Clear, concise and directly to the point. Great presentation, as always. Thank you for sharing with the world. I bought an Artic Cat M1000 with a twin 999cc 2-stroke engine. Specs say 162HP and 120lbs/ft of torque. I stripped the sled all the way down and salvaged the engine, electronics, and all sub systems to build a super powerful minibike. Looking forward to using your software to build the header pipes. Thanks again.
I've independently confirmed this idle off idle tuning, going down rabbit holes and then empirically testing these concepts with my specific application, ABA testing needles, float height, etc. I confirmed it with a wide range O2 lambda sensor. Michael Forrest is a 2 stroke treasure and should be supported. I have experience as an automotive engineer calibrating engines, if you aren't that experienced here, he has a bunch of tools to help figure this stuff out.
thanks for the backup, man. u wouldn't believe how many people hate my guts for no reason. that kind of nonsense started in grade school + just never stopped.
@@MichaelForrestChnl Lol you'll get a kick out of this. Years ago I was piled on and berated in the r/mechanics subreddit (yes, reddit) during a discussion about engine bay intakes (hot air intakes) vs. cold air intakes. I said, "A higher intake charge temps leads to a faster flame fronts." as a main comment. Everyone thought I said higher intake charge temps give you more power! Initially I thought this was an easy one being an random fact, during the witch trials where the onlookers spit on you and call you names, no one comprehended my replies saying that it indeed leads to knock therefore loses power with turbos and agreed the air is less dense, and that I never said it made power. Later I provided multiple credible sources showing charge temp vs. flame front speeds and proved my statement was 100% fact. Not many saw the links as they were buried deep in replies. No one responded to these sources, no one backed me up. Probably why I went from being a car mechanic to an engineer, the mechanics I worked with said I was too smart and would be dumb to be a mechanic.
Great video, surprised how little people understand about fuel delivery at idle, i just went from a 2.73 diameter needle to 2.74 and made such a difference If i may make a video request, can you cover the progression port in carbs,if that is the correct terminology
@@MichaelForrestChnlthe pilot circuit has 2 orifices that exit in to the Venturi, one is the main circuit for the pilot, the other is know as a progression port, it comes in to play just off idle With a 4 stroke carb the fuel screw orifice is the progression port CV carbs often have 3 progression ports right by the butterfly
Flying my Paramotor I got an engine out and landed in a football field. While descending i pull started it so many times I bruised my arm pretty bad. Ended up being a sliver of plastic that clogged my main jet. The engine would not start because the main jet was clogged.
I didn't know that the main jet was involved in idle jetting until my jetting calculator showed me that it was. about half of the fuel comes up through the main jet at idle. The clearance in between the needle and the needle jet is very influential at idle, and just above idle.
A 10% area change of the main jet at WOT produces around a 10% jetting change. A 10% needle taper change produces around a 8% jetting change at WOT. The main jet has the most influence at WOT. dragonfly75.com/moto/images/jetrange3.png
Clear, concise and directly to the point. Great presentation, as always. Thank you for sharing with the world. I bought an Artic Cat M1000 with a twin 999cc 2-stroke engine. Specs say 162HP and 120lbs/ft of torque. I stripped the sled all the way down and salvaged the engine, electronics, and all sub systems to build a super powerful minibike. Looking forward to using your software to build the header pipes. Thanks again.
I'm glad to help
I've independently confirmed this idle off idle tuning, going down rabbit holes and then empirically testing these concepts with my specific application, ABA testing needles, float height, etc. I confirmed it with a wide range O2 lambda sensor. Michael Forrest is a 2 stroke treasure and should be supported. I have experience as an automotive engineer calibrating engines, if you aren't that experienced here, he has a bunch of tools to help figure this stuff out.
thanks for the backup, man. u wouldn't believe how many people hate my guts for no reason. that kind of nonsense started in grade school + just never stopped.
@@MichaelForrestChnl Lol you'll get a kick out of this. Years ago I was piled on and berated in the r/mechanics subreddit (yes, reddit) during a discussion about engine bay intakes (hot air intakes) vs. cold air intakes.
I said, "A higher intake charge temps leads to a faster flame fronts." as a main comment. Everyone thought I said higher intake charge temps give you more power! Initially I thought this was an easy one being an random fact, during the witch trials where the onlookers spit on you and call you names, no one comprehended my replies saying that it indeed leads to knock therefore loses power with turbos and agreed the air is less dense, and that I never said it made power.
Later I provided multiple credible sources showing charge temp vs. flame front speeds and proved my statement was 100% fact. Not many saw the links as they were buried deep in replies. No one responded to these sources, no one backed me up. Probably why I went from being a car mechanic to an engineer, the mechanics I worked with said I was too smart and would be dumb to be a mechanic.
Great video, surprised how little people understand about fuel delivery at idle, i just went from a 2.73 diameter needle to 2.74 and made such a difference
If i may make a video request, can you cover the progression port in carbs,if that is the correct terminology
What part of the carb is that?
@@MichaelForrestChnlthe pilot circuit has 2 orifices that exit in to the Venturi, one is the main circuit for the pilot, the other is know as a progression port, it comes in to play just off idle
With a 4 stroke carb the fuel screw orifice is the progression port
CV carbs often have 3 progression ports right by the butterfly
Flying my Paramotor I got an engine out and landed in a football field. While descending i pull started it so many times I bruised my arm pretty bad. Ended up being a sliver of plastic that clogged my main jet. The engine would not start because the main jet was clogged.
I didn't know that the main jet was involved in idle jetting until my jetting calculator showed me that it was. about half of the fuel comes up through the main jet at idle. The clearance in between the needle and the needle jet is very influential at idle, and just above idle.
As pertains to the jetting chart;
I am surprised that the main-jet is relatively non-responsive per 10% move as many others on the chat are.
A 10% area change of the main jet at WOT produces around a 10% jetting change. A 10% needle taper change produces around a 8% jetting change at WOT. The main jet has the most influence at WOT. dragonfly75.com/moto/images/jetrange3.png
does that calculator work for Keihin carbs also??
yes it does. Also Dellorto, Mikuni, and the old classic carbs.