GooseMan
Well-Known Member
Is tuning a 2 stroke similar to 4 strokes? Can you do that little idle trick (turn the air/fuel screw while its idling and note the rpm change.
Tuning 2stroke's
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my67xr
Miniriders Legend and Master Spanner Spinning Mode
yeah, same for setting the mixture screw.
raise the idle a bit, by turning the screw in that adjusts the slide height
then adjust the air/fuel screw till it reaches the smoothest/highest idle speed.
then drop the idle speed back down again.
doing a plug chop, by turning it off at WOT will tell you if your main jet is correct
raise the idle a bit, by turning the screw in that adjusts the slide height
then adjust the air/fuel screw till it reaches the smoothest/highest idle speed.
then drop the idle speed back down again.
doing a plug chop, by turning it off at WOT will tell you if your main jet is correct
GooseMan
Well-Known Member
allright then so pretty much the same then. Took the kdx250 for a good burn today and did a quick turn and guess of the mixture screw which was not bad but top end at WOT would start to hunt and choke but that could be an airflow problem. Also when whipping the throttle open it chokes so I'm guessing it is probably a touch rich so will do some plug reading.
Cheers guys
Cheers guys
With the older 2smokes i have never found they that they allow a "blip" of the throttle from idle otherwise they'll choke, but then again i never used to play with jetting when i was kid, just ride until it stops then give it to dad and say "FIX PLEASE" it's kind of like you have to get the revs up a touch b4 hitting full throttle then the band kicks in and it'll use as much juice as the carby throws at it.
headsmess
Miniriders OG
ahhhh, two smokes...
they can be fairly easy to tune when theyre just brushcutters. hi and lo. get the high first, lean it out til it screams, back off a touch, then the lo...idle, tweak til it peaks, back off adjust idle screw...easy.
once they get a pipe on them they get funky and airflow becomes a strange thing with pressure waves and harmonics and stuff that fills up thick books.
while yes, you can get a fairly good tune on a two smoker, theyre inherently a resonant system, and can only really be tuned for a certain rpm. the exhausts are called "tuned pipes" for a reason. the shorter they are, the higher the peak rpm or powerband. the fatter they are the stronger the peak. as a general rule.
but most of the basic stuff from 4 strokes applies still. too lean they bog and die, melt plugs and pistons, sieze, etc whilst being too rich they just blow smoke and dont rev very high.
jetting is much the same, plug chops and swapping mains, carbs usually dont have emulsion tubes. pilots and screw for idle and transition via needle.
they can be fairly easy to tune when theyre just brushcutters. hi and lo. get the high first, lean it out til it screams, back off a touch, then the lo...idle, tweak til it peaks, back off adjust idle screw...easy.
once they get a pipe on them they get funky and airflow becomes a strange thing with pressure waves and harmonics and stuff that fills up thick books.
while yes, you can get a fairly good tune on a two smoker, theyre inherently a resonant system, and can only really be tuned for a certain rpm. the exhausts are called "tuned pipes" for a reason. the shorter they are, the higher the peak rpm or powerband. the fatter they are the stronger the peak. as a general rule.
but most of the basic stuff from 4 strokes applies still. too lean they bog and die, melt plugs and pistons, sieze, etc whilst being too rich they just blow smoke and dont rev very high.
jetting is much the same, plug chops and swapping mains, carbs usually dont have emulsion tubes. pilots and screw for idle and transition via needle.
DHZ_XR8cing
Master Spanner Spinner
On Older 2 strokes or ones with plenty of use the expansion chambers gum up with years of carbon.
We use to burn the carbon out when I was younger. Used to make a huge difference.
Not sure if our method was correct. Surelly was not safe but as a teenager was fun.
We use to burn the carbon out when I was younger. Used to make a huge difference.
Not sure if our method was correct. Surelly was not safe but as a teenager was fun.
headsmess
Miniriders OG
pulling em off and chucking on the fire? or was you more delicate likes?
GooseMan
Well-Known Member
I've almost got it right now, If I remove the cover of the airbox I can get it to blip on like you siad and it will top out alright too but not quite as it is a touch rich I think.
DHZ_XR8cing
Master Spanner Spinner
Fill it with fuel and light it. Nah just kidding. But if you do this method please film it and post here.
We would put a little bit of fuel in it and light it. Do it a few times and the thick black honey looking stuff coming out was cool. I aint messed around with 2 strokes in many years. All that will change very soon. I'm going to venture into Vintage Motorcross
When i get the YZ back in my shed, this is gonna be one of the first things i attempt 
[video=youtube;Kj76_4-xw6E]http://www.youtube.com/watch?v=Kj76_4-xw6E[/video]
[video=youtube;Kj76_4-xw6E]http://www.youtube.com/watch?v=Kj76_4-xw6E[/video]
Hillz
WC ST Killa
haha they use to do this back in the late 80's early 90's when my old man had a motorcycle shop.. i remember seeing one of the mechanics out the back with a oxy de carboning an exhaust.. could barely see him there was so much smoke
my67xr
Miniriders Legend and Master Spanner Spinning Mode
When i get the YZ back in my shed, this is gonna be one of the first things i attempt
[video=youtube;Kj76_4-xw6E]http://www.youtube.com/watch?v=Kj76_4-xw6E[/video]
thats is just like when i did my DS80 expansion chamber,
but you need to start the heat at the engine end of it, thats where most of the carbon/oil is built up
then it starts to glow a red ring around the pipe, put the compressed air into the engine end and keep blowing it through.
the red ring will move down the chamber as it burns off, and should continue right to the end where the muffler pipe slips on.
there are tonnes of little fireballs that spit out, carbon/oil on fire, and heaps of explosions when the oil pools and catches on fire.
you need to do it on a windy day, as the smoke is very thick and smelly (burning oil)
the difference after doing this, when compared to before is like fitting a Pro Circuit expansion chamber on.
well worth doing.....
i did my '84 IT200 pipe 4 years ago, it was bad too.
So not in the garage then? Or in the housing complex?
or just add some herbs and spices in there to make it more interesting
GooseMan
Well-Known Member
lol^, yeah the bloke I bought it off siad he had burnt the carbon out and cleaned it but isn't really sure if he did a real good job or not, nor am I so I think I might give this a shot. I'll just have to go get one of these gas bottle torch things. may as well do my ds80 while I'm at it.
haha ohh no the ds 80 may be further restricted by the carbon lol
headsmess
Miniriders OG
ah, the good old days, riding around on a DS80 whilst on a powerful mind altering substance . i got video evidence that it enhanced my riding skills!
stupid twostrokes. im going to have a gripe
1. the lady my mum knew, that used to race so had a collection of bikes... like an early cr250 and a pair of old kawa 350 triple twostrokers. been sitting there so long the rims had rusted away to the axle line. would she part? oh no, saving them. what the $#%# for? you got both tits hacked off, half a lung, and theyre giving you a year to go? (she lasted four more months actually, just couldnt stop puffin away...).
instead of having a loving home, they got mashed up and turned into landfill. now its a retirement village
i hate hoarders with rare 2 strokes.
2. all the wreckers that had good yards have vanished. now instead of wandering and grabbing bits to make gokarts or finding suitable alternatives to that flogged out suspension link thats no longer available fullstop, you have to know the year, the model, the everything and the computer always, ALWAYS, SAYS NO! and if it was built before 2012, give up mate.
stupid wreckers with rare two strokers and parts for rare twostrokers closing down and scrapping everything.
3. another hoarder, had the rarest of rare. a suzuki rs90... big fat wheels, only a few thousand made and again, a 2 smoker. it ended up as a pile of rusty steel and molten aluminium after the shed caught fire (in the middle of a thunderstorm? taking out 3 insured tractors?)
stupid honest fools that dont just steal these things when the chance is available....
i really want an old 2stroker so i can REALLY have a go at making a good pipe
anyways. enough! the more i think the more i recall! like a ds250! :'( waaaaaah!!!!
im gunna go play with my brushcutter brand new honda 4banger graft job
. i got video evidence that it enhanced my riding skills! stupid twostrokes. im going to have a gripe
1. the lady my mum knew, that used to race so had a collection of bikes... like an early cr250 and a pair of old kawa 350 triple twostrokers. been sitting there so long the rims had rusted away to the axle line. would she part? oh no, saving them. what the $#%# for? you got both tits hacked off, half a lung, and theyre giving you a year to go? (she lasted four more months actually, just couldnt stop puffin away...).
instead of having a loving home, they got mashed up and turned into landfill. now its a retirement village
i hate hoarders with rare 2 strokes.
2. all the wreckers that had good yards have vanished. now instead of wandering and grabbing bits to make gokarts or finding suitable alternatives to that flogged out suspension link thats no longer available fullstop, you have to know the year, the model, the everything and the computer always, ALWAYS, SAYS NO! and if it was built before 2012, give up mate.
stupid wreckers with rare two strokers and parts for rare twostrokers closing down and scrapping everything.
3. another hoarder, had the rarest of rare. a suzuki rs90... big fat wheels, only a few thousand made and again, a 2 smoker. it ended up as a pile of rusty steel and molten aluminium after the shed caught fire (in the middle of a thunderstorm? taking out 3 insured tractors?)
stupid honest fools that dont just steal these things when the chance is available....
i really want an old 2stroker so i can REALLY have a go at making a good pipe
anyways. enough! the more i think the more i recall! like a ds250! :'( waaaaaah!!!!
im gunna go play with my brushcutter
brand new honda 4banger graft job ah, the good old days, riding around on a DS80 whilst on a powerful mind altering substance
you mean booze yeah? it makes you wild as of rider
if its anything else... tripping **** and riding are a bad combo... fun tho..
headsmess
Miniriders OG
nah, booze makes ya ****y then you fall over cus you overdo it... and you fail to realise you just ground half ya face off. stupid open face helmets!
100% albert hoffman interesting that the "double helix" of DNA was first visualised by some guy on it. prattle on about genetics but forget to mention that small fact. i love our education system
100% albert hoffman
interesting that the "double helix" of DNA was first visualised by some guy on it. prattle on about genetics but forget to mention that small fact. i love our education system 
