Lost a lot of power

[HeadSmess]

you will never go back to a float style carburettor, not just for the ease of jetting but for the fact that they don't suffer air or fuel leaks.

I agree. they also dont briefly DIE when you hit large bumps, due to the fuel sloshing round and exposing the jet... i HATE that!

but i still use the floaters...

 

[Deleted member 12676]

a standard NT carburettor is surprisingly unreliable and works horrible as it has no idle circuit and if you adjust it for proper running at high speed then it is off at mid throttle.
Anyone that is happy with a NT has never had a properly tuned 2 stroke.

 

[Fabian]

i been thinking of making a separate bowl for the NT... with a nice simple adjustable main jet hooked up to the existing straw via a hose

already been done with a few different variations on the theme:

http://motorizedbikeforum.the-talk.net/t304-adjustable-main-jet#472

 

[HeadSmess]

*speed reads through new link*

that, my dear sir, is exactly what i have in mind, except far simpler...and stuck on the stock old nt carb.

bit of profile milling to some alloy, to replace the bowl. reminding me i need windows again cus i cant get certain software to work on linux....grrr! i have about 8 jobs lined up, waiting for me to get a new PC for the mill...

a right angle junction, M5 up top for the nt straw, to REPLACE the main jet entirely, simple needle valve and a fuel nipple. much like this thing...



and then the bowl, which still requires a float, and to stay at the same level, hanging off the side...knowing me, with either tek screws or zip ties. or wire cus zip ties cost money!

simply adjust as suits the load/speed. i did say its mainly for the dyno testing but cnc does make for mass manufacturing processes...as mass as a guy using scrap can get, at least... scored with one job, i have a couple of kg of 65X16X "whatever length it is" billet kicking round now...


that link included a link to the hijet! now im off on a tangent...i need a gearbox that will fit a daihatsu charade 800cc, but is for a rear wheel drive car, not the FWD transaxle.... hijet, i believe it should be...hard to find

 

[HeadSmess]

a standard NT carburettor is surprisingly unreliable and works horrible as it has no idle circuit and if you adjust it for proper running at high speed then it is off at mid throttle.
Anyone that is happy with a NT has never had a properly tuned 2 stroke.

please explain why this idle circuit is so important on a POS engine that can barely make 2hp and most people are perfectly content with it at WOT? 99% of us dont use the mids...its either idling (NT deals with that fairly well IMHO) or we're attempting to pull the nipple off the cable...why the need for the "mid range"?

oh. right. because with 2hp on demand, one needs to be very careful with how they apply the throttle...my bad


now, lets talk about needle tapers, and changing the angle on the bottom of the slide, or even, if one dares, changing the needle jet orifice size... all small modifications that are quite easily made.


though, i do agree....theres NO WAY i would stick something like an NT on to a real 2 stroke, like a good old kx, cr, or yz 80... then, they need some throttle control, despite being lil 80's. gets even worse as we go up the scale into the 250 or 500 sizes... its a brave man (or girl, i know some crazy ones) that will go WOT on a RM250...

a lawnmower style carb for a lawnmower style engine.... suits most of us


the bandsaws just stopped! back to the welder!

 

[justin.fiveash]

a standard NT carburettor is surprisingly unreliable and works horrible as it has no idle circuit and if you adjust it for proper running at high speed then it is off at mid throttle.
Anyone that is happy with a NT has never had a properly tuned 2 stroke.

I'm really happy with my NT, and I got that thing tuned perfectly. There is a little rattle in the mids but it's almost unnoticeable. I am very happy with this machine!

 

[Deleted member 12676]

Justin, what if that little rattle is detonation and you think everything is great till one day it just dies and upon diasassembly/inspection you see a hole in the top of the piston? Then will you still be happy with the NT? No, because you can't separately adjust it for all three throttle ranges.
I believe in doing things right and for all of you in believe things are fine if they aren't bothering you well that is your own bizarro world and you can just have it.

 

[Fabian]

It's highly unlikely that part throttle detonation would ever be able to put a hole in the piston or even damage an engine making less than 2 horsepower at the rpm these things run at.

Because of their low power, they have effectively 2 throttle positions: idle and wide open.
So long as the engine is correctly jetted for wide open throttle, every other throttle position will work itself out, because you just don't spend any meaningful time there.

The rattle in the mid range is most likely piston slap.

 

[Nutsandbolts]

hey everybody my 80cc motorised bike would start then turn off

my 80cc bike will start then turn off i pedal down hill and i relased the clutch, it goes for 2 seconds then turns off i need help please anyone

 

[Fabian]

@ Nutsandbolts

Where abouts in Australia are you located?