Kmx 125 tuning

[RobertCuthber...]

Hi I am wondering about tuning my Kmx 125 further I have already de-restricted the exhaust, activated the KIPS properly, changed to a twin air air filter element and installed carbon reeds and the bike runs well so I was wondering if there is any other way I could squeeze more power out of it. I don't really care about rely ability as I just use it for off roading so any suggestions would be much appreciated.
( I was also thinking of installing a kx 125 carb, kx manifold and kx reeblock as I have these parts lying around from a kx of the same year but all parts are bigger basically. Would this make a diffidence in power)

Thanks

[P.]

If you want it to go faster, just sell it and buy a 250?

[stevo as b4]

What do you want to gain?
More top speed? Better acceleration? better low speed pulling power?

A full power 24bhp 125 trailbike, should have reasonable go for most things really, and as long as your not trying to keep up with 125cc enduro or MX bikes on tracks etc, then I don't think you need to do a lot?

What gearing are you running? I would run lower than std gearing for 100% off road, either 13/48t or 13/50t depending on where your riding it?

[bezzabsa]

many moons ago when I was a lot younger and slimmer I had a KMX125...it would power wheelie in 1st,2nd,3rd and 4th...would wheelspin off the lights on wet roads, and had a great habit of trying to wheelie when banked over....That was all in fairly bog standard trim...they were listed at 16bhp IIRC and with airbox and KIPS (I tink) activated close to 25bhp..flat out would do 85 so guess its in the gearing!!

PS Red ones are faster

[bikersupermot...]

[Fladdem]

[andyscooter]

im with paddy

get a bigger bike

guessing op has a cbt only so cant go bigger

in wich case the mods would make the bike illeagal anyway so may as well have a bigger bike and get done for the no insurance anyway
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if its spelt wrong its my fat fingers and daft auto correct on my tablet

[RobertCuthber...]

At least some people get me, I like tuning bikes. I don't have a CBT I use the bike of road cause I'm 15. I was just wondering how I could tune it more, don't really care if it blows up or anything as Ill just rebuild it (hopefully it won't as I have just fully rebuilt the top and bottom end).So does anyone know how to tune it more. And also will putting the kx 125 carb, manifold and reed block increase power as I have that sitting around I'm presuming it will as all parts are larger and all fit the same. The bike is already pretty fast with what I have done to it, but just want to tune it as much as I can for fun and see what It can do for a bit of a laugh as it's a 25 year old bike.

Thanks

[bikersupermot...]

[Blau Zedong]

Tuning is stupid. Anything other than standard is folly.


Discuss.
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18:54:59 Rob Fzs: unless its their clothes/ hair/ golden teeth

[bezzabsa]

Corsa boiz know all about tuning.......

2.0 turbo diesel zafira still out drags them at the lights....


power aint everything...its all about Torque!!!!

[Rogerborg]

[G]

[RobertCuthber...]

Actually I never wrote "power aint everything...its all about Torque!!!!"

And I used the word power in general I just mean over all performance as in bhp and torque

[G]

My apologies, I got my quotes mixed up it seems; however my point still stands without that bit of evidence.

[P.]

A 250 2 stroke will have more power standard. Just grab one and use that.

Why fiddle with a grenade to make it louder when you can buy a pre-made nuclear bomb.

Bikerperson, you love your 250 right? Why don't you have a 125?

[RobertCuthber...]

Easy enough mistake to make, I actually do know a lot about tuning but I am fairly knew to the world of tuning 2 strokes but it's more 4 stroke engines but especially cg engines and Chinese engines i am used to tuning. so that's why I'm asking these questions as I have heard that 2 strokes are very easy to seize if you are not carful when tuning due to the fuel/airmixture. So I want to know if it's worth the hassle of putting these parts on and setting them up right and may not get a power/performance/torque increase.

[G]

You're not instilling confidence in your knowledge.

However, my point STILL stands; even more so.

Your best bet for what you claim is an 'interest' of yours would be to learn about it, rather than have someone say yay or nay.
If your interest is in having a faster bike, then that's another matter and tuning often isn't the best way.

[Fladdem]

[Fladdem]

Maybe, have a look at losing weight, within reason, i.e. titanium bolts are overkill. You could get your suspension set up nicely. Won't be a faster bike, but you could ride it faster. I'd look at brakes next too. In fact I'd look at brakes before any more engine mods.
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Current:1991 Honda MT50 (Soon to be a H100/MTX/MT5 hybrid), 1976 Honda Cub C70, 2005 Honda Varadero 125, 1993 Yamaha TTR250 Open Enduro , 2010 Road Legal Stomp YX140, 1994 Honda CRM 250 MK III, 1999 Cagiva Mito 125, 1992 Honda CB400 Super Four, Stomp T4 230, 1984 Honda H100s, 2009 Sym XS125K
Past:2003 Aprilia RS125, 1982 Kawasaki GPZ550(FREE BIKE!)
I'm having more fun than a well-oiled midget.

[pits]

Tuning a CG engine? Surely that's an oxymoron per sè.

The point trying to be made is simple, you're going to spend a load of cash doing everything to your 125, and it does seem that you have somewhat of an idea to what you're doing, but the next thing will be a 150 or 170 kit, why not just skip all that, sell it and buy 250 and the make that faster.

There is no replacement for displacement at the end of the day.


Nice spelling by the way, one suggestion, add some paragraphs to your posts
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Stinkwheel: You have no right to free speech
00:32:08 Blau Zedong: yes, i am a massive CB400 fan and collector
00:33:00 Blau Zedong: the CB400 is my favourite road bike

[stevo as b4]

I'm not going suggest doing anything either, as I think back to when I was 15 and inquisitive about 2strokes and tuning, and I really didn't know anything useful or have experience of carrying out successful engine work, despite reading a lot of books etc.

I also didn't have the funds to fully re-build a KMX125 or similar engine from the crank up with all new parts and to as good as new std, which I doubt the OP has?

If I wanted to learn about tuning for fun, I'd try to do it with someone else's bike and not my own, and I don't believe anymore in messing with things or fitting different parts without:
1, knowing or having a good idea of what I'm doing and what to expect afterwards.

2, Someone else having already done similar work and put in the experimentation/development time before I spend my money

3, access to and funds to pay for back to back dyno testing and tuning from someone who know's how to set up carbs on 2strokes and get the best from them

Messing with performance 2strokes at home, and trying to jet up an unknown carb etc from scratch to fuel just right is beyond most home mechanics IMO, and a lot of the time you will see blow up's before they even have got it run in or running right. You see this a lot with scooter boys and people with 125cc sportsbikes like RS125's that have re-built an engine 2-3times in quick succession after trying to tune or fitting aftermarket parts.

[nathan k]

I would say having the extra riding time will make you far faster then tuning and being off the road (field whatever) due to repairs and headaches. When you're spending, or risking, expensive bills for marginal power increases it all seems a little pointless.

Sure I understand the fun in it, i wasted all my savings on 'tuning' but at the end of it I was stuck with a broken bike and an empty bank wishing i'd have been content with going slower, focusing on developing the skills where it matters.

As mentioned, if you really want to tune focus on grip and brakes first.

[C1REX]

I think that a better suspension would make the biggest difference.
Spending a fortune to make the bike 10mph faster is not worth it.
It wouldn't be 125cc anymore anyway.
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[bladerunner]

I'm a great fan of tuning little bikes...it's fun if done right but tbh a well setup kmx is good for 85 mph anyhow which ain't bad for a 125 with aerodynamic drag of a typical brick!

Kawasaki did know how to make good smokers back in the day when they wanted to. Kinda thinking along the lines of the kmx and kr1's here!

If your off road riding then I'd gear the thing down for a lot more pull and less gaps between the gears.my kdx 200 pulls 65 mph max after I geared it up a bit for a bit more on road use ability.....a good kx125 does about 60 mph tops but both get there in short time and both make a lot more peak power than your kmx

It's cheap and dropping a tooth or 2 on the front sprocket will mean you probably end up with more go than you can use in the lower gears off road on a kmx anyhow.....I know it sounds boring but it's going to cost you £6 to try it and 10 minutes work to revert back to std if you find your not liking the wheelie prone rooster monster your over geared kmx has turned into. Failing that you can fit a kmx200 top end and crank and have the option of the same engine with a lot more go and similar reliability. Tbh....just fitting a kdx carb and reeds is not going to get you any more hp as the exhaust is the first thing to change if your after hp and even then....having the head machined for better squish and CR is going to yield better results. The porting on the std kmx motor is good to start with and yields little in the way of extra bhp....same with the reeds....std is good to start off with unlike some of the earlier 2t motors. Also first I'd start by making sure the engine is in good nick to start with...kips valves failing is common .....ask me how I know! That will make a big difference trust me!
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's