DT125R ARCHIVE

FunkeyMunkeyDavid · Guru

crankcase tuning...

mr karnage · Guru

it wont affect it

and have a look at this http://www.chuckbunnell.com/kart/jennings/jennings.html

ive started porting a spare barrel i bought, just need to do the port windows and that link helped me out alot

only thing i need to do is what youve done to match the barrel

did you use grinding stones on it?

FunkeyMunkeyDavid · Guru

awesome,cheers for the link biggrin i found grinding stones skipped too much under presssure disbelief i used those little sanding drums in the end,so much easier and quicker wink

mr karnage · Guru

ive only got a couple but they must be rough ones, didnt think you could get finer grade ones

where you get them from?

just realised the carbide burrs are different

im using carbide cutters lol

-- Edited by mr karnage on Saturday 19th of May 2012 01:26:03 PM

NORFE · DTR Trusted Engine Builder

u need carbide burrs mate

i do all my case porting with them

radius every edge -smooth and match to the cylinder

have a look at these i did on my cr it made it loads better for supermnoto road use was nice and smooth not as hard hitting as std form

cant find em now lol

but it makes a big difference in the power delivery

the term "blue printing" is the process of getting the engine to its ideal working performance by removing all mismatches in castings and rough castings marks and getting every thing in to proper spec

all engines are mass produces so are near enough put together with out final detailing

mr karnage · Guru

yh get some of those carbide bits

they go through metal like butter

i use stones to smooth everything off coz the carbide bits leave it very rough

if you use oil with the stones, it leaves a more smoother finish, keeps the stones from wearing down and it wont skip

NORFE · DTR Trusted Engine Builder

iv got about 30 in me box all shapes and sizes never had a problem with it leaving rounh tho got some fine 1s wich leave a good finish,any other bits i some times use them foam sanding blocks as they follow all the surface and work a treat

NORFE · DTR Trusted Engine Builder

http://www.ebay.co.uk/itm/10-pieces-Tungsten-Carbide-Rotary-Burr-SET-1-8-shank-6mm-1-4-head-/150817862432?pt=UK_BOI_Metalworking_Milling_Welding_Metalworking_Supplies_ET&hash=item231d71f320#ht_872wt_952

got 15 of those all different shapes and lenths and then big ones all dif shapes n lenths, its like a knife fru butter ha, small ones fit in a dremel aswell, big ones i have to use flexi on the drill in a vise

FunkeyMunkeyDavid · Guru

your a star norfe,cheers! didn't know they made them lol looks like i'll be having a go at blue printing next biggrin

NORFE · DTR Trusted Engine Builder

FunkeyMunkeyDavid wrote:
your a star norfe,cheers! didn't know they made them lol looks like i'll be having a go at blue printing next

ha u need to no every oem spec the engine was designed to mate not as simple as getting at it lol

i just do the rough stuff and knife edging lol

to complex all the 2 stroke physics lol had great results from all my own work so ill stick to what i no lol

have a good read of some tuning manuals b4 u hack in to it to get a basic knoledge of what ur doing as some people cause more damaga than mods lol been there done that and its expensive when u fook up

FunkeyMunkeyDavid · Guru

lol sound advice that...i like to read as many tuning books and blogs as i can,but when it gets to pulse waves an that my brain gets fried lol just tryin one thing at a time,little by little.....

NORFE · DTR Trusted Engine Builder

best way mate

easiest thing to think is the easyiest/fastest & free flowing a fuel charge go in and out the better

smooth and sharp knife edges to direct the fuel flow

mr karnage · Guru

if your stripping the engine

matching the crank width to the crankcase means there is no space for a bit of movement will give you zero vibration and a smoother engine

i might aswell post the link

http://klemmvintage.com/mxblueprint.htm

mr karnage · Guru

only thing you could do after that is the head because its only a single cylinder

NORFE · DTR Trusted Engine Builder

yeah good link...so much to engine tuning people over look

FunkeyMunkeyDavid · Guru

its no wonder engineers are perverts for detail lol trouble is,how far do you go and where do you stop? biggrin need a lotto win.....

NORFE · DTR Trusted Engine Builder

only limits with tuning is the size of your wallet smile

FunkeyMunkeyDavid · Guru

NORFE wrote:
http://www.ebay.co.uk/itm/10-pieces-Tungsten-Carbide-Rotary-Burr-SET-1-8-shank-6mm-1-4-head-/150817862432?pt=UK_BOI_Metalworking_Milling_Welding_Metalworking_Supplies_ET&hash=item231d71f320#ht_872wt_952
got 15 of those all different shapes and lenths and then big ones all dif shapes n lenths, its like a knife fru butter ha, small ones fit in a dremel aswell, big ones i have to use flexi on the drill in a vise

got mine this morning and fook me! knife thru butter aint the word lol top tip that

NorDt · Guru

i think i missed something, Why are you doing this ? is there a big project going on ? :o

FunkeyMunkeyDavid · Guru

NorDt wrote:
i think i missed something, Why are you doing this ? is there a big project going on ? :o

i'm just having a play at the minute lol reading more and more on tuning theory and practice,and just trying to learn more about these engines... i already did this to a top end

that went back in my off road toy that i use as a test bed

i'm doing the crankcases to match a cylinder head i'm doing

its all just to see if i can get anymore power out of it (or if it goes bang/fudge/squelch) biggrin once its reliable i'll transfer all the work onto my project engine (when i get off me ars3 an do it lol ) http://yamahaclub.com/forums/topic/28861-my-ol-toy-1990-dt-125-r/

-- Edited by FunkeyMunkeyDavid on Sunday 27th of May 2012 04:54:24 PM

the only way is YAMAHA DTR · Guru

to get more fuel in the combustion chamber you need to widen the port windows in the sleeve, if you make them higher or lower you will change the timing and it wont run or run crap

fun stuff tuning wink

looks to me like your making the crank case transfer port similar to the dt200r

i am doing the same thing tomorrow when i strip my spare engine down for the 200cc prodject

NORFE · DTR Trusted Engine Builder

yeah removing the skirt of the barrel is a good mod, it made quite a difrence in the power on mine, loads more smoothness not as abrupt and a good spread of the power off the bottom

did u feel a change in it also after u fitted it

FunkeyMunkeyDavid · Guru

NORFE wrote:
yeah removing the skirt of the barrel is a good mod, it made quite a difrence in the power on mine, loads more smoothness not as abrupt and a good spread of the power off the bottom
did u feel a change in it also after u fitted it

defo biggrin mates got a stock dt and mine whips it now... seems to rev a little easier and a little further. feels like it needs bigger transfers and exhaust now though if that makes sense? feels like its being held back... and the only way,i'm sort of copying dt 200/rd 350 tuned transfers and cases. i'm hoping to change the height of the ports then skim the head. with a bit of luck it wont oink like a big pig in knickers biggrin

mr karnage · Guru

you want to widen the ports before you raise them

making the ports higher will shift the powerband higher into the rev range whereas you can get the same boost in power through all of the rev range through widening them

im doing the same as you mate with a spare barrel i bought

ive been in two minds whether to cut those two little barrel skirts off, now i might aswell

NORFE · DTR Trusted Engine Builder

yes mate all mick abbys are like it, if u lookin the redd housing with the barrel fitted they hang well down cramping the flow of intake chARGE, if u look in line theres a few to copy biggrin

mr karnage · Guru

yh i had a look at his site and those sp barrels are just about the same

FunkeyMunkeyDavid · Guru

defo worth doing,its nice and noticeable biggrin i've been doing the same as everyone else,collecting pics for reference and sizing it all up lol

mr karnage · Guru

that two stroke tuning book really helped me out

and those carbide bits lol i can see where theyve tried running off haha

FunkeyMunkeyDavid · Guru

mr karnage wrote:
that two stroke tuning book really helped me out

and those carbide bits lol i can see where theyve tried running off haha

lol yeah it all needs smoothing out lol i get carried away tryin to take too much out at once biggrin reading thru the book at the mo,there's so much theory to it all confuse trying to find measurements/specs for the ports on the sp,gotta be the way to go... just trying to figure out how i can do the exhaust boost ports? reckon thats a biatch lol

might start with a powervalve and go from there

NorDt · Guru

I dont get why removing parts or all of the skirts gives any more power ?, Does it have something to do with you making the ports from the engine itself bigger ?

Please explain ? xD.