DT125R ARCHIVE

Energized · DTR Legend

RE: magnito weight removal/reduction

Calum122 · Guru

Ralzy wrote:
75 flying there hardly say that Yours must be supersonic then ?

-- Edited by Ralzy on Monday 4th of June 2012 07:39:39 PM

It's nothing compared to my aprilia.

But yeah it feels rapid. Takes a long stretch of road to get to 85 but it'll get there. Screaming its tits off anyway!

NorDt · Guru

Ralzy wrote:
Yes it is my bike it does have the modded flywheel on there yes. It is quicker than it was well it is for me its derestricted obviously & it does have carbon race reeds in there running standard bore it doesn`t have any other mods at the mo as I haven`t fitted bigger carb as of yet as im waiting for a conicol filter to arrive. TBF Can you tell me what type of sound for quicker or responsive should be like?

Do you need me to tell you what quicker and more responsive sounds like ?. Its the sound of the engine going from 1k rpm to 10 k rpm faster.

I wasnt trying to be rude or anything but i didnt actually hear that your bike with the modded flywheel was any more responsive or quicker than what else i heard.

But it could just be me, im proboably just used too the sound of mine..

Ralzy · Guru

lol Yeah but come on 85 on a DT for long periods just makes the engine unstable risky business at the end of the day

Ralzy · Guru

NorDt wrote:
Ralzy wrote:
Yes it is my bike it does have the modded flywheel on there yes. It is quicker than it was well it is for me its derestricted obviously & it does have carbon race reeds in there running standard bore it doesn`t have any other mods at the mo as I haven`t fitted bigger carb as of yet as im waiting for a conicol filter to arrive. TBF Can you tell me what type of sound for quicker or responsive should be like?

Do you need me to tell you what quicker and more responsive sounds like ?. Its the sound of the engine going from 1k rpm to 10 k rpm faster.

I wasnt trying to be rude or anything but i didnt actually hear that your bike with the modded flywheel was any more responsive or quicker than what else i heard.

But it could just be me, im proboably just used too the sound of mine..

Thats a fair enough comment mate if you don`t think it sounds quicker then it doesn`t. We are all entitled to our opinons smile I just know how my bike performed before and how it does now and thats all I can say if I didn`t think it was an improvement to my bike I would simply say no drama smile

Energized · DTR Legend

He he , it's hit and miss with a lot of dts isn't it tho boys? like some top out at 70-75 and others 80-85, i think the only difference in that is the type of head you're running once all bikes are de-restricted right?

I was coming back from manchester earlier this evening with my mate on his rs because we wanted a nice long ride out to test his new exhaust bracket thing, i wasnt quite going flat out but was able to cruise at 75-80 down the A500 back to my buds house so i'm not fussed, these bikes were never about top end, just about how they got there :) but i'll agree with you ralzy mate, it does make you touch cotton hearing the pistion jerking off in her cylinder at 12k rpm a second at that speed lol.

Ralzy · Guru

lol funny shizzle mate smile

Ralzy · Guru

Yes it did create abit of a stir lol
What I can`t understand that things are still being said for e.g yesterday about it may have effects to main bearing & yet I have already stated on the 2nd April (this kind of mod will proberley require regular maintenance as it runs outside of the standard oem spec. Lads you have to face the fact if you mod things from standard guidelines it will require attention proberly more often rebuild etcs depending on the type of mod. I still think what NORFE has achieved is a star job and achievement in pushing our DT engine to its limits)
Man did not get where he is today without pushing himself & the things he created to the limits

-- Edited by Ralzy on Tuesday 5th of June 2012 11:48:57 AM

NORFE · DTR Trusted Engine Builder

caused quite a stir

simples

if you want a reliable bike buy a bike and keep it std and dont mod it

if u weant to live ,learn & experiment do every little mod u can and explore the ways and works of the machine do every thing u can

if it blows up u live and learn

as soon as u alter any machine from std u make it unreliable as its not running as mr yamaha intended it to

big bores on to any engine wont perform as good as any std top end as the piston is not balanced to the engine

so with out modding the balance shaft to match it will not rev as good as a std engine

you would get more power out of a std proply tuned engine than u do just chucking a big bore kit on

for a 2 stroke the carburation and expantion chamber has to be 100% or near enough in tune with the cylinder cc's for its optimum performance

so any one thinking of a big bore kit will be better spending money on cylinder work/exhaust/carb and suspension and brakes

unless your going to have an exhaust built,carb matched and the bottom end matched/crank & balance shaft then a few dyno runs to dial it in

simples

iv had every 2 stroke iv had in pieces playing with it, and apart from the kx-cr 500 wich i added weight to the rotor as there so aggressive iv reduced weight on the rotors never had a problem with any ov them killing mains

so if ur gonna worry about hurting your engine simply dont toutch it like ralzy sed

biggrin

NorDt · Guru

Okay Norfe,

Yeah i agree that you can get the standard barrel faster than than the athena 170cc if you mod the standard barrel but then you loose alot of reliability.

And i heard stuff about unbalance in the engine when you put on a big bore. But i cant really say i have noticed that for me. I even think i can push my dt to even a bit higher revs then what i could with the standard bore.

i can do 70 mph in 5th gear for example.

But you gotta understand that the 170cc is a cyllinder that gives more power on the low end rpms. And its supposed to be a good strong power up to the engine. It is 10 mm bigger than the standard piston. And therefore it can have bigger exhaust ports etc to without making it unreliable.

If you were to take the standard barrel and make the ports like the 170cc then your piston rings would proboably open up on the way past the exhaust port and kill em xD. Would proboably not take long either.

But yeah if you want to push the maximum out of your dt you could mod the standard barrel. Because it can proboably get more aggressive than the 170cc can ever be. But if you do that. Your not gonna end up with a engine you can use for everyday riding to school for example.

I wanna get into porting and stuff and try porting my standard barrel sometime. If i keep my dt long enough. Ive started considering taking up a loan next summer maybe and buying a bigger supermoto.

NorDt · Guru

And if you do the magneto weight removal right. Using a lathe. And you get it right. Because even if you use a lathe something can go wrong and it can go unbalanced. But if you manage to put it in the lathe. Turn it on and you see that the magneto is balanced, Like it doesent go any up or down while it spinning around. Then you can start cutting. And after youve done that and its right. Theres no reason why it should make the engine less reliable. In my mind atleast xD .

And Ralzy, The part about the main bearings is this. If the magneto is unbalanced it will do as i explained it will do in the lathe if its not fixed properly. It will go a bit up and down.

If you do it with a grinder you might end up with a magneto that is a bit heavier on one of the sides, And that should cause wear on especially the left main bearing.

the only way is YAMAHA DTR · Guru

FunkeyMunkeyDavid wrote:
had to check..1 has it other 2 don't.....
i'll weigh them both when the missus is out,see what the difference is? they also look slightly different sizes? magnets inside are defo different too

are these fly wheels interchangerble, mine looks like the one on the right and the wr200 looks like the left, just want to know , if i can fit the wr200 one on my engine (for my 200cc prdject) to change the timing,

also people lighten flywheels all the time, like stan stefans, the crank has a balancer shaft so it should be stable, you should weigh how much you have lightend it by

NORFE · DTR Trusted Engine Builder

as long as u change the stator as the older coils n stator wont fit inside the newer 1 vice vercer smile

NorDt · Guru

Yeah people lighten the flywheel all the time. But it should be done properly.

Maybe the shaft on the dt is strong enough to not feel any of the unbalance if theres just a little unbalance.

My friends have gotten their bearings killed, shortly after lightening the flywheel. But that was on a 50cc.

But it seems people is thinking im saying " Dont lighten the flywheel the engine will blow " but thats not what im saying, Im just saying do it properly so your shure its in balance, cause if you get it in balance thats not gonna do any harm to the engine at all.

mr karnage · Guru

you cant open up 125 cylinder ports to 170cc spec

port time area's relate to engine cc

unless the 170cc port time area's are the optimum for a 125 cylinder but that would render the 170cc cylinder as ****e

NorDt · Guru

I know a bit about porting. And my point was that if you were to push the maximum out of the standard barrel. Making the ports that put fuel in wider and the exhaust port wider. squish clearance smaller and stuff like that, You would be able to make the standard barrel faster than the 170cc barrel. But it wouldnt be as reliable as the 170cc barrel.

NorDt · Guru

When i said i know a bit, That was exactly what i ment, a bit. I know the basics xD

mr karnage · Guru

ring life would suffer a little but that would be it lol

NorDt · Guru

Yeah ^^

Ralzy · Guru

Maybe I need to get a helmet cam as she will rev up to 11/12 mark in using gears as mine without it the conversion would usually only rev up to 10 and a half mark it revs more freely for me thats what I`m trying to say mate smile

-- Edited by Ralzy on Thursday 12th of July 2012 03:20:14 AM

Ralzy · Guru

Updated video of magnito conversion

http://youtu.be/QCfWRdsxX_k

the only way is YAMAHA DTR · Guru

tbh mate i cant tell anything from that vid, just looks like normal reving

NEV · Guru

Get one of these smartphone/ iphone neoprene wriststraps off Ebay only a couple of quid,

NEV · Guru

Found this on another forum regarding lightened flywheels, I'm not saying it shouldn't be done, but there's always two sides to a coin, fair enough Norfe reckoned his worked ok.
But on reading this, and seeing what benefits it achieves, I'd be inclined to leave it myself.

A lighter flywheel does allow an engine to rev up quicker, but at the sacrifice of low end, yes.
It is due to a reduction of rotational inertia, which means there is less mass to get moving, which means the engine will spool up quicker.
But you will loose drive at low end when riding with torque rather than horsepower, as there'll be less momentum in the engine, due to loss of said rotational inertia.
It is intended for race bikes and not road bikes, as it can make riding uphill problematic, due to lack of rotational inertia in the engine. This matters not on big engines and also v-twins, but could be noticeable on a road going 2T, as they have f*ck all torque to start with and a lightened flywheel will reduce that further.

stillbroke · Guru

well i dont know whats different with my bike its gone off the clocks and next to mates car indicates 98?

stillbroke · Guru

whats up with it do you think?

NEV · Guru

By the sounds of it, bugger all, top end wise anyroad, what's it like at the lower revs?
If you have an iphone or similar, there's an app called 'DASHBOARD' gives you a true reading using GPS, I've a feeling it'll read a bit less than 98mph mind.

stillbroke · Guru

cheers nev but it does eat top ends,ive only done this speed a couple times once with eglogikz and the next with my mate it still wants to go more in some cases and it doesnt take long to get there

Ralzy · Guru

If I`m honest I never really found it any more difficult than normal with negotiating hills when I was living in Somerset with this mod. If I had the time again I wouldn`t have the modded flywheel again as it did help spin it faster compared to my original mag so that was a success.

But to be honest I was expecting it to be alot better than it was. That is no reflection towards Norfe`s workmanship, perhaps my expections was to high I don`t know?

stillbroke · Guru

Ralzy wrote:
If I`m honest I never really found it any more difficult than normal with negotiating hills when I was living in Somerset with this mod. If I had the time again I wouldn`t have the modded flywheel again as it did help spin it faster compared to my original mag so that was a success.

But to be honest I was expecting it to be alot better than it was. That is no reflection towards Norfe`s workmanship, perhaps my expections was to high I don`t know?

id lose weight off off myself before cutting the fly wheel to bits! surely removing al un nescersary parts having the right tyres etc will give you the same gains maybe not bottom end but overall