DT125R ARCHIVE

NORFE · DTR Trusted Engine Builder

RE: magnito weight removal/reduction

mr karnage · Guru

the only thing a heavy flywheel hides is an unbalanced engine

the reason why some cars have such heavy flywheels

thats what ive been told

but a single cylinder wont exactly be that unbalanaced it would cause extra wear

NorDt · Guru

Are you going to get it dyno tested ? Would be awesome to see how many hp. Have you ever dyno tested it before the mod ?

Calum122 · Guru

Ok. Well like I said i did a little research. The guys on the other forum were on about pit bikes. So what you guys are saying is that the clutch is not in direct contact with the fly wheel. They seemed to think it would have a direct effect to the clutch. But this was about inner rotor kits conversions. But i'm a noob and don't deserve the title 'Guru' lol. Leave that to NORFE and what not!

NORFE · DTR Trusted Engine Builder

only on a car transmission does the clutch sit on the fly wheel

in a bike engine the clutch sits on the end of the main shaft and just drives off the crank

another plus side the dtr had A balance shaft to counter act most of the vibration, so that helps even more with the removal of the mag weight

went out on it again yesterday its loads more fun

even better on the lanes to

quick slip of the clutch and its in the band with the valve lifting & back end trying to take over the front round the corners

-- Edited by NORFE on Monday 2nd of April 2012 11:21:40 AM

Calum122 · Guru

That sounds quality tbf!

Ralzy · Guru

mx bikes are defo built with a view with that regular rebuilds are carried out so this kind of mod is defo ok but what you have to bare mind this is 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 Nice 1 m8

-- Edited by Ralzy on Monday 2nd of April 2012 09:09:26 PM

mr karnage · Guru

init

how much you charging for this

Derbyian · DTR Respected Member

Just read this.... Does it make a big difference? If so I'll be doing it

NORFE · DTR Trusted Engine Builder

i think £17 should cover the lot inc postage back to you

tenner for me devoted time & effort smile

it took me about 35 mins with time cleaning it up after

£1 for cutting discs as it took 2 to do mine ( i use the 1 mm discs) dont last long but best for cutting

£6 ish post back to your self

hows that sound

NORFE · DTR Trusted Engine Builder

Derbyian wrote:
Just read this.... Does it make a big difference? If so I'll be doing it

WELL WHEN I TOOK BIKE OUT satdy, id forgot id dun it lol

i was flying round thinkin **** me shes runnin well today ha ha

did abit off off roading and it was just spot on like riding me old cr r8 revvy & responsive

then was riding home and remembered id put it on in the week

so yeah i noticed a big difrence biggrin

NorDt · Guru

Sounds cool :D , But are there no bad sides about this ? Will this reduce the reliability of the engine in any way ? :S maybe ill consider doing it too.

eG x LoGiKzZ · Guru

you really reckon if makes that much difference? does it make the bike rev more or just rev up quicker?

Calum122 · Guru

NorDt wrote:
Sounds cool :D , But are there no bad sides about this ? Will this reduce the reliability of the engine in any way ? :S maybe ill consider doing it too.

We've been through all this before. Check the previous page FML :\

NORFE · DTR Trusted Engine Builder

had it off the clock ona down hil screaming like lol

the engine spinning up was loads quicker getting you off quicker felt like it was totally different thats the reason i thort it was running r8 well screaming allover place lol, valve opens quicker as your in the band faster with the reduction in mas spinning the engine dont have as much work to do to get it goin if you get me

smile

eG x LoGiKzZ · Guru

ahh when you put it that way it sounds like a good idea, less work for the engine, think ill try this soon

mr karnage · Guru

break it, upgrade it

NORFE · DTR Trusted Engine Builder

mr karnage wrote:
break it, upgrade it

exactly lads

i only use mine the odd hour a week due to 1 naggin mrs and 2 rug razts so dont get much free time, so i want it to be as much fun as possible, and if it breaks im not fussed, it just gives me sumets to do fixing it...then breaking it again ha

no pain no gain ha ha

NorDt · Guru

But i dont think this should be in the de restricting really xD, This isnt no restriction to make it slower, What ive heard is that with a heavier magneto wheel you get more torque, More power from the bottom.

Have you noticed loosing any power on the lower rpms norfe ?

NORFE · DTR Trusted Engine Builder

NO MATE

was flat out every where other day up hills off roading and wheelien and shooting off from the lights, and im 19 stone, it never missed a beat and did every fin i wanted it 2 do

smile

NorDt · Guru

Okay, Sounds great :D!

Derbyian · DTR Respected Member

How's the bike running since?

NORFE · DTR Trusted Engine Builder

no change mate still good as ! biggrin

mr karnage · Guru

once my bikes run in im defo sending my spare flywheel your way mate

NORFE · DTR Trusted Engine Builder

no probs iv got one ready for exchange any way biggrin

DT-R_bradders · Guru

the only way is YAMAHA DTR wrote:
Calum122 wrote:
I've done a little research!

The Magnito weight acts like a damper for resonance (that is a dramtic increase in amplitude when a driving frequency, i.e. the engine, equals the natrual frequency, i.e. any part on the bike, of an oscillating system. And no I didn't look that up that's from memory ). So by altering that weight you change the natrual frequency of the bike. Reducing the weight increases it's natrual frequency (I think). This means that your bike now needs a higher frequency in orfer to resonate. Which isn't hard since there are so many mechanical parts moving a different frequencies. If you encounter such dramatic 'vibrations' then you've reached resonance.

That's one problem that you face by reducing the weight. I don't think you'll meet it due to the small reduction in weight. However that added weight is also to reduce wear on the engine. Parts like the small end bearings, big end bearings, conrod etc.

More importantly (I think this is factor of the inner rotor kit) is that you will unbalance the clutch. With such a light weight on one side and a heavy weight on the other you unbalance the clutch and effectively ruin it. I really think that's for the inner rotor kit. They say that if you do do a inner rotor kit then you need to have the whole engine rebalanced.

For you NORFE I think you'll be alright. I'm not sure how you ride your bike but I use mine as my sole transport. If you just ride it for fun then I don't think it will make much difference to the reliability.

What would be interesting is to see the performance gain. Is the performance well worth the loss in reliabilty. Hey NORFE if it breaks let us know lol.
won't unbalance the clutch because the clutch is on a separate shaft and not the crank shaft

+1 on tht "only way", if wat calum says was true imagen the weight ur effectivly be adding wen the clutch is engaged and the engine is pulling u and the bike along...**** loads, i was gonna do the same to mine but iv got the oldskool flywheel wer the flywheel weight is the big chunky magnets thats bolted to the inside of the flywheel, was gonna remove 2/4 of them to see wat would happen but my flywheel is on there solid!plus i think the stator/reg wouldnt like it too much lol

the only thing i woulda done different norfe is i woulda turned it down on a lathe, that way it would of been near perfect balance, providing u can get the flywheel on the chuck bang on true lol

you done a good job there tho m8 if ur gettin no vibes thru the bike, great bit of craftsmanship there wink u know u can still turn it on a lathe to remove the pointed areas plus urll loose an extra few grams on top or jus drill out thos big ass rivets n loose the lot lol

NORFE · DTR Trusted Engine Builder

thats what i was gonna do to start with but the weight is actuall riveted on to a cup with the magnets in, the bit that mounts on to the crank is part of the weight if u get me the only way to get round it is to cut the centre out and weld it to the outer casing with the magnets in

i did get my mat to turn it down on laith but he only made it flush on the front like a tit and i **** wait to do it again so cut the rest off misen

no vibration what so ever so dunt bother me its alsio covered up so cant see it fitted

smile

birdys3 · DTR Respected Member

How dee into flywheel have u cut m8?

NORFE · DTR Trusted Engine Builder

i havent mate,just cut the excess weight off the front smile

Cameron · Guru

Might have to give this a go tomorrow as I can't ride it atm lol. Can't see it doing any damage, never seen a 125 with a massive weight on it anyway tbh, know the rs doesn't anyway.