use of a remappable CDI box.  At that, you'd more likely only make big gains in the middle range.

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Aftermarket coils won't fix a problem unless there is one.  If you have spark hot enough to ignite the fuel charge reliably and on time as it stands, there's nothing that increasing the strength of the spark can accomplish.

 

ATF works OK in most 2-Stroke transmissions, and the clutch will get along with it, but you won't get a lot of free power from it.

 

Castor oil is very simply the best engine oil that exists, looking only at its lubricating abilities and its tolerance for heat.  The claim of 3 HP is a little suspect, however.  The thing is that you would need to compare both the oil and the mix ratios to get any clearer picture of their findings.  The other thing is that 3 is a smaller percentage of probably something like 60 that the CR500 may have had than of the 40 or so your KX has.   Castor is also messy.  It leaves a stubborn gummy scum on everything it touches, and has been know to gum up power valves.  Excellent oil, nevertheless.

 

If you aren't interested in porting, about the only way to gain much of any significance is through the use of a remappable CDI box.  At that, you'd more likely only make big gains in the middle range.

cheers for the response,

there isnt nessasarilly a problem with my coil atm but it is looking a bit tired and wondered if its worth getting aftermarket or oem.

if you can gain or more apropriately loose less power from atf fluid i might try it, 

the only real reason im not interested in porting atm is not knowing of anyone who specialises in the type of thing and would rather not do it myself really. also the time having the bike unusuable while its getting done. il look into cdi boxes :) 

cheers

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....a few hours later and im starting to consider porting seriously haha, does anyone know of any well known companies etc (in uk) which can do a proper job?, going to look into prices etc 

Edited by pwalker

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For a two-stroke, porting is by far the biggest bang for the buck. A good tuner can make far greater performance gains than all the bolt-ons you can throw at it put together, for a fraction of the cost.

 

However, a bad tuner can easily ruin a perfectly good cylinder in five minutes or less. Don't try it yourself if you don't  know what you're doing.

 

No idea who you would use over there on that side of the pond though... :excuseme:

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Just shouting out a name doesn't mean anything.

Why choose them?

Why does it matter? Lol

I use him for all of my porting he's been doing it since the 70s

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Have you had your suspension set up for the type of riding you do and your weight already? If not, do that first. If you want a preceived change, change your gear ratio. Lower gearing will make your bike feel more powerful.

 

After a while and you feel you need more, make sure the squish band is correct, port match the cases to the cylinder head, and have someone port your cylinder for the type of riding you do.

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Have you had your suspension set up for the type of riding you do and your weight already? If not, do that first. If you want a preceived change, change your gear ratio. Lower gearing will make your bike feel more powerful.

After a while and you feel you need more, make sure the squish band is correct, port match the cases to the cylinder head, and have someone port your cylinder for the type of riding you do.

Yeah suspension has all been sorted, I don't NEED more power now for track riding but I do quite a lot of play/free riding and going to the beach etc aswell and just want it haha, I'm basicay just minting the bike up to make it perfect and then going to look at getting a 450 for track riding and keeping this as a proper sorted play bike

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You said the suspension has been sorted out.  Keep a fresh top end in it, fresh tires, fresh muffler packing and tweak the jetting as necessary. IMHO, porting and cylinder head mods are comprimises that move the power band around a bit , effect max power that you rarely use, and may narrow or broaden the power slightly.  I prefer to keep it close to stock, running reliably, and invest in improving the rider's performance...

And keep the suspension fluids fresh, especially the shock oil....

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Yeah it's had pretty much everything lately, within last few month it's had

Suspension revalved/resprung, Skf seals

Pro circuit pipe and silencer (yesterday :D)

Awaiting delivery of boysen rad valve

New Dunlops front and back

New pads front and back

Piston done, cleaned all power valve etc same time,

Spark plugs and gear oil changed regularily,

Full hose kit

New plastics and graphics,

New handlebars/grips etc

Front brake master cylinder rebuilt

Carb stripped and cleaned

New rear chain guide

Ordered new gear selector shaft and apico lever as my splines are a bit worn

Proberbly more iv forgot,

All that's left on my current to do list is:

Jet it for pipe and rad valve

Tall seat

Some nice wheels and hubs

Maybe some bling pegs

And finaly powder coat the frame

After that I don't think there will be much more money I can throw at it lol, so thaught if consider other power mods might just leave it as it is...I haven't actualy rode it with even the pipe on yet so with the pipe and rad valve and jetted I might be happy anyway

Edited by pwalker

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Don't do so many power until you can ride it in the top end pretty much the whole track, or you will not get the power from the mods.

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Don't do so many power until you can ride it in the top end pretty much the whole track, or you will not get the power from the mods.

i know i dont need it for track riding as i said but i dont just ride tracks alone. and your just referring to peak power anyway im interested in any mods that can improve lower down power aswell which would obviously still benefit my track riding

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Caster oil is, as said, the best protection. But not only is it messy, but it denatures the gas after its mixed in a few days. The means you should not use premix that is a week old. This is bad for dirt riders, since we often don't use that much gas in a month. Years ago, Klotz sold caster pre-mix with 100 octane gas that was homogenized, and it would not denature. Great stuff, you could drain it out of your gas tank into a 5 gallon can and use it much later. Last time I checked, they no longer offered it.

Back in the 70s, I used to just pour premix into my truck's gas tank on the way home from a race. Can't do that with modern trucks with catalytic convertors.

 

One big thing to know about porting, it can only move around the torque curve. Sure, done right, you get more peak power, but over a narrower powerband. Perfect for road racing. Probably OK for Motocross. Not at all good for trail riding, enduro, or ISDE riding.

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One big thing to know about porting, it can only move around the torque curve. Sure, done right, you get more peak power, but over a narrower powerband. Perfect for road racing. Probably OK for Motocross. Not at all good for trail riding, enduro, or ISDE riding.

 

 

This is a generalized blanket statement, and as such is not necessarily true. On some engines, the engineers did an excellent job of squeezing power out, and there's not a lot of easy power to be found by aftermarket tuners. On other engines big gains can be found everywhere by someone that knows what they're doing.

 

It also depends on what you tell the tuner you want out of the engine. Are you looking for big peak numbers? Better torque spread? Improved low-to-mid? Improved top? What sort of fuel do you want to run?

 

Most of the engines that I have had ported over the years have been improved everywhere.

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This is a generalized blanket statement....Most of the engines that I have had ported over the years have been improved everywhere.

 

Sure, my statement is a generalization. Its not as sweeping as yours. Improving everywhere is really hard to do. Some basic cleanup, matching ports to case, removing rough casting lines, etc. can improve stuff everywhere, but only by a small amount.

If I were in a bad mood, I'd ask you to substantiate with dyno runs, timing slips, etc. that most have improved. But there is no point in being pedantic.

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Sure, my statement is a generalization. Its not as sweeping as yours. Improving everywhere is really hard to do. Some basic cleanup, matching ports to case, removing rough casting lines, etc. can improve stuff everywhere, but only by a small amount.

If I were in a bad mood, I'd ask you to substantiate with dyno runs, timing slips, etc. that most have improved. But there is no point in being pedantic.

 

 

:lol: I did say "most", not all. But point taken. :thumbsup:

 

The worst port job I ever got was from Pro Circuit. I sent my KDX250 cylinder to them, and explained that I wanted a broad spread with emphasis on low-to-mid, for tight technical mountain trails. What I got back was apparently a cookie-cutter Pro-MX port job, that resulted in a brutally aggressive, abrupt, hard-hitting mid-range-only power curve that was all but useless for off-road. I fought with them over it but got nowhere, and ended up simply buying a new cylinder and sending it elsewhere for work. This time I chose Eric Gorr, and what I got back was improved low-end grunt, smoother transition into a stronger mid, and better pull up top that revved out a little higher than stock. It was most definitely improved "everywhere" over stock.That bike would climb a tree if you could hang on,but would still run with MX bikes of the day in the more open areas. Eric gave me a sweet engine.

Edited by Chokey
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resulted in a brutally aggressive, abrupt, hard-hitting mid-range-only power curve that was all but useless for off-road. 

 

The typical hack job is aggressive, abrupt, hard-hitting top-end only with no mid-range and a negative bottom end. I hate it when you have to trash a cylinder, or worse, pair of cylinders.

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The typical hack job is aggressive, abrupt, hard-hitting top-end only with no mid-range and a negative bottom end. I hate it when you have to trash a cylinder, or worse, pair of cylinders.

 

 

Well I don't think I would call it a hack job, it was far more powerful than stock, and didn't have non-existant low-end or top-end, but they were overshadowed by the very punchy mid-range. But it was NOT what I asked for, it was best suited to a National caliber Supercross rider, not a trail spode like myself.

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