madass gantry system - back to cables...

maylar · Mar 24, 2020

joe czech said:
not to go off topic - i'm sure I can find this, but what is a nominal idle speed (engine at temp)?

1000-1100 rpm. Any lower risks low oil pressure when hot.

maylar · Mar 24, 2020

MexicoMike said:
FWIW, if a conventional, carbureted engine can start from cold and idle smoothly with no choke or other means of enriching the fuel/air mixture, the idle system is too rich when the engine is at normal operating temperature. It is not possible to have a proper mixture when the engine is cold and a proper mixture when the engine is at normal temp without some sort of 'adjustment' that can alter the mixture for those two extremes.

Exactly. Everything is different today with computer controlled fuel injection, but consider carburetors of days past. On a cold engine we'd pump the gas a few times to prime the intake (tickle) and set the choke. Once the engine starts intake vacuum pulls the choke open a bit (partial choke). Then as the engine warms up some thermally controlled device opens the choke completely.

marshg246 · Mar 24, 2020

bill said:
and you have again stated what i keep saying. if you dont need the chokes IT IS TO RICH.

I would agree on most carbs, but these have a tickler to make them rich at start and for several seconds after start. We can also turn that around - if you need a choke, it is too lean

grandpaul · Mar 24, 2020

Tornado said:
Could it be that when fully off, the choke slider leaves a cavity within the throttle slider and this makes a difference in how the air is behaving as it goes through the throttle gap? A partially closed choke slide would change that cavity dimension and may change the air to a different turbulent flow.

I think you are onto something here...

baz · Mar 24, 2020

marshg246 said:
Also, anyone who means turn the choke all the way on and then back off a little when they say "a little choke" are actually using a little choke. Definitely not disputing that.

I got us down this rabbit hole by asking someone to explain. You obviously understand how the choke works and your 1/2 choke makes sense. Lots of people have no idea how it works.

I even had a guy that after 40 years of riding with the choke full on and starting with it full off was amazed when I pointed out what was wrong and why he had 40 years of jetting issues! His riding experience got so much better when I removed the choke and re-jetted his carbs to standard.

I had exactly the same thing with a t160 I was going to buy
The bloke let me have a ride on the bike
It was running like shit,I pulled up where he was standing and told him such
Then I looked down and the choke was full on!
As I turned it off he proclaimed I was turning it on!
Anyway after that the bike revved like a scalded cat and guess what he decided not to sell!!!
Should have kept my big mouth shut!!

baz · Mar 24, 2020

I have never needed a choke on any twin carburated British bike
I have with a single carb but never a twin
And I run my bikes lean because that's where the power is

Onder · Mar 24, 2020

...and of course, that is where the holed pistons are too!

baz · Mar 24, 2020

Onder said:
...and of course, that is where the holed pistons are too!

Yep that is very true
But let's not go that lean!!!!

madass140 · Mar 24, 2020

I have my carb kit on my Interstate with chokes installed as many others have. I cant see why you would
have issues fitting chokes.Its no more a pain of fitting the chokes with or without the kit

madass gantry system - back to cables...

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